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Messages - SimonD

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51
General Mach Discussion / Re: Spindle Index problem.
« on: May 10, 2008, 07:48:36 AM »
Rich,

Check your index debounce level. Try 0 or 1 and see if that makes it better.

Simon

52
General Mach Discussion / Re: Spindle Index problem.
« on: May 10, 2008, 04:35:48 AM »
Rich,

Where is your slotted disc mounted? actually on the spindle or on an intermediate pulley? If it is mounted on the spindle then I would not think you need to adjust the spindle speed using a ratio.

I cannot speak from experience as I have onlyjust got my spindle to work properly, I haven't actually cut anything yet but I would imagine you need to get a good reliable rpm reading from Mach3 before you consider trying to cut a thread otherwise who knows what the result will be!

Simon

53
General Mach Discussion / Re: Spindle Index problem.
« on: May 09, 2008, 05:21:54 PM »
Ian,

Yes, both directions work ok. and yes there is a settable delay for switching the M03/M04 on and off.
The rundown time when a E-Stop is activated is a bit too long for my liking so I still need to add a breaking resistor somehow but I will work on that later. I tried switching in a resistor across the windings but it didn't seem to do much. I need to readup on it a bit.

Simon

54
General Mach Discussion / Re: Spindle Index problem.
« on: May 09, 2008, 03:53:50 PM »
OK...
Here is my guide for setting up the Speed control...
All the usual disclaimers apply...
"Your mileage may vary"
"Keep out of reach of children"
"These instructions are packed by weight not volume, contents may settle in transit"
etc
etc



I am using the following hardware...

Boxford 160TCL
CNC4PC C11G Breakout Board
CNC4PC C3   Index Pulse Board
CNC4PC C15  Dual relay Board
Lenze 534   DC Speed Controller


Setting up The Index or Timing Pulse
------------------------------------
Initially I had a single ~6mm wide slot on a 125mm disc. This is the original timing disc on the Boxford. The choice of ~6mm was made for me as it was the distance between the outside edges of 2 of the existing holes in the disc.

Make sure that the sensor is not lined up with the miriad of holes, but the solid area on the disc.

I have connected the Signal to Pin15 on the C11G card as that is the fastest input on the card.
Be carefull to connect the ground to a ground pin on the C11G. The pin next to Pin15 is a 5v pin NOT ground!

The C3 card defaults to outputting a signal when it is NOT aligned with the slot. So you need to flip the "active low" setting in Mach3 until the dignostic page "Index" or "Timing" LED lights when it is aligned with the slot.

Mach3 sets the default "Index Debounce" level to 100. On my system this was way too high and resulted in being able to get whatever RPM value I wanted just by changing the debounce value. The higher the debounce the lower the RPM.
I have my debounce set to 2.

At this point I didn't believe the speed reading I was getting so I decided to try the "Timing" input instead.

I changed the slots to 3 off ~10mm wide and 1 off ~20mm wide and changed the "Inputs" section of Mach3 to see the "Timing" instead of the "Index" on Pin 15 and hey presto I got exactly the same RPM values!

NOTE - If you go to the "Calibrate Spindle" dialog the "number of pulses per rev" should tell you how many slots you have, ignore the note in the dialog which tells you it should show 0 for 1 slot. Mine allways said 1 when I had 1 slot and now says 4.


Setting the Analogue Output
---------------------------
The C11G has an analogue out section which converts a STEP/DIR signal to a 0-10v signal.
The C11G only has 1 mechanical relay. This *can* be used as the direction relay for the spindle, however, when I tried it, I found that when you hit the E-Stop the power would be cut and the direction relay would reset and the spindle would suddenly run down in the opposite direction.

I did not like this so I decided to use the C15 relay board to change the direction of rotation using the M3 & M4 signals.

First you need to set the "Ports and Pins" to send out STEP on Pin14, I left the DIR set to pin 0 and I am not using it.

The C11G manual tells you to go into motor tuning and set the Steps Per to 1000 and the Velocity to 1500. On my system I found that this maxed out the pulse train and made it so the POT on the board would not change the final voltage.
Despite what the C11G manual states, I found that the maximum voltage put out was directly proportional to the "Steps Per" value and the pulse length made very little difference.
So I reduced the Velocity to 1000 and the "Steps Per" to 1000.

I then set the pulley1 set to min and max of 320 and 3200 rpm. This sets the allowable S range that can be commanded.

I then needed to adjust the C11G output voltage to 10v at maximum speed.

NOTE - Do not have the speed controller connected at this point!

Entering M3 S3200 starts the voltage flowing and I could fine tune the output to 10v using the POT on the C11G board.

I then commanded S400 to S3200 in steps of 400 to see how linear the voltage was and it turned out to be very good.

Connect up the speed controller.

At this point I remembered that the original speed controller was used to getting 8v from the original board and so I started the spindle with a low speed and turned down the "Nmax" on the speed controller.

Next is to command a S3200 and adjust the Nmax setting on the speed controller until the Mach3 speed showed 3200 rpm.
At this point you will more than likely find that the speed control is fairly linear but does not give you the right readings.

