[neorules]

Hey all,
Just purchased a pieces of a router table that wasn't assembled.
The linear rails are Hiwin25 on the X and Z axis 1520mm long.

The original intent was to use 3x3 (3030 extruded aluminum from 80/20) but I am upgrading to 3x5x.250 steel tubing.

The question is will my Nema 34 1600 oz steppers (2 for the X) be able to handle a gantry of approximately 150 lbs or more?
The ball screws are double nut 25mm 5mm pitch.

First foray into building something myself so I would appreciate advice from the masters.

The build itself is 3x5x.250 tubing (a36 or a500) with a couple pieces of .25 1018 cold roll as the straight edge to mount the rails too.
The cold roll will be bolted to the tubing and then a damn placed on the other side so it can be filled with a nice self leveling epoxy for the rails to mount too.
The gantry will be mounted directly to the X linear rails with no uprights and the table will hang below the X. Sort of like those big Z designs (even though M Z will be limited to 300mm).

So far the only thing I have done is get the Nema 34 steppers and drivers, the 4 Hiwin Hg25CA with light preload for x and y, HG20CA for the Z axis.
The ball screws 2x 25mm double nut for x, 1 x 25mm double nut for the y and 1x16mm double nut for the Z.

Haven't chosen a spindle yet but I am working on it.
I may use a simple dewalt rig to get it up and running (money is tight after the above purchases) and then move on to a real spindle.

Suggestions on the overall build and if the NEMA 34 steppers are enough to push the heavy gantry.

Thanks JC

[Jim Dawson]

Hey all,

The question is will my Nema 34 1600 oz steppers (2 for the X) be able to handle a gantry of approximately 150 lbs or more?
The ball screws are double nut 25mm 5mm pitch.


Suggestions on the overall build and if the NEMA 34 steppers are enough to push the heavy gantry.

Thanks JC

Just to put this in perspective, my 4x8 foot moving table router had a single NEMA 34 1200 oz/in stepper driving a 700 lb table with a 40mm, 40mm lead, ball screw using a 1.5:1 belt reduction. Would run rapids at 600 IPM max, 500 IPM rapids in normal operation.

The Y axis carriage weighed about 300-400 lb, also driven by a 1200 oz/in NEMA 34 stepper, at a 1:1 ratio, driving a 25mm, 25mm lead ball screw.

I had the micro stepping set up to give 0.0001'' resolution (not to be confused with over all system accuracy which was in the range of +/- 0.001 inch)

Running 5mm lead ball screws implies high motor rpms to get any speed out of the system, which your 1600 oz/in motors are not capable of. The torque is way overkill, you could gear the motor a 1:4 step up (20mm movement/motor revolution) and be OK.

I like the double nut ball screws, but I would have used a greater lead.

You might also look at the Porter Cable 75182 router motor

[ger21]

The question is will my Nema 34 1600 oz steppers (2 for the X) be able to handle a gantry of approximately 150 lbs or more?
The ball screws are double nut 25mm 5mm pitch.

With 5mm pitch screws, you'll get terrible performance from 1600 oz steppers, which have very little torque at higher speeds. Your best bet would probably be low inductance ±650 oz steppers.

Ideally, you would want to use 10mm or 25mm pitch screws.

150lbs is not heavy at all. The inertia of the 25mm screws is more of an issue.

[neorules]

Jom and Gerry,
Thank you for your prompt replies.

So either Gear them down or get higher lead ball screws hmmmm...
Probably better off getting higher lead ball screws I think.
Investigating prices now.

Thanks for the Advice!!
The stuff I purchased was from another CNC guy and his design was also for cutting metal on occasion so that may be the reason for the 5mm lead.
He was also using Nema 23 420 oz low inductance steppers with an aluminum gantry.

I just happen to have the monster Nema 34's that I purchased a long time ago in a kit for retrofitting an old mill.
I just thought bigger was better at the time I guess.

Thanks again !!
time to rethink
JC

[Jim Dawson]

If you are going to purchase new motors, take a look at DMM Tech https://store.dmm-tech.com/ or Clearpath https://www.teknic.com/products/clea...-servo-motors/