Silly Spindle Speed Stuff

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DICKEYBIRD
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Silly Spindle Speed Stuff

Post by DICKEYBIRD »

I'm sure it's something I've setup incorrectly but I can't get my spindle speeds to cooperate. It's a PM DC 3/4 HP Baldor motor with KBCC-125R Speed Control & KBSI-240D Signal Isolator.

In the Wizard I set up the spindle low speed at 350 & the high at 1650 rpm. With an M3 S350 MDI command I read 2.12 volts at the analog out connections on the Acorn & 5.13 volts with an S1650 command. I can easily twiddle the adj. pots on the isolator board or the speed control to match the commanded high & low rpm but when I command anything in between the speeds are way off ie: S500 shows over 800 rpm? The previous CNC4PC C11 BOB with Mach3 dialed in the same motor control setup within 20 rpms over the whole range of desired speeds. (Not whining, just another fact to help diagnose it.)

Report is attached; hopefully someone can spot where I've gone astray with the setup.
Attachments
report_985DAD887BFB-0605170051_2017-12-20_12-56-44.zip
(172.39 KiB) Downloaded 131 times
Milton in Collierville, TN

"Accuracy is the sum total of your compensating mistakes."
Dave_C
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Re: Silly Spindle Speed Stuff

Post by Dave_C »

Milton,

I'm not that far along with my Acorn setup so I can't give you an exact answer but I can share with you what I have seen cause the problem in hundreds of drive setups I've worked on.

I am making an assumption that you are working with 0-10 VDC as that is what Acorn has as an output.

So herein lies the issue;

If you were to run a setup that actually starts at 0 RPM the 0 VDC command would match and lets say the high end is 2250 and the 10 VDC would match that as well. What happens is this. You change the minimum speed to be let's say 200 RPM but what does Acorn do with the minimum voltage?

So now the "SPAN" or range has changed and they no longer match the output voltage. I have had to "Respan" outputs on drives for the last 20 years to get this to work properly. Even Mach 3 had the same issue and the way I solved it was to us a tach and check my actual speeds and get them right in the min and max tables. I think I used a minimum speed in my drives of 20% as I did not want to bog them down on the low end. Once I got all my spans to match, it made no difference what speed I dialed in, it matched perfectly.

So the question is this, how does Acorn handle the 0-10VDC span issue if you want something other than 0 as the minimum speed?

I'm still learning the Centroid/Acorn stuff but my board is coming this Friday and I'll have to solve this issue as well.

So if you figure it out before I do, we'll trade secrets! ;)

Dave C.
Grizzly G0678 Mill ,CNC conversion with Acorn. G4004G Lathe, Mach 3 conversion to Acorn.
DICKEYBIRD
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Re: Silly Spindle Speed Stuff

Post by DICKEYBIRD »

Thanks Dave, it may be as simple as setting the low speed to zero in the Wiz...I'll check a bit later. Just got back with with a sack full of Corky's BBQ for lunch! :D
Milton in Collierville, TN

"Accuracy is the sum total of your compensating mistakes."
Dave_C
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Re: Silly Spindle Speed Stuff

Post by Dave_C »

Milton,

I should have said something about "turning the pots" to match. Almost every drive I have worked on handles the span a bit different. Most have has a setting internally to change the span or the ramp (some call it offset). It appears you have pots of some sort to play with.

Ideally you want a linear ramp that if you were to plot it on a graph it would make a 45 degree incline ramp line.

I've had to change "spans" sometimes as the controller was actually putting out a little more or less than the 0-10vdc signal. So it may have set the low end to a -.01vdc and the top end to 11.1 vdc to get the span to match.

It's all doable, it just depends on which end the correction gets applied to. Acorn may take care of it in the setup wizard! If it does, then the drive needs to be set for a nice smooth linear ramp. (basically the default settings)

Just a little black magic, no big deal.

