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Mach4 use with XHC card
« on: April 20, 2020, 08:54:07 PM »
Hi everyone.

I am new here and finally (with great help from Craig) I got my machine configured in Mach 4 and running. Now I got stuck on running a g code file created in vectric aspire to test my machine. As I use the infamous XHC Chinese controller card, (MK4-M4) I am limited to using wxMach.exe instead of Mach4GUI.exe to start my Mach 4. This restricts my screen settings to fix set and some buttons are not even displayed. ( If you would like to see what I am left with just start your Mach 4 from wxMach.exe inside your Mach 4 folder.)

Now I finished my soft limits setup and when I try to run a file I ref all axis home, then jog to the corner of the material, jog down on Z axis to the thickness of a paper, I load G code file ( see in attachment) and cycle start gives me a warning about Z axis exceeding my max soft limits, ( it sends me above Z=0 into positive) and when I changed my soft limits for Z, another warning on X axis soft limit. (I will not change that as I am worried about clamps and possibly sending me to work outside of my table).

I have a problem with setting a work zero as the button is not visible on wxMach.exe settings ( check attachment of my screen) and unsure if this is the cause of my problems or the G code created in Aspire is wrong.

Any help will be greatly appreciated. Thanks.

Adam
« Last Edit: April 20, 2020, 09:04:38 PM by Adamus »

Offline Graham Waterworth

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Re: Mach4 use with XHC card
« Reply #1 on: April 21, 2020, 07:09:05 AM »
What is the date on the wxMach file you are using?  you should have more than that on screen.
Without engineers the world stops
Re: Mach4 use with XHC card
« Reply #2 on: April 21, 2020, 03:28:18 PM »
The mach was installed few days ago from Artsoft web. The date of wxMach.exe file is 27/08/2019.

I finally managed to make it run my g-code files, but the circles are not round (ellipse shape) and the depth of cut is incorrect by one mm per six mm set on g code. Not sure what could cause it apart from wrong counts per unit in motor settings. The factory provided me with some complete wrong value for z axis motor and I struggle with setting it right...

Thanks for any ideas on how to fix it..

Adam

Offline Graham Waterworth

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Re: Mach4 use with XHC card
« Reply #3 on: April 21, 2020, 07:22:15 PM »
Some pictures of the machine would be a help

If all the axis are driven the same then all the values for steps/per should be the same only the acceleration and velocity could be different.

 
Without engineers the world stops
Re: Mach4 use with XHC card
« Reply #4 on: April 21, 2020, 07:49:52 PM »
I am attaching picture. It's a servo machine. Y and X axis seem to be fine just Z is not corresponding with DRO ( one mm does not mach one in physical travel). Do you know the formula for counts per unit calculation? I assume I would need a lot of info about my servo revolution and ball-screws diameter, teeth count etc. For that I will have to remove cover.
Re: Mach4 use with XHC card
« Reply #5 on: April 22, 2020, 12:01:32 AM »
Hi,
given that it is a servo machine calculating the 'steps/unit' from first principles may not be that easy.

You are correct we would need to know the pitch of the ballscrews, any gearing between the servo and ballscrew
but would also need to know the pulses per rev of the servo. This last item may not be available to you. Many
servos have 'electronic gearing' programmed into them and most likely you don't have that information nor
will the machine builder provide it.

All is not lost however. You can do it manually.

Lets say you MDI a a command g0 x100, you would expect the x axis to move 100mm right? If however you measure it and find
it moves only 91mm then you have a problem.

If you do the calculation 100/91=1.0989, then you open the x axis motor tuning page to see what the current 'steps/unit'
are, then you need to increase it by a factor of 1.0989.

For example lets say the current 'steps/unit' are 2450, then 2450 x 1.0989=2692.23. Substitute the new number, restart
Mach to have the new setting be propagated through the machine and try again.

When you MDIed a 100mm move, measure how far it ACTUALLY moves. The more accurately you can do this the better.

Using this 'suck it and see' appraoch means that you don't have to know anything like screw pitches etc.

Craig
My wife left with my best friend...
     and I miss him!
Re: Mach4 use with XHC card
« Reply #6 on: April 22, 2020, 03:20:05 AM »
Thanks for the idea of manual check ,Craig I have been doing it even before your message, but I do not trust it to be very accurate. What about me calculating a deviation on the pass of 1000 mm,as precise as I can, still there would be to some fractions of the mm. Then running a code which will move the machine a mile or two? My tiny error would grow to the point of being a big problem.
I intend to work on 3d carving with very tiny details and the tool paths are going to be extremely long. Essentially I agree this kind of "reverse engineering" measuring should greatly improve my motor settings, but I am still worried. Z axis is the biggest problem as is to short to catch the error with great precision, and deviation here will have a major impact on my 3d carving. I can ask manufacturer for all the info required to calculate, but would you help me to run it through the formula, Craig? There is a poor communication with Chinese factory, but they do respond. If you could list all what is required to calculate I will try to contact them, it may take few days though for them to answer.

Thanks.
Re: Mach4 use with XHC card
« Reply #7 on: April 22, 2020, 03:40:18 AM »
Hi,

Quote
There is a poor communication with Chinese factory, but they do respond.

By all means try them. We really need to know how they have set up the servo, how many pulses per rev.
Ballscrew ptch and gearing would mean that you don't have to stri the machine.

Good luck
Craig
My wife left with my best friend...
     and I miss him!
Re: Mach4 use with XHC card
« Reply #8 on: April 22, 2020, 04:18:09 AM »
I have sent the request to the manufacturer, as soon as I have the info I will post it here.

Thanks