Acme Lead Screws......spec and source?

Olddaddy

Olddaddy

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I have a BMW R100 and an R69S that need work. I've looked around for lifts that work well, are affordable and are not a design abomination....and I've decided to build my own. I'm thinking of using an Acme lead screw on a vertical post with a bottom plate on some really good casters. The arm would ride up and down the vertical tube. Question is, how to spec the size and mounts for the lead screw. I am guessing the actual weight lifted is around 3-400 lbs, so figured on doubling that to get a good size screw and bushing/bearings. Anyone here speak the language of lead screws? Appreciate any insight or advice.
 
Just by the seat of the pants, I'd look at a 1 1/4" diameter 4 tpi or 1" diameter 5 or 6 tpi
 
I was thinking just that. My questions come in about how to mounth the lead screw, are there bearings it can pass through, the screw itself, can it be bolted to the arm?
 
I'd turn down one end of the screw to fit a self aligning flange bearing and mount the nut to the arm in a manner that it can align itself with the screw, that is, not ridigidley. Are you planning on powering the screw? I made a slide device with hooks at each end to pick up and insert Jaguar engines into the engine bay; it had a sliding block that the hoist lifted and was adjustable towards one end and the other so the engine could be tipped one way or the other, I used an acme screw and nut and made an adaptor for one end of the screw that allowed an air ratchet to do the adjusting.
 
I was thinking of a flange bearing facing up, mounted on the baseplate. The nut bolted to a flange on the lifting arm, and a second bearing mounted at the top of the post facing down. The lifting arm would move up and down on roller bearings to remove any play or side loading on the screw. I figured either an impact wrench, air ratchet or drill motor to provide the rotating force needed. I think bigger may be better in terms of the screw diameter and bearing/nuts, at least 1 1/4" as suggested by you earlier. I did a sketch in autocad that I will send over to a local Motion Industries branch tomorrow and see what they recommend.
 
Olddaddy said:
I was thinking of a flange bearing facing up, mounted on the baseplate. The nut bolted to a flange on the lifting arm, and a second bearing mounted at the top of the post facing down. The lifting arm would move up and down on roller bearings to remove any play or side loading on the screw. I figured either an impact wrench, air ratchet or drill motor to provide the rotating force needed. I think bigger may be better in terms of the screw diameter and bearing/nuts, at least 1 1/4" as suggested by you earlier. I did a sketch in autocad that I will send over to a local Motion Industries branch tomorrow and see what they recommend.
Click to expand...
Sounds like you have it aced!
 
I'm not so sure it's Aced just yet! Still in the thinking "discovery" phase. I have looked at the HF lifts and many others. Both bike will be taken down to bare frames, so I want a lift that can be fastened to the frame since the suspension is coming off altogether. I also want one that has really good easily rolled casters with locks. My shop is small and if I can't move it around easily it becomes a dead zone. And since it will likely sit for a long while I don't want hydraulics. I'll report back as I make progress, but do appreciate the input so far.
 
I have seen an example of the 8 ton high lift hydraulic jack; each stroke of the pump raises the ram a quite tiny amount; you'd be there all day!
 
I rarely use my lift table which I think is rated 1200#
Even though it sits most of the time I got it fairly cheep from a craigs list
and I couldn't do without it. It also doubles as a handy table that can be height adjusted.
Check around, the lift tables are ready to go and can be found at reasonable cost.
Much cheaper than building one.
 
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