Aluminium profile cnc build

[valdis034]

I am not so used to this machine terminology, but cross bracing in my case are these aluminium extrusions which are joining longest (x) axis, yes?
And if i understand right i cant have middle legs because that cross brace between gantry, but that aplies only for single ballscrew on x axis. I am going to have two ballscrews on x axis driven with belts by separate motors.
The bed probably i will have several 40×40 extrusions attached to the main frame, and on those extrusions i think should be good to have sacrificial plywood or mdf.

Does that sound good?

And sorry for my terminology, i promise i will get used to that! :)

Išsiųsta naudojantis SM-G900F Tapatalk 4 Lt

[JAZZCNC]

I am not so used to this machine terminology, but cross bracing in my case are these aluminium extrusions which are joining longest (x) axis, yes?
And if i understand right i cant have middle legs because that cross brace between gantry, but that aplies only for single ballscrew on x axis. I am going to have two ballscrews on x axis driven with belts by separate motors.

YES. But 2 screws will mean having them on the outside where they are unprotected from Debris. The Cross brace allows you to keep them under the table out the way.

The bed probably i will have several 40×40 extrusions attached to the main frame, and on those extrusions i think should be good to have sacrificial plywood or mdf.

Does that sound good?

No 40 x 40 isn't strong enough really you want 80 x 40 for the bed supports. Or at least two with 40 x40 filling the in betweens.

[valdis034]

Yes, so today i changed a profile size, and added extrusions as cross braces and as a bed, on which should go plywood, and added adjustable legs. Not sure how it is better to do with middle legs, if i want keep ballscrews under the bed, it means i cant have them in the middle. On the other hand seen a lot designs with screws on the sides, what is better?
About taking screens in solidworks, i take them view>screen capture>image capture and then paste into paint and the quality of pictures when i upload them here doesnt seem as good as seen in other threads, thats the way it should be done or there are some other ways ? Cheers! :)

[JAZZCNC]

Much much better. Could drop one 40x40 from each section if wanted. Less drilling and material for not much loss of support.
The main difference with screws under bed is they are obviously more protected from debris. This may seem a little detail but in practise it does make big difference to life span of screws and to some smaller degree performance because they don't get clogged with debris.

[valdis034]

Thank you for you replies! :) Now i need to position rails and ballscrews on x (longest) axis. To do that i think is good to start from side plates then i see where to put rails and screws. Aswell thinking about thicknes of the plate, 20mm would be enough?

I am going to use wide bocks. Wondering what distance should be between them. The lenght of block is 61.4mm if i add 27.2mm between them it will be 150mm. So if am using 1500mm rails the usable travel distance will be 1350mm. Maybe i need bigger gap between the blocks or maybe even smaller?

Here are my corners, should be allright?
I could use anchors, like these or even combination of 90 degree angle and anchors under them? Lots of thoughts how to start everything and put together, so sorry if all those questions sound silly :)