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Author Topic: Spindle Speed setup  (Read 7174 times)

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Offline TonyP

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Spindle Speed setup
« on: December 27, 2007, 10:46:20 AM »
Hi all,

I've just upgraded to V3.0 and am having some problems with the spindle calibration. I had, by trial & error got a pretty good calibration both in open & closed loop on my old V2.52 installation. I created a profile and carefully saved the xml, then re-installed it after the upgrade. I found that my hard won calibration had vanished!
I've not found any information about using the spindle calibration function and have always had a problem getting it to perform.  The defaults button doesn't seem to get rid of existing corrections.
Can anybody give me ?
1: A clear explanation of how Mach handles spindle speed. Is the data really in the xml?
2: How to use the setup procedure correctly.
I'm using turn, if it makes any difference.

Tony
Re: Spindle Speed setup
« Reply #1 on: December 27, 2007, 06:14:50 PM »
TonyP,
I tried the 'calibration wizard' when I fitted spindle control and could not use it successfully.
I was told to forget it, and I obtained reasonable calibration and good control without it.
In fact if you want to ruin your good control just run the wizard.

My 2p worth.

tmsmith
Re: Spindle Speed setup
« Reply #2 on: December 28, 2007, 03:50:16 AM »
HI everyone,
I have the same problem after upgrading to V3.0. it worked OK on v2.5xx.
With the upgrade my XML file got screwed up and no i didn't have a backup,because i was a fool I didn't think it would be affected by upgrading.
I was in the process of testing Mach3 after getting frustrated with EMC, Linux doesn't work for me.
I have been using TurboCNC for a few years now, so my electronics are tried and tested. but TurboCNC has some funnies with tool offsets
With V3.0 I get the setting changing after a restart the PC even after saving settings.
With V2.5xx i was having a close loop problem with the index pulse and PWM. but after reading some of the posts I was getting there, till the upgrade. once again I wiped the old version so I cant go back.
I think my problem may have been related to the 25k limit on the demo.
so before i purchase Mach3
1. can any one tell me if they have success with the spindle feed back loop as this is used for threading and i do a lot of very fine threading 0.4mm pitch.
2. does Mach3 initialize the LPT at start up, i sometimes experience a flutter on some of the outputs
My breakout goes via a buffer (74HC541) chip and pull up resistors on both ends and the enable line is controlled by the charge pump circuit.
Thanks in advance.
Friedrich

Offline TonyP

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Re: Spindle Speed setup
« Reply #3 on: December 28, 2007, 05:19:39 AM »
I'm slowly getting back where I was by a process of altering the step & velocity in motor tuning, while asking for the max spindle speed for the pulley setting. I've done this in open loop and can get within a few revs of the speed this way. When I close the loop it all comes in pretty well. I think that the setup process would linearise the open loop once the basic settings are about right. The problem is that the 'default' doesn't seem to do anything so any corrections seem to be cumulative.
Friedrich, apart from my problems with the upgrading, the feedback seems to work fine for threading. I haven't done a lot yet, but the tests that I have run seem ok. I'm just using one slot on the spindle disc (the wizard doesn't seem to get this right either). I don't think that you need to use closed loop for threading.
Not sure about the LPT flutter. If you're using a charge pump nothing should be enabled until about halfway through boot-up, but only if you have 'chargepump on in Estop' checked in general config.

Tony
Re: Spindle Speed setup
« Reply #4 on: December 28, 2007, 05:33:47 AM »
Hi TonyP,
Thanks for the reply, I am of the opinion that the flutter has something to do with the LPT base address, the card I am using emulates LPT1 base address at E378, so until the driver kicks in it toggels on the port but not on the machine due to the charge pump, I will remedy this with a new LPT card, the problem is with fancy plug and play and PCI you cant predict what will be the base address.
I picked this up by having my scope connected to the port pins (before the breaout)
If you are happy with Mach3 performance I will purchase a licence that way eliminating the 25k kernel restriction.
Thanks Friedrich ;)

Offline jimpinder

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Re: Spindle Speed setup
« Reply #5 on: December 28, 2007, 06:06:14 AM »
I am interested in this subject because I have just purchased a board to convert the PWM signal to a 0 - 10 v signal to regulate my Omron inverter (the spindle motor driver). I already have feedback from the spindle to the computer for r.p.m. measurement.

Are we saying there are difficulties in marrying the two together, to get true automatic speed regulation of the spindle ????
Not me driving the engine - I'm better looking.

Offline TonyP

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Re: Spindle Speed setup
« Reply #6 on: December 28, 2007, 06:43:06 AM »
Jim,
no the system works ok. It's just that the setting up is a bit vague. There is a paragraph or so in the manual about it, but you really have to play with it a bit to understand what's going on. ( I think I know now, but I'd really like to know for sure)
The key seems to be to start with the control system giving out it's max (pwm ratio 1). Set that speed as max for that pulley, ask for it in spindle revs, then juggle the step & velocity numbers to actually get that speed or a little more. (all in open loop). When you've done that you can close the loop. The spindle should settle at the correct speed. It is probable that you'll then have to play with the three PID numbers to obtain a fast speed change with a minimum overshoot.
Friedrich, don't worry about my grumblings. I think Mach is great, and a real bargain for what it does. I just think some of the nuts & bolts need tightening!

Tony

Offline jimpinder

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Re: Spindle Speed setup
« Reply #7 on: December 28, 2007, 08:55:17 AM »
Tony - thanks for that - because the board is on it's way from Australia !!!

I will have another read of the Mach3 set up manual when it comes.
Not me driving the engine - I'm better looking.

Offline jimpinder

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Re: Spindle Speed setup
« Reply #8 on: January 02, 2008, 09:39:41 PM »
Got my board and fitted it up, and after a bit of fiddling with the settings, it worked.

I used the automatic calibration. If you do this manuall, you never seem to get anywhere. The machine says successful run, store data, or something similar. So I stored the data. Then I manually  put in an M3 S600 command - and the speed was nowhere near. Did the automatic set-up about 4 times - no better.

I closed Mach3 Turn and opened Mach 3 Mill and tried again - same result.

I went back to Mach 3 Turn and put in a speed and it came out spot on with the requested speed. Back to Mill - same thing.

You must have to close down and restart for the data to have effect.
Not me driving the engine - I'm better looking.

Offline TonyP

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Re: Spindle Speed setup
« Reply #9 on: January 03, 2008, 04:51:48 AM »
Hi,
glad you're getting going. I've not tried running in Mill (as I only have the lathe) but the spindle data won't be the same for both, I think. I've been poking around some of the files to see If I can find where the data lives & I think it's in the Macros folder under the appropriate machine profile. There is a .DAT file in there 'linearity.dat' which may be it. It makes reasonable sense to have different data for different machines, but I suspect that these files get overwritten when you upgrade - which explains the loss of calibration.
I would expect to have to do a setup for every different machine, as Mach can't know that they really are the same one.
On the speed & index front I have, thanks to Graham Waterworth, improved matters. He told me that instead of using the INDEX input in config, he uses the TIMING input and has 4 slots on his disc, with one 50% larger than the others. I knew about the slots, but hadn't done it because I couldn't see how Mach could know there were 4 if it couldn't get 1 right.
I went halfway and cut a second slot opposite the first, which I doubled in width. The software came up with 2 slots ok, but didn't at first show a spindle speed. After I changed the Hi/Lo active setting it started reading ok. I cut a few threads with the loop closed, but the speed wouldn't hold steady & I got pitch errors. With the loop open I managed a couple of satisfactory runs in brass. Today I'll put the other 2 slots in & see if there is any further improvement.

Tony