Running CNC Router at 25mtr/minute

**Boyan Silyavski** · 31-07-2017

I agree, but now that he has the screws to change them with rack seems a big waste to me.

**Desertboy** · 31-07-2017

I have scrapped a few R&P systems from commercial magazine printers and they are always set up anti backlash with 2 pinions with 2 motors, unfortunately I stupidly let this stuff go the the scrap yard.

R&P has another advantage over the ballscrew I've been toying with a dual gantry for an 8*4 setup the idea being I can use park 1 gantry at the end for normal large operations or use both gantries (One a clone) to turn the router into 2 4*4 router's working on the identical jobs.

Whilst you could do this with 4 ballscrews you only need 2 racks (But 8 Pinions lol)

**Gary** · 31-07-2017

Absolutely, my point was not to advise a change.
I was only pointing out that there is more to it than just resolution, and you need to also consider the critical speed on the screw.

Originally Posted by Boyan Silyavski

I agree, but now that he has the screws to change them with rack seems a big waste to me.

**Boyan Silyavski** · 31-07-2017

I still think using rack and pinion is mainly for 2 reasons: the size of machine and the ability to put together a long machine from short separate pieces and make it as long as you wish. At least that's how is in my eyes. Maybe also the ability to be hidden and facing downwards in a very polluted environment

**kmeshal9** · 31-07-2017

Originally Posted by Boyan Silyavski

I still think using rack and pinion is mainly for 2 reasons: the size of machine and the ability to put together a long machine from short separate pieces and make it as long as you wish. At least that's how is in my eyes. Maybe also the ability to be hidden and facing downwards in a very polluted environment

I am new in cnc i don't have that much experience
My gantry weighs almost same as yours.
2×3210 on X
1×2510 on Y
1610 on Z
How to size servo what specs to look.
What should be rated torque?
I will do whatever it takse to make my machine upto my expectations
Please enlight me more
Thanks in advance

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**Boyan Silyavski** · 02-08-2017

Please read very carefully from my second build log post #33 and from #133 to #140 .

That will answer all your questions. But before that, as was suggested above with a link to a calculator, find what's your screw maximum speed before it starts whipping for given length.

3210 screw is a very serious mass to move and to be snappy opposed to less than 1kg ball nut. Do your calculations, but the way i see it Rotating ball screw nut is the way to go and 400-750W servo motors each side.