AndyUK's Build - 1.2x1.0m Gantry

[AndyUK]

Okay, so its been approximately a year. I suppose I'd better post an update or two!

First things first, current drawings:






I mulled over the advice I got from Clive and routercnc for a long time. far too long. I repeated my deformation calculations with various materials and geometries. Ultimately, Aluminium won :) There's a few solid reasons:

• Cost - It isn't as bad as I expected. The aluminium profiles are only about £50.
• Ease of working with. The connection to the side plates is just so much easier.
• Deformation is tolerable. I think it increases vs my steel design from 3.0um to 4.9um - Lets be honest, its never getting close to those tolerances elsewhere!
• Proven history of this configuration working for others on this forum.

That decision also cemented the plan for making the side plates out of 20mm aluminium plate - and I think they look reasonable. The other factor is that the milling machine is currently in storage a couple of hundred miles away, and at least I can work aluminium in my garage :D This means I'm also planning on going down the epoxy route for levelling the x-axis, and my belief is that the y axis on the ali-profile should be reasonable out of the box (?). That also allowed me to further copy Joe (thanks bud!) and start designing my motor mount locations etc.

Plan for the motors is that they're all going to have a 15mm timing belt connection to the ballscrews. I believe this allows me some flexibility to gear up/down in the future.

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?