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View Full Version : Chinese 10x18 Lathe Spindle Noise - I think I know what's wrong?



mattthegamer463
12-07-2016, 11:22 AM
Hey guys, my Craftex B2227L 10x18 lathe has given me grief since the day I got it (used) but the latest issue is a lot of spindle noise after running it for extended periods. I think I know the issue but I wanted to see if I could get a second opinion.

The lathe relies in "splash lubrication" or something, basically the gearbox throws oil around when spinning. It does this fine, I've seen it.

The issue seems to be that the spindle is lubricated by oil getting thrown up on the lid of the gearbox, some of it makes its way into a trough that runs around the edge of the box and into a hole above the front spindle bearing. I've marked it in a picture here;

http://img.photobucket.com/albums/v321/mattthegamer463/20161105_002746%20-%20Copy_1.jpg (http://smg.photobucket.com/user/mattthegamer463/media/20161105_002746%20-%20Copy_1.jpg.html)

The trough is slightly sloped, seems to get oil in it as when I open the gearbox its usually filled up with oil.

The lathe makes a lot of noise at low gears due to some poorly-made and improperly spaced gears for the low-end speeds, but the high speeds sound pretty smooth except this new sound after extended use. I think the spindle bearing is spinning out its oil or something and this drip system doesn't replenish it fast enough. After sitting for a day enough seeps in that it runs quiet again for a while until its all spun out again. There is a ball fitting above the hole in the top cover, I can squirt oil into there and that helps the sound a bit for about 10 seconds before its back again.

Another possible cause, I replaced the original cover gasket which was soft rubber and terribly deformed, I took care to cut the new gasket to give clearance for the trough, and the cover has a recess inside which makes the edge that meets the gasket thinner than the edge on the gearbox, so I don't think it should interfere with the trough even without a gasket at all. But I could be wrong.

The rear bearing has no such trough and so I think must be packed with grease.

A guy with a similar lathe had a similar problem. He took his apart to find no grease, and bearings that were not happy. His unit doesn't have a gearbox like mine so I don't know what his lube situation is intended to be. http://users.picknowl.com.au/~gloaming_agnet/cq9325rev-g.html

Should I take my spindle out and pack the bearing with grease?

After I do that should I plug the oil hole so oil and grease don't get mixed up?

Thanks for any tips. Someday this lathe will work decent, I swear.

enginuity
12-07-2016, 11:39 AM
Hi Matt,

I have the same lathe. One the top of the cover mine has an oiler that lines up with the hole for the bearing. I think this may have been added in newer lathes, but I'm not 100% sure.

I oil it daily with AW hydraulic oil (same oil that i use in the headstock).

Edit: I reread your post and you also have the oiler. On reading this I think the bearing maybe cooked. I know lots of people forget to oil this port as they put a tool tray on the top and cover up the oiler. Grease might work, but the oil really does splash around a lot in there. You could cut a small plastic shield to try to keep the grease in. Grease is a viable option for spindle lubrication.

Gearbox is noisy, but comes with the territory.

enginuity
12-07-2016, 12:13 PM
You may also want to check the preload before you take it all apart. Have you cut anything with the lathe?

mattthegamer463
12-07-2016, 12:27 PM
I was doing some substantial removal in hot roll steel when the issue started up. Bought the lathe used about a year ago, made in 2006. Didn't seem to have much use on it and the guy selling said he never used it much.

I'm thinking if I block that oil trough route and grease the bearing, that would make for a good fix. I hope the bearing isn't cooked already.

When you say check the preload do you mean check it before taking apart so I have an idea what it should be, or check that it's properly loaded to begin with? Either way don't know how to do that so I'd have to read up before tackling it.

Lathe seems to be performing alright, only just started doing steel with it, but it seems to be having a hard time taking much off. 0.005" feed rate, 0.015" DOC, 350 RPM, 1.5" diameter hot roll steel after the scale is cleared, with oil, chips are coming off coloured. Using high speed steel with a pretty big nose radius, finish is alright but the heat has me surprised. My reading says the only thing that should affect DOC is horsepower, but I'm getting a lot of chip welding on the tip and its messing up the effectiveness pretty quick.

J Tiers
12-07-2016, 01:08 PM
Roller bearings do not need a LOT of oil, but they do need some. Just enough to carry off heat, lubricate the cages, and lube the rollers to take care of "scuffing". It's not a lot.

Possibly the gears are not picking up and throwing off enough oil at high speeds.

The 10 seconds of quiet after oiling is interesting.... suggests the oil is damping something and after much of it is slung off, the "something" is again not damped.

Agree on preload.

Put an indicator against the spindle nose. Stick a piece of wood down the spindle bore, and try to move the spindle around. You basically should not be able to do that, it should be in the low tenths at most (NOT the same thing as "accuracy", don't be confused).

Move the indicator 90 deg, repeat.

If you cannot move the spindle, that's good, but eliminates a source of noise. You might try it directly after the machine is turned off after it has been making the noise. If it is a heat expansion issue that will show it up.

If you CAN move it noticeably, take up on the spindle nut until you just cannot move it. Give it oil and run to see if the noise remains.

I somewhat suspect the noise could be from the heat expansion after running a while, which may loosen the preload and allow the spindle and inner cone/rollers to rattle around in the bearing race. Then the oil might damp down the spindle rattling for a bit, but not for long. Your previous work may have backed off the preload spindle nut due to vibration, etc just enough.

In bad cases of that, where tight enough hot is stupid tight when cold, Belleville washers can help out, that's a standard use (if you have room and can get the right size). But odds are that yours can be adjusted i that is the issue.

I'd think there must be a way to get more oil in, even the oiler fitting is not a great solution, it probably should have a feed. A collector plate feeding a second angled drilled hole into that vertical hole (careful with chips if you do that), or the like.

I don't like grease that much especially when they seem to intend oil.

Toolguy
12-07-2016, 01:10 PM
With chip welding, you're probably better off with a carbide cutting tool. I would replace the bearing and make sure the oil passages are clear. You will get better lubrication and cooling with circulating oil than with grease. Proper preload is important. Too little, and the spindle won't be solid. Too much and it will quickly overheat.

BCRider
12-07-2016, 01:31 PM
The nuts that folks are talking about are the two ring nuts on the outboard end of the spindle in case you didn't know. If your tool kit does not include them take the time to make up a set of G wrenches so the slots do not get chewed up and keep them aside for next time. Don't be one of those folks that just uses a pinch punch.

When checking for any play in the bearings watch the indicator dial for a sudden step that comes from moving through the range of play. This is quite different from looking at a smooth spring like travel that might occur from you just flexing the spindle.

I tend to suspect that it's more of an issue of improper preload that opens up after the spindle warms up as mentioned above. You need a touch of preload on the bearings when cold so they remain at zero or slight preload when warm. It's a fussy sort of adjustment too. Be prepared to play with two and three degree adjustments of the nuts as they tighten up and the outer one takes up the play in the threads of the inner nut. Which is another good reason for taking the time to make the proper wrenches. If beaten up with a pin punch or pipe wrench the burrs won't allow you to perform the delicate adjustments to nail the preload as the rings tighten against each other.


