where to start?

[Jonathan]

Oh be carefull Jon your on sacred ground with the Acme brigade.! . . . They'll be after your Balls (screws).:naughty:

We'll see...

What about using 16mm ballscrews (RM1610) and rotating ballnuts. You save buying the end bearings, and the angular contact bearings aren't so expensive as they're not so big as with 25mm screws. Should get a very decent feedrate. Just a thought...

[JAZZCNC]

What about using 16mm ballscrews (RM1610) and rotating ballnuts. You save buying the end bearings, and the angular contact bearings aren't so expensive as they're not so big as with 25mm screws. Should get a very decent feedrate. Just a thought...

Yes if it was me I'd be seriously considering it. . . I'm a massive ballscrew fan has you know.!

But I was giving easy options that could be bought off the shelf at sensible money. Rotating nut is OK if you have the equipment IE: Mill etc and knowledge to make one. Don't think neil has the equipment.? The knowledge could be gained but probably daunting for someone new and was aiming my suggestions with this newness in mind.!

Think I'd also go with a higher 20mm pitch if being used solely for cutting woods n plastics so the cutting feed is in the meat of the motors torque. Reason being think for a machine this size nema34 would be needed and they don't spin as fast as 23's so with 10mm pitch then gearing would be needed to bring the speeds/feeds up and that will affect the torque.
You have to think when cutting wood you need high feeds and deep DOC for best performance and even faster for plastics, so better to put the right pitch screws on in the first place than use gearing IMO. . . . . Back to horse's for course's. .:confused:

[Jonathan]

But I was giving easy options that could be bought off the shelf at sensible money

Welcome to buy one from my shelf...

Think I'd also go with a higher 20mm pitch if being used solely for cutting woods n plastics

Same, but you couldn't get 20mm pitch from eBay seller last time I checked. I would have done the same otherwise.
Thinking about it since end machining isn't strictly neccecary with a rotating ballnut setup (helps, but I reckon you could do it without by making mounts that clamp the screws, rather like the mounts for round rails) you could buy the 20mm pitch ballscrew from Zapp without spending £7.5*10^99 on end machining. This one:

http://www.zappautomation.co.uk/r161...121c620028629f

or

http://www.zappautomation.co.uk/r202...121c620028629f


Oh, just noticed the ball-nuts are a bit pricey ... shame.
I'd love to try it with some 20mm pitch screws and big motors / servos and see just how fast you can get with rotating nuts.

[JAZZCNC]

I'd love to try it with some 20mm pitch screws and big motors / servos and see just how fast you can get with rotating nuts.

Jonathan Don't understand the facination with speed.? . . . It's only any good upto a point then it's a waste. It's like very high rapid speeds there only of any use on certain types of jobs but in the main there useless and come at too costly a price.! . . . . Impressive, great for bragging right's but mostly pointless.

To be of any real use and cutt at high feed rates you need fast high horse power spindles, expensize tooling and a very ridged machines which can handle the force's involved

The cutter and material specs mostly dictate feeds anyway so IMO most high pitch screws are more than enough when it comes to DIY cnc and even small production use.

[Jonathan]

I know up to a point extra speed gives diminishing returns. Sometimes it just compensates for bad Gcode with lots of G0's. It would be good if you wanted to add a laser ... though of course there's easier ways to move just a laser.