Core XY movement issues

JoergS5

@fxxtoo I thought about the pulleys slipping. This depends on the tension you have on the belts.
1.5 A seems to be ok for 1.8 steppers. There is some valuable information in
https://duet3d.dozuki.com/Wiki/Choosing_and_connecting_stepper_motors
Nema23 has more torque than 17er, so you might not notice the slip.

You can file into the shaft, but I prefer nondestructive means like loctite 221.

pro3d

@fxxtoo

I think you should up your accel a little. 500 is very low - I dont know if it will help but you could try 1000 as I see you have 10 in jerk

FxxToo

@pro3d
Thanks! I have been trying to figure this belt, timing or driver issue out and haven't got into the finer tweaks yet. I will try that.
rj

deckingman

IMO, higher acceleration is likely to make things worse. Start slow, get everything working, then increase speed and acceleration in small steps.

deckingman

Try this. Do a longish move in X, say 100 mm and measure the Y distance and direction. Then swap the A and B motors (the ones that do X and Y). Repeat the X move. If the movement in Y changes direction, then it's an issue with the motor. At least that will eliminate one variable.

FxxToo

@deckingman
Excellent I will try that. I was just starting to pull the Duet board out. Wiil try that right after lunch. and Post the results.
Do you mean remap the motors or physically swap the motors?
Thanks!
RJ

Phaedrux

@fxxtoo I would think to physically swap them.

FxxToo

@phaedrux
Thanks. I just did that. Same thing. ARRGG!
RJ

Phaedrux

@fxxtoo at least you know it doesn't follow the motor, so the motors are ok.

FxxToo

@deckingman
just finished swapping the steppers. I left the M92 the same. Before I swapped the motors, I did a G1 x250, the head did not move in the Y. I just did a I did a G1 x250 and Y did not move. So the same as before.
RJ

FxxToo

@phaedrux
Thanks. At least that is some progress.
RJ

JoergS5

@fxxtoo

I looked at
https://forum.duet3d.com/topic/4958/y-axis-moves-when-only-x-is-commanded/10
again, where you made some pictures of your printer.

I wondered whether the linear X guide is connected stable enough (I mean the linear guide in the middle, connected to hotend). I had a problem at my own CoreXY printer that moving by hand was ok on one side, but not at the other. It blocked totally because the connection bends a bit and the one linear guide blocks.

In your picture the one side is connected by a screw, on the other by a linear mgn guide which is very good to level temperature effects. But the disctance between linear guide and aluminium cage seems to be different at both sides and the linear guide alone seems to be too little support (one or two screws on one side). The difference at the mgn side seems to be less than the other side. On the mgn side the belts are not in the middle in respect to the cage.

The difference leads to different Y positions at the both sides and leads to become stuck because the pulleys have different positions.

JoergS5

@fxxtoo

At this side

the left belt side is very strange. It seems to go around a shaft and so a nonlinear movement is introduced.

mrehorstdmd

@fxxtoo I don't think it has anything to do with your printer's problem, but what @JoergS5 is pointing out is that the X axis bearing block at the P2 pulley assembly appears to be thicker than the spacer at the end of the X axis rail at the P1 pulley assembly. When I built my printer, I made the spacer to match the thickness of the bearing block. That keeps the P1 and P2 pulleys at exactly the same Y position when the rails are square.

It shouldn't make any difference as long as you ensure that the X and Y guide rails are square when you tension the belts. In other words, don't use the pulley position along Y to determine if it's square, use the guide rails as the reference.

@JoergS5 The left side belt comes off the pulley in the block and goes directly to the extruder carriage. You're seeing parallax - there's no shaft- the top of the pulley assembly has 4 tool access holes for screwing the assembly to the Y axis bearing block..

deckingman

@fxxtoo said in Core XY movement issues:

@deckingman
just finished swapping the steppers. I left the M92 the same. Before I swapped the motors, I did a G1 x250, the head did not move in the Y. I just did a I did a G1 x250 and Y did not move. So the same as before.
RJ

What? I thought you were saying that when you moved in X, there was movement in Y as well. Now you are saying there isn't. Totally confused now by what the problem actually is.

JoergS5

@mrehorstdmd Thank you for explaining the holes. It's difficult to analyze from a photo.

The reason for this all is still mysterious, we should place bets. I heard the British like to bet.

FxxToo

@deckingman I changed the settings in the M92 from X320 Y319 and the movement stopped and appears to be working normally. I did this based upon the 2nd link I posted as that was a similar problem as mine.
I left the M92 setting the same,adjusted so there was no movement in the Y when X was moved. I still have it set up with the motors swapped. I can set the M92 back to x320 y320 and try it both ways. I was going to take the board out of the enclosure to really examine the boardto see what I find. After some of the post I have found about board issues and pictures I have found, missing or bad solder joints, etc.

pro3d

@fxxtoo
I am looking at the belt alignment. Are they the same on both sides? Optimal would be to run them inline and not in an angle like you do as this might influence the movement if not mirrored perfectly. Or am I watching something the wrong way

FxxToo

@joergs5 I thought I made the distance from the pulley blocks on the Y axis to the rail on the X axis were the same on both sides. I will check that when I get off work. Thanks for bringing that up!
rj

deckingman

@fxxtoo Ah I see. Sorry I forgot that you had set the X and Y steps per mm differently as a work around. I guess I kind of assumed that you would use the same steps per mm on both X and Y for the purpose of that test. No matter. The fact that you get the same movement with the motors physically swapped at least eliminates the motors as a cause of the problem.