Bob,

Very few DIY PDBs get anywhere near 3000#. The very few I've seen that do, and do it reliably, use hydraulics. The Tormach PDB uses a huge air cylinder, but only gets about 2500#, and many who have that one consider it for "light duty" only, lest they get pull-out. Also, I would not want to put all that force on the spindle bearings. It might not hurt them, but why take the chance? A really huge lever can put really huge forces on the column and ways - not good. Do what you want, but, other than the God-awful impact wrench kind, I've only ever seen a few PDBs get up into the right range of tension to completely eliminate TTS pull-out, and they've all been either hydraulic, or, like mine, electric. Most are in the 1000-2000# range, which is simply not enough, unless you're machine is under 1HP. The Belleville spring ones are mostly using a short stack of springs - 3-6 or so. They get away with this due to the low force they require.

Regards,
Ray L.