First Proper CNC Router

[Doddy]

Going to try tidying up the wiring to see if that helps. Got twisted pair for the control side. For the motor side, this might be a silly question, should I run all 8 wires all the way to the driver and connect the pairs there, or join the pairs close to the motor and just run 4 wires from there. For the purpose of testing I'm not using shielded cables at the moment, would that impact motor performance at all?

I'm assuming you mean you have 8-wire steppers? In which case it depends on how you're wiring them. If in series then definitely wire the phases together at the motor - you'll reduce your losses due to the resistance of the wiring that way. If in parallel then its less obvious to me (5:30am in the morning for me) - paralleling at the motor and only taking half of the cables back to the driver suggests greater losses in the motor leads. Ideally short the motor pairs at the motor without cutting the cables and take the pairs back to the driver and terminate there as well (i.e. run the cables in parallel back to the driver). Or just wire in parallel at the motor and use wire with a large CSA to export the motor drive back to the driver. It will make some marginal difference.

Shielding will not affect motor performance, thought it might help to avoid any induced noise into signal cables.

[diycnc]

Could someone help shed some light on the correct orientation of AC bearings?
I thought I had a handle on it, but iv just come to install some pulleys and iv spotted iv got some face to face, and some back to back, so now I think i must have misunderstood something.

My current understanding it face to face is the preferred orientation and to preload them to remove any backlash I shim the outer race.
Face to face is with the larger inner race face pointing towards each other?

A second opinion on this would be great!

[diycnc]

Scratch that.

If I'm shimming the outer race, I need them back to back.... with the larger inner race face pointing away from each other...?

[Lee Roberts]

Yea, for this application back to back is what you want.

[diycnc]

I'm struggling to decide between to different belt arrangements for my y axis (the one that moves the gantry). I will have to ball screws driven by one motor, with either one belt connecting all three pulleys. Or two separate belts, one connecting the screws, and one connecting the motor to a single screw.
I have space for either setup, and enough shaft on the end of the ball screws for the two pulleys needed for the dual belt arrangement.
I can see pros and cons for each, but struggling to make a decision.
Any suggestion?

[JAZZCNC]

Use the one that allows the shortest belt arrangement. They will all work equally well as each other but shorter belts are easier to find and implement.

This is my preferred setup.

[diycnc]

Thanks Jazzcnc.

Can anyone recommend a method of reinforcing my bolted connections on my steel frame. Currently have 4 m5 bolts at each connection between the steel box section, and after moving the machine around a few times during construction I'm certain the joints have moved.
I'd rather avoid buying a welder, so that leaves either more bolts, or glue.
There isn't much room for more bolts, so I think glue would be better, but I'm not sure what type would be best. Would a slow setting epoxy be a good idea?

[Voicecoil]

What's the orientation of the sections you're joining? Do you have plates/brackets? (a pic or drawing might help) Either way, 4 x M5's sounds a bit light duty to me, do you have room to go up in diameter? Properly done with the correct surface preparation and curing, epoxy can give a very strong bond - seems to work OK in aeroplanes :-)

[diycnc]

I'm not in the workshop at the moment, but take a look at the pic in post 36.
Agree 4 x m5 isn't enough, and I dont think there is room to go up in diameter. The existing bolt holes are a little too close to the side walls to go up in size.
Will try some thin slow setting epoxy on a test piece befor I apply to the frame

[Voicecoil]

I'm not in the workshop at the moment, but take a look at the pic in post 36.
Agree 4 x m5 isn't enough, and I dont think there is room to go up in diameter. The existing bolt holes are a little too close to the side walls to go up in size.
Will try some thin slow setting epoxy on a test piece before I apply to the frame

From the pic. and the few screws that are visible it looks like there might be a bit of room to go larger - but then again it's not a close-up, so do check it. If you're using slow setting epoxy do check the manufacturers curing instructions. Araldite Precision for instance cures with better strength at a slightly elevated temperature - as well a a lot quicker. And remember that once it sets you can't adjust stuff any more - so make sure everything gets properly lined up!