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Author Topic: Spindle Speed Troubles  (Read 11988 times)

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Offline Katoh

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Spindle Speed Troubles
« on: November 07, 2008, 08:40:04 AM »
Hi to All
Ive recently connected a Digispeed DC06 to my router to control a high speed spindle motor.
NO Problems through Mach I can get Start Stop Forward Reverse and spindle speed (big Grin)
The problem arises when I move an axis being Either X, Y, Z the spindle will accelerate with the movement of the axis.
Ive checked the incoming voltage under movement doesn't change. The digispeed uses power from the VFD to use as its 0-10v logic well that doesn't change under movement either. I'm sure I have got the Digispeed configured correctly, according to the manual it does what it should. I thought I may have a floating voltage somewere between the VFD and the control box, I even connected the VFD neutrals to the main neutrals to no success. Ive been told it may be noise? All my cables are shielded and earthed, I don't seem to have a problem with anything else. My assumption is somewere in Mach when an axis is moved its also sending extra signals to the digispeed. Remember with no axis movement but the machine powered up it works like a dream.
Please any suggestions, Ideas I'm running out.
HELP
Cheers
Katoh

Offline Chip

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Re: Spindle Speed Troubles
« Reply #1 on: November 07, 2008, 01:09:43 PM »
Hi, Katoh

This may be causing your Problem.

Check for a stable (locked in)  Pulse Frequency on the Diagnostic Page, It should show a value corresponding to your set hernial speed (25k, 25***, 45k, 44***),

If it's not stable your p-port output will vary during running of g-code and mouse movements, Causing your step-dir spindle output to vary your VFD output.

Look at the Optimization link for windows XP,  http://www.machsupport.com/downloads/XP_Optimization.txt

Do the item's one at a time, As you may not need all of them, May fix it.

Hope this Helps, Chip



Offline Katoh

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Re: Spindle Speed Troubles
« Reply #2 on: November 07, 2008, 07:39:42 PM »
Hi Chip
I did a windows optimisation when I first loaded mach. I went through it again and I could not see anything wrong.
I don't really understand kernel speed, but I tried all the different speeds and they all do the same thing. With kernel speed are you after a speed that comes closest to matching what you set? Say if I set it to 35k then in diagnostics it comes in at 33k,
but if I set it to 60K and comes in diagnostics as 60.5k that would be a better option?
Anyhow that's not the problem.
one thing I noticed if I turn on the power to the spindle and the drives first then start the computer as it starts loading windows it will sent what seems to be a small pulse to the steppers and the spindle as the machine gets a little shutter and the spindle fires up for a fraction of a second. Or is this normal?
Cheers
Katoh

Offline Hood

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Re: Spindle Speed Troubles
« Reply #3 on: November 07, 2008, 08:01:46 PM »
When windows is booting it often queries the parallel port and this can cause your motors to twitch.
That is why most breakouts have a Charge Pump function, they will not allow movement of the motors until Mach is in control of the port.
 There was someone with a similar issue a few days ago and they resolved it, I will see if I can find the thread and post a link if I can.
Hood

Offline Hood

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Re: Spindle Speed Troubles
« Reply #4 on: November 07, 2008, 08:03:51 PM »
Heres the post I was thinking about, hopefully it will help you. http://www.machsupport.com/forum/index.php/topic,9377.msg57283.html#msg57283
Hood

Offline Katoh

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Re: Spindle Speed Troubles
« Reply #5 on: November 07, 2008, 09:33:51 PM »
hi Hood
Read the thread tried what they found out still no avail.
Funny thing that I just found out The spindle will only increase in speed when the axis movement is forward, backward movement will not increase spindle speed, well at least not noticeable.
Cheers
Katoh

Offline jimpinder

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Re: Spindle Speed Troubles
« Reply #6 on: November 08, 2008, 04:53:55 AM »
You don't say whether this increase in speed is while the axis are moving, i.e. it slows again when the axis are stopped - or just carries on at the higher speed.

You don't say whether  you are using LPT1 port or Smooth Stepper, or what.

I was wondering if there is some fault in your port output which is causing some "cross signalling". Try altering the pin number that the PWM speed signal to the Digispeed goes out on and see if the problem persists.

Pins 2 - 9 are one address on the port, pins 1,14, 16 and 17 are a seperate address. The "dir" output on your spindle drive (bottom of Ports and Pins/Motor Putputs) should be configured port 0, pin0 since it is not used.
Not me driving the engine - I'm better looking.

Offline Katoh

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Re: Spindle Speed Troubles
« Reply #7 on: November 08, 2008, 07:16:03 AM »
Hello Jimpinder
The spindle will increase speed while the axis is moving, once the axis has stopped the spindle will then go back to its set speed setting.
The digispeed is wired from BOB NO2 I have two BOB's on the machine. I don't have problems with Bob 2 as it running other functions and also an axis that are running fine.
The way I have configured the DCO6 is as follows
In the Ports and pins.
Spindle Step pin 16 active low, Dir pin 1 active low both Port 2.
In the outputs Output 1 Pin 17 active low port 2
This was advised for me straight from Peter Homann the maker of the Digispeed.
While the machine is at rest You can give it the command say "S7350 M3" and the spindle will turn CW at 7350rpm which is have its Max Speed the digispeed will have an output value of 5v, Give it the command "M4" and the spindle will stop and turn CCW at 7350 rpm Increase speed via Mach and it will increase all the way to 14700rpm digispeed will have an output value of 10v. No problem there.
Lets say spindle speed set at 7000rpm jog the machine forward either X, Y, or Z and the spindle increases speed. Jog the machine Backward and the spindle stays at a constant, (or I cant notice a difference if there is One)
I have taken the the power supply for the digispeed of a 5v terminal on BOB2, I have tried taking the power from BOB1 still no difference.
The BOB's are CNC4PC c10
Cheers
Katoh

Offline jimpinder

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Re: Spindle Speed Troubles
« Reply #8 on: November 09, 2008, 05:02:08 AM »
I have no experience of the cnc4pc c10 boards, so I can only say we have heard of problems with them on the forum before.

I have a feeling that the common wires are something to do with the problem, and I think they reverse some of the input/output functions - i.e. a +5v input gives a 0v output from the board.

You do not need a Bob board attached to the Digispeed, your computer is powerful enough to drive it directly - mine does - so try running a single wire from the pin to your digispeed and cutting out the electronics on the Bob. You should be able to access the input side of the LPT1 wire on your Bob. See if this gives the correct performance. If it does, then this shows where the fault is.

You really need to trace the PWM signal from the computer to the Digispeed with an oscilloscope to see how it is corrupted. That is difficult if you don't have an oscilloscope - I don't either.
Not me driving the engine - I'm better looking.

Offline Katoh

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Re: Spindle Speed Troubles
« Reply #9 on: November 09, 2008, 06:17:51 AM »
Hi Again jimpinder
I had a good chance this afternoon to do some other tests and try different things. Firstly I took all the power and neutrals to the digispeed from a separate power source, no good. I am in the unique position as well were I am running two BOBs of Se perate Ports. I swapped the digispeed to the other port still to no success. I tried using different pin no.s to no avail.
I think there is something more menacing than a small glitch were I disabled the the spindle in the ports and pins motor outputs config. and the spindle still fires up with the same problem. I am really starting to lean to that the Digispeed board itself is faulty or has some glitch in it. Not sure to replace it with a C6 speed control from CNC4PC or try another Digispeed.
I can get hold of an Oscilloscope (I think if its still there)but I wouldn't have clue how to use it or what I'm looking at.
Cheers
Katoh