Mesh Compensation

Veti

@Corexy said in Mesh Compensation:

I should point out that x and y have homing switches...the probe only does the bed level.
Does that change anything?

no

Corexy

OK,

So my nozzle/probe offsets are:

X 4mm
Y 28mm

So my M557 becomes:

M557 X4:195 Y28:195 S10 (?)

Just a bit worried that the fans might bang into some hardware with these offsets. It's a tight fit in there.

My slicer start script:

G28 (home all?)
G29 (mesh probe?)

Nothing else at all? I should really tack the purge/wipe I was asking about in my other thread on here while I'm at it?

Any changes to bed.g?

Homing files...

homeall.g:

; homeall.g
; called to home all axes
;
; generated by RepRapFirmware Configuration Tool v2.1.2 on Thu Nov 21 2019 10:53:58 GMT+1100 (Australian Eastern Daylight Time)
G91 ; relative positioning
G1 H2 Z5 F6000 ; lift Z relative to current position
G1 H1 X-200 Y-200 F1800 ; move quickly to X and Y axis endstops and stop there (first pass)
G1 H2 X5 Y5 F6000 ; go back a few mm
G1 H1 X-200 Y-200 F360 ; move slowly to X and Y axis endstops once more (second pass)
G90 ; absolute positioning
G1 H2 X97.5 Y97.5 F6000 ; go to first bed probe point and home Z
G30 ; home Z by probing the bed

; Uncomment the following lines to lift Z after probing
G91 ; relative positioning
G1 S2 Z5 F100 ; lift Z relative to current position
G90 ; absolute positioning

homex.g:

; homex.g
; called to home the X axis
;
; generated by RepRapFirmware Configuration Tool v2.1.2 on Thu Nov 21 2019 10:53:59 GMT+1100 (Australian Eastern Daylight Time)
G91 ; relative positioning
G1 H2 Z5 F6000 ; lift Z relative to current position
G1 H1 X-200 F1800 ; move quickly to X axis endstop and stop there (first pass)
G1 H2 X5 F6000 ; go back a few mm
G1 H1 X-200 F360 ; move slowly to X axis endstop once more (second pass)
G1 H2 Z-5 F6000 ; lower Z again
G90 ; absolute positioning

homey.g:

; homey.g
; called to home the Y axis
;
; generated by RepRapFirmware Configuration Tool v2.1.2 on Thu Nov 21 2019 10:53:59 GMT+1100 (Australian Eastern Daylight Time)
G91 ; relative positioning
G1 H2 Z5 F6000 ; lift Z relative to current position
G1 H1 Y-200 F1800 ; move quickly to Y axis endstop and stop there (first pass)
G1 H2 Y5 F6000 ; go back a few mm
G1 H1 Y-200 F360 ; move slowly to Y axis endstop once more (second pass)
G1 H2 Z-5 F6000 ; lower Z again
G90 ; absolute positioning

homez.g:

; homez.g
; called to home the Z axis
;
; generated by RepRapFirmware Configuration Tool v2.1.2 on Thu Nov 21 2019 10:53:59 GMT+1100 (Australian Eastern Daylight Time)
G91 ; relative positioning
G1 H2 Z5 F6000 ; lift Z relative to current position
G90 ; absolute positioning
G1 H2 X15 Y15 F6000 ; go to first probe point
G30 ; home Z by probing the bed

; Uncomment the following lines to lift Z after probing
;G91 ; relative positioning
;G1 H2 Z5 F100 ; lift Z relative to current position
;G90 ; absolute positioning

I do suspect my files are messy. I come on here asking things and get a line to add here and there. Would really love to have an expert here with me in front of the thing for a day...

Veti

@Corexy said in Mesh Compensation:

M557 X4:195 Y28:195 S10 (?)

no you change the probe offset in the G31 command like i posted.

Nothing else at all? I should really tack the purge/wipe I was asking about in my other thread on here while I'm at it?

lets get your mesh working first.

Any changes to bed.g?

bed.g is for G32 command which you are not using.

your homing files look fine

Corexy

Ok, sorry my mistake

X and Y is the offset of the probe from the nozzle. X postive is to the your Y positive is behind. Without this your mesh will be inaccurate.

Not quite sure what you mean here...you mean that I enter a positive value offset if the probe is further "along" the axis than the nozzle tip, and negative if it is "behind"?

Thank you for your patience by the way.

Veti

that was posted regarding your
G31 P500 X0 Y0
command.

that command means the probe is at the same place as the nozzle is, which it is not as you are using a ir probe.

so you need to tell the duet where the ir senssor actualy is while assuming that the nozzle is at 0,0.

post a picture of your carriage.

Corexy

@Veti said in Mesh Compensation:

that was posted regarding your
G31 P500 X0 Y0
command.

that command means the probe is at the same place as the nozzle is, which it is not as you are using a ir probe.

so you need to tell the duet where the ir senssor actualy is while assuming that the nozzle is at 0,0.

post a picture of your carriage.

OK, so I just went out there and moved the nozzle around the absolute outside of the build area via the touchscreen, and the nozzle travels the absolute limits of the build area and obstacles as it is. If I add these offsets is there any chance I'll bump into things, or should I do something to avoid that.

[img]https://i.imgur.com/kCMHC1Q.jpg[/img]

[img]https://i.imgur.com/bC9SaMB.jpg[/img]

Veti

@Corexy

try it with the hand on the power switch.

but if i remember correctly the offset does not change the mesh coordinates, as they are absolute nozzle parameter.

Veti

@Veti

also
M208 X0 Y0 Z0 S1 ; Set axis minima
M208 X195 Y195 Z175 S0 ; Set axis maxima

this is a hard limit for your axis. if at X195 Y195 there is no problem. then you can not cause a problem with the mesh leveling.