Dave C.
Grizzly G0678 Mill ,CNC conversion with Acorn. G4004G Lathe, Mach 3 conversion to Acorn.
DICKEYBIRD
Posts: 536
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Re: Silly Spindle Speed Stuff

Post by DICKEYBIRD »

Man, oh man. The Centroid DIY Tech Support Division ought'a hire me. IN THEIR WORSE CASE DUFFUS INSTALLER TESTING DEPARTMENT! :lol:

In the de-Maching changeover, I had somehow slid the Voltage/Current selector slide switch to the "Current" position on the Signal Isolator board. Once I switched it back & screwed all the trim pots on back to where they should have been, it works even better than it did B.A. (Before Acorn)

OK Tech Support, what do yuse guys want me to screw up next?

ps: I found the problem by testing the analog out voltage with the Signal Isolator disconnected & the voltage suddenly tested in an absolutely linear slope from 0-10v in .6v increments...dead nuts perfect. So I says to m'self "Hmmm this isolator must be drawing too much CURRENT & is pulling the Acorn voltage low. Speaking of current...oops!"
Last edited by DICKEYBIRD on Wed Dec 20, 2017 10:19 pm, edited 1 time in total.
Milton in Collierville, TN

"Accuracy is the sum total of your compensating mistakes."
Dave_C
Posts: 669
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Re: Silly Spindle Speed Stuff

Post by Dave_C »

WHAT! Someone made a mistake, say it ain't so!

I thought I had the market cornered on that aspect. Glad to see I'm not alone.

Keep on keeping on Milton,

Dave C,
Grizzly G0678 Mill ,CNC conversion with Acorn. G4004G Lathe, Mach 3 conversion to Acorn.
midy
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Re: Silly Spindle Speed Stuff

Post by midy »

I'm having a similar problem with my spindle on first testing day. At rest acorn is sitting at 5volts on the analog out pins and showing approx 30hertz on the vfd. When i command an M3 S800 (which is max spindle speed in that range) the voltage drops to 1volt? and the spindle comes on at approx 120rpm which is the right speed for that voltage i think but not whats commanded so not sure why?? Is there another spindle speed over riding it somewhere?
diycncscott

Re: Silly Spindle Speed Stuff

Post by diycncscott »

Please always post a report.zip file when requesting support. With your configuration to reference, we can't provide any useful info in troubleshooting your issue. I'm going to guess that your spindle range ratios are incorrect but without the config info we are completely in the dark.

To create a report, from the main screen press F7-Utilities F7-Report and email the report.zip to support@centroidcnc.com and/or post here.

Also, the first rule in trouble shooting any issue is to cut the problem by half. The way to do that is to completely physically disconnect external devices when testing.

Disconnect the analog output wires from the Acorn, being sure to tighten down the screw terminals after removing the wires to be sure you have a good connection.

Use alt-i to bring up the realtime I/O screen.

Are the SpinFwd, Spin Rev outputs On? Or G540SpinRevOff or G540SpinRevOff outputs off?

Set Spindle Override to 100%, select Auto Spindle Mode (LED On) and use MDI to command 25%, 50%, 75% and 100% of max speed and measure analog output. Measurements?
midy
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Re: Silly Spindle Speed Stuff

Post by midy »

Thanks Scott, its late here now in England so I will post a report first thing and try your suggestions also.
Cheers
midy
Posts: 203
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Re: Silly Spindle Speed Stuff

Post by midy »

As you probably expected Scott, the acorn gave out the correct voltages when disconnected the 0-10 volt analog connections. Put them back in and no matter what you command there is only a fluctuating voltage of 0.9 to 1.2 volts. And the spindle turns at what you would expect for 1volt - aprox 100rpm. (i've tried to simplify the rpm by putting 0 to 1000 in the wizard.)

Could this be a noise problem? CNCman Russ helped me out with the wiring so i'm pretty sure we are good there and i've double checked wiring.

One thing I tried was removing the jumper in the VFD between PLC and 24v, then the voltages and frequencies all worked perfectly BUT the spindle does not turn, so if you command m3s500 there is 5 volts at acorn and 25.00hertz on the VFD but no power to the motor?

VFD and motor works perfectly if programmed back to panel operation.

Will keep reading the manual :?
Attachments
Kinco SV100 VFD User Manual-EN20120326[1346].pdf
(2.31 MiB) Downloaded 115 times
report_9884E39454A6-1024170180_2017-12-27_12-53-02.zip
(180.37 KiB) Downloaded 114 times
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