[kenrbass]

First, I have a multicam and a axyz machine in my shop, so this is not a real "need". I have rebuilt, repaired, bought and sold several machines. I ran across a set of round linear shafts and bearings along with a leadscrew with delrin nut for the z for a very cheap price. My neighbor has a steel rack pretty well stocked and he always told me to take anything I wanted. So with inexpensive rails and free steel, I figured what the heck.

I have a background in welding, mechanics, and electronic's.

I am at the point of having all axis moving smoothly and the Z working with a drill on the shaft. I have a set of nema 34 motors and leadshine drivers. The electrical end is easy for me, so I am leaving that for last.

Cutting size is working out to be 25"x37" with a 7 inch Z stroke.

I am doing this a little odd, because I had no real plan or drawings going into it. Welding and dealing with steel moving was interesting. I did some welding on the opposite sides of parts to pull things back and was selective about where to weld and where not to weld.

I am unshure if I want to buy more lead screws (5 start 1/2" is what I'm looking at), rack and pinion, or ball screws. At this time I have about $300 dollars in this build. My thought was to keep it cheap, but it's solid and smooth. I am looking for thoughts on placement and choices of drive systems.

Ken

[__Britt]

Oh WOW is that frame rusty! You are going to treat it with some rust converter & paint it, right?

As for the axis drives, I think I'd probably go for a rack&pinion setup; so you don't have to worry about screws whipping during rapids.

I have no personal experience with their products, so I can't recommend for or against them, but... this is the sort of setup I was thinking about:

Standard Rack and Pinion Drive, NEMA 23 | Avid CNC | CNC Router Parts

[mactec54]

Oh WOW is that frame rusty! You are going to treat it with some rust converter & paint it, right?

As for the axis drives, I think I'd probably go for a rack&pinion setup; so you don't have to worry about screws whipping during rapids.

I have no personal experience with their products, so I can't recommend for or against them, but... this is the sort of setup I was thinking about:

Standard Rack and Pinion Drive, NEMA 23 | Avid CNC | CNC Router Parts

It's not a big enough machine to be worrying about screws whipping if he has a Ballscrew of 20mm dia or bigger would be fine

The leadscrews would be a waste of time installing them, with what you have for this machine

[mactec54]

It's not a big enough machine to be worrying about screws whipping if he has a Ballscrew of 20mm dia or bigger would be fine

The leadscrews would be a waste of time installing them, with what you have for this machine

Rack and pinion are cheaper but you can get some cheap Ballscrews as well which are still better than a Rack and pinion

[__Britt]

Eh... yeah; I suppose. Just had a quick look on eBay; this is the first thing that popped up (not a recommendation - it's literally just the first link I found):

https://www.ebay.com/itm/Antibacklas...g/263897799531

I would tend to think that a stepper big enough to be a NEMA 34 would probably have enough torque to handle the 10mm/turn of that ballscrew; and with the ballscrew being so steep you'd get good rapids out of it. Assuming the motor is 200 steps per rev; and the drive is set to 16 microsteps; doing the math on that 10mm/turn ballscrew yields 0.003125mm/step, or 0.000123031496063in/step.

[kenrbass]

The motors are in the 900 in oz range so I have plenty. The little thing is very solid, strong, and straight. I guess I'll pony up for some ball screws. Maybe replace the lead screw on the z that came with the slides. The surface rust doesn't bother me and I'll fix that. I am still welding a little here and there, so clean up and paint will be later.