Acceptable spindle play, Logan 825 10” lathe

[J Tiers]

When it comes to lathe age, mine is coming up on 79. I replaced the original spindle bearing, which I still have, because there was uncleanable old grease in it that made it "bumpy" as it turned.. And on that replacement hangs a story, one not entirely to Logan's credit. But we can save that until the measurement has been further explained.

We really need to know where the base of the indicator holder was, and what the tip was on, before the 5 (or 8) thou can be evaluated properly.

Eh, that's what I get for dealing with supper before finishing the post.... OP posted before I hit the "save" button.

[nickel-city-fab]

We really need to know where the base of the indicator holder was, and what the tip was on, before the 5 (or 8) thou can be evaluated properly.

The base was on the gearbox cover and the indicator tip was on the chuck body. This eliminates anything to do with the carriage, cross-slide etc. (post #10)

[gambler]

When it comes to lathe age, mine is coming up on 79. I replaced the original spindle bearing, which I still have, because there was uncleanable old grease in it that made it "bumpy" as it turned.. And on that replacement hangs a story, one not entirely to Logan's credit. But we can save that until the measurement has been further explained.

We really need to know where the base of the indicator holder was, and what the tip was on, before the 5 (or 8) thou can be evaluated properly.

Eh, that's what I get for dealing with supper before finishing the post.... OP posted before I hit the "save" button.

when I got my logan it had a rough growling noise when running. The previous owner told me to let it run until the grease got soft and it quieted up. it never did, so I replaced the bearings with new ones from logan. runs good now.

[David Powell]

The base was on the gearbox cover and the indicator tip was on the chuck body. This eliminates anything to do with the carriage, cross-slide etc. (post #10)

I have been running lathes and other machine shop tools for 55 years. In that time I have had quite a lot of experiences, most good, some bad, and nearly all interesting.
One thing I have learned is that , very often, the man who says the most, really knows the least.
To say that a lathe cannot have eight thous lift on the mandrel is NONSENSE ! I have used and repaired old junkers with that and more.
I have met bearings loose in housings and bearings put in wrongly , not preloaded and some simply worn out.
One big heavy old bundle with plain bearings I ran had about 50 thous play, the owner tightened that up by using an angle grinder on the caps.
Best wishes to all those wanting to learn, lets give them real help not Nonsense, pretending to be facts.
Regards David Powell.

[RockingJ]

Let me update a bit.

I rechecked everything tonight. I set up the mag base on the side of the head stock, to remove any chance of the problem being from a movement of the gear cover. With the indicator tip on the top of the chuck backing plate. When I put a lever under the chuck I got .004” of lift. Then I took the chuck off and measured the lift doing the same lever under the spindle, I got .003 of lift. I then put the chuck back on and using a carbide insert in a holder on my axa quick change tool post of only the finest chineesium, when I tried to part off some hot rolled steel, I measured .004 of rise and then the part grabbed and broke the insert. If I raise the tool holder any at all ,all it will do is rub. I have verified the tool is right on dead center.

So my memory stretched the original measurements, hey I’m old, I can get away with it most of the time!

[danlb]

Well, sounds like you are back to bearings or adjustment of the preload. .004 is way to much.

Dan

[J Tiers]

"Gearbox"?

The only "gearbox" would be the QCGB, which the 825 has, but is not directly attached to the headstock, so there could be looseness in the headstock mounting. That is one of the few ways I can see for a lot of movement to happen

If "gearbox" means the headstock itself, then there is a real issue. If the bearing were worn that loose, it should sound like a gravel truck on a bumpy road, and be very hard to use.

Other possibilities, possibly more than one....depending....

A replacement bearing that is a looser clearance. Logan (unknowingly) sold me what looked to be a C3 clearance, which already was so sloppy that the machine became totally unusable as a "lathe". A machine with 5 or 8 thou should be just ridiculous to use, so I have a very hard time believing it. But the wrong bearing, or a bearing of the right general type, but wrong clearance, is at least possible as "part of" the problem.

A problem with the fit in the headstock bore. Wrong bearing, or fit messed up due to something (some "fix") done in the past to the machine.

A problem such as a cracked bearing bore, which would allow some spring that is dependent on the force applied. This might not ever show up in normal use, other than during a cutoff operation, depending on how aggressive a cut is taken. But I would expect chatter, maybe not. You could find that with an indicator tip on top of the bearing housing, base attached to the headstock.

The loose headstock issue mentioned above, probably the front mounting. You could find that with the indicator tip on the headstock and base on the bed or the QCGB.

That model may be one that has pre-loaded bearings and a set of Belleville spring washers. They need to be adjusted to take up the slack, without being flattened out. About halfway compressed is correct for most applications, it will be right in the center of the "constant force" range. if not adjusted right, the can be a scary amount of looseness. But that should have caused a problem that is very hard to ignore, if not set up right. (to fix the bad bearing Logan sold me, I actually set up a similar system on my Logan).

