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Author Topic: Losing Y position erratically  (Read 4222 times)

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Losing Y position erratically
« on: August 14, 2014, 08:25:02 PM »
Hello everyone.

I am new here. I have read through these forums MANY times but today I ran into an issue that I could no longer deal with.
I will try and keep this short and to the point.

My CNC is a Techno Isel 040 H830 with stepper motors. I am using the latest version of Mach 3.
I was running a guitar body today and after completing one toolpath, the CNC started the next toolpath 1" too far to the right. I have only had this problem once before. I was cutting out a guitar headstock shape and the CNC was too far in the Y+ axis by roughly 1". This has never happened to any other AXIS.


Upon reading through some forum posts, my issues are very similar to this post (I am pretty sure my Mach 3 is legit though):
http://www.machsupport.com/forum/index.php/topic,23270.0.html

If memory serves me, the DRO and Toolpath showed the travel was in position. When is reality (looking at the guitar body on the table), it was not.
If I remember correctly as well, the first time I had this issue the CNC had been running all day. This was the case this time as well. I felt the stepper motors today and they were quite warm to the touch. The controller felt warm as well (not as hot as the steppers).

I posted an image of the damaged area. The start of the neck pocket was supposed to be left by about 1"!


This problem has only happened twice but I would like to rectify the issue before destroying any more material.
I hope you all can help!

Thanks.

Offline Tweakie.CNC

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Re: Losing Y position erratically
« Reply #1 on: August 15, 2014, 07:00:03 AM »
Just a shot in the dark but I would be inclined to look at the stepper motor controller and make sure it has enough circulated air cooling. Perhaps fit another PAPST type fan ??

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Losing Y position erratically
« Reply #2 on: August 15, 2014, 08:52:51 AM »
Hello Tweakie.

I can try that. The controller box is held in a cabinet. I will pull it out of the cabinet and hopefully that will dissipate some of the heat. If it still gets hot, I will look at pointing another PAPST fan at the stepper controllers.

How cool should the whole controller box be? I take it the box shouldn't get hot at all, correct?

Offline Tweakie.CNC

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Re: Losing Y position erratically
« Reply #3 on: August 15, 2014, 11:15:38 AM »
The driver will run warm but the actual stepper motor driver chip must not be allowed to exceed the manufacturer's specification on working temperature.

(On another forum some have experienced similar problems to those you describe and fan cooling resolved the issue - thus my suggestion  :) ).

Tweakie. 
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Losing Y position erratically
« Reply #4 on: August 15, 2014, 11:19:09 AM »
Tweakie, I apologize for my lack of knowledge but what does a stepper motor driver chip look like? Where would it be located in my control box? Would there be a stepper motor driver chip for each AXIS?

I also wanted to state another thing. My router is a Porter Cable 75182. It does not have a ground in the power cable. Just two prong. Would this cause an issue? (Though the Y positioning problem has only happened twice and when I want to, I can not recreate the issue on cue)
« Last Edit: August 15, 2014, 11:23:48 AM by AlexanderJamesGuitars »

Offline Tweakie.CNC

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Re: Losing Y position erratically
« Reply #5 on: August 15, 2014, 11:37:45 AM »
Yes, one driver chip for each axis is usually the case.

Most single phase routers are "double insulated" and only have the two wires. If electrical noise was an issue I think you would see the axis position fault on a much more regular basis, if not continually.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Losing Y position erratically
« Reply #6 on: August 15, 2014, 12:43:44 PM »
I took a picture of my controller box. What parts in here need to be cooled? Are the stepper driver chips in the slo-syn translator motor drives (on the right)?. Or are they on the board closest to the fan, the microstepping system (on the left)?

As you can see, only one fan is in the box. How would I wire in a PAPST fan?
Sorry for my inexperience. Just learning the tech side of it all now.

Offline Tweakie.CNC

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Re: Losing Y position erratically
« Reply #7 on: August 16, 2014, 02:23:52 AM »
Well, it looks to me like the existing fan is more than adequate to do the job so I don't think adding another fan would serve any useful purpose. I assume that the board closest to the fan is your Z axis and the two slo-syn's are your X an Y ??

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Losing Y position erratically
« Reply #8 on: August 16, 2014, 03:45:47 AM »
Well, it looks to me like the existing fan is more than adequate to do the job so I don't think adding another fan would serve any useful purpose. I assume that the board closest to the fan is your Z axis and the two slo-syn's are your X an Y ??

Tweakie.

It sure 'looks like' a fan, but has it been seen running under power? I've had two fans go down from China (well one gone and the other sounding like it's dying fast :v )

Offline Tweakie.CNC

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Re: Losing Y position erratically
« Reply #9 on: August 16, 2014, 03:50:58 AM »
Good point DoubleTrouble - is the existing fan operating correctly and efficiently ??

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.