A Wood Lathe vibration problem. My son gave me an old Sears Model No. 101-06280,
12 in swing x 46 in bed, wood lathe. I have replaced the bearings and mounted
the unit on a wooden stand that seems substantial. The unit has a jackshaft
that is connected with the new red link belt system that has been installed
for proper rotation. The lathe is powered by a new Marathon 1 HP motor that is
mounted to a hinged 2×8 that is allowed to float. The vibration exists at all
speeds and is not constant. It tends to throb in and out. It is impossible to
do any work as the vibration translates into the work piece. I have not
checked for run out as I don’t own an indicator. By eye, the pulleys seem to
be tracking correctly. One person suggested that the motor should be rigidly
mounted. Any suggestions before this machine is consigned to the scrap heap?
Replies
hello
would suggest you start the search for the solution by either putting weight or prop on floating motor bed and see if this makes any difference.You could also damp the vibration with sand bags on the lathe legs /shelf etc.
don't give up ,you will love turning when you get round to it (round - lathe , get it )sorry.
regards Tea-bag
The throbbing in and out suggests two (or more) vibrations at different frequencies. When the vibration is at maximum, how long does it take for it to throb out to a minimum and then come back to maximum? The longer the period of the throb, the closer are the two interfering frequencies. Does the throb frequency vary with the lathe speed? The obvious suspects for generating slightly different frequencies are the different size pulleys.
In my trade, we talk about trying the easy tests first. It may not be obvious how a rigid motor mount would help, but it's relatively easy to do, and if it works, you're done.
If it doesn't, keep looking. Does the motor vibrate when you run it without a belt? Do the motor and the jackshaft vibrate when you run them without a belt to the spindle? Since you've got link belts, can you bypass the jackshaft and run a belt directly from the motor to the spindle?
Could you rig the motor to drive the spindle directly? Or another motor, known to be a smooth runner?
There's no delicate way to ask this, so I'll just be blunt. :) How sure are you that the new bearings are properly installed?
The motor does not vibrate without the belt. It is brand new.
I can mount the motor rigidly.
Yes I have other motors, but they all have different bases.
In order to isolate the vibration, the jackshaft has been removed from the system. I am running from the the motor thru the link belt to the lathe pulleys.
The bearings (two SKF tapered roller bearings $125 total cost) were intalled using a brass punch to seat the races. I have installed several bearings and am well quailfied to seat and adjust bearings. I served an apprenticeship as a Machinist. Thank you for asking.
I will follow your recommendation and somehow mount the motor with a solid mount and keep you posted of my results.
Had I known in advance the trouble I was letting myself in for I would have declined the offer of a"free" lathe and opted for a new one. But then, I would have missed out on the experience of correcting a lathe vibration.
Thank you for your advice,
George
Sucess at last. The vibration problem is almost gone. At first, I tried to rigidly mount the motor. This didn't work as the motor has a vibration and the vibration was transmitted into the machine through the lathe stand. I then isolated the motor entirely from the lathe stand by anchoring it to the ceiling joists. This really improved the situation. There is still a slight vibration that is tolerable, but should be tracked down and eliminated.
Thank you for your advice,
George
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