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Dirty jittery movement on one axis
« on: November 09, 2013, 11:31:26 AM »
Afternoon All,

I wonder if anybody could help me with an issue I'm having setting up my new DIY CNC?

After about a year of this project being on the backburner I finally got around to finishing it; it's your basic 3 axis diy cnc setup with a high speed router and a parallel port interface. I have six 8 wire steppers (two per axis) connected to a board which has four outputs per axis (wired for torque rather than speed).

So, to the problem, once I got everything hooked up and configured in mach3 is that two axis run smooth as butter and the third is jumpy, weak and very noisy!

I did a fair but of goggling before posting here so these are the steps I have taken so far:

Slow the axis right down and other motor tuning; still just as bad.
Swap to motors over to eliminate a motor / wiring issue; whichever axis I hook up to this output has the same problem.
Reflow soldering on the section of the board related to this axis. Some joints looked a bit dry and a few needed a little extra solder; but no improvement.
Reflow the whole board right from the ports to the outputs; no improvement.

Any advice much appreciated.

Thanks, Alex

Offline Tweakie.CNC

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Re: Dirty jittery movement on one axis
« Reply #1 on: November 09, 2013, 12:36:23 PM »
Hi Alex,

Welcome to the forum.

Seems like you have done the right sort of trouble-shooting and assuming you have the micro-steps and drive current set correctly for the axis in question I would suspect the driver IC chip on your circuit board for that axis. If it is Toshiba then perhaps not too difficult or expensive to replace it and see what transpires ?

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Dirty jittery movement on one axis
« Reply #2 on: November 09, 2013, 01:18:02 PM »
With the micro steps and current I assume that's just the jumper settings? All three axis are set the same so I guess it is fine?

I can just about make out "TOSHIBA" on one IC very faintly; no idea what they are or where to buy one?

A
Re: Dirty jittery movement on one axis
« Reply #3 on: November 09, 2013, 01:24:45 PM »
Just had a thought, could I just swap two of them over and see if the problem moved to another axis?
Re: Dirty jittery movement on one axis
« Reply #4 on: November 09, 2013, 02:26:37 PM »
Well, I have just swapped two of the IC's over (on a quite badly designed board I might add) and you hit the nail on the head; the problem moved to the other axis so pretty damn sure that it's that IC now!

Question is, what is the part number and where can I get one?

Thanks again

Offline Tweakie.CNC

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Re: Dirty jittery movement on one axis
« Reply #5 on: November 10, 2013, 12:58:22 AM »
Do you have any details on the controller board or a picture perhaps ?

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Dirty jittery movement on one axis
« Reply #6 on: November 10, 2013, 10:31:12 AM »
The board says hyu68.com on it and it's a three axis board. I can get a picture later if it helps.

Thanks for your help, A

Offline Tweakie.CNC

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Re: Dirty jittery movement on one axis
« Reply #7 on: November 10, 2013, 12:12:52 PM »
HYU…
Dongguan Hungyu manufacture various stepper driver boards which are then marketed by other distributors etc under different names so it is difficult to identify which one you actually have.
As far as I am aware they all use either the Toshiba TA8435H or the Toshiba TB6560HQ driver chips and you need to identify which of these you have fitted.
Replacement chips are available from many different sources / suppliers but I would suggest an ebay search for the best price.

(Interesting that you are using 2 stepper motors for each of the 3 axes. As a general rule, it is not considered good practice to connect more than one stepper motor to each axis output from any driver board although I understand that it can be done).

Hope this helps.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Dirty jittery movement on one axis
« Reply #8 on: November 10, 2013, 12:42:27 PM »
Could you tell me why it's considered bad practice? I had plenty of motors and I figured that double the motors would be double the torque? Plus I have a 22,000rpm router as my cutter so I'm just using the slide on that for my z axis and it needs the two pressure points to keep it nice and straight.

I'm petty sure it's a TB given the choice of TA or TB so I will order one of them; thanks.

A

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Re: Dirty jittery movement on one axis
« Reply #9 on: November 10, 2013, 01:40:22 PM »
Quote
Could you tell me why it's considered bad practice? I had plenty of motors and I figured that double the motors would be double the torque? Plus I have a 22,000rpm router as my cutter so I'm just using the slide on that for my z axis and it needs the two pressure points to keep it nice and straight.

I understand your reasoning but both the TA8435H and TB6560HQ chips have been designed to handle just one motor. A web search should reveal the technical data, design data and manufacturers application notes should you wish to research this in more detail.

Basically, each stepper motor should have its own, dedicated, driver and ‘slaving’ of two axes (within Mach3) is the usual practice when two motors are used to drive together.

However, don’t let this stop you from trying your design ideas – stretching the envelope and thinking outside the box is true innovation but you should perhaps be prepared to run into problems which others before you have already discovered.

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