SD3 keeps shifting where it is printing after a couple of layers

Are any mods done to the printer? Could be a driver or stepper over heating. Could be bad rods and or  bearings/sleeves binding up.

it is actually shifting on the y axis. I just re lubed the rods. it does it around the 15th layer. Its very frustrating

the belts feel tight. Im watching it and i see when it shifts. So i felt the motors. none of them were hot. I paused the print homed it and it still goes back to the incorrect spot. Usually if I home it mid print when I hit resume it goes right back to where its supposed to.

Sounds like a failing endstop or endstop harness. I would check the harness by flexing it along it's length during operation. I would swap the endstops between the axis and see if the issue follows. I would also swap the driver between the two axis and see if the problem follows.

i swapped the end stops and the motors for X and Y on the board. It still shifts. just in a different direction now. It was shifting forward on the Y now it shifts to the left on the X. So, is it a stepper motor  need to replace or an end stop?

what controller board is on this printer?

im putting a new motor on today to test it out. I have the original board. What board would I replace it with if thats the issue?

no need to replace the main board, there are small pots on main board that you can turn to adjust motor current, you can google on this subject to get guides and instructions.

i have a sang board from what I can tell based off the print on the board. I was pretty certain it wasn't a driver bc when I swapped the motor from the y to the x axis it then shift on the x axis. The shift didn't occur in the y direction as before so I know its not an end-stop issue and its not some sort of belt or pulley issue. That's what leads me to believe it isn't a driver issue bc when I put the x axis motor on the y spot it didn't have any issues. I should have the new motor next Friday so ill be able to tell then for certain.

Had this problem with my SD3 before I placed a fan near the Sang to keep the board cool. Once that happened, it never printed in odd places midway through the print. Before I did that, it happened often.

Just a quick easy idea that *might* work... Place a small fan near the pcb and give it a shot...

I don't know if this fixed your problem, but if not, I have a couple theories that I have experienced myself.

1) Y shift may be caused from the front Y pulleys. Through extensive use, I've found that lubricating the inside of the pulley helps prevent wear on the bolt. This is a dead giveaway if it squeaks or grinds during the shifts. If this is the case, use white lithium grease and upgrade to the Y Overkill Brackets if you have not done so.
2) If you still have the stock Y drive bushings (the ones hammered into the frame in the rear) may have rusted, or, as I have seen on some used machines I've picked up, white lithium dried and gummed up which causes the bushings to seize and prevent any compensation for Y movement. To correct this, simply undo your belts and rear pulleys, remove the drive rod, and take a trusty scredriver to be inserted into the 6mm opening and rotate (forcefully if needed) to be certain it can move freely. I used 3 in 1 inside the bushing and never had a problem again.

Hope this helps.

This is the problem i am having now. I have 8825 drivers to install. I am looking for a write up on Vref & setting micro-stepping in a Sang 1.3a .