Calculate steps

Discussion of Mach3 CNC control software
lioramsalem
Posts: 88
Joined: Mon Jun 09, 2014 1:43 pm

Re: Calculate steps

Post by lioramsalem » Wed Feb 25, 2015 6:47 pm

kjetilhansen wrote:I just can't seem to get this to work... With the 54,6806... when it is suppose to move 10mm it moves 9,5, I then use the auto calibrating tool, ask it to move 10mm, and I punch in that it moved 9,5. I then try again, and it is still off...
So I belive something I do or have is wrong...

I counted, I have a 18 tooth pulley, so I am guessing that XML is also right...
The steppers I have is sm42ht47-1684b
And I use the G540 (witch I have not changed anything on, so it should be 10 micro steps)

I may also add that when I used GRBL it was accuate..
10mm is pretty tight, can you try longer moves measurement?

LA
ShapeOko 2 #5840 w/ NEMA23, ACME Z axe belt upgrade, limit switches, spindle speed control, 400w brushless spindle, 9mm belts, aluminum bed, eShapeoko X carriage and belts system

Build log: http://www.shapeoko.com/forum/viewtopic.php?f=5&t=3650

kjetilhansen
Posts: 46
Joined: Tue Nov 05, 2013 10:55 am

Re: Calculate steps

Post by kjetilhansen » Wed Feb 25, 2015 9:12 pm

I used to try with 20mm, but the same error then... You said something about backlash, this might be right, do you know what part that I need to fix to remove backlash?

lioramsalem
Posts: 88
Joined: Mon Jun 09, 2014 1:43 pm

Re: Calculate steps

Post by lioramsalem » Wed Feb 25, 2015 10:37 pm

kjetilhansen wrote:I used to try with 20mm, but the same error then... You said something about backlash, this might be right, do you know what part that I need to fix to remove backlash?
Same 0.5mm error with with 20mm travel?

I'm not sure it's backlash..
Backlash represent the error (or the free play) of the pulley and belt while changing directions..
Also, the backlash error I measured on my machine is around 0.3mm on X and really low 0.1 on Y.
ShapeOko 2 #5840 w/ NEMA23, ACME Z axe belt upgrade, limit switches, spindle speed control, 400w brushless spindle, 9mm belts, aluminum bed, eShapeoko X carriage and belts system

Build log: http://www.shapeoko.com/forum/viewtopic.php?f=5&t=3650

lioramsalem
Posts: 88
Joined: Mon Jun 09, 2014 1:43 pm

Re: Calculate steps

Post by lioramsalem » Wed Feb 25, 2015 10:52 pm

If you want to measure the backlash and setup compensation, it's pretty easy:
1. Move relatively long distance (let's say more then 10mm) to one direction.
2. Place digital caliper or dial and measure the movement to the opposite direction of 1mm.
3. Did the machine traveled 1mm or less?
4. If less, enter the missing distance as a backlash compensation for the measured axis.

Try again :)

Anyway, it a good idea to first try a solve backlash issue mechanically of course: belt tension, centered pulleys and tight, etc...
ShapeOko 2 #5840 w/ NEMA23, ACME Z axe belt upgrade, limit switches, spindle speed control, 400w brushless spindle, 9mm belts, aluminum bed, eShapeoko X carriage and belts system

Build log: http://www.shapeoko.com/forum/viewtopic.php?f=5&t=3650

kjetilhansen
Posts: 46
Joined: Tue Nov 05, 2013 10:55 am

Re: Calculate steps

Post by kjetilhansen » Mon Mar 23, 2015 9:31 pm

Finally found the time to investigate this. A big probem as I see it is that if you mill MDF without a dust collector the dust will settle on the makerslide and clogg up the delrin wheels and make the movment uneaven. I also found that there are some bungee in the belts that came with the shapeoko 1. I ordered a new belt from ebay that I hope will remove this issue.

When calibrating axis 20mm is 20mm, on X and Y, but when I have (maybe to much feed) milling the squares in MDF one axis is 20.1 and the other was 19mm so there is definitely backlash problem with MY shapeoko 1.

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