Concept Z axis

[duluthboat]

This is a prototype for a 5” Z axis. The parts are motor, timing pulleys, ½” Acme lead screw and nut, 8020 1.5 extrusion, and an 8020 slide. The nut turns not the screw.

Are there any obvious problems with this approach? Comments? Has anyone tried this?

Gary

[wjbzone]

I like the idea Gary.

Will your router/spindle clear the pully at the top of the travel?

What kind of bearing surface will the nut turn against and will it have backlash?

Bill

[High Seas]

Thinking outa the box eh?
I might turn it sideways and use that idea on my gantry - same question - clearance, and in a gantry would it be stable enough? I like it though.
If I do the gantry that way, I might go 2x height with 80/20 on the gantry to increase the moment of inertia.
Jim

[HomeCNC]

That is a similar idea I used on my Z axis conversion for my Drill/mill.

[anoel]

How are you going to kee the nut from creeping on the screw or from locking down against the plate? You'd have to come up with a thrust bearing arrangement to keep the Nut from moving any direction but in radial motion.

Also how are you going to attach the leadscrew to the slide?

A spacer would be able to be used to move the spindle away from the slide's face so that it could clear the timing gear.

Just a few of my first reactions.

[duluthboat]

All good questions. I can answer some of them. A short piece of extrusion like this would be very rigid. The clearance is in the art not the mechanics. My pulley is likely to large and there will be a tooling plate mounted to the slide. The problem area becomes the nut. I can make a very complex bearing housing using 2 nuts and thrust washers. I would like to find a simpler solution.

This Z axis is to be mounted on an 18”x18” fixed gantry. The size was determined by the most economical use of a 12’ piece of 1.5” 8020 extrusion. When the design is complete the whole works will be available free. This design started at another forum and for now will remain there, but it hasn’t got much response. For me it is as much an exercise in 3D modeling as it is tool design.

Gary

[HuFlungDung]

Hi Gary,

You could sandwich the pulleys between an upper and lower plate, to provide the thrust surfaces. I would probably suggest that you provide room for a thin layer of polyethylene sheet (or cut some disks out) to serve as the bearing surfaces.

[duluthboat]

HFD,

Yes you could, and I like it. Back to the drawing board.

Thank you

Gary

[duluthboat]

Might as well show you the rest. I haven’t given much thought to motors or controls yet.

[duluthboat]

From down under.

Gary

[duluthboat]

And one more.

Gary

[jimini]

Duluth I like your idea.
You could try making a couple of lazy suzan type bearings running in a circular groove, one above and one below the nut.