AndyUK's Build - 1.2x1.0m Gantry

[AndyUK]

I want to start ordering the linear motion bits - so I've got a few questions:

I've up-beefed the x-axis ballscrews to 2010 1100mm. The y axis is currently 1610 750mm, and the z is 1605 250mm. I'm having a little crisis of confidence in these though, so before I bother Fred for a quote, does that sound right to everyone? Does that get appropriate speeds for what I'm planning on doing? I'm probably mostly cutting wood and occasionally glass and aluminium - I guess I can gear the x axis if it becomes a problem? I was planning on 4x 6nm Nema 23s.

Second crisis of confidence about the screws is the bearings. I'm planning for a BK15 and BF15 (one either end, fixed at motor) for the x axis, then BK12 and BF12s for the Y and Z. Add to that a ballnut for each screw, and thats everything right? :)

Finally, I think my linear rails are as follows: All 20mm, 1200 on X, 850 on Y, and 400 on Z. I think I'll need 12 carriages. Sound good?

No readers objected violently, so I've got a quote for the above from Fred. Very helpful and quick service.

First thing he pointed out was that I needed to specify that I'm planning to use timing belts on the ballscrews rather than direct connections, as the machining will be different. Can anyone shed some light on why? Is it a different shaft diameter or is it keyed or flatspotted for a grub screw?

Second point is he has offered two types of BK support, one with upgraded P5 AC bearings. Any thoughts?

[Clive S]

No readers objected violently, so I've got a quote for the above from Fred. Very helpful and quick service.

First thing he pointed out was that I needed to specify that I'm planning to use timing belts on the ballscrews rather than direct connections, as the machining will be different. Can anyone shed some light on why? Is it a different shaft diameter or is it keyed or flatspotted for a grub screw?

Second point is he has offered two types of BK support, one with upgraded P5 AC bearings. Any thoughts?

Probably because on the ball screw where the pulley fits is called the F length I think from memory this is about 25mm if you are using pulleys then tell him to make it 30 or 35mm you can always cut it shorter.

Go for the best bearings re the BK