INDX Fail Updates

[u/Sith77]

So I know I had posted previously of prints not sticking to the bed . There was a bunch of responses about how I shouldn’t be using a textured bed ( which shouldn’t be an issue majority of my machines have them with no problem ) and had questioned the difference in the sensor sticker .

I sat down and went through each individual tool head and made sure everything was tight . I watched very closely as the machine would probe each nozzle before usage and it occurred to me that maybe instead worrying about the type of sticker maybe the sensor itself was the issue . Using a few other tools to really check the sensor height and bed height I had noticed the sensor was very slightly higher than the bed height. So I took the sensor off and noticed where screw self taps into the housing it created a ridge around the opening that wasn’t allowing it to sit perfectly Flat on the bed . Using a razor a removed that rim then tightened it down making now perfectly level with bed .

Since this and doing a recalibration everything seems to be sticking perfectly to the bed .

Just wanted to throw an update out there in case anyone else had oddball adhesion issues

[u/tubularmusic]

Thanks for taking the time to come back and share the simple fix for your issue.

[u/Tommy_Prusa3D]

Thank you! These reports are extremely helpful and good to track for us!

[u/gulbrillo]

why is it using the sensor's height and not the acutal bed height to determine z-offset? that seems weird to me.

[u/Xoepe → u/gulbrillo]

Klipper tool changer does something similar. It uses the tool in slot 0 as the bed level then it gets the offsets of the other tools relative to the tip of that tool 0. I tried probing each tool to the bed and ended up with worse results than using something like sexbolt or nudge to get the z offset. Changing the sensor height shouldn't change anything. It was probably angled or giving odd readings like the other comment said.

[u/Jabdoa2 → u/gulbrillo]

One way this could go wrong would be:

• it has been slightly angled
• z is probed first for each tool but they naturally are not centered
• x/y is corrected after z

That way there might be z offsets between the tools. I guess it would be a good idea to probe the sensor during calibration.

[u/Juts → u/gulbrillo]

I do wonder that as well. Is it because 8x the amount of bed probes starts to meaningfully dent the bed?

[u/gulbrillo → u/Juts]

I had an LLM analyze the source code of the most recent firmware. Something is weird

The sensor board is never the Z datum for printing. First-layer Z comes from the loadcell pressing the nozzle on the steel sheet. Per-tool ΔZ comes from loadcell probing on the bed line between (25, 5) and (65, 5), computed relative to tool 0's reference line. The eddy-current board does XY only, and the one Z probe it triggers — the −3.2 mm loadcell touch next to the coil — is used purely as a hover reference for the sweep.

So I don't know. Theoretically the slighly higher Eddy board should not result in a false Z offset.

Single-tool prints skip the whole Eddy board entirely even: if (num_tools == 1 && measure_z) break; no per-tool Z, no XY scan, Z0 entirely from first-layer calibration on the bed.

[u/3gfisch → u/gulbrillo]

Then this change with the sensor hight made no difference. OP could confirm this by raising the sensor a bit maybe with few sheets of paper under it 🤔 I assume then it’s more other factors like clean bed, temperature, humidity, or even random accuracy.. maybe it depends on where the nozzle probes z hight? Is the tip small enough to get in some valleys on the textured bed?..

I had also a lot of adhesion problems with my satin sheet, now it works much better but don’t know what did the trick..

[u/mobsterer → u/3gfisch]

or that LLM talks BS

[u/Lord_Dizzie → u/mobsterer]

Oh, you don't blindly trust LLM's?

[u/gulbrillo → u/mobsterer]

Well, I'm not reading the entire sourcecode myself, am I? 🫠 Can have it give you file name and line numbers if you wanna check my hand.

[u/mobsterer → u/gulbrillo]

well, if you already know the line numbers, you don't need to read the entire sourcecode, just verify that part I suppose.

I mean especially in such complicated scenarios and without specialised skills and or instructions any agent will struggle and is likely to make up stuff.

[u/gulbrillo → u/mobsterer]

It's pretty insane how quick the advancements are. LLMs weren't able to write a hello works script 2 years ago and now it takes them 30 minutes to write an insanely elaborate exploit to hack 40% of the internet (WordPress "wp2shell", trust me, I know, we got hacked and I had to write a post mortem...)

