operation cnc

[irving2008]

...[stuff]

1,)What is the maximum length I can have, with a conventional 'spun-ballscrew' setup (keeping the nut static)?

I intend to have two screws for the x axis, (one on either side)

The ballscrews descibed in the ebay auctions (linearmotionbearings2008) detail as being 'end machined'

4 pcs of anti backlash ballscrews RM1605-350/800/1450/1450mm-C7(4screws+4ballnuts+4endmachined)
4PCS NUT HOUSINGS/BRACKETS FOR THESE 3 BALLNUTS
4 sets of BK/BF12 with locknuts and circlips+ 4pcs 6.35mm*10mm flexible couplers
Linear slide rails SBR20-600mm(2 supported rails+4 SBR20UU bearing blocks)
Linear slide rails SBR20-300/1400mm(4 supported rails+8 SBR20UU bearing blocks)

so with the 'flexible couplers' also supplied in the kit, I assume will fit my steppers ?
Nema23 Stepper Motor 3.1Nm x 3

Given the BK/BF mountings you have a fixed/supported arrangement (supported BF at the far end, fixed double BK near the stepper) the critical speeds are:

350mm:10000rpm (lots of m/min)

800mm: 1965rpm (9.8m/min)

1450mm: 598rpm (3m/min)

To get closer to 6m/min on X you either need 10mm pitch screws, or you need to increase diameter to 25mm but then the inertia of the screws is going to be limiting on acceleration.

Another option is to upgrade the bearings to be double angular bearings (BK) at both ends. This will increase the critical speed to 880rpm (4.4m/min), better but still not great.

Here is a good PDF that shows how these are assembled: https://tech.thk.com/en/products/pdf/en_a15_314.pdf

And the critical speed calculator is here: http://www.nookindustries.com/engine....x=0&reset.y=0


Couplers are fine: 6mm stepper shaft to 10mm end machined screw.