Large 3 Axis Router, Clearpath SDSK, Rotating Ballnuts

[johannes]

I have built a large 3-axis router, based on Acorn and Clearpath SDSK servos.

4.5meter / 15 foot Y axis with dual motors
2.1 meters / 7 foot X axis
400mm /16inches Z travel, with 200mm/8 inches Z clearance.

3232 ballscrews on X and Y, 2005 ballscrew on Z. Ballscrews are rigid/fixed mounted, and the ballscrew nut is rotated.

Steel welded frame, with thick wall aluminium extrusion on top.
Has a removable front section to allow for vertical clamping.

Uses Clearpath Precision Hard Stop homing, with adjustable end stops for gantry auto-squaring

6 KW air cooled ER32 spindle.

[cnckeith]

right on! what a great machine. thanks for posting the photos and videos, always very cool to see what Centroid users are doing.
love the rotating nuts to eliminate ball screw whip but still have the accuracy of a ball screw on a big machine.

[csabel8539]

Hi….where did you source the linear rail and the ballscrews? I have my router currently in design. Great job….

[avp]

Yes, Nice. Before I went with helical rack an pinion I was looking for the rotating ballnut option. I could not find any definitive sources for them.
Where did you get them?
Thank you
Bill

[johannes]

Hi….where did you source the linear rail and the ballscrews? I have my router currently in design. Great job….

The linear rails are not a problem, you can butt-join multiple rails to cover the entire length. In my case, each side of the gantry is made up of 2x 2250mm rails.

The ballscrew is the real problem, since you cannot ship more than 3000mm items from china, so AliExpress etc is out. Unless you pay for shipping by boat.

So I found a supplier in Europe (I'm in Europe) that could ship 4500mm long ballscrews by truck.
I chose to buy as much of the heavy stuff as I could from them (aluminum extrusions, linear rails) to combine shipping.

https://www.tuli-shop.com/linear-motion

[csabel8539]

Thank you.
Are you seeing any flex or movement in the frame as the gantry moves or loads up under the cut?

Chris

[johannes]

Thank you.
Are you seeing any flex or movement in the frame as the gantry moves or loads up under the cut?

Chris

No, the frame is solid. It sits on a steel foundation, and is bolted to it.
The gantry beam is driven by motors on both sides, and the beam itself does not flex. It's a 90mm by 180mm thick wall extrusion.
I haven't tried - but it feels like you could use it as a loading ramp for driving a car on it. It's pretty stout.
When you bolt the two linear rails to it, that also helps stiffen it up.
And I'm not planning on cutting steel or heavy metals with it. Aluminum perhaps, but mostly for solid hardwoods (Oak, Walnut, etc) and some MDF.
You'd definitely break your tool before you break the beam...

[johannes]

Yes, Nice. Before I went with helical rack an pinion I was looking for the rotating ballnut option. I could not find any definitive sources for them.
Where did you get them?
Thank you
Bill

Same with me. I looked around a lot for it. Eventually found a design, and modified it to fit.
I used this a inspiration:
https://haase-cnc.de/index.php/rotation ... 6mm-3.html

Happy to share the fusion 360 file I made for it if it's helpful.
The only problem I had was the ball screw nuts that came with the ballscrews was larger/longer than the dimensions I found on that website. So I had to redo it based on my own measurements.

[ShawnM]

HIWIN also make two different rotating ball nuts, a standard size and a compact size. They are the R1 and R2 series ball nuts. Available in 16, 20, 25, 32 and 40mm. Catalogs available online.

https://www.hiwin.sg/product-category/b ... ating-nut/

[johannes]

HIWIN also make two different rotating ball nuts, a standard size and a compact size. They are the R1 and R2 series ball nuts. Available in 16, 20, 25, 32 and 40mm. Catalogs available online.

https://www.hiwin.sg/product-category/b ... ating-nut/

I think this is a good example of the challenge I was facing here in Europe (Norway). It's almost impossible to find information about these, other than the Hiwin web page. But it doesn't show details, such as how to make a complete assembly including motor and greasing etc.
The Norwegian dealer for Hiwin wanted $2,000 USD per piece for a 4500mm ball screw in C7 grade. So that would be almost $4K just for the dual gantry screws, plus another $1,000 in shipping, plus the screw for the X axis, looking at a total around $6500 USD.

I bought TBI Motion ballscrews and 6012 angular contact bearings for the entire machine, as well as all the aluminum extrusion plus all the linear rails and still paid less than that.