Poor X axis homing accuracy

Troubleshooting the Pocket NC
#1

The homing on my X axis has become noticeably worse over time. I regularly see it home nearly a millimeter off in random directions. Is there a chance something came loose that would be not too hard to glue back in place?

#2

Hi Josh,

There are a couple of things that come to mind that could cause homing inaccuracy, but neither of them are likely to cause the axis to be that much off. Could you fill me in on how you are getting that value?

And the offset isn’t consistently positive or negative, it can be either, correct?

Thanks,
Q

#3

I’m getting my values probing a precision ground 8mm pin mounted in the ER40 collet. However, I can observe it pretty easily as well, if I ever have to re-home during the middle of a part, all the subsequent features are off by up to that much in the X axis.

The X axis homing is all over the place within about that range. I was dialing in my home offsets in the config, so there isn’t really a “sign” to it (since it is always relative to whatever I have the home position set at the moment).

#4

Thanks for that additional information, Josh.

After thinking about it a little more, the first thing I would make sure of is that the X circuit board is seated tightly under the X carriage. There should be a fastener that is accessible with the X axis in about the middle of its travel, make sure that is tight and the board cannot be moved around easily.

Here is a picture showing the location of the board to make all of this a bit clearer.

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20220217_1256081920×2560 340 KB

#5

That board seems plenty secure. Now that I see where the X axis homing magnet is, I wonder if my problems were just caused by chips laying on top of it. I admit to not being 100% fastidious in removing them from that area in the past. Let me try keeping it clear and seeing if my problems go away.

#6

Hi Josh,

Thanks for checking that board, I am glad to hear it was still secure.

The chips theory was the next thing I was going to bring up so I am glad we are thinking along the same lines. Let us know how things go moving forward and then we can keep troubleshooting if it is necessary.

Thanks,
Q