Hi all,

I just finished the heavy top cnc (nema17). now I am doing some manual movements in cncjs (without makita attached)

Here happens some issues:

- the biggest issue is that the Y-axis gets unaligned on both sides and gets stuck (resulting in very high pitching sound of the steppermotors trying to move). I can move both Y-axis freely en smooth by hand when the motors are off so the spindles are not stuck. small steps is ok but when moving faster one side get stuck and the y-axis is crooked. 

- movements on the x-axis gets the lead screw (t8x2 (should have bought the t8x8)) shaken/vibrating. dont know if this normal.

- the z-axis also gives high pitching sound when giving multiple movement commands and stops moving.

(setting now are $111=1500 and $121=200.) 

I see alot of you guys building the same machine, so hopefully you can help.

thanks,

Alexander

Hi Alexander

- Y: I would triple check the settings of the drivers - are they exactly the same for both motors? That would explain that they get out of sync after a few rotations. I assume you don't use ext drivers since you're on Nema17, so probably worth using an ampmeter to adjust current to be the same?
- X: how long is it? I have read here about that effect, especially if long. I use SFU1204 on 1200mm and it's fine. But it is 12mm in diam, you're 8
- Z : maybe check the internal pressure of your anti slack metal pieces on the screw. Could be too tight?

Hope this helps, good luck

Hi Dany,

thanks for the reply.

- I use the cnc shield, so i quess they are the same. when moving slow it is ok, but moving to fast it gets stuck. Could it be that i want to move too fast? I've read that T8x2 are very slow compared to T8x8. 

Is there anyone who uses T8x2 leadscrews. What are your settings?

- the leadscrews are all 1000mm. 

- I made the second leadscrew-nuts very loose, so that the spindle is moving freely.

I would back up and make sure the Y axes motors are working properly. Unplug everything even the drivers. Then just one driver to one motor and see if they  move the same independently. You can set the movement in cncjr to just one revolution, put a peice of tape on the motor shaft and see what you get. If they are both the same you know you have eliminated the electronics. The other thing is possible binding on the square block that drives the threaded rod.

thanks for the help.

I found out the issue with my X-axis. it was also getting stuck on the sides. the reason was that i added and extra spacer of 1mm on the spindle holder (giving it more clearance). this caused that the X-as square block was disalligned with 1mm with the steppermotor. 

the Y-axis seems ok if I put the speed down to 1200mm/min. I didn't do a test with my makita yet, i need to see if that causes the Y-axis to get stuck more.

I also ordered new T8 lead screws (8mm instead of 2mm)