3 Axis CNC router

[njhussey]

Joe, I'd put a plate over the square steel section your rails are moumted on, move the top pulley to the right and move the other pulley next to it. That way you'll have more teeth in contact with the ball screw pulley.

[JoeHarris]

Joe, I'd put a plate over the square steel section your rails are moumted on, move the top pulley to the right and move the other pulley next to it. That way you'll have more teeth in contact with the ball screw pulley.

Yeah that's quite a nice idea. I think I might be too tight for space to get a good depth to tap for the idlers. I could certainly pull the lower left one up though which will improve things. This was a quick and dirty to test. I still need to draw a nema 34 as this is still based on the smaller nema 23 frame. Going from 56 to 86mm will change the setting out quite a bit...

Also any ideas why the SY85STH118-6004B Nema 34 Stepper motor from Zapp costs £94 and the cnc4you 86HS115-4208 8.7Nm Nema 34 Stepper Motor costs £71? Same size and torque and Inductance is the same...

[JoeHarris]

More or less complete design for the single motor, long belt method.
The idlers are both fixed and made from standard skate bearings spaced in the middle with a washer and edged with two penny washers to provide flanges - these will be mounted on a M8x40 bolt taped into the aluminum plate and stood off with a stack of washers. I can adjust the height of the whole motor assembly if necessary and fine adjustment can be made by raising or lowering the motor on 10mm slotted mounts, this was the max I could achieve with the large circular projection (which I assume houses the bearings) at the center of the motor.

Both lengths of the long belt (top and bottom) are supported on UHMWPE (blue stips on the image below) which will be bolted down to steel angle which in turn will be welded or bolted to the frame with strips of 90x6mm flat bar. This support framework can then double up as the framework for a belt cover.



The motor this is all based on is the cnc4you 86HS115-4208 8.7Nm Nema 34 Stepper Motor as highlighted on the data sheet below:

[njhussey]

I'd still put the top idler on the end of the square section (with a suitable thick plate welded/bolted in) and move the lower idler to the first idler's position.....

[JoeHarris]

I'd still put the top idler on the end of the square section (with a suitable thick plate welded/bolted in) and move the lower idler to the first idler's position.....

Like the blue lines in this?:

[njhussey]

Like this....excuse the freehand scribble!!



Edit...Hah just seen the lines you drew....need to open my eyes!! Yes like that, will give much more teeth in contact, I know 5 is the min but I always think the more the merrier!!

[JoeHarris]

[QUOTE=njhussey;76714]Like this....excuse the freehand scribble!!

Yes, sorry that's what the really faint blue lines were supposed to show!!!

[JoeHarris]

If at first you don't succeed... be glad you modeled it first!