How screwed am I?



  • Rebuilding my Voron, and wanted to do PEI + IR Sensor right. Everything was going great - PEI was painted with 3 coats, cured successfully, etc. Until the very last step. I attached the 10"x10" PEI to my 9"x9" aluminum bed, and that went perfectly. But when I flipped it over to trim off the excess PEI, I guess I wasn't pressing down hard enough on the bottom of the bed, so I apparently pulled the newly attached PEI away from the bed, which (thanks to the incredibly strong 3M adhesive) ripped off some of the paint around the edges. Some paint stayed on the PEI, while some paint stuck to the aluminum bed.

    So now it looks like crap. The PEI still feels perfectly flat/smooth, but it's very clear where the paint was pulled off the PEI.

    My question is: will it look as bad to the IR sensor as it does to the human eye?

    Lesson learned: Cut PEI to size before painting (and definitely before gluing).


  • administrators

    I suspect that will cause problems for the IR sensor.

    When I painted the underside of my PEI black, after curing the paint in an oven I tested the adhesion by putting some sticky tape on the paint the then ripping the tape off. The paint remained attached to the PEI. So I wonder whether there is something different about the paint you used, or the PEI surface preparation, or the curing.



  • Could be. I didn't remove the PEI protector until immediately before painting, did a quick alcohol/microfiber wipe, sprayed on 3 coats of "High Heat" Enamel Grill Paint, and cured for 2 hours at 170C. Not sure what else I could have done there.

    But isn't that 3M adhesive to sticky tape what dynamite is to firecrackers? All I know is that I shouldn't have put pressure on the PEI like I did when I was trimming the excess (bed was upside down so I was effectively pushing PEI away from bed).

    Live and learn!



  • And just to fully close this out - the lifted paint totally throws off the IR sensor. Fortunately my bed's pretty flat and enough of the surface works with the sensor so I can print pretty well while I slowly build up the energy to buy and install new PEI…



  • You could try a piezo sensor. I would recommend that for PEI anyways. IR worked great for me on glass but I never got it accurate on PEI



  • I may try piezo on my next major rebuild. The IR sensor has been pretty repeatable (on the parts of the bed where I didn't screw up the paint), though. I'm pretty happy with it - I just can't do full-bed mesh leveling.



  • @Yonkiman:

    I may try piezo on my next major rebuild. The IR sensor has been pretty repeatable (on the parts of the bed where I didn't screw up the paint), though. I'm pretty happy with it - I just can't do full-bed mesh leveling.

    Please don't take this the wrong way but if you are planning a major rebuild, then consider using aluminium tool plate which will give a you flat build surface thus negating the need to compensate for deviations. If you can build it rigid and square and use three lifting screws, you can also negate the need for any form of software level compensation. It doesn't cost much extra to do and it's so nice to be able to simply home the printer, then print something. I just put G28 (home all) in my start gcode as well as any heating commands. So if I want to print something, I turn on the printer, select the file to print then walk away and come back when it's finished. No messing around having to probe the bed.



  • @deckingman:

    Please don't take this the wrong way but if you are planning a major rebuild, then consider using aluminium tool plate which will give a you flat build surface thus negating the need to compensate for deviations. If you can build it rigid and square and use three lifting screws, you can also negate the need for any form of software level compensation. It doesn't cost much extra to do and it's so nice to be able to simply home the printer, then print something. I just put G28 (home all) in my start gcode as well as any heating commands. So if I want to print something, I turn on the printer, select the file to print then walk away and come back when it's finished. No messing around having to probe the bed.

    I agree 100% with this. Build it with a good flat print bed and move on…. My current printer has a flat bed and has no need for bed compensation. I am building a new IDEX version with a flat piece of jig plate that will be indicated flat and parallel to the hotend travels. I will use a switch mounted on the back of my bed as a touch height for setting my hotends Z zero's when ever I change them. This will also allow me to run a regular nozzle along with a volcano nozzle on the U drive during the same print.


 

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