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Faster Z axis motor

z-axis
motors
encoder

#1

Hello,

can someone please post their experience with faster Z axis motors, which optimal RPM and model do you use/recommend?

I tried using the 107rpm motor but the test procedure (even though it completes successfully) rotates the 8mm shaft up/down 12cm in one direction!! I`m also experiencing weird motor behavior after changing the encoder steps per rev value…

On a 35rpm z motor everything works fine.

Tnx


#2

What is the pitch you set in GC? (mm per 1 revolution of z-motor)

Edit procedure: Measure how high your bit/router or mount is over the sled. Make a thin mark on the coupler with a good reference point somewhere in front. Use the z-menu in GC and set the amount to move to a fairly small amount. Use ‘raise’ or ‘lower’ to make 1 exact rotation. If you overshoot lower the distance to move and go back until your mark is exact 1 turn. Measure again and put the difference in the Maslow settings.

(I’ve discovered issues with going faster on Z but a second pair of eyes would be nice)


#3

It is -8mm, it works flawlessly with 35rpm motor.

Do you suggest that I should measure the pitch movement for faster motor, and adjust the pitch accordingly? Isn’t this value dependent on the rod?


#4

The GC setting is movement per 1 rotation of the motor and the encoder steps are counted and translated to the distance you measure. Is your encoder the same as on the Maslow Z-motor?

The instruction above should work. If not I guess the encoder could have different steps and that would need some adjustment in the FW. (only guessing, no expert but tester Is the feedrate for Z-Axis hard coded? (solved))


#5

This motor has 16 ppr, as far as I `m aware Maslow z motor has 7ppr.

I calculated the encoder steps per rev correctly for both motors, but for some reason the 107rpm motor bahaves differently…

I will look at your post and see what can be done. Thanks!


#6

One more thing, are you testing with the z-menu or with g-code? If using g-code you want to test with low feedrates on Z and slowly work your way up.


#7

z-menu, but I will look into g-code as well

Tnx


#8

Adding some more info for myself:

, via the $20=7560 command and in the groundcontrol.ini -> zencodersteps = 7560.0

Edit adding links:


#9

My feeling is that a faster z motor using the Ridgid router’s existing height adjustment mechanism will not be worth the effort. In the grand scheme of things, the stock z axis motor compliments the cutting speed of the Maslow pretty well. Making it faster will do nothing to improve the inherent weaknesses we encounter with the sloppy mechanics of the stock router.

Take a look at the following for a solution that kills many birds with one alternate approach to the z axis…


#10

Hi,

Im using a Bosch 1400 router and I can say it performs really stable, with only slight modifications. The problem for me is that the 35rpm z-axis takes 2/3 of the total time needed to cut a project! This is why I was interested in other peoples experiences/opinions…

Anyway, thanks for the suggestion.


#11

can someone please help me dial in our z axis motor for the “metal maslow”?
this is the motor being used highlighed in blue but it is 12v version with a 3ppr encoder (not 7ppr default one). I do not understand the above formula. Isn’t the PPR needed in the equation? Yet I do not see it.


#12

The formula uses CPR (counts per revolution) vs PPR. https://www.cui.com/blog/what-is-encoder-ppr-cpr-and-lpr


#13

so the motors I am using have an output of 120rpm
I took one apart and there are several gears. the motor gear has 12 teeth and the drive gear has 40 teeth so the gear ratio is 40/12 = 3.33
the encoder is 3ppr and the cbeam is 2mm lead screw
3ppr x 4x 3.33 x 400rpm motor speed = 15,984 steps/revolution

I think the math above is correct. My last problem is I cannot find where to put this value into ground control v 1.25??? I spent 10 minutes looking for advanced settings and can’t find it. If I click on the Action button there is an advanced button, but no zaxis settings there? Thanks in advance for any help.


#14

Settings, click on the grey bar on the title Maslow Settings, a menu with advanced will show up.


#15

posting this in case other people need a visual.
This deffinetely needs to be improved. I would of never known to click on that to pull down the advanced menu :slight_smile:


#16

I guess it might have a reason to hide the stuff you should not touch, if you are not sure you know what you are doing :wink: