New build – input/comments appreciated

[Clive S]

I think you will need more teeth in mesh on the motor there are several examples of how to do it on the build logs.

[JAZZCNC]

I'm Going to contradict myself now..!!! . . . If your not going straight across with the belts then I wouldn't bother has it's very complicated and messy with belt that long winding around the machine. Keep it simple else stay with Slaved Motors.

Yes the belt approach is much more reliable and gives great piece of mind your always in sync. But not if the setup is overly complex it's needing constant attention and with belt this long threading around the back I fear it may cause trouble.?

So I'd say either change the design and keep it more direct or keep with slaved motors which if properly tuned and connected to good drives don't give too much trouble.

[Lee Roberts]

All fixed!

.Me

[ngundtoft]

I am back.
I have not been able to post mails, because my thread suddenly disappeared. Lee has been very helpful and has recreated most of it. However, there are still some drawings/pictures missing. JAZZ can you please mail the very instructive gantry pictures again and CharlieRam can you also please send your nice drawings again?
Anyway, I agree with JAZZ, I was not too happy with the very long and complicated belt in my (now missing) drawing. The drawing from CharlieRam is a much better Construction, from a mechanical point of view, but, (as JAZZ also points out) I do not like that it blocks the end of the bed if you need to route long structures.

Previous drawing with long, complicated belt:

Drawing where I have put back the extended cantilevers at the top of the machine and moved the now longer, ballscrews, and crossed the belt over directly between them. The bracket serves as cover for the belt, and the motor/idler-pulley assembly goes on top of it, so that it doesn't block the end of the bed.

[Boyan Silyavski]

I would go even further and make it so that the belt is tightened by some screw that moves the motor up and down. Additional plate that slides or sth similar.

As for how far the Z should extend is suggest you contemplate this screen snip and read post #8 where i am trying to explain the benefits of properly designed Z axis


The idea is to achieve maximum Z extension with minimum effort and maximum rigidity as a result, using the spindle body to make Z super stiff.
is more than enough for more


My advice is to understand this/about the Z/ and check your design backwards from there. 150mm Z travel is more than enough for all purposes.

The Z on the picture will extend 200mm with 3kw spindle , but that would seriously question a beginners design. As a precaution the plate should be 20mm steel or 30mm aluminum and reinforced with side braces /against front back deflection/ exactly where the black line is especially at the yellow area. Of course another design problems will arise from such an extension so you have to make sure left/ right you dont have any weeak element on gantry, gantry sides, ball screw mounts, etc.