Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: PeteG on December 26, 2019, 07:17:22 AM

Title: Non repeatable movement
Post by: PeteG on December 26, 2019, 07:17:22 AM

Hi, I'm having some issues with non repeatability. I shall explain:

X0 (Ref 0 in the software)
X15 (In inches)
X0

Cutter head moves 15" to the right, stops and returns to zero, but it doesn't. It says 0 in the software but the cutter head stops short by about 0.25". Similar situation with the Y and Z axis.

Hema 23 motors, standard driver boards, Mach 3 software (obviously), timing belt for X/Y axis, lead screw for Z axis.

So what am I doing wrong?

Title: Re: Non repeatable movement
Post by: Tweakie.CNC on December 26, 2019, 07:27:26 AM

Sounds like you could be loosing steps because your max. Velocity / Acceleration is set too high.

Add the line;

G01 F30

to the start of your Gcode. Does this resolve the issue ?

Tweakie.

Title: Re: Non repeatable movement
Post by: PeteG on December 26, 2019, 10:16:44 AM

Thanks, I'll give it a try and let you know.

Love your profile pic.

Title: Re: Non repeatable movement
Post by: Cad cam man on December 26, 2019, 07:04:46 PM

You may need to calibrate your motors to get the proper settings

Title: Re: Non repeatable movement
Post by: Cad cam man on December 26, 2019, 07:05:48 PM

Tweakie is right adding a feed line should help isolate were the problem is

Title: Re: Non repeatable movement
Post by: PeteG on December 29, 2019, 12:23:54 PM

Hi everyone

I have solved the issue: I had the step pulse far too short (I used the default of 3) and the number of steps per inch way too high, this must have resulted in lost pulses. Changing these settings, along with changing the feed rate and acceleration has resulted in repeatable results and a much smoother operation.

Thanks for your suggestions, no doubt I'll be asking more questions in the future.

Cheers and a happy new year to you all

Peter