Your lathe should be able to take a way heavier DOC then .015. But a .005 (sure it wasn't .0005?) is a pretty heavy feed rate. The way the chips are welding to the tip suggest that you've gone past the sweet spot for the cutter geometry and you're plowing off more than it should and that is causing the heat and chip welding.

I've found that running too much nose radius tends to alter the actual cutting corner and that it makes the cutter act suspiciously like a negative rake right at the nose. Perhaps try a smaller nose radius. Especially with a larger size nose radius and with some top rake and only a .015 DOC the metal will never see the straight portion of the cutter. It'll always be riding the trailing edge of the now lower than mid point nose radius. Been there got the shirt.... Since I found this I tend to err on the side of a very small nose radius and the tools seem to cut more cleanly. But HSS isn't a coated carbide. I also found that unless I was willing to live with big bird's nests of blue hot shavings that I needed to lower the feed speed. And in fact for anything other than longer cuts I just found it easier to feed by hand so I could interrupt the cuts to break the chips. And running by hand for the hogging cuts also allowed me to feel the cutter back through the handle and set a feed pressure that cut without excessive heating. Then I engage the feed for lighter sizing and finishing cuts for the even finish.

Dave C
12-07-2016, 01:38 PM
I don't see any facility for adjusting preload in the pic.

BCRider
12-07-2016, 01:40 PM
I don't see any facility for adjusting preload in the pic.

I've yet to find a lathe that didn't have the spindle bearing adjustment ring nuts on the outboard end of the spindle.

mattthegamer463
12-07-2016, 01:59 PM
Thanks guys, I'll do some fiddling around tonight, so far I've got;

1. Insert wood in spindle bore and try to push the spindle around, see what kind of deflection i can produce on an indicator, at different spindle positions
2. Check oil passage is clear. I'll try cleaning the trough and putting some oil in it, see if it flows. The lathe is almost level, but ever so slightly tilted towards the tailstock, shouldn't be an issue for the oil flow.
3. Start making a pair of G wrenches for the spindle nuts. Surely the preload is not well tuned as the previous owner of this lathe was an idiot and I'm sure the factory does the fastest job they possibly can. Hopefully it's all that's wrong.

mattthegamer463
12-07-2016, 02:00 PM
Nuts are in the box on the end

EDIT; to clarify the pic, I replaced a couple of bearings on the gear shafts because of noise, I thought I had it figured out that a bad bearing was on one of the shafts but it turned out the pair of gears on the spline that controls the high and low speed ranges are poorly made; the high speed gear meshes well but the low speed gear does not and makes a lot of shatter, especially when not under load.

Never touched the spindle shaft during that though. It's as it was when I got the lathe.

http://img.photobucket.com/albums/v321/mattthegamer463/20161104_203058.jpg (http://smg.photobucket.com/user/mattthegamer463/media/20161104_203058.jpg.html)

BCRider
12-07-2016, 02:07 PM
Oh geez. You'll have to limit the length of the handles if you have to make your own.

On my lathe the "box" is also the movable part. So I can reach the adjustment nuts as well as all the rest with any length of wrench.

It would be an interesting mod to zip cut off and attach the top and front sides to the movable door. That would sure open up a lot of nice working room for reaching the spindle nuts and gear retention nuts.

enginuity
12-07-2016, 02:07 PM
Those are the nuts.

Most Chinese tools are set without enough preload on the spindle. It is safer and quicker this way for them as they don't have to monitor the spindle temperature before they ship the machine.

You should be able to take a lot more DOC. The RPM is fast for HSS, and that is the biggest problem with this lathe. The higher speeds are great for smaller stock, but larger stuff is just way too fast. Make sure you also check your tooling geometry.

For what it's worth, I've taken a 1/8 DOC with the same model lathe in steel. It's in the video on the concrete workbench on my blog.

mattthegamer463
12-07-2016, 02:36 PM
Those are the nuts.

Most Chinese tools are set without enough preload on the spindle. It is safer and quicker this way for them as they don't have to monitor the spindle temperature before they ship the machine.

You should be able to take a lot more DOC. The RPM is fast for HSS, and that is the biggest problem with this lathe. The higher speeds are great for smaller stock, but larger stuff is just way too fast. Make sure you also check your tooling geometry.

For what it's worth, I've taken a 1/8 DOC with the same model lathe in steel. It's in the video on the concrete workbench on my blog.

Doesn't even seem to flinch with that cut. I need to get serious about angles on my HSS grinds, and watch more grinding videos.

BCRider
12-07-2016, 03:03 PM
Matt, when grinding my HSS I'll finish up with just a slight kiss on the corner to put about a .01 bevel on the very corner. Then a couple of strokes with a triangle india stone I need handy at the lathe for this use and generally freshening up between grindings dubs off the corners of the bevel to give me a sort of .006 to .008 sort of nose radius. For general cutting use I found that much is enough to extend the time between grindings by a good amount without causing issues on finer cuts with the radius becoming too significant for the tool. And for finer finishing cuts I don't even kiss the corner on the grinder. I either leave it sharp or I might lightly hone in a very fine nose radius. And when I do it's mostly to remove a burr that I might feel.

The only times I use a bigger nose radius is if I'm deliberately wanting to leave a radius at the shoulder of a cut for stress reasons.

mattthegamer463
12-07-2016, 03:29 PM
What's your feed rate, if its that sharp won't it end up leaving a thread-like texture? My lathe is running at 0.005"/rev right now but there are gears in the set to go to 0.0025"

Peter.
12-07-2016, 03:59 PM
I've yet to find a lathe that didn't have the spindle bearing adjustment ring nuts on the outboard end of the spindle.

Mine has them inside the headstock directly behind the nose bearings. A pair of ring nuts to be tightened with c-spanners. The rear bearing is floating so pre-load would not be drawn through it.

BCRider
12-07-2016, 04:39 PM
Mine has them inside the headstock directly behind the nose bearings. A pair of ring nuts to be tightened with c-spanners. The rear bearing is floating so pre-load would not be drawn through it.

CONGRATS! You're the FIRST :)

That method actually makes SO much more sense because it allows for heating up the spindle or housing having less of an effect. And clearly I need to start hanging around with a better class of machines than up to now.

Of course this DOES place a higher importance on a proper fit for the tail stock end. But that's not overly hard to do. I'll bet it coasts nicely when well set.

Mcostello
12-07-2016, 10:09 PM
I have a 15" Colchester that has the preload set by 24 springs on the outboard end of the spindle. Typical bearing nut on the end tightens the springs. Don't particularly care for this set up.

mattthegamer463
12-07-2016, 11:13 PM
I indicated the edge of the 5" chuck while rotating it, it showed a total maximum shift of about 1.2 thou, and when pressing it towards the indicator with a piece of wood in the bore as an arm, I could only get at maximum a half thou deflection.

