Hey machinists, I have a question. I was trying to face off on a piece of 1 1/2 diameter cold rolled steel, on my 5900 series clausing lathe, with a 3 jaw buck chuck. The stock was sticking out about 10 inches, so I had it supported on a steady rest with ball bearing rollers mounted on the steady rest "fingers". I was having a really tough time on something that should be so simple. After trying to figure out why my cuts were not even, I watched the stock slowly work it way out as the lathe rotated. I stopped the machine, re-tightened the chuck, and watched it continue to happen. I was turning about 600 rpm, and had lube on the steady rest rollers. I removed the stock, wiped it as clean as possible, but it still keeps happening. Anyone have any idea what I'm doing wrong? Could I possibly have too much pressure on the steady rest, or have mounted out of square? The chuck does not feel like it is working loose. Any thoughts, thanks Jim.
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Stock working loose on lathe chuck.
- Thread starter songbird
- Start date
Your steadyrest may be to low ,put a little more upward pressure on it and be sure its centered.
Steady might be low, high, front, back, or a combination. One thing is certain. It is off center. If you run a dial indicator on the OD with the rollers backed off and tap the stock with a deadblow or chunk of brass or lead, etc. you should be able to get it true within a couple of thousandths then, with the indicator still on it, start the lathe at a slow (~100 RM) speed and ease the rollers up to the stock. As soon as they start to spin, they are lightly touching the stock. If you can't get it to run very true, there may be a problem at the chuck, but I bet you can.Some people sort of pinch the rollers with their fingers as they bring them to bear against the rotating stock, but you might get pinched yourself if you try that. The indicator should be at 12 o'clock for this setup. Once the lower two rollers are in place, remove the indicator, close the rest and tighten the clamp nut, then ease the top roller onto the stock. Check frequently to make sure you're not too tight. It will heat the material, it will grow, then get tighter, repeat.
That should cure your walkout problem. It's not at all uncommon.
That should cure your walkout problem. It's not at all uncommon.
You are probably not using the tailstock to align the work piece, and most likly have no hole in the end for a centre anyway. But if possible use your tail stock, and centre to help you align your work piece before you ajust thee steady rest.
I have run into a steady that did the same thing as you mentioned. This steady had home made fingers that held the roller bearings. It was suspect to be the problem. We thought ok, if it trys to pull out of the chuck now, if we reversed the fingers so the wheels was on the opposite side of the fingers it should try to push the work piece inwards. We try it, and it did just that.
The fix,, make new fingers, and make certain they where flat and true. With roller bearings, any missalignment tends to make your work piece walk in, or out wards. This allso happens with roller lifter camshafts, they tend to go either way, and on race motors, they use cam button to prevent the cam from walking out wards, and for cams the tend to walk inwards they usually use a roller thrust bearing between the cam gear and the block, to prevent the cam gear from chewing into the block. Just a example of misaligned roller bearings.
If you have a spare set of fingers for your steady, you might just try the brass tipped non roller type.
I have a few sets for mine, and use non roller bearing fingers without brass tips, and they work fine aswell.
If you can use your tail stock to help align would help. Other wise, you could have a case of sprung chuck jaws that are not holding the work piece very well. Just a few things to look at.
I have run into a steady that did the same thing as you mentioned. This steady had home made fingers that held the roller bearings. It was suspect to be the problem. We thought ok, if it trys to pull out of the chuck now, if we reversed the fingers so the wheels was on the opposite side of the fingers it should try to push the work piece inwards. We try it, and it did just that.
The fix,, make new fingers, and make certain they where flat and true. With roller bearings, any missalignment tends to make your work piece walk in, or out wards. This allso happens with roller lifter camshafts, they tend to go either way, and on race motors, they use cam button to prevent the cam from walking out wards, and for cams the tend to walk inwards they usually use a roller thrust bearing between the cam gear and the block, to prevent the cam gear from chewing into the block. Just a example of misaligned roller bearings.
If you have a spare set of fingers for your steady, you might just try the brass tipped non roller type.
I have a few sets for mine, and use non roller bearing fingers without brass tips, and they work fine aswell.
If you can use your tail stock to help align would help. Other wise, you could have a case of sprung chuck jaws that are not holding the work piece very well. Just a few things to look at.
B
Bill Gruby
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As already said, it's not the chuck it's the steady rest. It is not aligned properly. A dial indicator willfix you right up.
"Billy G"
"Billy G"
Thanks, I'll check that out. I wonder, (remember I'm new to this), if this is a situation where I should be using "soft jaws" to get a better grip. Thanks again, Jim.
What is the overall lenght of the piece youre working on? Are you putting it as far back in to the chuck as you can?
The entire work piece is about 10" long, and I am pushing it back as far as I can in the chuck, thanks, Jim.
Thanks Billy G. I will try that, Jim.
Thanks Paul. These are in fact home made bearing/fingers, the way they clamp on the steady rest, only one side is clamped. That in itself may be causing the problem. I will turn them around and see if it helps, if not, I may remove the bearings completly and try that. I was attempting to face off the end prior to center drilling, and then using the tail stock. Thanks for the tips, Jim