[amirh]

Hi,

I'm a software engineer/manager. I never worked as a mechanical engineer. However I did worked in image processing and inspection algorithms for large scale inkjet printing machines.

Now I'm building a CNC milling by ordering parts from eBay.

I already ordered all the parts and currently I'm ordering the frame plates.

I'm trying to keep it simple and doable.

Best Regards,
Amir Hadar

[awerby]

It looks good so far, except I think those unsupported rails are a mistake, if you plan to cut anything harder than foam. Printers don't have to deal with the cutting forces that carving machines are up against; you need a lot more rigidity for a router than for an equivalent-sized printer.

Andrew Werby
www.computersculpture.com]ComputerSculpture.com

[amirh]

Thank for the reply,

I kind of hoped that the rigidity will come from this part.
However, all the X axis is held by two unsupported 16mm rails and one supported 1605 ballscrew.

I do hope to cut Aluminum with that machine.

[awerby]

Thank for the reply,

I kind of hoped that the rigidity will come from this part.

[Your machine will never be more rigid than its weakest part.]

However, all the X axis is held by two unsupported 16mm rails and one supported 1605 ballscrew.

[Supporting the rails is more important than supporting the screws.]

I do hope to cut Aluminum with that machine.

[Please write back and tell us how well that works for you, okay?]

Andrew Werby
www.computersculpture.com

[aarggh]

As Andrew rightly pointed out, that just doesn't look rigid enough. Your going to get a major amount of vibration on the X axis, and even more so on the Z axis if you plan to cut aluminium. I suspect the noise will be somewhat akin to a screaming banshee.

If your planning on routinely cutting aluminium to any decent degree, the X axis rails really should be the ones mounted on an alu support bar with as much perpendicular support on the frame as possible. I'd also spread them apart as far as possible while still allowing an appropriate depth of cut. I'd also do the same for the Z axis, the end supported rails may look strong, but they have a fair degree of flex. This flex will very strongly manifest when cutting a material like aluminium.

cheers,
Ian

[CarveOne]

It looks good so far, except I think those unsupported rails are a mistake, if you plan to cut anything harder than foam. Printers don't have to deal with the cutting forces that carving machines are up against; you need a lot more rigidity for a router than for an equivalent-sized printer.

Andrew Werby
www.computersculpture.com]ComputerSculpture.com

The round rails under the table have aluminum supports under them. The ones on the gantry appear to be unsupported. Those need to be supported also. Plunging into anything as hard as aluminum will cause the vertical axis rails to flex in the opposite direction. It will be worse in mid span. Ramping into a cut will help, but will not fully eliminate the problem.

[arizonavideo]

If you have not bought the round rails the supported ones don't cost much more

15mm rails and carts work well to.

Look here.

automation products from Automation Overstock: AGW15CA2U640Z1H, AG 15mm combo: TWO flange bearings and ONE rail, SPECIAL AG15 and AG20 Combo Deals

Two carts and 640mm of rail for $75.50

The ebay supported rails are fine too.

Have fun

Dave