Small lathe vibrations

[JasonW]

Noticed some small vibrations in my 12x36 " gear head. Has a 2 HP , single phase motor. I know the gear heads are not as smooth as the belts jobs, but had to look into it. It only had one long bolt to adjustthe motor belt tension.This was at the end opposite the motor pulley. I noticed that the motor appear to "flap" slightly on the pulley end. So I fabbed a bracket for the pulley side. I also mounted every contact point of the motor with thick rubber that I had around. Used 9 pieces in all. It appears to have helped a bit, but I can stil feel a 1-3 Hz pulse at the motor end. The belt appears have a small slap in it. The belt seemed tight, with a small amount of deflection. How tight should it be? I am afraid of killing the bearings if overtight. Could the belt be cheap? It looks cheap. The motor was ran with no belt attached and it ran smoothly. BTW I have not bolted the lathe yet. If and when I do , would it be a good idea to use thick rubber on the base with Loc tite on the bolts?

[bspooh]

Do not use Thick rubber underneath the lathe.....use metal!!! Rubber moves....you don't want your lathe to move...

brent

[Rotate]

I agree with Brent on not using rubber mount. Making things more rigid and stiff is the way to go and that includes the stand. As for the v-belt, my experience has been that they work best once they've been worn in,, so if they're fairly new they'll get smoother.

Albert

[Tim Clarke]

I trust that the belt you have is the one that came on the machine. The belts that came on my Import mill-drill and drill press were lumpy. Take the belt off and have it with you when you go to a industrial supplier, like Applied Industrial Technologies. Or, look in the yellow pages under power transmission or bearings. Somewhere near you will be a outlet for industrial belts. Get the one that has the
V cuts on the underside, these will conform to the sheave eaisier, giving a longer wrap with less tension. The Goodyear belts I bought were very smooth, and are much better than the originals.

Tim in Oregon

[Herb W]

Jason
Is the vibration showing up in the quality of the finish on your work?
There's a post that you might find helpfull - 03/06 by William van Fossan re chatter on an Enco lathe.
Herb

[SGW]

Agree -- mount the lathe solidly, try to isolate the motor (as you've done). A better-quality belt may help.

[Stepside]

I have "fixed" several new import machines by replacing the belts. One of the larger dealer in my area will not sell import machines with factory belts. He pulls them off and throws them away.

[mike thomas]

Just last week, I built a metal polisher. I set up an arbor in pillow blocks, and powered it with a 3/4 motor. I had a couple of belts around, and when I tried them, I could tell the difference in vibration from one belt to the other. Three trips to the parts house, and now very little vibration. These belts all looked fine. One more thing to worry over. Mike

[ralph mitchell]

Maybe your belts are too tight. My horizontal bandsaw shakes real bad when the belts are too tight. I loosen them up and it goes away. Your belts should be only tight enough so they dont slip.

If the viberation is showing up on the work then you could have a bad bearing.

[Jim Hubbell]

I have installed "segmented" belts on my 10" Atlas and got rid of most of the vibrations in the belt frequency range. This is from jack-shaft to spindle.

[spope14]

Here is one for you. have lathe vibration when the temp outside fluctuates in the spring and fall. The lathes in my shop are mounted but not bolted to a floor that has a seem between two slabs - the floor starts to warm or cool in one or the other, and wah lah, lathe vibe. No way to isolate, this was the way it was set up in the shop, there is no moving six lathes without hurting the floor plan or moving 12 machines worth of power supply.

What is your temp range in your shop, do you have floor cracks under the lathe? Slabs? Does tyhe vibe increase and decrease with speed, and does it shake the guards?

My solution was expensive, and is never complete. I have one of those Starrett precision levels, and I level the machines on a regular basis. When vibe hits, get it out and re-level and seat on steel seats on the floor. First time a bear, after that a three minute job.

Just a wierd observation.

[JasonW]

I don't think the belt tension is too tight. Yes the lathe is on one complete slab, but it is near a joint. I think the underside of this slab may be a little weak. I will try to shore up the slab, and get a new belt. The lathe is near a door that is usually open until 11:00 PM for my dog.

I will try to bolt the lathe down, but do not have a precision level. Is the procedure in the "Amateur's Lathe" a good procedure?? It uses a dial gage( attached to the tool post) aginst a chucked piece (as long as possible) near the tailstoke end. Bolt and watch for deflections.



------------------

[Oso]

If the lathe is not level, i.e. if it has the bed "racked" at all, the saddle cannot sit straight on it, because the saddle has 4 contact points.
It will act like a chair with one short leg, rocking back and forth. Hence a chatter can happen.

Not only can this allow vibrations, but it will cause wear in the long term that will necessitate re-scraping the saddle.

Get the machine "level" as soon as possible.

[Thrud]

JasonW:
I would see if you can borrow a precision level from someone or maybe rent one from a tool rental place or machinery dealer.

You can buy them cheaply on eBay. I paid $500 CAN (a year before eBay) for my Starrett #199 (new, unused - .ooo5/ft.). I have seen them go for under $100 on eBay and the Starrett #98 series (6" or larger .oo5"/ft.)can go for much less than than that. If you buy a #199 make sure it comes with the hardwood case to protect it properly when storing.

If sunlight hits your slab or machine this can also cause problems from uneven heating - maybe just prop the door up just enough for ol' yeller to get in and out.

Once you get a level and level the bed so it is not twisted it would be a good idea to anchor it to the floor as the others have suggested. I have seen problems with large injection molding machines, shears, and presses just because they were not level or anchored down properly. Two CNC turret punches we installed had to have special 6' deep steel reinforced concrete islands poured for them because the 12" pad flexxed (soil problems) bringing the machine out of alignment and breaking the punches (600 strokes/min.) under use.

[JasonW]

I bought a new belt for the lathe. It seemed to make a difference. The motor does not have that slapping vibration anymore. Another thing I noticed is the new belt makes the pulleys run cool. The original belt sure heated up the pulleys. The difference was like night and day. No it was not that tight. That belt must have had lumps or something.

Got a Starrett no 98 ,8 " level. Will bolt the lathe up soon. No rubber mounts.

------------------