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Author Topic: Help with Spindle RPM. %90 done jsut cant get MACH to see it  (Read 3747 times)

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Hi everyone,

I have done a lot of reading on this forum and finally got enough money to buy the software.
(i did think about waiting for mach4, but the 500 line limit was very annoying!)

Ok,
one of the first things i tried to get going was RPM sensing on my router, but i couldn't. so i moved on to well anything else.
Now the machine (JGRO variant, linear rails and belt drive, mainly used for model plan building atm) is up and running with less than 1mm in play,
I built a new spindle from a Brushless RC plane motor. so now i am back on the RPM bandwagon!

i have found lots of article's and questions regarding this and they all just seem to stop, probably when the user gets it going.
I even found a PDF someone produced of their setup that a lot a valuable information in it.

SO here is my setup

- Home made Spindle (made out of ER11 collet,  a really big Brush-less RC plane engine geared down with a 15tooth to 60 tooth pulleys)
   speed controlled by servo tester for the moment, building a (mach)PWM to (esc)PWM converter soon
- Single slotted disk for the index pulse (150-200mm is size with a single 10mm slot on the largest pulley connected to the ER11 extension shaft.)
- An Opto connected to pin 10
  (tested via automated setup in ports and pins + i can see the LED turn on in the diag page)
  (it has been assigned to 'index')

lastly under 'spindle setup'
i have
-de-selected 'use spindle  motor output'
-selected 'use spindle feedback in sync mode'
- selected 'spindle speed averaging'
- selected 'disable spindle relays' & "flood mist control" as i dont use them.


But try as i might the DRO on the standard mach3 screen set will not show anything.

I have found mention of 'de-bounce' ad changing it but i am not able to figure out where this 'de-bounce' is set at

thanks!




Re: Help with Spindle RPM. %90 done jsut cant get MACH to see it
« Reply #1 on: July 17, 2014, 09:02:39 AM »
Did you type M3 in the MDI window or click on the spindle button?  You can also press the F5 key if using the standard Mill screenset.  Even though you're not turning the spindle on & off with Mach, it still needs to think you are to display RPM in the DRO.:)
Milton from Tennessee ya'll.
Re: Help with Spindle RPM. %90 done jsut cant get MACH to see it
« Reply #2 on: July 17, 2014, 11:25:20 PM »
Hi DICKEYBIRD

actually, no, i didn't try that.
I just turned on the spindle and expected it the DRO to report the speed it was sensing.
When that did not work i "clicked" the spindle start button (watched the dwell 'button' light up for a second) then tried the spindle again, still nothing.
(interestingly the button did not look like it 'latch down' ie changed color or anything to say that the spindle was on.

I can also write simple square with the speeds and feed rates in it and see if that works.

I am currently getting all the parts together for the (MACH) PWM - (esc) PWM converter, as the only supplier i know of for pre-made ones 'Logicnc' does not answer emails anymore. I have found 2 different versions for the converter and they are very simple.

i will give that a go over teh weekend and report back.

(i am going to write a post in the mach4 forum to see if this has been changed in that version....)

chris.

Offline Tweakie.CNC

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Re: Help with Spindle RPM. %90 done jsut cant get MACH to see it
« Reply #3 on: July 18, 2014, 03:59:25 AM »
Hi Chris,

If it's of any assistance to you my rendition of the Mach3 / BLDC motor control is posted here :-

http://openbuilds.com/builds/software-speed-control-of-a-brushless-dc-bldc-motor-from-mach3.762/

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Help with Spindle RPM. %90 done jsut cant get MACH to see it
« Reply #4 on: July 20, 2014, 05:52:46 AM »
Hi everyone,

i managed to get the RPM feedback working, which is awesome! it turns out that i needed to turn on spindle motor output in spindle control. that did the tick.

tweakie,
thanks for that link, i found that after logicnc didnt return my emails.
 i have ordered some PIC's and a programmer. once i have that i can get full spindle control and it will be interesting to see how quickly MACH can respond to the spindle bogging down with the RPM feedback.

tweekie can you comment on how yours reacts?
ie on an internal corner the spindle / router boggs down does mach react to the change in spindle speed?

chris.