Looking at the oil hole, found the oil wasn't really interested in going down there. Pumped some oil down with the squirter and it just comes out onto the top of the spindle. Tried cleaning the trough out and runnign the lathe for a few minutes at medium speed, got some splash into the trough but the oil moves so slowly, I can see it moving only a couple thou per second along the trough. No oil sprays anywhere near the oil hole when running.

Also noticed the rear bearing is open and visible, no apparent route for oil except one random hole in the casting, can't see any grease either. Not sure what to think there.

Uploading a video of the sound it makes.

http://img.photobucket.com/albums/v321/mattthegamer463/20161207_222748.jpg (http://smg.photobucket.com/user/mattthegamer463/media/20161207_222748.jpg.html)

http://img.photobucket.com/albums/v321/mattthegamer463/20161207_222755.jpg (http://smg.photobucket.com/user/mattthegamer463/media/20161207_222755.jpg.html)

http://img.photobucket.com/albums/v321/mattthegamer463/20161207_223403.jpg (http://smg.photobucket.com/user/mattthegamer463/media/20161207_223403.jpg.html)

http://img.photobucket.com/albums/v321/mattthegamer463/20161207_224955.jpg (http://smg.photobucket.com/user/mattthegamer463/media/20161207_224955.jpg.html)

mattthegamer463
12-07-2016, 11:26 PM
Video:
http://img.photobucket.com/albums/v321/mattthegamer463/th_20161207_224510_1.mp4 (http://img.photobucket.com/albums/v321/mattthegamer463/20161207_224510_1.mp4)
Nicely obscured spindle nuts
http://img.photobucket.com/albums/v321/mattthegamer463/20161207_225152.jpg (http://smg.photobucket.com/user/mattthegamer463/media/20161207_225152.jpg.html)

mattthemuppet
12-07-2016, 11:27 PM
What oil are you using? Could it be too thick?

mattthegamer463
12-08-2016, 12:17 AM
What oil are you using? Could it be too thick?
Its what came with it, probably from factory. Pretty thick, seems like a 80 or 90 weight gear oil. Seems like it could be too thick for that oil trough. Manual says to fill the gearbox with No. 10 or No. 20 oil. If thats referring to the viscosity number, I have a severely incorrect oil. I never know with these chinese products what they mean when they give numbers. Also says it should be changed at regular intervals. Guilty.

Sent from my SM-G920W8 using Tapatalk

J Tiers
12-08-2016, 12:21 AM
I'd not expect really ANY movement of the spindle if preload is right. Not even half a thou. Not with the small forces you are putting on it.

Another diagnostic question: Do you ever get "chatter" or a pattern on the work piece? If so, in what sort of situations?

As for the oil holes, there is the question of where do the holes GO?

The rear one, by the look of it, is blocked off by the outer race, most likely. The open bearing will probably get more oil directly (along with metal particles from the gears, etc) than through the hole, it is likely to be useless.

Same question applies to the front one. You say the oil "comes out onto the spindle", but where has it been before that?

Also looks in the first of this pic group, as if the flow of oil is partly blocked by some sort of swarf or a burr on the hole edge.

I NOW see the system of oiling, and it is not a totally bad one. Assuming the oil ends up in a useful place, such as dripping down the face of the bearing, the oil groove is sensible. The gears WILL throw off oil to the sides, and some will get into the groove. Assuming the lathe is level or the headstock end is a little high, the oil will go to the oil hole, and presumably from there down to the bearing.

Naturally, if the headstock end is lower than the tailstock end, the oil flow will be bad to very bad, and eventual oil starvation could result.

As for oil type.... any oil is CLEARLY better than no oil for things that need oiled. The right oil MAY be better than just any oil.

lakeside53
12-08-2016, 12:49 AM
80-90 "gear oil" ? I'd be running it on on Hydraulic oil ISO68 or even 32. (10 SAE) roughly.

http://i238.photobucket.com/albums/ff150/lakeside53/misc%20linked%20uploads/viscositychart_zps0013d3bc.jpg (http://s238.photobucket.com/user/lakeside53/media/misc%20linked%20uploads/viscositychart_zps0013d3bc.jpg.html)

BCRider
12-08-2016, 01:13 AM
Given that you measured at the face of the chuck there's lots of sources for running out of true and flexing. Take the chuck off and indicate off the actual nose of the spindle.

Still, from how I read it there seems to be no play. And precious little flex too if you're only seeing half a thou.

I think you need to change your oil to something else. I've got a belt drive head but when I look up three different Grizzly models with gear heads they all list ISO32 oil And a check with a conversion table shows that this is the equivalent of SAE 10W weight oil. So if the stuff flows like rear end oil it is most certainly the wrong stuff. But don't trust this totally. Look around at some other lathes from various places and see what oil is suggested for them. Just for giggles I looked up the Precision Matthews manual and they call for ISO68. And again looking at the conversion chart this equates to SAE 20W. And that's still darn thin compared to what you are saying is in there. They call this ISO 68 oil "way oil" in a few places in the manual. That threw me until I checked the conversion chart. I don't know about you guys but the heavy stuff squeezes out fast enough. No way I'd want to rely on something that thin to float the carriage.

It's quite likely that the gears in the head stock were noisy when new and the previous owner thought to quiet them with this thicker oil rather than wait for them to wear in and quiet down on their own.

What can happen if you use the that thick an oil in bearings is that they will heat up from pushing the oil around. Also at higher speeds the balls or rollers can skid on the thick oil and that's not good for them either.

I looked at your video. But frankly since I've got a belt drive machine which is crazy quiet I can't say if that growl is normal for gear head lathes or not.

As mentioned by a few of us already it takes VERY LITTLE oil to lubricate a ball or roller bearing. It may not seem like that groove and hole is capturing much and feeding much but trust me and the others that it will catch and feed more than enough to the bearings. I totally agree with Jerry when he said that squirting oil down the hole and the sound going away was masking the REAL problem. Namely that you very likely have bad bearings that need replacing. And likely as not it's due to this way too thick an oil being used. And further even more likely if you or the previous guy ran it at some higher speed for a while.

The same thing applies to the exposed rear bearing. Far more than enough oil will splash into the bearing to keep it happy... .once it has the proper grade of oil.... Notice that there isn't a shield on the inside of the rear bearing. That's more than open enough for splash lubricating. In fact I suspect the only reason the chuck side bearings have the pickup groove and hole is due to the size of the bull gear for the back gearing being in the way so the chuck side bearings can't get adequately splashed. So they use this capture groove and delivery hole. The thing is even a few drops per hour down that hole is more than enough if the bearings are in good condition.

J Tiers
12-08-2016, 01:13 AM
Remember, the manual is probably using ISO numbers, in which case they are only recommending a viscosity like SAE 30 oil, corresponding to an 80 or 85 SAE gear oil, per your chart. Not a heck of a lot of difference, really. The "90 wt" gear oil is not as much thicker than SAE 20 engine oil as the numbers make it seem.