On plotting the speed against requested speed I found it to be quite linear but with the wrong gradient. This told me that the slow speed was too slow and the fast speed way too fast but it was quite linear inbetween.

Command the slow speed S320 and tune the "Nmin" setting on the speed controller until the RPM reading is 320rpm.
Now check the S3200 speed and I found it was now too high!

I then adjusted the S320 speed and S3200 speed alternately until they both resulted in the correct speed for the commanded speed.

The result is now within 1% of the commanded speed! I have no doubt I could get it even better, if I could be bothered to continue the iteration process. 1% is good enough for me!

Many thanks to everyone for their help, without which I would never have managed to get this far!

55
General Mach Discussion / Re: Help for a newbie please.....
« on: May 05, 2008, 01:23:19 PM »
Tony,

The similar problem on my machine was cured by changing the debounce level to somewhere between 0 and 5.

What is yours set to?

Thanks
Simon


56
General Mach Discussion / Re: Spindle Index problem.
« on: May 05, 2008, 01:14:49 PM »
Graham / Hood,

I decided that I should make the slot larger and while I was at it I added 3 more slots. I now have 3 off 10mm slots and 1 off 20mm slot. I configured Mach3 to look at timing instead of index and voila the speed readout is exactly the same as the timing input gave me with my one smaller slot!  It was definitely the debounce level far too high which was causing the bad reading at the start of this thread.

I will leave it at 4 slots for now, I can allways add some more later if the screwthreads are bad. As my builder allways told me "you can cut some off but you can't cut some on!"

I can't get the speed to match the requested speed but at least I can find out the speed it is actually running at now!
I have been advised by the Yahoo group that there is some wierd relationship between the motor tuning and the voltage output so I will try that tonight.
Currently my spindle calibration line looks more like a boomerang!

Thanks for all yours and everybody elses help.
Simon

57
General Mach Discussion / Re: Spindle Index problem.
« on: May 05, 2008, 11:04:06 AM »
Hi Graham,

Yes the current pulley is set to 1. I thought if I get the first pulley set up then I should be able to work the others out but...
I did try putting black tape around the disc but it made no difference as my disk has a myriad of holes around it on a different pitch from the original timing and I though maybe they were masking the signal.

I didn't realise I would need more slots to do threading. I will have to cut more.

Thanks
Simon

58
General Mach Discussion / Re: Spindle Index problem.
« on: May 05, 2008, 09:28:36 AM »
I take it back, The reading on the rpm is about right, certainly at slower speeds. I manually counted revolutions and am getting about the same although I can't count any faster than about 250 rpm!

Now how do I get the spindle range to be linear? I have tried the "calibrate spindle" dialog but it seems to be making it worse, not better. the lower end of the range seems to be fairly linear at present but only upto s2000

Thanks
Simon

59
General Mach Discussion / Re: Spindle Index problem.
« on: May 05, 2008, 07:35:48 AM »
Phil,

Thanks for the reply...

I have 1 pulley set up set to min 0 max 3200 rpm.
If I go to the motor tuning page and press the up arrow key then I get a solid 10v out of the BOB. I think this tells me the max speed is set ok.

If I then command a S3200 I get 9.15v out of the BOB. I also get this when I set the speed to S2000, in fact I get the same anywhere between S2000 and S3200 at S1600 I get 7.6v

I think I need to reset the spindle calibration but I can't seem to find out how to do it. Any ideas anybody?

As for the RPM reading, Thanks to Hood and Overloaded for pointing out the debounce value and that is was set too high. I am now getting a constant reading but I think it is reading twice as fast as it should be.


Thanks
Simon

60
General Mach Discussion / Re: Spindle Index problem.
« on: May 04, 2008, 05:31:44 PM »
Ian,

I might end up on manual speed control at this rate! seems a shame as it is all wired up!

kernel at 100kHz sounds scarey! my poor little PC can't cope with that. I will experiment with the kernal once it is all running.
4000mm/min is very scarey on a machine with only a 200mm or so of total travel!

I am just connecting up the front panel, it used to work off 12v but luckily it also works on 5v so all the buttons are trivial to wire up to a 2nd parallel port. (if the postman ever brings the card!)

I really wanted to get the spindle working while I was waiting for the smoothstepper and 2nd BOB to arrive.
It seems to run fine and I can change the speed using Mach3 it just doesn't go to the speed I request which is really annoying, I am so close yet so far away! I have a funny feeling it is something to do with pulley ratios but I don't know.

The "calibrate spindle" routine just seems to mess everything up completely. I start off with a fairly linear spindle range albeit producing the wrong values and after running the calibrate spindle I get complete rubbish! to the point this afternoon where I have had it running nothing but 0 and full speed for any commanded speed and then some wierd "calibration" where the spindle would respond to everything except s200-s300 where it was stationary!

Tomorrows job might be to make the slot wider, I can see it making a difference at the top end of the speed range but I don't see how it can help at the lower end of the speed range.

Simon




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