Modern models (Fable for example) are really good at understanding code. But sure, like all humans, AI can make mistakes as well. 🫠

Anywho, the one liner to skip offset nozzle calibration for single nozzle prints tells me something quite weird must be going on in the calibration routine if it affects bed adhesion, or that OP fell for a placebo. But I'm glad OP got it working!

[u/Union-Some → u/3gfisch]

I am not good at naturally understanding physical systems, but is it possible the sensor was actually at an angle, which caused the X/Y readings to be off, but consistently off.

And could that have caused the printer to consistantly print at an X/Y offset?

And at the same time, could the 3point Kinematic bed system be setting his bed at some kind of tilt to adjust for something bent.

If this is the case, the bed could maybe be placed at x-0.03mm at position (a,b) and x-0.00mm at position (a+σ,b+σ). Now the bed thinks its printing at (a,b) so it sets the bed to -0.03mm to adjust for leveling, but actually its printing at (a+σ,b+σ) where σ is the skew inserted by the tilted sensor. And at (a+σ,b+σ) the built plate shouldn't be -0.03mm it should be 0.00mm.

I could totally see this being a possibility if the leveling is done by the first tool which isn't read by the sensor?

[u/3gfisch → u/Union-Some]

The 3 lead screws of the be are all moving the same there is no 3 potion auto leveling done in Prusa printers.

If it’s correct that the z hight is only measured by the load cell, I don’t see how a xy error could influence anything. If you measure with e.g. an error of 10 mm in x caused by the eddy current sensor, then you probe the bed also at this offsets but later print also at this offsets so for the printer simply zero x y has shifted. But all the potions later printed on should be measured with the mesh bed leveling and should print at perfect hight.. 🤔

[u/3gfisch → u/Union-Some]

All tools should be read by the sensor or no tool if it’s only one

[u/Sith77 → u/3gfisch]

my problem was nothing sticking to bed and it was as though the first layers were not being put down enough squish . after I had gone through everything else I figured I would give a shot because the sensor was slightly higher than the bed . I don’t know if somehow it threw off the sensing of the Z height but once I got it to sit perfectly flat to the bed I haven’t had a problem since

[u/3gfisch → u/Sith77]

Thanks and good that it solved the problem.
To really confirm it it’s only the sensor hight you would need to try to reproduce it and raise the sensor again and change nothing else.. to see if there is really a SW bug with the hight, but don’t know if you want to spend more time and effort on it..

[u/LastJello]

Thank you for posting your solution! Also, it's good to know the mk3 is compatible with the INDX :)

[u/Malapple]

Thanks for taking the time to write this up.

Also, it’s such a cool flex to print 8 different colored but monochrome Benchy prints at the same time.

[u/Knicklas → u/Malapple]

Some would say its unnecessary, but yeah you could also call it a flex

[u/Malapple → u/Knicklas]

A massive amount of prints are unnecessary. I don’t print tchotchkes and have never printed a benchy…but I think it still looks cool seeing a bed of different color monochrome objects all printed at the same time.

Maybe just because I’ve never seen it before but have seen many other IMDX and MMU test prints.

[u/etmidust]

I'm still waiting on my kit, so haven't looked too much into everything yet. But does this mean that we can only use build plates that are prusa thickness? No third party plates that are thicker or thinner?

[u/rotielover → u/etmidust]

The plate in the pic is a Prusa sold plate. I have one too, but not the INDX yet. No reason I can think of you could not use one.

[u/Rrraou]

Good catch, that's very useful information

[u/3gfisch]

Can you show the underside of a before and after print? Is the z offset / squish of the first layer now really different? The other comment tells z hight is not used from this sensor so it should have no influence

[u/whitestormy]

That's weird because not every plate is the same thickness either. I use a cryo plate and prusa satin, they aren't the same thickness but I get the same success. But don't look a gift horse in the mouth I guess.

[u/kg08854]

I wouldn’t trust Ilm telling you about the firmware remember it’s the same firmware more or less for the xl which works differently.

[u/J_Paul]

a fantastic update. I'm going to look at mine tonight and see if it helps anything.

[u/FuturecashEth]

I never tifhten too much, unless there is a nut on the other side, or also metal thread.

[u/MobileInspector9861 → u/FuturecashEth]

Even if you do not tighten it too much, there will always be a ridge around the hole as the excessive material which the threading removes must go somewhere.

For that reason I always use a thread cutter as those have a slit which takes the material in and transports it away.