Corexy

Yes, I'll keep the switch handy ha ha. But It still must home the axis' against the limit switches, so yes no offset was probably only messing up my mesh.

G31 P500 X2 Y28 Z2.465

I measured it a bit more accurately. So I run G29 and see what happens??

Veti

@Corexy
yes

Corexy

M557 X20:180 Y20:180 S10

Ok, it's ticking over happily with the mesh (cold build plate), but it's going to take a lot longer with these 10mm intervals. Which is fine if it will give me a better first layer.

To probe the entire (195x195) bed, should I take it out to the edges?

M557 X5:190 Y5:190 S10

And I'm also thinking should I:

Warm build plate
Home all
Mesh probe (each time, as different bed temps will make different mesh)
Purge/wipe
Start print

It would be really good to do the mesh probe with a cold nozzle as the ooze is a pain and I'm using an IR probe anyway. I don't mind at all the mesh taking a long time if I'm not picking ooze off the nozzle with tweezers the whole time.

Veti

@Corexy said in Mesh Compensation:

Ok, it's ticking over happily with the mesh (cold build plate), but it's going to take a lot longer with these 10mm intervals. Which is fine if it will give me a better first layer.
To probe the entire (195x195) bed, should I take it out to the edges?
M557 X5:190 Y5:190 S10

post the picture of the mesh grid.

going to a higher spacing depends on the quality of your build plate. the wider the spacing the less details it has to correct with.
so if there are no irregulaties, you can get away with a wider spacing.

with the bigger mesh: if your Y offset is 28 to probe at 5 it would need to move to Y-23, which is not allowed. for X it would work

Corexy

Yes, I can't "reclaim" the Y offset...mechanical obstacles. Makes a case for ally extrusion chassis in my next printer, built well oversize to the build plate.

Running this now regardless, and it seems to be just doing what it can reach.

M557 X5:190 Y5:190 S10

Mate I really appreciate this help so much, but it's late now and the other half wants me to give it a rest for tonight.

I'll have another look in the morning, but this has been a win so far.

Cheers and thanks!

[img]https://i.imgur.com/3hQysIH.png[/img]

Veti

that picture suggests that the surface is not suited very well for ir probing.

see
https://miscsolutions.wordpress.com/mini-height-sensor-board/

Corexy

OK, really?

It's the original Printbite, supposedly OK. It does give very consistent readings when calibrating the Z height.

I have wondered about those BL touch probes, are they better?

I would really like to keep the Printbite, just because I don't have to replace it. That surface is 3 years old and going strong.

Are there any other surfaces that are similar out there that do work well with IR? I have really liked this probe to be honest, but the Printbite has been tricky with ABS.

I'll see how it performs with this new mesh tomorrow.

@dc42 @deckingman

Corexy

So how would one of these be as a bed sensor?:

https://www.ebay.com.au/itm/5mm-Noncontact-Inductive-Proximity-Sensor-Switch-Detect-DC-6-36V-NPN-TL-W5MC1/253114333447

I've thrown straight edges on this build plate, and while i's not perfect I don't think it runs out as much as this mesh suggests.

With the build plate under the printbite being cast ally, would this type of sensor work better? Is it a straight up fit, or would I need a daughter board of some sort?

I saw another thread where a guy was reporting good results with one of these (due to having trouble with the IR sensor on Printbite), but the thread seemed to die out.

Unless there's a comparable (long lasting/self releasing) surface out there with good IR sensor compatibility, would this be an option?

Corexy

[img]https://i.imgur.com/1Zczdwt.png[/img]

Here a mesh I ran with a plain sheet of white paper on the bed. It was certainly not flat, but I don't see the "spikyness" in the map that I get with Printbite.

Can someone tell me if I need to use a different sensor, and if so, what do I use?

I'm wondering if I've been printing for a few years now with a setup that was not capable of reading the bed properly....

Corexy

And at the risk of talking to myself it all seems to be working better now.

I took the ABS out, as it's known to be a bit difficult on Printbite (until you've got it dialed right in) and went back to a roll of PLA.

I had to babystep -0.15mm, which I then added as a Z offset in the slicer and it's printing a pretty perfect first layer with no sign of the problems I've had in the past.

On this surface I've always had to use a raft for ABS, so I guess that might still be required.

Veti

@Corexy said in Mesh Compensation:

[img]https://i.imgur.com/1Zczdwt.png[/img]

i have no ir sensor and i dont have the printbite surface, so i cant give you more information there.
That surface looks terrible if thats the real surface of the buildplate.

Corexy

@Veti said in Mesh Compensation:

@Corexy said in Mesh Compensation:

[img]https://i.imgur.com/1Zczdwt.png[/img]

i have no ir sensor and i dont have the printbite surface, so i cant give you more information there.
That surface looks terrible if thats the real surface of the buildplate.

It's not like that in person, pretty flat actually.

Right now the mesh compensation is working so amazingly I've removed it form the start script, and will only do a new map as a maintenance/corrective measure. I heated the bed to 100C, run the mesh and I'm leaving it at that unless problems show. First layers are as good as I've ever seen on this machine, and as they are consistent I'll assume it's all good.

I should point out that while I'm crap on a keyboard, 15 years of maintenance work on mines and oil rigs has taught me a trick or two on the spanners and feeler gauges (if I say so myself). My beds and axis' are all over engineered, rock solid and set up as straight as the material they're made of will allow. I don't expect my bed to change level, I hardly touch it ever.

I am amazed how much this compensation is working, and I'm sure your tip about the extra probe points is what did the trick.

So thanks very much for your help, and the result is good!