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It's been a while since I posted but want to thank all for the input regarding ideas of mounting my new lathe.
I recently bought a PM1228 and needed to build a stand. The lathe was going to be set up on the second floor of my garage which made the "foundation" somewhat susceptible to shifts over time and temperature. I looked at davidpbest torsion beam design and based my design on it. Apparently, this technique is used to mount lathes in ships where everything moves and shifts. I used two heavy 7"x2" C-channels welded together to form a 7x4 tube. As per david's design, I put an angle on either end of the beam with threaded adjusters on each end of the angles to act as levelers and bolts to lock it in place. I built a simple frame out of 2" square tubing 0.125" wall and put casters with built-in leveling pads so I can move the machine when/if needed but then lock it in place and level the frame. What I found was that after I leveled the frame on the uneven floor there wasn't much need to level the torsion beam. While testing a sample piece in the lathe with a DTI and looking at the twist, I found that the beam was so stiff that the twist adjusters had not effect on the beam itself. I did find that by varying the torque on the 4 mounting bolts the lathe frame would twist which meant that the beam wasn't truly flat. After a bit of shimming and torquing, the machine was solid and no twist and the lathe turned true.
Bottom line is that the torsion beam is so stiff that I doubt the 2" frame is having any effect which means that the shifting of the garage should have no effect either.
Once again, thanks for the input. I feel I ended up with a reasonably stable/stiff setup without being overly complicated or heavy.
steve
here are a few pics:
I recently bought a PM1228 and needed to build a stand. The lathe was going to be set up on the second floor of my garage which made the "foundation" somewhat susceptible to shifts over time and temperature. I looked at davidpbest torsion beam design and based my design on it. Apparently, this technique is used to mount lathes in ships where everything moves and shifts. I used two heavy 7"x2" C-channels welded together to form a 7x4 tube. As per david's design, I put an angle on either end of the beam with threaded adjusters on each end of the angles to act as levelers and bolts to lock it in place. I built a simple frame out of 2" square tubing 0.125" wall and put casters with built-in leveling pads so I can move the machine when/if needed but then lock it in place and level the frame. What I found was that after I leveled the frame on the uneven floor there wasn't much need to level the torsion beam. While testing a sample piece in the lathe with a DTI and looking at the twist, I found that the beam was so stiff that the twist adjusters had not effect on the beam itself. I did find that by varying the torque on the 4 mounting bolts the lathe frame would twist which meant that the beam wasn't truly flat. After a bit of shimming and torquing, the machine was solid and no twist and the lathe turned true.
Bottom line is that the torsion beam is so stiff that I doubt the 2" frame is having any effect which means that the shifting of the garage should have no effect either.
Once again, thanks for the input. I feel I ended up with a reasonably stable/stiff setup without being overly complicated or heavy.
steve
here are a few pics:
I'm retired now (finally) and do it all at my leisure and pace. I still have all the tools and still enjoy making something out of raw materials. You just whittle away the extra, weld it, pound on it, shape it, sand it, paint it and then bingo, there's a car. 
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