Purchasing ball screws and nuts

[jpfabricator]

I have a growing intrest in building a cnc plasma table, and would like to know who yall use for ballscrews and stepper supplies?

Jake Parker

 

[JimDawson]

Depending on the size of the table there are a lot of different ways to do this. Ebay one source for stepper motors & controllers, ball screws, and tracks, all kinds of stuff there. It really depends on your budget, and what software you want to use to drive the system. The vendor list for this hardware is endless, so recommending a specific vendor is difficult at best. I have my own personal preferences but, they are not the least cost.

I might be tempted to use timing belt drives on the X & Y axis, with a ball screw on the Z

 

[cjtoombs]

I have studied a lot of both the home built and comercial CNC plasma cutters, and as far as I can tell, none are using ballscrews (except, as stated above, perhaps on the z axis). There are several problems with using ballscrews on a plasma cutter. The reasons are somewhat intertwined. In order to get smooth corners, especialy in thin metal, you need fast rapids and acceleration. One thing you don't need is exceptional accuracy. Since the kerf that the cutter takes is wide, and somewhat vairiable, trying for more than .010-.015 inch accuracy is not neccicary. For the same reason, as small amount of backlash (the primary reson for using ballscrews to begin with) is not detrimental. Another major concern is the dust from the plasma process, which would quicly ruin a ballscrew. Combine the additional expense, short life expectancy and a lack of need for thier primary strenghts and you don't see many on pure plasma tables (a combination plasma/router table would be a different story, but those added requirements would drive a huge amount of cost into the build). Most that I have seen use belt, chain or rack and pinion, or a combination. I had planned on building a combination plasma/router that would use ballscrews, but the size was fairly small (2' x 4' capacity) and most of the design decisions were driven by the router capability, not the plasma. A small table in the 2' x 2' possibly up to the 4' x 4' range could probably be built with acme screws, but thier protection from grit and dust would drive more complexity into the system than is neccecary. Do some googling on home built CNC plasma tables, there quite a few out there, with nearly as many different designs.

 

[jpfabricator]

I have been looking over the course of the day, and the sticker shock on the ball screws has about rueled them out.
The dust and slag is another good point. The ball screws and lead screws will both suffer if not kept clean (read CRASH)
The mention of chain drive turned on a lightbulb! A true WDITOT moment. (Why Didnt I Think Of That)
Stay tuned as there's more to come!
Jake Parker

 

[cjtoombs]

I'd be interested in a thread on your build, when you get ready to start.

 

[dave2176]

Linear motion bearings on Ebay for screws or linear rails. Automation Technologies for stepper stuff.

Dave

 

[dave2176]

deleted....

 

[Andre]

I don't know what ballscrews your looking at, but rolled ballscrews are half the price of ground ballscrews. If you were looking at ground ones, no need to spend twice the price. It's a burnout table and even a few thou a foot is most likely acceptable.

Chain drive is easier on motors though, and easier to make. Plus there are no bearings at the end that you have to mess with.

 

[DMS]

I would look at timing belts. They are lighter, cheaper, smoother, and quieter than chains. And there is no need to lubricate them either

For something like a plasma table, you don't need much grunt, but you do want to be able to pour on the speed. As for motors, I have purchased both steppers and dc-servos from Keling Inc/Automation Technologies, and they are very nice quality.