Calibration destroyed part of my heat bed 🙁
 
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Calibration destroyed part of my heat bed 🙁  

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Lensdigital
(@lensdigital)
Active Member
Calibration destroyed part of my heat bed 🙁

I just finished assembling printer, everything looks great. I adjusted z-probe with zip tie as instructed (although it's EXTREMELY hard to move z-probe, I have no thing to grab onto it and it's held very tight even with screws removed).
Attempted to calibrate Z axis and after raising z-axis all the way up, pressed button and it kept going down never stopping hitting by heatbed until I powered machine off. No problem, no damaged.
Checked it again, powered on attempted to do XYZ calibration this time. It told me to place piece of paper on the bed so I did. This time it stopped at 1st point, then searched around it for a while and found point #1. It then went to point #2 and was searching and searching, gradually lowering head. Then it failed to find it, I removed paper and to my horror saw what it did to the heated bed, part of it ripped pretty bad. I don't know how deep damage goes, I hope it's just PEI film (or whatever surface is called). But it didn't rip the paper! I'm not sure what to do now. It's not 1st 3D printer I built, but it's the most expensive one 🙁

Posted : 10/08/2017 3:34 am
AJS
 AJS
(@ajs)
Noble Member
Re: Calibration destroyed part of my heat bed 🙁

The purpose of putting the paper down is to see if the nozzle touches the paper. If the paper starts to move you need to kill the calibration right away. Paper is about 0.1mm thick, so as soon as it touches the paper the paper will start to move with the head and you have time to stop it before the nozzle digs into the bed.

Your PINDA is too high. The calibration keeps searching for it, by moving around and slowly dropping the Z position. It will keep doing this for a while. The paper is to warn you if it is starting to search too low.

The PINDA sensor can only "sense" about 1mm. It sounds like your PINDA is higher than 1mm from the bed position at that point (but marginally below it at the prior points).

You can use a screw driver to gently spread the holder to make it easier to move up and down - with the screws loose of course.

For now get the printer working, and avoid that part of the bed. Check the nozzle to make sure it was not damaged.

THEN you can determine if you damaged the bed, or just the PEI covering over the bed (which is easily replaceable.) I am guessing the PEI sheet replacement will be sufficent to get you back to 100%.

I hope this helped.

Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage or loss. If you solve your problem, please post the solution…

Posted : 10/08/2017 4:05 am
Lensdigital
(@lensdigital)
Active Member
Topic starter answered:
Re: Calibration destroyed part of my heat bed 🙁

Thanks a lot Aaron! Wish paper part was mentioned in the assembly instructions or video... First time I saw any mentioning of it was on the LCD screen during calibration...
I'll adjust height of the probe as you suggested (zip tie is too thick I think)... But I'm not sure how I run calibration again, since that damaged area is wavy and raised 🙁

Posted : 10/08/2017 4:54 am
Tom
 Tom
(@tom)
Trusted Member
Re: Calibration destroyed part of my heat bed 🙁


Thanks a lot Aaron! Wish paper part was mentioned in the assembly instructions or video... First time I saw any mentioning of it was on the LCD screen during calibration...
I'll adjust height of the probe as you suggested (zip tie is too thick I think)... But I'm not sure how I run calibration again, since that damaged area is wavy and raised 🙁

As far as I'm aware it is actually mentioned in the handbook that you need to place a sheet of paper under it to check if it touches the paper during calibration or not. (unless they removed it lately, but wouldn't see why they would do that.
Before starting to calibrate I would personally remove the bed again from the printer and check if it's still flat, since it only scraped your bed I would guess it is.
Remove the damaged PEI sheet and replace it and then retry it with taking extra care and paying close attention to the nozzle and paper when doing the calibration.

I know that Aaron told to not do that right now, but since you will need to calibrate your printer again if you replace the PEI sheet in the future I would just do it right away. (but that's just me)

Tom

Posted : 10/08/2017 10:18 am
AJS
 AJS
(@ajs)
Noble Member
Re: Calibration destroyed part of my heat bed 🙁



But I'm not sure how I run calibration again, since that damaged area is wavy and raised 🙁

I know that Aaron told to not do that right now, but since you will need to calibrate your printer again if you replace the PEI sheet in the future I would just do it right away. (but that's just me)

I agree with Tom, disagreeing with me. If the waviness is too high to allow a calibration you have not choice but to address that first. I had erroneously assumed that it was small enough, or only negative, to allow you to continue.

Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage or loss. If you solve your problem, please post the solution…

Posted : 10/08/2017 3:05 pm
Lensdigital
(@lensdigital)
Active Member
Topic starter answered:
Re: Calibration destroyed part of my heat bed 🙁

All good now. I figured out different approach, a safer method to calibrate. It might take more time than official instructions, but will not result in PEI destruction.
My method is simple. Forget the nozzle, calibrate PINDA probe first. Lower it few mm BELOW nozzle. Don't guess which part of zip-tie it needs to be leveled with...
So once I lowered my probe below nozzle, I was able to calibrate everything pretty quickly. At this point settings are in the EEPROM so you can start fiddling with nozzle distance. Here I played it by ear, but with some effort exact steps can be outlined.
Basically I measured distance from the bed to the probe, unscrewed probe and using Live Z adjust lowered nozzle until it was paper distance from the bed. Then I lowered probe to the distance from the bead I measured in previous step. Approximately! I then raised Z axis and removed my "Live Z offset". Tried homing and saw how far nozzle distance was. It just just a little off so I adjusted it with "LIve Z offset". Then I tried calibration and voila it worked great, and didn't take much time. It didn't even catch wavy part of damaged PEI...
I did discovered a bug tho, that causes head to SLAM into bed every time. It doesn't home Y axis before moving down for calibration. It's an issue because bed could've been moved previously and calibration dot is off, so it will SLAM into bed and continue going down until you power machine off. Well not just Y, X axis needs to be homed too... Bed can be moved by hand at this point...
Anyway, it's pretty and looking good. I'm getting first layer lift off, but I think I can fix it with more "Live z offset"

Posted : 10/08/2017 5:44 pm
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