Are Linear bearing setups suitable for Milling Machines??????.

[Moondog]

If you were building a CNC Mill from scratch are THK Linear Bearing setups suitable for the Axis?...Most Mills seem to use the dovetail slide system.

Will the THK bearings be strong enough and provide enough accuracy?. Not talking about a Mill as big as the Bridgeport.

I have a Milling Head (spindle etc) that I am looking to turn into a CNC Mill.

cheers

[Graham S]

Yes:

http://www.5bears.com/cnc.htm

[Ken_Shea]

I am not aware of any modern commercial CNC mill that does not use them, extremely accurate and sizes to fit virtually any load. The older V-Ways are hardened and precision ground, expensive and almost an impossible task for the DIY'r. If you can afford them, THK is the way.

[JFettig]

I have been also looking into this, someone mentioned some mills in the mini mill section that have them. at work, when one of the haas' was milling I took a look up above the head and it didnt look like dovetails, more like linear bearings. I am now designing a mill that uses the linear bearings instead of dovetails. Should be able to get much higher speeds out of it. I am hoping to find me some 3000rpm servos for direct drive
The haas looked like it has linear bearing slides, not the round rod linear bearings.

Jon

[Stevie]

My Plan is to use 35mm THK linears
I have 2 sets (4 rails) of 1meter long now; with 14 blocks all new
Still need 2 rails 8ft long for the X axis

[Ken_Shea]

Hey Steve, good to see you found some time to get back to posting

8' rails, Do we have something big planned ?

Ken

[Stevie]

yes a rather big mill

Stay on the board Ken I'm just putting a post together with new pics of the new lathe

[Kmed]

Those will work fine. Just keep them clean so you dont have balls popping out all over. Get the rail beds ground and them get them laser aligned and you should have no problems. Post some pics as you go.. This seems interesting...

[Swede]

These linear bearings are a boon for scratch-built mills, if you can get them surplus or via ebay, or you have cash to burn. Combined with ballscrews, you can create axes that are stiff, accurate, and with torque requirements so low you can direct drive with ease. By lowering the resolution via software I was able to move at 500 ipm on a desktop mill with no problems. The double-stack NEMA 23's don't even get warm.

Using them to retrofit a standard dovetail mill would be a lot more work, but is possible.

One last suggestion - be sure the rails and screws are correctly guarded from swarf. This is easy to do if designed in this fashion, much harder to do once the mill/lathe is finished. Good luck!!