I am not so sure about the too thick oil being a damage issue.

The problem with thick oil is that it heats up from "stirring" friction, primarily. If the roller rode up "hydroplaning" on an oil film, they would not be rubbing, so there would not be wear.

A client had a high speed generator, 5 phase, 60,000 rpm. They apparently did not know much about bearings, and were pumping plenty of oil into the bearings. What they NEEDED to do was get an oil mist going in, not "solid" oil,even in drops. Well they were not gonna listen to the electrical guy about bearings and oil. By gum they were the mechanical engineers, and they KNEW that stuff.

I saw the bearing after the run at 50k rpm..... The bearing balls, the ones that could be found, were kinda square, and black. The races were torn up, and black. At 50k rpm, that oil was getting stirred up to a high temp, and cooking the bearing, drawing the temper of the balls (not hard to do with ball bearings) slightly and allowing them to become deformed, at which point they heated worse and got beaten to bits..

But that was at 50k rpm. Unless the OP's bearings got a lot hotter than I think they did, that has not happened here. I am still thinking preload or some related issue, and not toasted bearings. The noise stating after some time running is what does it for me....

I don't think he should see a half thou with decent preload. The preload should take the bearing past that initial steep deflection, and get into the area where the deflection vs force is much flatter, and anything he does with a piece of wood should not even show up.

I'd like to know what the movement is after the noise starts.

lakeside53
12-08-2016, 01:17 AM
Take care with "gear oils" look a the range 90 goes up to... and ....

MOST IMPORTANT. Read the very last note of the Chart. Big viscosity difference between 40C and 100C... The hydraulic oil viscosity is at 40C but the gear/engine at 100C. Never going to see 100C in the lathe

My Emco lathes (the basis for most of the Chinese lathes) used ISO 22 hydraulic oil.

J Tiers
12-08-2016, 01:39 AM
I was looking primarily at the 80W and 85W, which are based on LOW temp properties, per the note.

Anyhow, we don;t KNOW about the 90 in the first place..... All we have is a "seems pretty thick" statement. SAE 30 can seem pretty thick too.

And, in any case, it does not take a lot of oil to make roller bearings happy. A drop every few minutes would be perfectly OK for a lathe (but likely totally insufficient for a rear end ring gear and pinion). Lots and lots of Atlas machines with roller bearings have been running fine for decades on just a shot of oil before starting the lathe.

Willy
12-08-2016, 01:47 AM
80 "gear oil" ? I'd be running it on on Hydraulic oil ISO68 or even 32. (10 SAE) roughly.



Good conversion chart in order to differentiate between the various oil viscosity standards, allows one to gauge oil viscosity on a level playing field.
My thinking as well on a proper oil specification for the headstock. Straight ISO 32, 46, or 68 is available just about everywhere in convenient 1 liter or 4 liter sizes, heck even Walmart will have it. Pretty well most lathe gearboxes recommend these grades.

The thicker oil will mask looseness in the gearbox somewhat however it is also reluctant to flow where it's needed. A thorough cleaning of the inside of the headstock's oil supply will if nothing else result in a longer life.
Speaking of cleaning, have you looked into the very bottom of the oil reservoir for any metallic deposits that would indicate abnormal wear of the headstock's internal components?
It also might be an idea to use a stethoscope or even a screwdriver held to the ear in order to isolate the source of the noise. No point changing the spindle bearings when all of the clatter emanates from elsewhere. Of course you'll need to do this with an open gearbox so be sure to take your tie off beforehand.:)

However if you proceed to reset the spindle's bearing preload it would be prudent to do a thorough visual inspection, rather than just blindly tightening up what could be a bad bearing.

That oil travel scheme to the spindle bearing should be in the "Clever old time oil delivery mechanisms" thread.
Looks like the driven end of the spindle relies only on splash and whatever flows into the oil hole above the bearing not being loaded as heavily as the chuck end. Like J Tiers mentioned it does appear that the oil hole stops at the bearing race, unless it is angled. Have you cleaned out these ports and probed them to see if oil can reach the bearing? Tapered roller bearings do exhibit a self pumping action if any oil is close to their proximity, and as mentioned before they do not necessarily need to be flooded although a little more is always better than not enough especially in a preloaded bearing in order to carry heat away.

BCRider
12-08-2016, 03:07 AM
I don't think he should see a half thou with decent preload. The preload should take the bearing past that initial steep deflection, and get into the area where the deflection vs force is much flatter, and anything he does with a piece of wood should not even show up.

From his description of the testing it was all done with the gauge touching on the chuck. So it might be the chuck moving a hair as well. All of which is why I suggested that he remove the chuck. Or at least put the gauge's finger on a part of the actual spindle and not on the chuck or backing plate.

mattthegamer463
12-08-2016, 09:09 AM
Hey guys, thanks for the responses. I'll try to address questions without missing anything.

@J Tiers
I do get chatter if I take too deep a cut or have the part too far out of the chuck and poorly supported, or the tool is far out from the holder. Parting with a 3/32 HSS blade hasn't gone well for me in any materila, so I try to avoid parting altogether.

The oil hole goes down to land on part of the inner bearing race, I believe. Then spills out onto the spindle.

The oil did look blocked in that picture, it looked blocked in real life too but when I poked it, there was nothing there. I think it was just surface tension and lighting. The other picture shows better I think. If the lathe was tilted slightly towards the tail end, this last little bit of the trough might be hard to get up.

@All

The oil chart is a revelation to me. I made the foolishly logical conclusion that engine oils and gear oils were on the same scale. My oil experience is small and I've never changed oil in any machine beyond my engine oil in my old car. Compared to the detergent-free engine oil I keep in my little squirter, this stuff is thicker but not a whole lot thicker.

I should note that while I earlier said I first noticed the noise after a few hours of work, the noise is now immediate. Starting the lathe last night to do some tests, the noise was present within 10 seconds. The video I posted shows how quick it comes in after turning on. There's no time for heating up.

This could mean the bearing is already trashed though, doesn't mean that heat didn't kill it initially.

I'll redo the testing with the indicator running on the spindle nose, best I can.

What to do about the oil makes my head hurt.

enginuity
12-08-2016, 09:22 AM
I am running AW46 hydraulic oil in my lathe. 80W-90 gear lube is way too thick.

The AW in the hydraulic oil stands for anti-wear. This means that the hydraulic oil has additives in it for wear, such as zinc. Most hydraulic systems have piston or gear pumps and the AW oil is formulated for these systems. Hydraulic oil is also an excellent bearing lubricant, and is anti foaming which is good for high speed applications.

I know that it would seem natural to dump a gear lube into a gearbox on a lathe, but like many others have also added, most of these style of lathes require a light oil for the headstock. I'm sure the previous owner probably just though, hey I have some manual transmission fluid around and this looks like a standard gearbox when the oil was changed.

mattthegamer463
12-08-2016, 09:28 AM
I am running AW46 hydraulic oil in my lathe. 80W-90 gear lube is way too thick.

