[ShayArnett]

I didn't want to post this in my other thread so here it is.

What kind of speeds could I expect from a machine using 1/4-20 allthread for leadscrews with 276oz steppers(automation direct) and xylotex controllers with 24-28 volt power supply.

[buscht]

My estimate is 15" per minute depending upon the length of the allthread. The longer the rod, the slower you have to go because the rod starts whipping.

I have a similar setup, but use ball screws with about 5 turns per inch. I can rapid at 100" per minute, but have my system set at 60" per minute tops. It cuts well at 45" per minute.

Personally, I recommend going with a larger dia allthread

[ShayArnett]

I would like to move to 1/2-10 acme but I'm not sure if it will fit in my window channel with the cheap nylon i scavenged it will be tight. I have some 1/2-13 allthread i am gonna do some tests with to see if it will fit before ordering the acme.

[eman5oh]

I would have to agree with the 15 imp, if you are much more than 2-3 ft in lenght you will have to go much slower do to the wipping effect. With the stepper you have you should look for some 5tpi screws as you should have pleaty of torque to dive them.

[sol]

With double bearings supporting each end it is possible to get high RPM out of Allthread.

A 5 ft ½ -13 rod was test spun at 2800 RPM and the whipping was minimal. Currently on the machine the threaded rod rapids at 800+ RPM yielding 60+ IPM.
Before using double bearings for support the thing whipped terribly above 350 RPM.
The bearings at each end are about 4 inches apart.

Pics here; scroll to bottom of page. http://www.solsylva.com/cnc/1cnc54.html

[yukonho]

I have run 1/4-20 allthread on smaller steppers with 24V on the xylotex board. I got around 30-35 IPM. I had a 3 foot run, and slightly tensioned the allthread. There was some whipping at this speed. I use 3/8-12 Acme on my new machine and have 70-75 IPM rapids now.
colin