CamBam, wrong size (about 50%) when sent to machine

CamBam, wrong size (about 50%) when sent to machine

Postby typomaniac » Tue Mar 19, 2013 12:37 pm

Hey all,

i am playing around with cambam (trial) as CAM Software for my eshapeoko. I understood the basics of the software (at least i think so) and
now i have a little problem: Everything i create in cambam is smaller when being sent to the shapeoko (still with a pen in it). I changed all the units
to mm and tried to make some circles with 40 mm diameter. All of them are drawn with a diameter of about 20 mm (sent via g-code sender).
Any idea what went wrong? Additionally my gcode sender tells 2 errors (Unsupported statements) in the gcode. The results are good but too small ..

Please find the gcode File attached ...

kreis_vier_cm_gcode.nc
(488 Bytes) Downloaded 33 times


Thank you so much,

tm

P.S: This is a screenshot of the errors from the gcode sender
Unbenannt.PNG
Unbenannt.PNG (40.93 KiB) Viewed 519 times
Proud owner of eShapeOko #17 :-) (Dual-X, Grbl 0.8a)
typomaniac
 
Posts: 51
Joined: Mon Oct 29, 2012 6:11 am
Location: Hamburg, Germany

Re: CamBam, wrong size (about 50%) when sent to machine

Postby cvoinescu » Tue Mar 19, 2013 1:06 pm

Ignore the g-code errors, those commands are indeed not supported by GRBL, but they don't change anything anyway.

You probably have GRBL set up with the wrong steps-per-mm value for your steppers and driver microstepping setting. You need to know:
  • stepper motor: number of steps per revolution (200 or 400 steps/rev);
  • driver setting: number of microsteps per step (2x, 8x, 16x...);
  • pulley: number of teeth;
  • belt: pitch (mm);
If you're using the stock pulleys and belt, the pulley has 18 teeth and the belt pitch is 0.08", or 2.032 mm. If you're using grblShield, microstepping is probably 8x; with Pololu A4988 drivers, it can be set to 16x, which I recommend.

Many stepper motors use a numbering scheme like this example:
42BYGHM809, which reads:
  • 42: motor width in mm; 42 mm is NEMA17;
  • BYGH: appears to mean hybrid stepper motor (always the same four letters);
  • M: M indicates 400 steps/rev (0.9 degree/step); W or no fifth letter means 200 steps/rev (1.8 degree/step);
  • 8: motor length (larger is bigger); for NEMA17, 6 means 40 mm and 8 means 48 mm;
  • 09: winding type and current (generally, larger number means lower impedance and higher current); for this series, 09 means bipolar, 1.7 A or so.
In brief, BYGH and BYGHW are 200 steps/rev, BYGHM is 400 steps/rev.

TL;DR version: you probably need to double the value of the $0 and $1 GRBL parameters.
Proud owner of ShapeOko #709, eShapeOko #0, and of store.amberspyglass.co.uk
cvoinescu
 
Posts: 2611
Joined: Thu Jul 19, 2012 6:50 pm
Location: Camberley, UK

Re: CamBam, wrong size (about 50%) when sent to machine

Postby typomaniac » Tue Mar 19, 2013 2:49 pm

ok i am not sure if i understood all the choices and possibilities but: Changing the $0 and $1 parameters (doubling to: $0=87.489 and $1=87.489) worked : ). I use
exactly the 42BYGHM809 you were pointing at together with a grbl shield.

And finally the machine would like to say something:

Foto.JPG
Foto.JPG (167.32 KiB) Viewed 501 times


:-)) Thanks a lot!
Proud owner of eShapeOko #17 :-) (Dual-X, Grbl 0.8a)
typomaniac
 
Posts: 51
Joined: Mon Oct 29, 2012 6:11 am
Location: Hamburg, Germany

Re: CamBam, wrong size (about 50%) when sent to machine

Postby cvoinescu » Wed Mar 20, 2013 3:09 am

:D

You're welcome.

Sorry for the long bit about the motor part numbers. I tend to get lost into details when explaining something -- or at least that's what my wife always says. :)
Proud owner of ShapeOko #709, eShapeOko #0, and of store.amberspyglass.co.uk
cvoinescu
 
Posts: 2611
Joined: Thu Jul 19, 2012 6:50 pm
Location: Camberley, UK

Re: CamBam, wrong size (about 50%) when sent to machine

Postby typomaniac » Wed Mar 20, 2013 6:32 am

I really like those in-depth explanations so please do not stop :-) If i get into a new subject i usually like to learn everything (as far as possible) because
i want to understand what i do ...
Proud owner of eShapeOko #17 :-) (Dual-X, Grbl 0.8a)
typomaniac
 
Posts: 51
Joined: Mon Oct 29, 2012 6:11 am
Location: Hamburg, Germany


Return to Software - CAD, CAM, Workflow Help

Who is online

Users browsing this forum: No registered users and 2 guests