first layer height
-
Nice, a few more P3Steels around! I'm building up quite a list of mods for these!
With no z-probe how are you keeping your two z-axis screws aligned? Are they seperately driven? Do you drive to the end of the axis and stall?
-
@DocTrucker said in first layer height:
Nice, a few more P3Steels around! I'm building up quite a list of mods for these!
With no z-probe how are you keeping your two z-axis screws aligned? Are they seperately driven? Do you drive to the end of the axis and stall?
My error. I sent that without thinking. The only probe I have is the z end stop. I was thinking bed leveling probe when I responded. .
Yeah it’s a great machine. I was thinking of building a core xy, but this has worked out well for me for what I do at the moment. Yeah I’ve done my own mods over time.
-
@mlaustin6 said in first layer height:
I do not have a probe. I should probably comment out the probe section. It was put there using the reprap configurator.
You can leave the probe section. It's currently set as manual probing, so if you ever did send a probe command like G30 or G29 it would prompt you to manually job the nozzle to touch the bed. Not really practical for doing a heightmap, but can sometimes be handy.
I have not done baby stepping. How and why would I do that?
During the first layer you can use the baby stepping buttons in the DWC interface to adjust the Z height of the first layer to get it dialed in. By adding that amount to the G92 in your homeall you make the adjustment permanent.
I also suspect that your bed may not be flat, so even if it's level, there may be a raised section.
If you print a test object like this, does it cover the bed uniformly? bedlevel_nozzle_0.4_200x200-0.3-0.8.stl
So should I change it to x16 micro stepping? Why is it not recommended?
I would suggest x16 with interpolation to x256 enabled. You'd have to recalculate the steps per mm to match. Reason being that the Duet has drivers that will take a x16 microstep and internally translate it to x256 for the motors without putting that step generation load on the CPU. So you get the benefit of quieter and smoother motors without hitting the CPU with x256 stepping. You'll probably just notice that it's quieter. But in some cases if you try and move too many axis too fast at once you can saturate the step generation and hiccups will ensue causing micro pauses, or in worst cases long stalls. You can check to see if you're being affected by this by running M122 after a print and seeing if you have a large hiccup count. The only cases where using a higher microstepping could be beneficial is with an XY axis with a steps per mm below 80, or an extruder below 400 (usually ungeared direct drive).
-
@mlaustin6 no problem, I assumed you had got a limit switch but badly explained myself!
As steppers move under the control of the Duet it is likely that a stationary position will be part a few microsteps past a full step. When powered down the stepper naturally settles to the next physical step that can be in advance or retard of the steppers current position. The potential end result for systems with an x gantry like ours is the motors can move in opposing directions loosing aligment - or becoming less parrallel to - the bed surface.
With a z probe the duet can align the gantry to the bed by checking two points on either side of the bed and correcting. Other options with independent drives are two accurate z limit switches. If the motors are hard wired together then your only real options are; to force them into the top of the machine to stall the steppers and hope they settle at a consistant point, or check against the bed manually before each build.
Edit: if your board has stall detection then you can try using that without z-probe but it may not be very accurate due to the reduction drive of the screw.
Running 3 P3Steel with Duet 2. Duet 3 on the shelf looking for a suitable machine. One first generation Duet in a Logo/Turtle style robot!
-
The bed is flat to my eyes. It’s a new bed, and that is why I went 3 point leveling because the last one got warped. I have a flat tile it was put on, and no edges were lifted. No air gaps either as it didn’t move easily on the tile. Also, the .1mm feeler gauge moves around on all corners and in the middle, granted some spots are a little tighter but not enough to make it difficult to move with one finger. So doubling that at .2mm should not cause a smashed first layer.
So if I use the baby steps, would I add the value to the g92 line?
I’m going to try testing it tomorrow using a file without filament at a slow speed and insert a .1mm and .2mm feeler gauge as it moves. That will give me an idea if the is actually moving to .2. Another option is to use a .01mm feeler gauge and just say the bed is at zero at see what happens.
-
The motors are not hard wired together. They each have their own slot on the board. I assume that’s what you meant. Where can I find more info on how to setup this type of z probe?
-
Looking at M122 results, the hiccups are as follows:
Hiccups: 9898(0)
I'm guessing that means zero and not 9898 hiccups.
-
@mlaustin6 If the motors are using two sockets close together on the board, and near the z-driver then you are probably using the sockets that are wired together. If you have mapped drives to use one of the spare extruder drives for the second z axis then you can look at using either two z axis limit switches or a z-probe to level the bed.
I've not tried using two limit switches. You may get some information from this following thread and then reading through the gcode guide:
https://forum.duet3d.com/topic/11007/dual-z-axis-homing-problem/2
My toddler son is off nursery today (nothing serious) so I won't get much spare time but I will have a look at my machine and give you an example of z-probe assisted levelling.
Reason I mention the levelling is that it could easily give a squished first layer on one side of the bed.
-
@mlaustin6 said in first layer height:
Looking at M122 results, the hiccups are as follows:
Hiccups: 9898(0)
I'm guessing that means zero and not 9898 hiccups.
Nope those are hiccups. Enough to potentially be an issue. Is that after a full print? Or just homing?
What firmware verison exactly are you using? Send M115.
-
@Phaedrux
Hmm interesting. I ran M122 after a print finished.. I am on firmware 3.0.