The AW in the hydraulic oil stands for anti-wear. This means that the hydraulic oil has additives in it for wear, such as zinc. Most hydraulic systems have piston or gear pumps and the AW oil is formulated for these systems. Hydraulic oil is also an excellent bearing lubricant, and is anti foaming which is good for high speed applications.

I know that it would seem natural to dump a gear lube into a gearbox on a lathe, but like many others have also added, most of these style of lathes require a light oil for the headstock. I'm sure the previous owner probably just though, hey I have some manual transmission fluid around and this looks like a standard gearbox when the oil was changed.

Sounds like I know what a first step should be. Get some AW46 and swap it in. I did notice a lot of foaming when I was testing last night.

J Tiers
12-08-2016, 10:41 AM
Hey guys, thanks for the responses. I'll try to address questions without missing anything.

@J Tiers
I do get chatter if I take too deep a cut or have the part too far out of the chuck and poorly supported, or the tool is far out from the holder. Parting with a 3/32 HSS blade hasn't gone well for me in any materila, so I try to avoid parting altogether.

The oil hole goes down to land on part of the inner bearing race, I believe. Then spills out onto the spindle.

The oil did look blocked in that picture, it looked blocked in real life too but when I poked it, there was nothing there. I think it was just surface tension and lighting. The other picture shows better I think. If the lathe was tilted slightly towards the tail end, this last little bit of the trough might be hard to get up.

If tilted, the oil build-up would surely overcome the tiny upslope in that short bit. It would be logical to "ease" that slope a bit to encourage oil to go down, but I'd not do it unless the thing was taken apart, because chips would get to bad places.


@All

The oil chart is a revelation to me. I made the foolishly logical conclusion that engine oils and gear oils were on the same scale. My oil experience is small and I've never changed oil in any machine beyond my engine oil in my old car. Compared to the detergent-free engine oil I keep in my little squirter, this stuff is thicker but not a whole lot thicker.

The oil obviously does fill the trough, and presumably (not certainly) goes down the hole. Whether it gets onto the bearing is another issue. Even if it dumps onto the spindle near the bearing, SOME is bound to get into the bearing, but how much is a question.

EDIT: Does the cover go over that trough partly or completely? Or is it open on top when the cover is in place?

As for viscosity, it does seem to stay on the gear teeth more than one might expect, but I do not have a size reference, nor do Iknow how long it was since last run. With small gear teeth, and/or a short time since last run, that could be normal with light oil.

The oil is darkish, like gear oil, but could also just be chinese oil, which might be anything as far as color. If the oil does not have that sulfur smell, it may NOT be gear oil.


EDIT: Looking at the pictures and video again, I think the gears are just small, and the oil in the teeth is not a particular evidence of high viscosity.



I should note that while I earlier said I first noticed the noise after a few hours of work, the noise is now immediate. Starting the lathe last night to do some tests, the noise was present within 10 seconds. The video I posted shows how quick it comes in after turning on. There's no time for heating up.

This could mean the bearing is already trashed though, doesn't mean that heat didn't kill it initially.

Or it could mean that the preload has loosened up more.

Frankly, the two worries that folks tend to have are: A) bent spindle, and B) bad bearings. While neither is impossible, they are not nearly as common as they are suspected to be. And it is relatively difficult to kill a decent-sized roller bearing.

Edit: The noise is inconclusive to me. Through the camera (phone?) and then computer speakers, I don't suppose I am hearing what you do. It sounds like it could be many things. Which it really is I cannot tell.



I'll redo the testing with the indicator running on the spindle nose, best I can.

What to do about the oil makes my head hurt.

The only thing to do is to find out what the issue is. It may come down to pulling the spindle and looking. That will give a look at the bearings, and it will also allow deciding if the oil is getting to where it is supposed to be.

mattthegamer463
12-08-2016, 10:59 AM
The oil does not smell like sulfur at all, it smells somewhat sweet, like fresh motor oil does. Definitely no sulfur smell. Could be chinese stuff, could be hydraulic fluid, could be old motor oil, could be anything at this point.

The pictures were taken less than a minute after running, the oil hangs around for a while after running. If I open after it's sat for a day, it looks like the pic in Post 1.

Maybe a procedure of - Make wrenches -> remove spindle -> inspect bearings -> reassemble -> replace oil with AW46 hydraulic fluid -> tune preload would be a course of action which would render some of these points moot. If the bearings are ok, they're at least getting enough lubricant, and if the preload is bad, it'll get tuned in when reassembled. Whether or not it's correct from factory will be irrelevant.

However if I find the bearing is bad, I have to figure out what to do about that. Possibly I could use that opportunity to try to improve the trough system.

Changing the oil to something lighter right now would let me test if the lighter oil goes into the trough system better, once I have the spindle removed perhaps I will see how well that oil hole delivers the oil and whether or not the change in oil will make it more effective (in the event the bearing has failed or is failing, it could make the difference)

This lathe probably has less than 100 hours running time on it, I've probably put 20 on myself in the past year and I'm totally guessing about the other 80, my gut says the bearing would take longer to fail?

Willy
12-08-2016, 12:18 PM
.......................
This lathe probably has less than 100 hours running time on it, I've probably put 20 on myself in the past year and I'm totally guessing about the other 80, my gut says the bearing would take longer to fail?

You are probably right, everything else being the way should in regards to preload being as it should be, clean oil getting to the bearing, etc.
It is all speculation at this point though without closer inspection. It is common knowledge among those that have been into a number of lower cost Asian machinery internals that cleanliness of the manufacturing process is not a virtue of these machines. Leftovers of casting sand, voids in the castings themselves, and debris left inside from machining are all part of the package...sometimes.

Lack of lubricant should not be ruled out but as an example of the lack of oil required by a rolling element bearing, have a look at a tapered roller bearing as used on an automobile axle as an example. Lots of heat exposure, fairly heavy load, and a 100,000 miles of use on a bearing the size in your lathe, and they come out so dry that they rattle, and still look like new.
I've also seen motorcycle engines that use roller bearing lower ends loose all oil, unbeknownst to the rider. These engines will typically stop due to cylinder/piston seizure while the con rod and main bearings show no signs of distress. Try that with a shell type bearing.
Takes precious little oil to keep a roller happy, They don't take well to dirt for long though.

It's all speculation at this point until each facet of the issue is ruled out one by one.

BCRider
12-08-2016, 12:32 PM
The parting issues you mention do tend to point at either bad bearings or not enough preload to remove the last traces of play.

It should be apparent that the first step is at least to change the oil to something you know is the proper stuff. And then I'd at least try working on the preload. If that doesn't fix the noise and parting issues then look further.

mattthegamer463
12-08-2016, 12:41 PM
The parting issues you mention do tend to point at either bad bearings or not enough preload to remove the last traces of play.

It should be apparent that the first step is at least to change the oil to something you know is the proper stuff. And then I'd at least try working on the preload. If that doesn't fix the noise and parting issues then look further.

Sounds like a plan. I'll get some hydraulic oil and replace tonight. Seeing what kind of debris comes out, if any, will be useful.

