My first go at making a CNC router

[Norgmonster]

Most of you guys may know all about it but I have found a great resource of 3d CAD files on a site called www.b2b.partcommunity.com. The files are also available in a number of formats so they can be read by almost any program. https://grabcad.com/ only seams to support Solid Works.

If anyone is interested then let me know what they think.

My CNC router is moving along and i hope to have something to show you all tomorrow evening.

Good night all,

Norgmonster

[Norgmonster]

Hi All,

I've been working all week so no time to post much.

I'm learning Fusion and getting my design nicely visualized. In doing so i have come up with some questions:

For my X, Y and Z axis I'm thinking to use Hiwin rails and blocks. What size blocks would be sufficient / not overkill for a R&P driven, 4x8 bed? I'm thinking 20 but would 25 be better? Also, as the axis gets smaller can the rails get smaller as well? For example, 25 rails on the x, 20 on the y and 15 on the z.

Also, is it worth using a belt between the stepper motor and ball screw on the z axis to prevent backlash. If the stepper motor is directly driving the ball screw then will an anti backlash nut be sufficient seeing that the travel is only around 20 - 30cm?

[Neale]

20mm rails seem normal on that size of machine. Overkill in terms of strength for the Z axis, but when you start looking at the Z design in detail you are probably going to end up with two parallel plates, one fixed and one moving. 15mm rails don't really give you enough room between the plates for a ballnut. Use 20mm and you will need to cut some clearance slots and pockets, but it's a much easier fit. Belt or direct drive won't make any difference to backlash in a ballnut (assuming that you use a decent quality coupling between motor and ballscrew) - it's only the way that the ballscrew is driven and backlash comes down to the quality (=price!) of the components you use which affects the fit between nut and screw.

[mekanik]

The use of a belt between your ballscrew and motor can help prevent resonance in motor, so would include them on X & Y drive.
Mike

[Norgmonster]

Thanks Mike.

I'm only using a ball screw on the z axis. I'll be use a belt with the pinion stepper motor mounting plate on the X and Y.

[Norgmonster]

When it comes to the Linear Guideways, what is the differences in performances between a "standard" block and a "flat" block? Could I use standards for the x axis that will be taking the most load and flats for the y?

[Norgmonster]

This is my first stage design for my router. I will add more photos from different sides soon but if you have any comments or questions then let me know.