Bit dancing off course...suggestions?

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devildoc87
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Joined: Wed Oct 05, 2022 1:19 pm
Model of CNC Machine: Shapeoko Pro XXL

Bit dancing off course...suggestions?

Post by devildoc87 »

Ok this weeks nightmare brought to you by African Mahogany and a 1/4 upcut bit.

The profile path was going fine until it took an unexpected turn.

Settings: depth of pass 0.15, Rate 80 inch/min, plunge 40 inches/min

10 passes. The collet was clean and the bit seated firmly.

The photos are attached. The bit basically does a 90 degree angle when supposed to be cutting out a circle and then cuts a helix instead of the circle.
Attachments
20221118_191827.jpg
20221118_191847.jpg

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Tex_Lawrence
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Re: Bit dancing off course...suggestions?

Post by Tex_Lawrence »

This very much seems like the typical loss of communication from the PC to the control board on your Shapeoko. Some call it "static", but it may be anything. We're getting into the winter dry season.

One way to solve it is make sure that everything is grounded well (and hasn't come loose recently.)

Another way is to change your USB cable to a shielded cable. This seems to provide a better common connection to the control board.

It can be completely random and may never show up again, but it's not likely to happen that way.
Crooked Wood Products - Custom Wood
Truth lies dormant in our future history ― Tex LXX

devildoc87
Posts: 24
Joined: Wed Oct 05, 2022 1:19 pm
Model of CNC Machine: Shapeoko Pro XXL

Re: Bit dancing off course...suggestions?

Post by devildoc87 »

Thank you. I'll look into that!

devildoc87
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Re: Bit dancing off course...suggestions?

Post by devildoc87 »

This is why I am starting to fear my machine. I slowed down all the feeds and lowered my depth of pass to 0.08 on this cherry cribbage board. 6 hours later as I'm in the LAST profile cut out pass it screws me. I have no words for the level of frustration I am having right now.

I've ruined about $60 of wood projects this week because the machine went off track on profile cuts. I've tried new bits, slower feeds, and it keeps screwing me.
Attachments
20221119_174425.jpg

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gkas
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Re: Bit dancing off course...suggestions?

Post by gkas »

That's why you have to ground everything and check out your usb cables for shorts.

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Re: Bit dancing off course...suggestions?

Post by Tailmaker »

A common problem is ground loops. If your (grounded) machine controller is plugged into one outlet and your (grounded) PC into another outlet, maybe even on different breakers, the USB cable will connect all that to a very large ground loop that is prone to pick up a lot of EMI noise from spindle, router, steppers and the like. So, make sure when you ground your system, that ideally all component grounds connect to a single point.
Some things that can help with that are:
- plug in the PC very next to the machine into the same outlet (assuming the machine is not 240V)
- use a laptop or stand-alone desktop as PC, many of them are not grounded in their power supply.
- use a USB isolator (like Linear Technologies LTP2884)
But:
- do not just break out the grounding pin from your PC power plug. That may solve the noise problem but would not be safe and against the code.
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Tex_Lawrence
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Re: Bit dancing off course...suggestions?

Post by Tex_Lawrence »

devildoc87 wrote:
Sun Nov 20, 2022 12:03 am
This is why I am starting to fear my machine. I slowed down all the feeds and lowered my depth of pass to 0.08 on this cherry cribbage board. 6 hours later as I'm in the LAST profile cut out pass it screws me. I have no words for the level of frustration I am having right now.

I've ruined about $60 of wood projects this week because the machine went off track on profile cuts. I've tried new bits, slower feeds, and it keeps screwing me.
It isn't your machine's fault! Its a machine. :lol: If you are going to test for solutions, perhaps don't do it on an expensive project? :lol:

You might be better posting this on the C3D Shapeoko forum (http://community.carbide3d.com/). There will be many very hardware related solutions for you to try. Perhaps do a search first for some of the previous suggestions for your particular model. Highly recommended.

[ C.3.D S.h.a.p.e.o.k.o forum (http://community.c a r b i d e 3 d.com/) ]
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scottp55
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Re: Bit dancing off course...suggestions?

Post by scottp55 »

Static Season is upon us....don't forget the bare wire INSIDE the hose. :)
This is good from Gary!
https://www.youtube.com/watch?v=zKzjhp-yDkE
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devildoc87
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Re: Bit dancing off course...suggestions?

Post by devildoc87 »

Thank you all!

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