Willy
12-08-2016, 01:05 PM
I wouldn't take the parting off issue as an indicator of problems.
This has probably been one of the most problematic issues with hobby sized lathes. It's been discussed on these pages ad nauseum, it's the nature of the beast. Doesn't mean it can't be done successfully but you definitely have keep all of your ducks in a row.:)

J Tiers
12-08-2016, 01:22 PM
I wouldn't take the parting off issue as an indicator of problems.
This has probably been one of the most problematic issues with hobby sized lathes. It's been discussed on these pages ad nauseum, it's the nature of the beast. Doesn't mean it can't be done successfully but you definitely have keep all of your ducks in a row.:)

Yes and no.

Had a preload issue once, that made ANY turning, let alone parting off, problematic. Parting has many things that can go wrong, but can be done on virtually any machine successfully, unless it is crazy loose.

WE can speculate forever, the proof of the matter will be

1) checking looseness at the spindle with indicator.

2) tightening preload a bit, see if it changes "feel" of the spindle, see if it changes looseness.

3) if spindle seems OK for spinning, and oil seems acceptable, then run a while with new preload and see if the bearing gets hot. See if the noise has changed. If worse, stop. If no change or better, keep up the heat test.

I'd expect a turn or so of rotation if the spindle alone is spun sharply by hand with a chuck on it (grab chuck, give it a sharp spin). Anywhere from most of a turn to a turn and a half If the spindle cannot be unclutched from other gears and shafts, that check cannot be done.

Some might suggest pulling the spindle and looking for grit in the bearing/cleaning it. Maybe a good plan, but if it has run 100 hours, the grit probably has done whatever it can, and cleaning may be no help, so your choice.

oldtiffie
12-08-2016, 09:12 PM
I have the same lathe as I recall do some here from Canada.

Its reasonably cheap and quite sturdy and accurate and despite no power longitudinal or cross feeds it serves my requirements quite well.

I'd like a new and better one but that's way in the "offing" here.

Gear box oil is not a problem as I but it for "machinery gear-boxes and drives (machine slides, dove-tails, beds, lead-screws and what-ever under those as a typical list.

I do not have any problems with gear-box oil/lubrication - but I do keep all the oil ways cleaned and draining.

I buy it from my machine and tool supplier - here is a typical oil that I use.

http://i200.photobucket.com/albums/aa294/oldtiffie/Lubrication/Machine_lub_oil1.jpg (http://s200.photobucket.com/user/oldtiffie/media/Lubrication/Machine_lub_oil1.jpg.html)'

http://i200.photobucket.com/albums/aa294/oldtiffie/Lubrication/Machine_lub_oil2.jpg (http://s200.photobucket.com/user/oldtiffie/media/Lubrication/Machine_lub_oil2.jpg.html)

And I use Lanolin for machine etc. preservation - works well and is easy to apply and remove.

http://i200.photobucket.com/albums/aa294/oldtiffie/Lubrication/Lanotec_lanolin1.jpg (http://s200.photobucket.com/user/oldtiffie/media/Lubrication/Lanotec_lanolin1.jpg.html)

mattthegamer463
12-08-2016, 11:29 PM
Thank you photobucket, for "moving" all the photos I've uploaded and linked on this site in the past week to somewhere unknown. I'll have to take the time to fix it and replace all the links tomorrow. :mad:

Drained the oil, thick and dark stuff, looked and ran like room temperature maple syrup. Dark enough I couldn't see the bottom of the foil baking pan I caught it in, and it was only half an inch deep. The 1.5 litres or so took about 10 minutes to trickle out.

Replaced it, noises are same as before with a few minutes of running. I'll run longer tomorrow.

Tried to indicate the spindle nose using a DTI while applying pressure towards the DTI with a stick in the bore, maximum deflection I could get was only about a quarter thou.

Lastly, I tried the chuck spinning technique to see how far it can coast. I disengaged the gears but the spindle is still always connected to the reducing gears for the leadscrew. I removed the thread cutting gears and so minimized what I could. Grabbing the chuck with one hand and pulling back, trying to spin as hard as possible, it goes about 1/2 revolution after my hand is clear.

http://img.photobucket.com/albums/v321/mattthegamer463/20161208_224745.jpg (http://smg.photobucket.com/user/mattthegamer463/media/20161208_224745.jpg.html)

Tomorrow's job is to start on wrenches.

mattthegamer463
12-30-2016, 12:37 AM
Made a junky wrench that I can use with my torque wrench, for getting the nuts set
http://img.photobucket.com/albums/v321/mattthegamer463/20161227_154532.jpg (http://smg.photobucket.com/user/mattthegamer463/media/20161227_154532.jpg.html)

Set it to 20 ft-lbs, after running 5-10 minutes it heats up quite a bit, 1620 RPM, from 11C to almost 50C on the inside spinde wall at the rear, using an IR sensor. Sounds pretty good though. At 350 RPM in some 1018 with a brazed carbide tool, 5th/rev feed, cuts great at 30/50/70th DOC. No chatter, pretty good finish.

Reducing the torque to 15 ft-lbs makes more noise, still got pretty hot. I really don't have a clue what it was set to originally but I think maybe only like 10 ft-lbs.

http://img.photobucket.com/albums/v321/mattthegamer463/20161227_161724.jpg (http://smg.photobucket.com/user/mattthegamer463/media/20161227_161724.jpg.html)

http://img.photobucket.com/albums/v321/mattthegamer463/20161227_161428.jpg (http://smg.photobucket.com/user/mattthegamer463/media/20161227_161428.jpg.html)
Finish in aluminum with HSS is nice.
http://img.photobucket.com/albums/v321/mattthegamer463/20161228_180444.jpg (http://smg.photobucket.com/user/mattthegamer463/media/20161228_180444.jpg.html)

Seems to be working pretty well, aside from the heat but I'm not overly worried.

lakeside53
12-30-2016, 12:48 AM
If you reduce pre-load, tap the spindle "loose" between re-tightening. Personally... I do not use a torque wrench. Tighten and "feel", then spin the chuck "hard/fast" by hand. If it stops in 1/2 to 2/3 revolutions (like you said in an earlier post), then try it on power for 20 minutes at about 1000 rpm and watch for temperature rise.

Excessive temperature rise indicates a bearing issue or simply "too tight".

mattthegamer463
12-30-2016, 12:56 AM
If you reduce pre-load, tap the spindle "loose" between re-tightening. Personally... I do not use a torque wrench. Tighten and "feel", then spin the chuck "hard/fast" by hand. If it stops in 1/2 to 2/3 revolutions (like you said in an earlier post), then try it on power for 20 minutes at about 1000 rpm and watch for temperature rise.

Excessive temperature rise indicates a bearing issue or simply "too tight".
I was using the torque wrench to try to quantify how much I was putting on, rather than my standard gorilla tight.

The chuck would spin about 1/2 after my hand comes off, giving a hard spin. After warming it goes 1-1/2 rotations with the same spin.

Sent from my SM-G920W8 using Tapatalk

Jaakko Fagerlund
12-30-2016, 01:51 AM
Yup, 50-60 Celsius on a bearing is healthy and indicates good preload, so I would go with that :)

enginuity
12-30-2016, 08:48 AM
Thanks for posting a follow up!.

A little too much pre load is better than too little. 50 degrees isn't that hot for a bearing - but you'll want to monitor it as the ambient goes up as well.

I'd just go by marking the nut vs a torque wrench.

mattthegamer463
12-30-2016, 10:10 AM
Thanks for posting a follow up!.

A little too much pre load is better than too little. 50 degrees isn't that hot for a bearing - but you'll want to monitor it as the ambient goes up as well.

I'd just go by marking the nut vs a torque wrench.
Is there a reason against a torque wrench? I've got it, seemed like the right tool for the job.

Also knowing the torque tells me how hard I'm trying to crush this weak cast iron box. 29 ft lbs on a 1-5/8 nut comes out to around 950 lbs of clamping force.

I hooked the lathe to my power meter, at 1620 RPM it eats 850W from the wall, and once heated drops to around 625W. Can't be much power left in that chinese 3/4hp motor for getting work done!



Sent from my SM-G920W8 using Tapatalk

J Tiers
12-30-2016, 10:10 AM
....

The chuck would spin about 1/2 after my hand comes off, giving a hard spin. After warming it goes 1-1/2 rotations with the same spin.

....

That suggests one or both of two conditions:

Either the grease/oil warms up and becomes thinner with heating, OR the warming causes heat expansion of the spindle, reducing the preload.

I think you can guarantee some of each effect. Certainly the spindle will heat up first, as it is considerably less massive, is directly heated, and has fewer ways to lose heat, since it is smaller, can conduct heat down its length. and is inside the case.

The cast iron case may warm up in the vicinity of the bearings, but most of the length between the bearings is well supplied with ample surface area to radiate away heat, so it will likely remain cooler and not expand in the lengthwise direction as much as the spindle.

Therefore one can confidently expect the preload to be reduced as the heating occurs. You want to start off with enough preload that it is still effective even with the reduction. In your case, that means applying a little more than you need in the cold condition. You seem to have found that balance. Good work

Jaakko Fagerlund
12-30-2016, 11:44 AM
Therefore one can confidently expect the preload to be reduced as the heating occurs. You want to start off with enough preload that it is still effective even with the reduction. In your case, that means applying a little more than you need in the cold condition. You seem to have found that balance. Good work
That is a good explanation also why anyone caring of their bearings in a machine will warm up the thing at low RPM before asking the biggest from it. If the preload as cold is stiff as a granny in snow, putting full RPM on it asks for trouble as the oil isn't in there in the amounts required and the heat builds up too fast.

PStechPaul
12-30-2016, 01:33 PM
Is there a reason against a torque wrench? I've got it, seemed like the right tool for the job.

Also knowing the torque tells me how hard I'm trying to crush this weak cast iron box. 29 ft lbs on a 1-5/8 nut comes out to around 950 lbs of clamping force.

I hooked the lathe to my power meter, at 1620 RPM it eats 850W from the wall, and once heated drops to around 625W. Can't be much power left in that chinese 3/4hp motor for getting work done!

1620 RPM sounds rather low for a 4 pole motor on 60 Hz. It should be closer to 1720 RPM (unloaded), although if it is actually drawing 850 watts that is 1.14 HP or a 50% overload. Of course that is input power, so efficiency comes into play. But it should be at least 75% and hopefully more like 85%. Maybe Chinese motors really are that bad?

Does the power meter actually measure true power? The motor could easily be drawing 850 VA with 120V and 7.1 amps, with a power factor as low as 50% with true power only 425 watts. You should be able to estimate the power in the spindle bearings by using the 15 ft-lbs from the torque wrench and the speed (350 RPM), which would be 15*350/5252 = 0.999 HP or 748 watts. The running torque may be less than static torque, but it seems that the input power of 850 watts to provide 748 watts in the spindle means losses of only about 100 watts or 87% efficiency.

Off-hand, I think it may be better to set the torque to about 10 ft-lb, which would still be 667 watts or 2/3 HP in the spindle and headstock belts and gears.

lakeside53
12-30-2016, 01:41 PM
Just a POS motor or some other problem.

And yes, 1620 (assuming you mean motor not "spindle speed"), is pretty much "overload" territory so what is pulling all that power? 850w... loaded only with the free moving spindle? PF should be really low and rpm much higher without serious load. At 850 input watts... and almost no load, most the power is in the motor - going to get really hot.

J Tiers
12-30-2016, 02:26 PM
What was the power meter?

Does it measure true power?

I am questioning the 850W.... that is pretty high. Might be that there is a significant CURRENT, but with the low unloaded power factor (unloaded, we hope), the current represents very little real power, because it is "out of phase", and occurs at a low voltage during the AC cycle.

The power factor is the fraction of the apparent power (amps x volts) that is actually doing work. The rest is "reactive power", basically due to current "sloshing back and forth" without doing anything. Reactive power is "moved around" but not "used".

You have to have a special meter that multiplies volts x amps throughout the cycle to obtain the "real power" drawn.

In case of questions, the motor can be unhooked from its belts, and the power meter used to check the draw when truly not-loaded.

Joe Gwinn
12-30-2016, 06:17 PM
Therefore one can confidently expect the preload to be reduced as the heating occurs. You want to start off with enough preload that it is still effective even with the reduction. In your case, that means applying a little more than you need in the cold condition.

Yes. If the preload instead increases as the headstock warms up, the headstock will likely be destroyed - positive feedback leading to runaway overheating, unless stopped pronto. So spindles are always designed to loosen when heating up.

MattiJ
12-30-2016, 06:51 PM
So spindles are always designed to loosen when heating up.
Well, most of the time. Kerry has done it exactly opposite in some models like my 11x24"
No idea whatsoever what is the reasoning for that.

Jaakko Fagerlund
12-30-2016, 07:58 PM
Well, most of the time. Kerry has done it exactly opposite in some models like my 11x24"
No idea whatsoever what is the reasoning for that.
Really makes you warm it before use, as otherwise the bearing preload doesn't exist. But yeah, I have no idea either why anyone would do such a design that could destroy itself, though I've seen a few nuclear plants use reactors that can do a positive feedback....

PStechPaul
12-31-2016, 12:17 AM
After thinking about the calculations I made for the spindle power based on preload torque, I realize that it is unlikely that it is measured by using a torque wrench on the spindle itself. I doubt that there would ever be as much as 10-20 lb-ft of torque needed to turn the spindle of a lathe. I am assuming that the OP measured torque on the bearing adjustment nut. However, my calculations closely matched the power measured on the motor input, and accounts for the low speed and heating. And if the preload torque is actually 15 lb-ft at 350 RPM (750 watts) and it remains at that level at higher speeds, it would need 4 HP to attain 1400 RPM.

