Help me select some ground ballscrews please and other stuff

[seanreit]

The first thing I want to accomplish is CNC of my lathe.

I have already bought two THK Linear Slides for the long axis of the Lathe, they are 18" long. Two of them.

What I need to finish the lathe is as follows:

A 400oz or greater Stepper Motor for the long axis, and a Ground Ball Screw at least 18" long with Nut assembly for mouting to the aluminum housing that will mount to the linear slides (I don't know the precise word for this part, but I will be making it).

On the short axis of the lathe (The axis that the tool is set to) I need , ball screw, nut, and a recommended stepper motor. I also need the recommended Board and parts for RPM control.


For a large CNC metal machine I am building I need recommendations for everything. I don't have a budget, but I do have the cash right now to get pretty much everything I can think of.

I have bought this for the x axis: http://cgi.ebay.com/ws/eBayISAPI.dll...m=380028807837

And this for the Y axis: http://cgi.ebay.com/ws/eBayISAPI.dll...m=380028813472

Whatever head assembly is recommended IE a treadmill motor?, the controller for that, etc. I will be using Gecko Drives I believe (I already have two spare geckodrives). I also want to get a breakout board to control RPM of the spindle. Please make a recommended list for everything. I want to get all the parts on order in the next 10 days or so.

Basically I want to build my version of the dream machine with 36" of X and 12 inches of Y with thousand ounce stepper motors. I will be buying G grade aluminum for mounting the linear slides on. At the moment, ground ball screws seams to be the hiccup in my ordering process.

Sean

[seanreit]

When sizing the ballscrew, is it the same length as the linear slides? Shorter? Or longer, I'm not clear on that.

[LeeWay]

I will let others comment some. I will just say that you will never get 12" travel from 11 3/4" slides.

The slides you mention are on the small side as well considering the X is normally mounted on top of the Y.

On the slides, you will loose whatever distance from outside to outside of the trucks. In other words, you automatically loose the combined truck lengths in travel plus any spacing you will have between the two.

As for screws, the same applies to the ball nut and mounting points including the ball nut mount. You simply loose this amount off the top. The design will determine the other criteria.

I would suggest if this is for a mill, that you buy at least Nema 23 495 oz. since you are using Gecko's. These have a 3/8" shaft and are very robust for the size. I run these on my mill. Consider also going with timing belts. A little more difficult than direct drive, but well worth it in the torque department.
I run these on my mill with 203V's and a 72 vdc power supply. I get power supplies and motors from Keling. Nice to do business with and quality stuff.

[seanreit]

Thank you for your comments, would this be a better choice for the Y then?
http://cgi.ebay.com/ws/eBayISAPI.dll...m=150252281250

Or would you go even longer?

[LeeWay]

I think those would be a better choice and would get you closer to you intended 12" travel.