Author Topic: Change Inches to MMs  (Read 2085 times)

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Offline eoinie

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Change Inches to MMs
« on: May 25, 2018, 10:43:33 AM »
hi all
I'm having problems setting up my machine in millimetres in mach3. I changed the units in Config but when I save and open the DROs are reading in inches. So if I create a new offset for x0 y0 the machine goes to that offset. But if I load a code with a G21 my offset is altered. Previously my DROs were in mm on startup. How can I make Mach3 default to mm on startup?

Offline joeaverage

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Re: Change Inches to MMs
« Reply #1 on: May 25, 2018, 11:18:14 AM »
Hi,
Config/Select Native Units sets the units which you tune your motors and set soft limits etc. Set them once then leave it alone.

Config/General Config.... near the centre is a text box 'Initialisation String' put a G21 in there with whatever else is already there. This is a string of instructions that Mach runs
when it powers up. G21 should cause all the DROs to display in mm.

Craig
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Offline eoinie

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Re: Change Inches to MMs
« Reply #2 on: May 25, 2018, 11:39:06 AM »
Thanks Craig. Did all that, saved settings an re-started Mach3. G21 shows up in the Active Modes window but DROs still in inches

Offline joeaverage

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Re: Change Inches to MMs
« Reply #3 on: May 25, 2018, 02:45:05 PM »
Hi,
the DROs just display numeric text, could it be that the machine is in fact in mm but the steps per unit are such that they give you the impression that the numbers reflect inches not mm?
Look on the Settings tab, lower RH corner. What is indicated as units?

Craig
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Offline eoinie

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Re: Change Inches to MMs
« Reply #4 on: May 25, 2018, 04:55:43 PM »
Hi
I'm using the Legacy interface so it doesn't have the setting tab. However, I did measure the distance travelled by the tool and it is moving in inches as per DRO

Eoin


Offline joeaverage

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Re: Change Inches to MMs
« Reply #5 on: May 25, 2018, 06:02:02 PM »
Hi,
that rather suggests your steps per unit value is in inches also.

Issue an MDI
G0 X0
G0 X1
how far does the x axis move? If it moves one inch then effectively your steps per unit is 25,4 times to big.

Craig
My wife left with my best friend...
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Offline eoinie

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Re: Change Inches to MMs
« Reply #6 on: May 26, 2018, 05:16:17 AM »
Yes Craig. The tool moves an inch. The DROs are still in inches but I have a G21 in the initialisation string which is showing up in the active modes window.

Offline eoinie

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Re: Change Inches to MMs
« Reply #7 on: May 26, 2018, 05:28:59 AM »
For some reason the Motor Tuning window now won't open. This is a re-installation of Mach so it should be good.

Offline joeaverage

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Re: Change Inches to MMs
« Reply #8 on: May 26, 2018, 05:32:56 AM »
Hi,
I think your steps per unit calibration is out.

You commanded a move of 1 unit with the MDI. With G21 active Mach interprets that as 1 mm. It moves A CERTIN NUMBER OF STEPS per your step per unit figure.
It actually moved 1 inch, ERGO the Steps Per Unit Value you have programmed is to high by a factor of 25.4

Go to the X axis motor tuning page and reduce the Step per unit value you have there by a factor of 25.4. Now try the experiment again.

Craig
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     and I miss him!

Offline eoinie

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Re: Change Inches to MMs
« Reply #9 on: May 26, 2018, 05:52:38 AM »
Can't open the Motor tuning window