Aluminium profile CNC

[routercnc]

Your question about linear bearings - do you mean size? If so 20mm on all axes.
What is the plan on the Y ball screw? It goes straight through the Y and Z axis? With that type of layout some people space the YZ away from the gantry and run the ball screw behind. But this weakens it because of the overhang.
A more popular design is the L shaped gantry with the ballscrew running behind allowing the YZ to be close into the gantry.

[BriceO]

Your question about linear bearings - do you mean size? If so 20mm on all axes.

I mean which lead should I take, 20 or 10mm lead? I calculated a max speed of 500 IPM, does it seems to be correct? And do I need to have a ballscrew preload ?

What is the plan on the Y ball screw? It goes straight through the Y and Z axis? With that type of layout some people space the YZ away from the gantry and run the ball screw behind. But this weakens it because of the overhang.
A more popular design is the L shaped gantry with the ballscrew running behind allowing the YZ to be close into the gantry.

I planned to run the ball screw behind the gantry for this axis, but you're right I'll change it for the L shaped gantry.

For the longest axis, which one is the "best" design?
Add a spacer to the ballscrew. The ballscrew runs behind the plate and this plate will be near the bearing blocks. Something like this:

[Nr1madman]

I mean which lead should I take, 20 or 10mm lead? I calculated a max speed of 500 IPM, does it seems to be correct? And do I need to have a ballscrew preload ?



I planned to run the ball screw behind the gantry for this axis, but you're right I'll change it for the L shaped gantry.

For the longest axis, which one is the "best" design?
Add a spacer to the ballscrew. The ballscrew runs behind the plate and this plate will be near the bearing blocks. Something like this:

Hmm don't really understand but is "lead" the same as "pitch"?
Have read a lot about lead on the zone but that seems to talk about trapezoidal screws and not ballscrews?
Anyway what do you want to cut and in what resolution?

If you plan on having the ballscrew on the outside of the plate as in the picture then please don't forget that the screw must be longer then the calculated travel as the plate will travel inside the bearings :)

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[BriceO]

Hmm don't really understand but is "lead" the same as "pitch"?

Yes, exactly I mean pitch. I would like to cut mainly wood and a few tests with aluminium.

My goal is to have a resolution of 0.01 and an accuracy of 0.1mm. I tried to calculate the speed with a hiwin 2020 ballscrew, KL23H2100-35-4B NEMA23 and found a max speed of 500 IPM. Is it possible?

Here is the specs of the motors (4X):

[routercnc]

Ok thought you meant the linear bearings on the rails

For ballscrews my machine is 5mm pitch all round but if I was starting again then 5mm Z and 10 mm for X and Y. This gives better rapids in wood and should be Ok for aluminium but if you drive the X and Y via belt and pulley you can swap out the ratio on X and Y to give 2:1 to give more torque (and less speed) if needed on the aluminium
Not sure about 20 mm pitch - will give very high rapids but you loose some torque and could stall the steppers? Anyone tried this much pitch? May be ok with enough voltage on the steppers . . .

[BriceO]

Not sure about 20 mm pitch too :) Belt and pulley can offer more possibilities, good idea! Do you know where I could find good ones?

Someone made a graph for me for the same motor with different pitch considering the weight of the gantry, ballscrew type, motors specs,... :


10mm seems to be a good compromise. What do you think about that?