[Black Forest]

I am in the process of building a CNC plasma table with the hopes of also being able to drill on the machine. It will be heavy duty and so I will use ballscrews with most likely a driven nut. Have any of you all built a plasma table with ballscrews? Supplier here in Germany has recommended 3220 ballscrews. The machine will be a servo driven machine utilizing 3 phase power. Another supplier has mentioned but not really recommended 3232 ballscrews. I would be concerned with the resolution with a 3232.

I won't say that cost is no issue but also I don't want to cut corners. This table will be for my personal use and I want to build it myself. The building of the table is as much a part of my motivation as having the machine.

Many of my questions are probably idiotic to some of you experienced builders and to at least one vendor in USA. This project has been ongoing for 2 to 3 years because of other projects and having a life! Having no CNC experience there is a big learning curve ahead of me!

Thank you for sharing what you can.

[hanermo]

32 size screws will be fine, unless you have extreme length.
Maybe good for upto 2 m or so, imo, ime.

I can see zero desire for fast rise on the screws.

With servos, you are getting
1. more than enough acceleration
2. more than enough speed

I would use as small a rise as was available, without extra costs.
This will increase resolution, accuracy, and rigidity, all of which are desirable.

Driven nut is an excellent approach.

My mill will go onto a driven nut, as soon as I have time.
I use 3204 screws on my mill, with 1600 mm wide table.

Max speed you want at the nut is about 1000 rpm.
(Wear goes up after this. Check with screw supplier).
= 16 revs/second.
At a rise of 5 mm per rev, thats 80 mm/sec => 4.8 metres per minute.

At most, maybe a 10 mm rise for twice that.
I would think that 4.8 m/min is much more than needed. Especially in a plasma, that never does multipass toolpaths.

Rapid speeds are mostly unnneeded, imo, ime, and I really dont see why people even think about them.
Acceleration and repeatability is much more important.

[Black Forest]

32 size screws will be fine, unless you have extreme length.
Maybe good for upto 2 m or so, imo, ime.

I can see zero desire for fast rise on the screws.

With servos, you are getting
1. more than enough acceleration
2. more than enough speed

I would use as small a rise as was available, without extra costs.
This will increase resolution, accuracy, and rigidity, all of which are desirable.

Driven nut is an excellent approach.

My mill will go onto a driven nut, as soon as I have time.
I use 3204 screws on my mill, with 1600 mm wide table.

Max speed you want at the nut is about 1000 rpm.
(Wear goes up after this. Check with screw supplier).
= 16 revs/second.
At a rise of 5 mm per rev, thats 80 mm/sec => 4.8 metres per minute.

At most, maybe a 10 mm rise for twice that.
I would think that 4.8 m/min is much more than needed. Especially in a plasma, that never does multipass toolpaths.

Rapid speeds are mostly unnneeded, imo, ime, and I really dont see why people even think about them.
Acceleration and repeatability is much more important.

Thank you for the reply.

4.8 meters per minute is too slow for plasma cutting on thin material. The minimum I want is 10 meters a minute.

The wear thing is also why my ballscrew supplier here in Germany recommended I go with at least a 32mm diamter ballscrew because the nut will have 6 rows of balls and not 4. He said they last longer and move easier under load.

[JL-WSHVAC]

ball screws , lead screws are often limited by the wobbling factor. You have too look up the screw drives specs and choose the one that best matches your desired speed and length. ball screw and lead screw and be very fast, again , it all depends on their design. I have seen screw drives with 3 grooves on each flute , the manufacturer says that will increase the stability and speed...... well of course they are very expensive. for plasma cutting , I cut with 8~7m/min on 0.5 to 0.8mm thk., then 4~6m/min on 1.0 to 1.5 mm