Bolts/No Bolts
Tying one's kangaroo down has been often discussed. It is generally regarded as a bad idea because the net effect seems to be to transfer all the vibration and centrifugal[sp] force in the running machine directly to the two moving surfaces, the spindle bearings, causing rapid wear. This is why few industrial machines are actually bolted down rather than being put on vibration isolator pads or feet. It's better to allow the machine to oscillate at its own frequency than try to kill all vibration.
If you'd really like to dampen the vibration on your lathe, I suggest you look over John Williams' solution at the link. It's certainly not as pretty as a Birds Eye Maple box filled with sand or lead under your lathe, but it WORKS.
http://www3.sympatico.ca/3jdw8/antivibration.htm
For a lathe to operate properly, it is more important for the spindle, the bed, and the attachments to all be tuned on the same axis. Beds, whether cast iron or steel will all twist, especially if the frame is not properly set. If you wish to have your machine tuned to optimum, there are several steps:
First, (as John said) level your bed (not the under-frame) to be dead-nuts level in both directions with the feet "firmly" on the floor surface. Use as long a level as you have to reduce any error in the tool, and check the vials at both ends to see if they "agree." This may involve both adjustable feet on the legs and shims (metal flashing is great) in the bed-to-leg joints.
Second, check your female morse tapers (head & tail stocks) to make sure they are clean, accurate and without damage. Galls, bumps, dirt and burrs can be carefully removed
by hand with an MT reamer.
Third, check your male morse tapers, drive spur and live center, and gently remove and correct any burrs.
Fourth, make sure the points on your centers are straight and true and the bearing surfaces of the bed, tailstock (and for sliding heads, the headstock) are clean, and smooth.
Fifth, insert the centers and bring the points together with the TS locked down and the ram fully retracted into the casting. If the points align precisely, you're done. If however, they are off, you have more work to do.
For lateral misalignment (front-to-back), you will need to torque the bed (not the legs) in the direction opposite to the divergence. Thus, to align a TS point which is off towards the rear, you add a shim(s) to the rear bed/leg joint on the tailstock end, and visa-versa.
For vertical misalignment, the task is tougher because you must change the pitch, front-to-back of either the tailstock or the headstock. For fixed-head lathes, you can shim the attachment joints (inboard or outboard) to raise or lower the spur point a "smige." For sliding headstock lathes you're probably looking at machine shop work to regrind the two surfaces on the head's casting that meet the bed rails. Same thing would be needed for the tailstock.
Last step is to recheck your level. If the bed adjustment has thrown the level off, you re-level using the adjustable feet only so you don't undo the alignment work.
mm
