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Back lash comp while jogging
« on: April 20, 2017, 11:20:49 PM »
Is backlash comp while jogging an Mach4 thing or a plugin thing?
Have a Hicon Intergra, the backlash is set in the Plugin.
But it does not apply backlash comp using the screen jogging controls, or MPG.

Thank you
Re: Back lash comp while jogging
« Reply #1 on: April 24, 2017, 08:35:29 AM »
Hey Sparky3,
Just finished a mill with the Hicon Integra.  Backlash is working as expected for us.  We have about .002 backlash in our Y and utilizing the backlash compensation it doesn't have any now. 
You can post this question on the 3rd party hardware support forum, the guys at vital system get back pretty quick.  This is the link to the Hicon Motion Controller Forum.
http://www.machsupport.com/forum/index.php/board,89.0.html
Chad Byrd
Re: Back lash comp while jogging
« Reply #2 on: April 26, 2017, 12:37:11 AM »
I will pose the question down there. it works while jogging but wont compensate for .0001 moves. only .001 and .01 moves.
Now that I think about it I have not tried .0001 moves with the MDI. I will try that tomorrow then pose the question.

Offline Mauri

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Re: Back lash comp while jogging
« Reply #3 on: April 26, 2017, 06:03:01 PM »
Hi,
Mach4 MPG works perfectly in the increment movements, except for Backlash compensation of the DRO Mach4 Screen.
HicCON reports accurately back to Mach4 in whole number pulses.
The accuracy is dependant on the Steps Per at the Motor Settings and the amount of Pulses Generated by the accuracy of your Mill.
So for example if you are working in MM then most CNC setups the best you will get is .01mm spot on accuracy incremental movements.
The Mach4 increments will not be accurate if you have fractional pulses as Hicon will only use Whole Pulse Numbers in reporting back to Mach4 DRO's.
To Check this out do the following for mm machines.
lets say you have 800 Steps per mm then 800 * 0.01mm increments = 8 Pulses (this will work 100%)
But if  you have 800 Steps per mm then 800 * 0.001mm increments = 0.8 Pulses (this will not work and will not be accurately)
So no matter what equipment you have mm/inch, Stepper/Servo Microsteps or Not  in the end the more Steps per you have the higher the accuracy you will achieve with your incremental steps.
If your working with Imperial measurement then:
lets say you have 10000 Steps per inch then 10000 * 0.01mm increments = 100 Pulses (this will work 100%)
But if  you have 10000 Steps per inch then 10000 * 0.001mm increments = 10 Pulses (this will work 100%)
But if  you have 10000 Steps per inch then 10000 * 0.0001mm increments =1 Pulses (this will work 100%)
So if you steps per inch are less then 10000 then that is the reason why it will not work.
So no matter what equipment you have mm/inch, Stepper/Servo Microsteps or Not  in the end the more Steps per you have the higher the accuracy you will achieve with your incremental steps.
Similar issues will happen if have fine tuned in your Axis accuracy to use say 9500.5687 as your Steps per inch instead of 9500 this will calculate decimalized pulses, but the HiCON will rounded up the nearest Pulse so keep the value to no more than say 2 decimal places.
If you combine these two issues then you will get some pulses that will show different values om the Mach4 DRO's.
Hope this helps.

Regards,
Mauri.

Offline Mauri

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Re: Back lash comp while jogging
« Reply #4 on: April 26, 2017, 06:04:26 PM »
Hi, The mm in the latter part of my note should have been in Inch increments.
To used to mm.
Regards,
Mauri.
Re: Back lash comp while jogging
« Reply #5 on: April 27, 2017, 11:13:05 PM »
Hi Mauri.

Yes i understand all of that. The machine has 5mm ball screws, servo are 10,000 pules per revolution, 50800 steps per inch, the machine does move .0001inch no problems just no backlash comp while doing so.
this has been tested with MPG plugged into the  interface on the hicon7766, the Modbus mpg, the Mach4 jog screen, and MDI.  
I know it always best to remove all the backlash out of the mechanics first. I work on Commercial machines for a living and my poor Novakon is just not in the same class. It has .0009 inch backlash in Y, it had .0015 in it to begin with.
while checking the bearings on the Y axis, the preload got set a little to tight and ruined that set, Replaced them with 7004 P4 ABEC7 from NSK, checked the bearing block and found some bad machining on the bearing bores and corrected that.
that made up for about 6thents of movement. All that can be take out with out machining, scraping, and upgrading ball screw and bearings has been done.  So it is at .0009 and is with in spec for Novakon.

Made a new discovery about backlash comp on the Hicon last night. I think it is just a bug in the Firmware and can be corrected
It will comp when moving in thousandths all day long, or so I thought, every now and then it will not apply the comp to the move at all.
Learned this while running a backlash test for repeat ability last night, ninth run of the program it did not return to the same spot, then again on the 12th run of the program.
started watching the diagnostics  page while running the program and checking encoder/ step gen. to the first touch and the last touch, when the part was first touched encoder/step gen was 238386 move off the part past zero then back to zero the encoder/step gen was 238343, this is the base with backlash working.
when backlash was skipped by the by the controller both numbers were 238386.  It happened several more times 5 out of 21 runs of the program.

I am send the guys at Vital System a email to see what else they need to test. Still not sure if this is a Hicon issue or a Mach4 issue, or a set up issue. But i will add this to the backlash not comping on .0001 moves with the MPG or jog screens

I will report back when I hear something from them.

explanation on steps per unit is great and should be posted saved some where for the less experienced
the hicon will do the math for backlash for you, in this set up when .0009 is entered it rounded it down to .00088??? don't remember off the top of my head did not write it down probably should have. so it will round it up a pulse or down a pulse depending on the move.
I do love the Hicon, this one is set up with encoder feedback and using home switched and index for homing. it is just great you can indicate a part in set the zeros, shut it all down,  leave the indicator set up where it is at, Turn it all back on reference it hit the goto zero button, and it is on the money indicator is back at zero.  
« Last Edit: April 27, 2017, 11:18:25 PM by sparky3 »

Offline Mauri

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Re: Back lash comp while jogging
« Reply #6 on: April 28, 2017, 03:58:53 PM »
Sparky3,
I agree with you with those machine specifications .0001inch should work every time.
Please post your response from HiCON here or on the HiCON Forum http://www.machsupport.com/forum/index.php/board,89.0.html
Although I do not expect our Mill to be accurate to .001mm I would expect the program and firmware to be accurate to every pulse movement.
We are carving some fine detailed Medallions out of Brass with a final cut using a .05Rmm cutter so we hope your find does not affect our final machined result.
Regards,
Mauri.
Re: Back lash comp while jogging
« Reply #7 on: May 06, 2017, 10:18:29 PM »
Mauri
I doubt I would ever notice .001 of backlash in the parts i do they are mostly just brackets.
I did not get a response from sending vital system a email. i posted in the Hicon forum below, they tested it with 3.51 firmware and did not have a problem.
so i will wait for the next release to test again.