Wow! This place is awesome, I seriously did not expect this kind of response. Thanks SO much for helping me out. I will be replacing the belts as suggested below.
Summary of info below:
* No Idea what modifications have been made to this lathe RE: Housing cut out.
* Vibrates only when motor is on, without having to be cutting.
* Lathe is bolted to the bench, and motor is on a floating platform
* There is no damage to the chuck, works great. I completely disassembled it, oiled it, cleaned it of rust.
Is the lathe bolted to the bench? If not, clamp it down to see if the vibration is still there.
If the ways are not moving then it's likely bad spindle bearings.
The lathe is bolted to the table, yes.
Check for run out of the drive center?
Could be the belt has taken a set, from sitting too long un-used. Try a new link belt.
http://www.rockler.com/product.cfm?page=6040&site=ROCKLER&filter=power twist link belt
Belt should also be snug, but not tight.
Alright! Thank you, I'll see if I can get some new belts at the local auto parts store and see if it will fix it.
Whenever youre trying to cure a vibration issue, just as with troubleshooting an engine, you need to isolate the possible problems and test each possibility. In this case, assuming it vibrates without a cut occuring (it does right?) something is likely loose where it shouldnt be.
I would start by disconnecting the best from the motor and testing the motor itself. Does it start, stop, and run fairly smoothly without a lot of chatter or jumping around? Visually check the pulley on it and make sure its running straight and not wobbling as if the motor shaft is bent. If these check out, is the motor mount solid? If the motor can jump around at all, it may cause issues like you describe so try to fix the mount (without welding it to the bench or eliminating your speed changing abilities) so its solid.
I would then open the change gear cover and remove the necessary gear to disconnect the quick change gear box and change gears from the spindle drive. Does this help it run smoother? Once those are disconnected, grab hold of the check with two hands and give it a good HARD shake. If you can feel any movement at all you need to either adjust or replace spindle bearings. Ive seen many times where the bearings wear egg shaped and turn fairly smoothly/accurately by hand but under power the noise and chatter is noticeable.
Beyond those basic checks, I cant think of much at this early hour. Hope this helps.
Wonderful! I will try this. I appreciate your help!
A couple of things are unclear in your post. I'm getting the impression all is well until you begin making a cut, but the lathe is smooth when the cutter isn't in the picture. If that is the case, it sounds more likely to be a dull cutter and possibly the wrong spindle speed. Too fast can create all sorts of problems that compound if the cutter is not ground right. A bit of cutting oil or even WD40 on the work piece might help as well.
Bronzes are also notoriously ticklish to turn, depending on the specific alloy. Any of the above can make a lathe squeal, moan, chatter and yes, jump around. I have some nickle bronze that nearly defies all attempts to turn it. It's one nasty alloy... even less friendly than copper. Try a different metal, vary the spindle speed (slower is usually better) and your feed rate. You are troubleshooting, so listen to the lathe and it will tell you what it needs and wants.
Steve
Hey Steve, thanks for the reply. The lathe turns fine without any power, the piece is solid. When I turn on the motor is when it's all out of wack. The motor visibly bounces a small amount.
Also, the bronze was just what I had on the table from some casting that got turned down so I just used it to show an example. It does this with everything in the chuck. I had some brand new carbide cutters in it so it's not the cutter. I greatly appreciate your response though.
You have been given suggestions about all of the most likely culprits already, but I will re-iterate that old belts run like a square wheel, and bit sharpness, approach angle, and surface speed of cut are critical, especially with materials like bronze.
If your headstock bearings are tight and smooth, and if things measure up to be true when un-powered, I would look first to those things that change under power, as mentioned above.
Note: I have a Craftsman/Atlas metal lathe of almost that vintage, and when I got it, the belts were hard and had taken a set. Even though solidly bolted to a square and flat table, the machine vibrated badly when turned on. New belts cured that.
I will be replacing the belts, and will inspect the bearings. Thanks for the reply!
Is the entire lathe "bouncing around" ? Or primarilly the motor which is shaking the lathe? I would check the belt. I have a 12" Atlas and put on a green link belt from HF and it smoothed things out a lot.
It would be the motor that seems to be bouncing, however the piece in the chuck is also visibly bouncing. If I can't fix it with new belts I will post a video. Either way I'll keep this updated.
All good advice.
Go through the isolation routine, take the belt off the motor, the motor by itself should run quiet and smooth with little vibration. But that belt back on, run the motor and jackshaft with the spindle belt off the pulleys. Again, should run smooth and quiet. Put all the belts on and run it again with the lead screw dis-engaged. If you run into your vibration, investigate.
Use the link belts, they made a HUGE difference in my Atlas lathe.
Fantastic idea! Will do!
I would be curious as to why the housing is broken out in this picture. It would make me think that someone was having a problem, and either changed out the pulley or something to do with the motor.
First thing I would do is take the belt off and see how smooth the motor runs. It should run smooth with no vibration. Next, take the chuck off and inspect it. There could be chips, dirt behind it that is not letting it seat perfectly.
If the motor has no vibration, put the belt back on and see if it runs smooth without the chuck on it. If it does, then it is the chuck. If it vibrates still without the chuck, put the chuck on, grab the chuck and see if you can move it back and forth or in and out. If you can, then you have bad bearings most likely.
Also, does it run smooth until you start making a cut, then vibrate? If it starts vibrating only when you make a cut, than I would venture to guess the gibs are wore allowing the compound to move up and down. Sometimes you can adjust it to where it won't do it, but then it's tight either all the way in or going out. The gibs wear where the compound is mostly when cutting. Going back and forth in a certain inch or so will wear them over the years.
It shouldn't be too hard to find the cause, it's just a matter of process of elimination.
I don't know what has been done to the lathe, to be honest. It's been sitting there untouched for the past 20 years. I spent about 15 hours cleaning the whole thing up, oiling it, and tightening everything up. It does not run smooth while the motor is running so it must be something with the motor. I'm going to replace the belts and such as suggested. I'll update when I find anything out!
