Centroid Community CNC Support Forum

I added some info to the original post, the newest additions are in the blue text so if you are coming back to this anything I add to this thread as progress is made then it will be right there at the top. As new information gets added I will change the color of the last add back to black as to try and not confuse, or so I hope. I also added a link to the bottom of the first post to a google photo album for the pictures.

So I definitely think limit switches are my best bet on this setup then, seeing how that was how I was originally setting them up to begin with anyway.

I hope to have this up and running this weekend (my weekends are Sunday/Monday FYI) I have on e of the 3 tensoners almost done now and I just need to wire the switches up, which means I need to find my soldering iron and go to the store and pick up some heat shrink.

My Y axis is set up similar to the z axis in the photo it is just a little harder to see because the switch is mostly hidden under the aluminum channel but there is a bump stop brazed to the inside of the channel that pushes the down when it reaches its set distance. Unfortunately not adjustable for travel distance.

the tensoner set up
https://photos.app.goo.gl/5HAH4TSqeUiWyfGL8
https://photos.app.goo.gl/csEZ3Uz759U1aovF9

roughly how it will look on the z axis
https://photos.app.goo.gl/MguU2LE8Z1Ae8BAo9

the limit switch on the z axis not the most elegant but functional
https://photos.app.goo.gl/2PVu4rh8gTLjAY699

You know that feeling you get when you are getting sooooo close to being done with something and you are all like...
So I have 2 of 3 axis set up and tensoners in place, all my limit switches connected (but not working correctly). I have to go thru and re-setup up some things in setting and it will be functional.....

https://photos.app.goo.gl/44L9wxjuEnEBFez26

Sort of like being 90% finished and 90% to go?

Looks like you are making progress for sure, thanks for sharing.

All-righty then. Made the last of the headway on mechanical setup today. I had an issue with my limit switches being physically connected wrong. I had 3 of them wired NO instead of NC. That is fixed now and the last of the belt tensoners is installed.... Now comes the fun part. Setting up the software to run correctly. I have the limit and e-stop working and all 3 axis are connected and moving under power. or basically is will go something like this order if I am reading this correctly.
Figure out soft limits and machine travel limits
Figure out # of steps to make 1 full rotation
Calculate and configure the travel distance
Finally backlash. That will be the fun one. I will probably need to run thru this several times as I will need to tear down a few parts and make some adjustments/upgrades to minimize mechanical backlash in the system. Things like modifying the ACME nuts to reduce backlash and modify the ACME nut mounts to more solidly hold the nuts in place. This last part has been done on Y and Z, I still need to do X. With pictures as I get things done of course...

mikecowhey wrote: ↑Sun Sep 25, 2022 11:29 pm All-righty then. Made the last of the headway on mechanical setup today. I had an issue with my limit switches being physically connected wrong. I had 3 of them wired NO instead of NC. That is fixed now and the last of the belt tensoners is installed.... Now comes the fun part. Setting up the software to run correctly. I have the limit and e-stop working and all 3 axis are connected and moving under power. or basically is will go something like this order if I am reading this correctly.
Figure out soft limits and machine travel limits
Figure out # of steps to make 1 full rotation
Calculate and configure the travel distance
Finally backlash. That will be the fun one. I will probably need to run thru this several times as I will need to tear down a few parts and make some adjustments/upgrades to minimize mechanical backlash in the system. Things like modifying the ACME nuts to reduce backlash and modify the ACME nut mounts to more solidly hold the nuts in place. This last part has been done on Y and Z, I still need to do X. With pictures as I get things done of course...

before you do anything..set these correctly

#1 steps to spin motor 1 revolution. easy.. set Wizard to match Drive step selection and then verify with G1x1F20. 1600 steps is minimum recommended value. 3200 is better for a mill.
#2 overall turns ratio. (how many turns of the motor will result in 1" of travel on each machine tool axis.

Yes, as Keith stated be sure to set your steps/rev the same in Acorn and on the drive with 1600 minimum. Then calculate your overall turns ratio. You have to do this first. You cant set any travel limits or soft limits or any other limits until the machine movement is accurate.

cnckeith wrote: ↑Mon Sep 26, 2022 5:58 pm

mikecowhey wrote: ↑Sun Sep 25, 2022 11:29 pm All-righty then. Made the last of the headway on mechanical setup today. I had an issue with my limit switches being physically connected wrong. I had 3 of them wired NO instead of NC. That is fixed now and the last of the belt tensoners is installed.... Now comes the fun part. Setting up the software to run correctly. I have the limit and e-stop working and all 3 axis are connected and moving under power. or basically is will go something like this order if I am reading this correctly.
Figure out soft limits and machine travel limits
Figure out # of steps to make 1 full rotation
Calculate and configure the travel distance
Finally backlash. That will be the fun one. I will probably need to run thru this several times as I will need to tear down a few parts and make some adjustments/upgrades to minimize mechanical backlash in the system. Things like modifying the ACME nuts to reduce backlash and modify the ACME nut mounts to more solidly hold the nuts in place. This last part has been done on Y and Z, I still need to do X. With pictures as I get things done of course...

before you do anything..set these correctly

#1 steps to spin motor 1 revolution. easy.. set Wizard to match Drive step selection and then verify with G1x1F20. 1600 steps is minimum recommended value. 3200 is better for a mill.
#2 overall turns ratio. (how many turns of the motor will result in 1" of travel on each machine tool axis.

Is that linear? In other words, would more steps be better for a mill or is there a point of diminishing returns? My motors/drivers go up to 20k steps.

more steps is not better just like making smaller and smaller g code vectors is not better

Machine sweet spots for steps per rev and overall turns ratios.

Milling machines 3200 to 8000 steps per rev. , overall turns ratio 5 to 10

Lathes 3200 to 8000 steps per rev. , overall turns ratio 5 to 10

Routers 1600 to 3200, overall turns ratio 1.5 to 2.5

Routers used like milling machines 2000 to 4000 with overall turns ratio at 2.5+

Plasma 1600 to 3200, overall turns ratio 1 to 2.5

cnckeith wrote: ↑Wed Sep 28, 2022 1:46 pm more steps is not better just like making smaller and smaller g code vectors is not better

Machine sweet spots for steps per rev and overall turns ratios.

Milling machines 3200 to 8000 steps per rev. , overall turns ratio 5 to 10

Lathes 3200 to 8000 steps per rev. , overall turns ratio 5 to 10

Routers 1600 to 3200, overall turns ratio 1.5 to 2.5

Routers used like milling machines 2000 to 4000 with overall turns ratio at 2.5+

Plasma 1600 to 3200, overall turns ratio 1 to 2.5

Got it. So maybe a dumb question but, with the x and y having identical motors, ball screws and drivers, would you assume the turns ratio to be identical? Mine end up being a bit different and want to make sure I didn't screw up along the way.

This should be required reading: https://centroidcncforum.com/viewtopic.php?f=63&t=1801

Final turns ratio will probably be a little different.