There are not a lot of other things that can cause a problem. It seems that the one thing that is unlikely is that the slop is actually in the actual bearing, because it should make the lathe nearly impossible to use. If I found that a bit over 1 thou slop caused insane chatter, I would think 5 or 8 thou would be far far worse.

EDIT: (I must have been typing when you did, and never saw the update. I was actually spending quite a bit of time trying to find a parts diagram for your model on-line (did not find one for the 800 series)...... so ignore the bed and headstock lift stuff, obviously not there.

If the unit has the Belleville washers, but they are the wrong ones, too light, or not all present, or possibly just not tight enough, THEN a lot of what you say can be explained. I used about 100lb preload, and I can part off fine, but I have a different bearing than you do. Mine is just the wrong clearance, not one that can be super loose.

Anyhow, you COULD have a situation where you have enough preload to avoid chatter, in most use, but not enough to keep things steady.

Do you have any pics of the parts from when you cleaned iy up? You are new and probably cannot post them, but I, or someone else could do it for you. I'd be happy to do it. Pics might help determine if you have the right parts and they are in the right arrangement.

Mine was AFU when I got it, but I did not know that until I got a manual. I assume you have the manual for yours?

The base was on the gearbox cover and the indicator tip was on the chuck body. This eliminates anything to do with the carriage, cross-slide etc. (post #10)

Yeah. he posted while I was dealing with dinner before I finished the post.....

I have been running lathes and other machine shop tools for 55 years. In that time I have had quite a lot of experiences, most good, some bad, and nearly all interesting.
One thing I have learned is that , very often, the man who says the most, really knows the least.
To say that a lathe cannot have eight thous lift on the mandrel is NONSENSE ! I have used and repaired old junkers with that and more.
I have met bearings loose in housings and bearings put in wrongly , not preloaded and some simply worn out.
One big heavy old bundle with plain bearings I ran had about 50 thous play, the owner tightened that up by using an angle grinder on the caps.
Best wishes to all those wanting to learn, lets give them real help not Nonsense, pretending to be facts.
Regards David Powell.

Thanks for saying I am a damn fool. I appreciate your opinion, of course.

He COULD have X thou of slop... Sure. I REALLY REALLY doubt it would be due to "wear" in the bearing..... ball bearings do not "wear" like that unless they get grit in them, or are just used way past the point they are noisy as heck. And if they ARE worn that much, they would not be "smooth" as the OP says they are.

I happen to have EXPERIENCE with a very similar machine, that had 0.0014" of slop due to the wrong bearing sold to me by Logan.. Repeating what I already said, it was unusable, it chattered the moment you tried to take a cut... The OP says he has been using it for 10 years, and has "known about the problem". Boy howdy I bet he'd "know about it" if it were the bearing being that loose.... I sure did. It was a really obvious difference. it was a crazy radical difference. Preload too light, OK could be that.

[nickel-city-fab]

I have been running lathes and other machine shop tools for 55 years. In that time I have had quite a lot of experiences, most good, some bad, and nearly all interesting.
One thing I have learned is that , very often, the man who says the most, really knows the least.
To say that a lathe cannot have eight thous lift on the mandrel is NONSENSE ! I have used and repaired old junkers with that and more.
I have met bearings loose in housings and bearings put in wrongly , not preloaded and some simply worn out.
One big heavy old bundle with plain bearings I ran had about 50 thous play, the owner tightened that up by using an angle grinder on the caps.
Best wishes to all those wanting to learn, lets give them real help not Nonsense, pretending to be facts.
Regards David Powell.

Very true, a common issue online. I have ~ 35 yrs in fabrication, pipe welding, and machining, now working as a millwright (not by choice, I hate it...) and last week the production guys locked out one of their favorite machines. I found the bearing balls down ion the bottom of the belt cover. The newest blueprints we have are from 1957 with revisions. I've decided to leave the trade which is why I'm on a hobby site.

[RockingJ]

Let’s talk about the bearing preload that was mentioned. My lathe has no belville washers, I really see no was to adjust the preload. There is around .015 or so of end play when I use a pry air to move the spindle forward and back but it does take a decent amount of force to get it to move at all.

One other thing that I was thinking about was the rear bearing ( smaller of the two bearings) was loose and rotating in the bore of the headstock. I degreased the bore and the outer shell of the bearing and applied red locktite and that seemed to tighten up the bearing. Maybe I will need to remove the headstock and bore it on my mill for a sleeve to get the bore back to size, unless someone here has a better option.

[old mart]

I have looked at the illustration of Logan spindle bearings on the lathes website: http://www.lathes.co.uk/logan/
I wonder, seeing the high cost of new bearings whether it would be possible to have the slop removed by either surface grinding, or cylindrical grinding at a machine shop. If it is possible to do, I would start with 0.002" to see what difference that made. You have very little to loose, as a replacement lathe would likely cost less than new bearings.