motor polleys with more teeth

[geostein8888]

Hello,
while my nemas came with an 10mm axis, i had to buy another set of pulleys who have 32GT2-B10 instead of the 20GT-B6.35. So now my question is, where do i have to adjust this. Right now my acxis are moving around 15mm instead of the 10mm

Georg

[mstrens]

You have to send a command to GRBL (using the keyboard on the PC of a file stored on the SD card) in order to change the steps/mm parameter.
The commands looks like $xx=yyy.
See doc of GRBL here:
https://github.com/gnea/grbl/wiki/Grbl- ... figuration

[geostein8888]

Hello,
are these changes then permanently?

Georg

[hiphouser]

Yes

[geostein8888]

Hello,
i found the formula for $100 (currently set to 60.000)
STEPS_PER_REV = 200.0 //from config.h
MM_PER_REV = ??
MICROSTEPS = 2 //from config.h
X_STEPS_PER_MM = STEPS_PER_REV*MICROSTEPS/MM_PER_REV

the original pulley was with 20T, diameter 12.2mm, with a circumference of 40mm
my new pulley is 32T, diameter 19,8mm and circumference of 64mm
means mm_per_rev the 40 (old) or 64(new) mm
or do i have to use here another formula to get this?

equally what i put in the formula above its not matching the current result of 60.0

Georg

[mstrens]

Do not look at the diameter.
GT2 means 2 mm/teeth
So when 20T on the long loop => 20*2 = 40mm /tour (for 200 steps). There is a reduction with 2 pulleys 20/60: so 200 steps = 40mm*20/60 => step/mm = 200/(40*20) *60 =15step/mm.
Still when you use 4 microsteps (set up in the driver and not on the config) then GRBL has to generates more "steps" for the distance. So with 4 microsteps, $100 must be 15 * 4 = 60

You can easily recalculate with your pulleys and microsteps

[geostein8888]

Hello,
on german i would say "ich steh auf dem Schlauch" - i feel like a dummie

so from where is the 20 in this part, the 40 is form the previous calculation:

There is a reduction with 2 pulleys 20/60: so 200 steps = 40mm*20/60 => step/mm = 200/(40*20) *60 =15step/mm.

the 40 is from the first calculation with 20T, this will be 64 with my new pulley, or comes this also from the 20T and i have to exchange with 32 - or is this from the 20T pulley on the other end where the belt is turning?

200 steps = 64mm*32/60 => step/mm = 200/(64*32) *60 = 5,85step/mm.
or
200 steps = 64mm*20/60 => step/mm = 200/(64*20) *60 = 9,5step/mm.

and how do i calculate the z-axis with the spindle?


Georg

[geostein8888]

Hello,
thanks for the help, the x and y axis are now working correct.
now i only need to adjust the z axis, is there also a formula for the threaded rod pitch 2mm, lead 2mm

Georg