I've never checked or adjusted spindle preload on my lathe or mill, but I'm pretty sure it's no more than a couple lb-ft of static torque, with no load. It did require substantial force on the spindle crank for chasing the 3/4" - 8 LH SQ threads in 4140 alloy steel with DOC about 5 thousandths and width of 0.034". According to the turning equations in http://user.engineering.uiowa.edu/~mie032/Lectures/11-Turning_Equations_Full.pdf, steel requires about 2 HP-min/in^3. I was turning the hand crank at about 60 RPM, and each turn removed about 0.005*0.034*0.75*PI = 0.0004 in^3 of material or 0.024 in^3/min, which would require 0.048 HP. At 60 RPM, that would be 4.2 lb-ft. I would guess that it required at least 5-10 pounds of force on the spindle crank, so that seems like a reasonable figure. And when it was not cutting, it seemed like no more than a pound.

J Tiers
12-31-2016, 01:14 AM
Are things getting conflated here?

The temperatures SEEM to be related to the bearings, but a few posters are apparently relating temps to the motor.

There are RPM numbers mentioned, which I would assume are spindle, but again some posters are apparently relating the rpm to the motor.

The POWER readings are surely related to motor electrical input, but we still don't know if they are actual watt power readings, OR are "apparent power", i.e. Volts x amps as measured by a meter.

Can these sources of uncertainty be cleared up?

mattthegamer463
12-31-2016, 01:24 AM
Hey guys, seems some clarifications are in order.

The torque wrench was used on the spindle nut with the spindle locked via a bar in the chuck. Even at 120 rpm spindle gear I don't think I could click my torque wrench on the minimum setting.

The power meter is a cheap "kill-a-watt" type from ebay. It certainly isn't meant for motors so the reactive load is probably throwing it off. I did note the current was around 11A, again not sure how accurate their current measuring is either. Probably no big deal anyway. I should see what it says with the belts off.

Also the 1620 RPM is the max spindle speed. I assume this motor runs at 1800 RPM or similar. The motor doesn't seem to struggle but sometimes false starts when the gearbox is set to 1620.

Sent from my SM-G920W8 using Tapatalk

johansen
12-31-2016, 03:42 AM
1620 RPM sounds rather low for a 4 pole motor on 60 Hz. It should be closer to 1720 RPM (unloaded), although if it is actually drawing 850 watts that is 1.14 HP or a 50% overload. Of course that is input power, so efficiency comes into play. But it should be at least 75% and hopefully more like 85%. Maybe Chinese motors really are that bad?

yes they can be that bad. we have a grizzly drill press at work and in half an hour at 65F ambient temps the 16/3 power cord is fairly warm. In that half hour or less the "3/4 hp" motor does not heat up enough to make a perceptible difference in temperature of the finned aluminum cast motor housing. the load is negligible.


as far as efficiency: if you have a 1 hp single phase motor that gets better than 67% efficiency, then its probably rather heavy and relatively new. most induction motors 1/2 hp and smaller are less than 50% efficient and if you drive them as a generator, they won't even generate enough power back to the grid to supply their own internal losses.

J Tiers
12-31-2016, 10:56 AM
The NEMA current rating for a 3/4 HP motor is 13.8A. That calls for a 14 ga wire, so it is not a surprise that a 16ga cord might get "warm". The cord is BOTH undersized AND well insulated heat wise, so it holds the heat.

That cannot be blamed just on a lousy chinese motor. It's the wrong cord, really.

NEMA current for 1 HP is 16A at 120V. Power factor is likely 0.7 at best. That means the actual power current is 10.2A. Power is therefore about 1200W. That comes out to about 62% efficiency. If the power factor is worse, the efficiency will come out better, so it's a guess.

A 1/4 HP motor will be worse.

enginuity
12-31-2016, 11:16 AM
Edit:

I'm pretty sure it is a standard rpm motor after looking at the pulley sizes. The name plate on my motor is obviously wrong.

AntonLargiader
01-02-2017, 09:12 PM
I read this thread with interest since I have chatter when parting and grooving especially, but also in some turning ops. I have a Smithy 1340.

Today I locked down the table and with a slat of wood pried the spindle upward from the table. Maybe 80~100 pounds of force. The spindle moved up about 0.15mm but it didn't feel like true play, it was more like flex. Rather than solidly bumping against the other end of the looseness, if you know what I mean, it just felt like the harder I pried the farther it would go. I did verify that the table was not moving.

I ran the spindle at 600 RPM for 10 minutes and then 1000 RPM for another 10 minutes and the play did not change. Furthermore, there was hardly any discernible heating up of bearings as measured by feeling around the headstock casting.

I get about one turn when spinning the spindle (with chuck).

What should I check next?

BCRider
01-02-2017, 09:22 PM
Anton, in looking up your lathe it seems to be one of the regular sort of import 13x40 size machines with the "usual" MT5 spindle taper which provides you with the more or less usual 1.5" through hole.

As a guide to your chatter issues first off I'll ask how it is mounted. I see that Smithy provides the usual imported tin box pedestals. Is that what you are using? Are the box pedestals at least clamped to the floor?

AntonLargiader
01-03-2017, 07:17 AM
No, it's on a wooden bench (4x4 frame) on a concrete floor. I'm moving it to a new shop this month, which will give me the opportunity to revisit the support. I don't know that I will build the solid concrete table that some feel to be the holy grail, though.

Different mounting may improve the performance, but the spindle flex relative to the table is my focus for the moment. It seems like WAY more than the OP had, and mounting isn't going to fix that.

Speaking of bearing preload, in my work (BMW motorcycles) tapered roller bearings are used in a few places and they have different ways of setting correct preload:

- In older applications such as wheel bearings, the breakaway torque is measured; with the assembled bearings lightly oiled you measure the force needed to start the assembly turning. This is in the inch-ounce range.

- With assemblies like transmissions, that technique gave way to simple measurement of the preload distance. In this case the elastic properties of the housing are known.

- Steering head bearings went from observation (kind of like the spin-down method) to fastener torque to the present, where it tends to be a sequence of torque followed by a distance adjustment.

If the machine's properties are understood, there are going to be better methods of setting spindle bearing preload than spin-down observation. Funny how I've seen bits and pieces of all these methods in the recommendations here. Does anyone here know how modern lathe manufacturers specify the preload? I can't quite picture the Swiss or Germans saying, "Give it a spin and see how far it goes."

Baz
01-03-2017, 07:51 AM
The Grizzly 9249 manual which I'm sure you can all find as an example of a 12" import has a detailed procedure involving nipping up accurately by observing end movement ceasing using a DTI, then turning the nut an additional 130 thou measured on its periphery. That is followed by a 20 minute run and hand hot check.

lakeside53
01-03-2017, 11:27 AM
I can't quite picture the Swiss or Germans saying, "Give it a spin and see how far it goes."

Well.. that is exactly how Emco specified their pre-load adjustment. 1/2 turn from spin then 20 minutes at 1000rpm to observe temperature rise.