@jens55 I forgot to answer that in the last post. Without belts the carriage is so smooth that it moves to one corner under gravity because my workbench is not perfectly level. With the belts on and the set screws of the stepper pulley loose it is still +very smooth and easy to move so I don't think it's that.

The last picture I posted doesn't really seem to have an offset like the first photo did it looked more to me like under extrusion at the end of a move but as I said I have pressure advance turned off. Well I decided to take a look at the PA settings while printing and found out that Prusa Slicer was modifying my PA settings during the print. I didn't even know this was a setting in there but it was set to 0.4 which is way too high for the Hemera hotend I have. I set the PA in Prusa Slicer to 0 until I have time to properly calibrate and now the first layer is looking more like what I would expect so I think I had a combination of skipping steps and bad PA settings. Still a lot of calibration to do but at least i'm now where I expect to be. Thanks for all the input.

I turned everything way way down and I get slightly different but similar results:

@jens55 Yes I suppose I should clarify. There is a gap on the left perimeter that should not be there. At the top and bottom the gap is small and in the middle it is bigger. On the right the infill actually overlaps the perimeter. On the right side at the top it overlaps so much that it goes past the perimeter. So it's like the entire infill is shifted off to the right. I have the steppers set to 800mA. They are from an old CR10S, they are JD42HS40-1004A-02F. Best I could find max current is most likely 1A so I tried to play it safe.

I am running mesh bed levelling with a BL Touch. The bed is 400 x 400 and it's not very flat so right now i'm running 100 probe points until I can do some more testing to find out what is necessary.

Hopefully this is okay to ask here. I guess if it's not you can delete it.

I am hoping someone can point me in the right direction on a weird issue i'm having with my first test print of a new printer. I am building a homebrew CoreXY with a Duet3 6HC mainboard. I can get in to specific specs if you want but I don't know where to start so i'm hoping the picture will lead to questions.

I have been 3d printing for a very long time and I have owned a lot of different machines but I have never built my own from scratch and I have never had a CoreXY printer. I tried my first test print today and below is a photo of my first layer and I have never seen anything like this.

I don't believe I am skipping steps as I'm not hearing anything from the steppers. I even tried making the belts very loose to alleviate some stress on the steppers and the result was the same, and I have the print speed very low. Lastly I have done a backlash test with a dial indicator in both X and Y at max speed and max accel and I always return to within .001 or .002" of where I started.

The gantry and bed are very rigid so I don't think they are to culprit. I don't currently have any features turned on like input shaping or pressure advance. I'm wondering if it could be something weird with the way the steppers interpolate their position?

Any advise would be much appreciated. Thanks.

@dc42 Ok interesting so for now I will just comment out my homez file and finish writing my homeall file and once that is done it should no longer run homez after. Thanks!

Is it common for homeall to run homez after all of the gcode in homeall? It is happening for me and I can't find any documentation that this is supposed to happen. I am writing my x and y homing code in homeall and during testing it's still running homez. I can confirm this because if I go comment out everything in homez and run homeall again it doesn't do it. After further testing if I remove everything in my homeall except this:

G91               			; relative positioning
G1 H2 Z10 F3000    			; lift Z relative to current position

It works fine. It just lifts Z up 10mm. But as soon as I add the next line:

G91               			; relative positioning
G1 H2 Z10 F3000    			; lift Z relative to current position

G1 H1 X-325 Y400 F6000 			; move quickly to X and Y axis endstop and stop there (first pass)

It now lifts Z 10mm, homes X and Y once, then runs whatever is in my homez file. I am completely lost here.

Common problem on a lot of forums but I hoped this one was going to be different. I came here to ask for help to do something, not to ask for recommendations on what to do. Everyone has different ways of doing things and reasons for that. I have decided what I want to do and just needed help figuring out how to do it. I was not asking for something crazy that isn't supported so there wasn't any reason to tell me to do something else. And lastly my BL Touch doesn't get close enough to my screws for this to work. In one corner the probe is probably at least 4" away from the screw

I was able to figure it out on my own and it works absolutely perfectly. For those that think a lead screw doesn't work with sensorless homing that is 100% inaccurate as long as you have a hard stop that will completely stall the motor and not just flex when the end is reached. As long as your axis hits a hard stop and the motor completely stalls sensorless homing works just fine.

@gloomyandy

That's not the same thing. When the gantry is crooked the nozzle is crooked to the bed and you will end up with artifacts on flat top layer surfaces because the nozzle is not flat.

@gloomyandy said in Quad Z Sensorless Homing + BLTouch:

sure if you spend a little time searching you will find other similar comments.
I'm still not sure why you want to home the bed this way, if you have a probe why not use that

When I shut the machine off and some of the motors fall down and the entire gantry is slightly crooked, then what do I do?

In all of those other posts people mention mechanical advantage which doesn't really make sense. A stall is a stall. When it hits the mechanical end stop the motor can not turn any further regardless if it is driven by a belt or a screw. I could see mid print stall detection on a screw not working well but sensorless homing should not matter in this way. I am convinced that I have some settings wrong. I have previously only used Marlin and Rep Rap is a whole different beast that i'm still struggling to understand.

I changed it to M915 X Y Z S-64 R0 F0 and it still does not seem to work.

The G92 Z0 is left over from the default file I just haven't changed it yet, I was more concerned with getting the stall detection to work first.

I am using rods, this is the first I have heard anyone mention it being harder to do than with belts. My prusa minis use sensorless homing on the Z axis with rods. What in particular makes it harder to do?