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problem im at a loss with
« on: August 07, 2016, 06:30:30 PM »
building a mill with a sieg X2 mini mill, my first attempt at a cnc mill. ive been using mach3 and sheetcam for plasma cutting for several years and both work great, now my problem. i am doing my first part its just 2 straight lines with some lettering in between the lines and 3 holes below the lines, a pretty simple part. i did the lines and holes in turbo cad and add the lettering with sheetcam. everything in sheetcam looks correct but when i cut it on the mill everything is squeezed together about 1/4" but everything still looks proportionally correct, the lettering isnt weird shaped which leads me to believe the axis's arent way far off (i first though maybe my X axis was off) any ideas?

thanks,
Justin
Re: problem im at a loss with
« Reply #1 on: August 07, 2016, 06:59:12 PM »
It sounds like your steps/unit setting is wrong in your stepper motor tuning setting
Cheers

Peter
----------------------------------------------------
Homann Designs
http://www.homanndesigns.com
email: peter at homanndesigns.com
Re: problem im at a loss with
« Reply #2 on: August 07, 2016, 07:26:56 PM »
im sure they are, which is another problem ive been having that i havent figured out. to get the machine to have any real movement my steps per are.

X 254,572
Y 261,951
Z 263,178

which are what mach set them at using the "set steps per unit" option in settings

when i first got it going it was set at 2000 (default im guessing) you couldnt even see the table move, the only reason i knew they were was because i could see the ball screws moving just a little. top speed my machine runs about 6 IPM no matter what i do to jog settings and or percentages. so i kept going up and they would move a little faster and i was able to get an indicator on it and when i tell it to move 1.00 it moves pretty close to an inch (usually .997-.998 which i was ok with for testing)

Offline olf20

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Re: problem im at a loss with
« Reply #3 on: August 07, 2016, 08:35:22 PM »
Setting your steps is to get the correct movement of the machine.
Example if you command a 1.00 movement on any axis you should
get 1.00 movement.
To get your speed you need to go to the motor tuning tab and
experiment based on your motors, machine, drivers, and power supply.
I'm sure you have set this with your other machine.
olf20 / Bob
Mach3, Atlas Knee Mill, 4th Axis, VcarvePro, ESS, Super PID.
Been Heating with corn since 1998
Re: problem im at a loss with
« Reply #4 on: August 07, 2016, 08:44:54 PM »
yea i went through that, and have just come to the conclusion that its just gonna run super slow, not sure how guys get them to move fast i would think it should rapid at a reasonable speed. with the steps per so high, on my Y axis the fastest velocity i can get is 5.92 and acceleration is 1.499. i dont have this issue with my plasma table but my mill is slow.
Re: problem im at a loss with
« Reply #5 on: August 08, 2016, 06:07:39 AM »
You can't accurately measure the steps/unit values or get mach3 to calculate it for you on a machine like this.You need to calculate it.
It's quite simple.
1. Presumably,  you are using 200 steps per revolution motors.?
2. Can you tell me the lead in your axis screws. Are they 5mm pitch ballscrews? If not what are they.
3. How many microsteps is your stepper driver set to/

If you can provide the answers to the above, I'll calculate the correct steps per unit.

Cheers,

Peter

----------------------------------------------------
Homann Designs
http://www.homanndesigns.com
email: peter at homanndesigns.com

Offline olf20

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Re: problem im at a loss with
« Reply #6 on: August 08, 2016, 05:50:59 PM »
What about gearing from the motor to the lead screw,
or are they direct coupled?
olf20 / Bob
Mach3, Atlas Knee Mill, 4th Axis, VcarvePro, ESS, Super PID.
Been Heating with corn since 1998
Re: problem im at a loss with
« Reply #7 on: August 08, 2016, 06:33:56 PM »
Yes. I was assuming direct coupling as is common with most G0704 conversions. If there are pulleys in the drive train then the ratio will need to be taken into account

Cheers

Peter
----------------------------------------------------
Homann Designs
http://www.homanndesigns.com
email: peter at homanndesigns.com
Re: problem im at a loss with
« Reply #8 on: August 08, 2016, 06:38:14 PM »
What about gearing from the motor to the lead screw,
or are they direct coupled?
olf20 / Bob

They are directly coupled with lovejoy couplers.

You can't accurately measure the steps/unit values or get mach3 to calculate it for you on a machine like this.You need to calculate it.
It's quite simple.
1. Presumably,  you are using 200 steps per revolution motors.?
2. Can you tell me the lead in your axis screws. Are they 5mm pitch ballscrews? If not what are they.
3. How many microsteps is your stepper driver set to/

If you can provide the answers to the above, I'll calculate the correct steps per unit.

Cheers,

Peter



The steps per are 200 and the leadscrews are .200/inch I'll have to check the motor driver
Re: problem im at a loss with
« Reply #9 on: August 08, 2016, 07:53:55 PM »
With the above information,
200 full steps (1 revolution) will move the axis 0.2". So each step moves the axis 0.2/200 =0.001"

So you need 1000 steps to move the axis 1 inch. Now, if you have a 10 micro step drive then you need ten times the number of steps to move the axis an inch, so the steps per unit would now be 10,000.

If your stepper drive is set to 8 micro steps then it is 8000 (8 x 1000) steps per unit.  By the way, there is no advantage in settings the drive micro steps to anything greater than 10.

The above assumes that you have set the native units in Mach3 to inches.

Cheers,

Peter
----------------------------------------------------
Homann Designs
http://www.homanndesigns.com
email: peter at homanndesigns.com