Chattering X motors

[Mayo]

I've been plagued by chattering noises on my X motors.
Today I tried isolating what was happening and here are the results:

X1 motor alone plugged into X1 or X2 or Y = No chatter
X2 motor alone plugged into X1 or X2 or Y = No chatter
in these tests, other motors were not plugged in.

X1 and X2 both plugged in to their respective drivers or swapped, = Chatter - with or without other motors plugged in.

This leads me to believe either the Y carriage is misaligned possibly by one tooth on the pinion gears? Or that there is an electronic issue or software setting issue.

If it's electronics, I guess this would be the time to upgrade the PRT to the 4G control board.

If it's software setting related, anyone have any ideas what might be set incorrectly?

[Brady Watson]

Try checking square using 3,4,5. A 30x40 rectangle should measure exactly 50" on the diagonal. See where that puts you; go larger with the rectangle for a more precise indicator. You can scribe the table using a small bit and use your tape to measure...burn an inch first to get a more accurate reading. You only need to go deep enough to see/measure it.

You are probably running the old angle iron motor mounts on your tool, which are not as stiff as the 4G mounts. I'm pretty sure SB still sells them. That would keep the pinion to rack in better alignment by reducing flex/twist. For the heck of it, take a couple of wood wedges say 4x1 x 0.5" thick (tapering down to nothing) and gently wedge in between the motor mount and the gantry. With the tool running down the X, put a little pressure on those wedges and see if that helps any. That will tell you there is some flex going on there if the noise goes away. Don't put too much pressure on them.

-B

[Mayo]

Thanks for the reply, Brady.
Yes, my motor mounts are the angle iron (blue painted, as supplied by Shopbot)

I tried the wood shims however I put them between the motor body and the gantry. This didn't change anything. I'll try between the motor mount and the gantry tonight and see if that does anything.

The X motor mounts have a large washer between it and the gantry. I think that's how the installation manual said to put things together but maybe that's allowing the motors to move sideways. I'm going to drop the motors and remove the washer. If that doesn't change the chatter, I'll put the washer back on each motor mount.

Now that I've resurfaced my spoilboard, I'll run the 3,4,5 test for square.

[Brady Watson]

You don't want to remove the washer. Keep it in there.

-B