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Re: Help with Spindle RPM. %90 done jsut cant get MACH to see it
« Reply #5 on: July 20, 2014, 06:31:21 AM »
Hi Chris,

As far as I am aware (but I am always pleased to learn something new) Mach3 just shows the change in spindle RPM proportionate to tool loading and as G97 (constant surface speed) does not work correctly in Mach3 there is no speed compensation via the PWM duty cycle.

My approach would be to use a Constant Speed ESC as this would be a simple solution to providing the necessary RPM compensation in relation to variable tool loading.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Help with Spindle RPM. %90 done jsut cant get MACH to see it
« Reply #6 on: July 20, 2014, 07:48:36 AM »
Hi tweakie,

Thanks for that info, I thought that Mach would compensate for the difference in the "set" RPM to the RPM shown in the RPM DRO. Interesting.
Do we have any information  with this regarding mach4?

Lastly I have not heard of a constant speed esc before. Can u link me to some infor on one?

Chris.

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Re: Help with Spindle RPM. %90 done jsut cant get MACH to see it
« Reply #7 on: July 20, 2014, 08:35:35 AM »
Hi Chris,

I am led to believe that Mach4 will handle the speed compensation perfectly but it may be some time before Mach4 is fully operational and ready for release. It should be noted that Mach4 will not be outputting a PWM signal directly, it will be the responsibility of the various, third party, external motion controllers software / hardware to interpret the Mach4 output data and generate the relevant PWM duty cycle accordingly.

If you Google "rc gov esc" you should find a few links of interest.

Tweakie.
« Last Edit: July 20, 2014, 08:46:03 AM by Tweakie.CNC »
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Help with Spindle RPM. %90 done jsut cant get MACH to see it
« Reply #8 on: July 20, 2014, 09:01:08 AM »
Thanks tweekie,
That is good news on the Mach4 side of things.

Also I will fire up google tomorrow and have a look at those links.


Thanks again for your time and posting the link to your (Mach)PWM to (esc)PWM


Sent from my iPhone using Tapatalk
Re: Help with Spindle RPM. %90 done jsut cant get MACH to see it
« Reply #9 on: July 20, 2014, 09:42:32 PM »
Hi Tweekie,

thanks for that info!
with a bit of flexing of my google-fu i fouund a good explanation of the Govenor feature for Heli's.
Basically it is designed for constant head speed on the heli's.

For other people who find this thread.

-=-=-=-=-=-
(pasted from http://www.rcgroups.com/forums/showthread.php?t=134039)

OK, I think several things are being misunderstood ... let's see if I can clear things up a bit.

First of all, the percentage of throttle on the STICK doesn't have anything to do with % of throttle at the motor when in governor mode. The stick (or throttle%) from the radio commands the controller to a given RPM -- the controller will determine how much throttle is required to maintain that RPM, and will modulate the throttle accordingly.

For example -- in Governor Mode 1 (low RPM mode) the motor speed range is approximately 12000-36000 on a two pole motor (like a Hacker) or 6000-18000 on a four pole motor (like an Neu) or 4000-12000 RPM on a six pole motor (like a Mega.) So if you set a 50% throttle point on a Hacker motor, the controller will set the throttle automatically to run at 24000 RPM. If you are running a high RPM hacker motor (Like a B20-12L) with no load, the controller might only have to use 10-12% of throttle to maintain that RPM. Under load, it might take 50% throttle to maintain that RPM. If you put a really big load on the motor, the controller will go to 100% throttle to try to maintain the 24000 RPM point.

A good illustration of Governor mode can be made by using a motor with no load. If you run the motor up, and then put a finger against the motor shaft to load it up, you will notice that the motor (for a brief period of time) will slow down, then the controller will increase throttle to compensate, and the RPM will return to the set point. When you then unload the motor, it will (again for a brief period of time) increase in RPM, and then the controller will reduce the throttle to bring the RPM back to the set point.

The idea is that a constant head speed (regardless of collective setting) is desirable. The controller will increase throttle automatically when the collective is increased, and decrease throttle automatically when collective is decreased, in order to hold the head speed constant.


-=-=-=-=-=-
thanks again for your help.

Chris