this post was submitted on 11 Aug 2023
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My printer drilled through my hotbed. Can you help? (lemm.ee)
submitted 1 year ago* (last edited 1 year ago) by [email protected] to c/3dprinting
19 comments fedilink hide all child comments
 

I got my Kywoo Slim printer last week, and it's done well for its price of £200, although it was slightly bad at detail as it would drag the filament along with it, rather than the filament adhering properly to the build plate.

Today I tried to fix that issue by increasing the nozzle temperature from 200° to 210°, which is in the recommended range for PLA filament (190 to 220). My hotbed temperature has stayed constant at 60°. Quite to my surprise, instead of printing normally or even at all, my nozzle instead dove down straight into my build plate, through the hotbed underneath it, and started melting the plastic and vibrating, drilling through the hotbed.

I stopped it printing immediately and inspected the damage. There was a hemispherical dip in my build plate, with a hole all the way through it in the center. In the hotbed directly underneath it, there was an indentation probably about 1mm deep in the exact size and shape of the nozzle.

Can you help me understand why changing the nozzle temperature would have caused it to do this, or if my printer is safe to use now? Also, can I fix it, and if so how?

Edit: terms

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[–] Hazdaz 22 points 1 year ago (2 children)

Your issues are not related.

Either you changed some other setting, you mistakenly unplugged the limit switch or some other mechanical problem was created. Your Z "0" position is off for some reason which made the printer think it needed to continue to go down. A picture would always be helpful in seeing exactly what happened, but if the divot is only 1 mm, I wouldn't even worry about it. Just shift your prints so they don't print in that area whenever possible. If it really bothers you, you can replace the bed plate on most printers.

Also, it's called a "print bed" or just plain "bed". I've never heard the term "hot base" before.

[–] [email protected] 16 points 1 year ago (2 children)

You sure? I have an alternate theory, that increasing the temperature just so was enough to open a dimensional beacon to one of the planes of Dante's inferno and drawing an evil spirit to posess the system, resulting in said behavior...

[–] Hazdaz 10 points 1 year ago

Your ideas are intriguing to me, amd I wish to subscribe to your newsletter.

[–] Thurkeau 1 points 1 year ago

I would have figured the printer would have reacted more strongly to posession, including to continue to remain powered and try to destroy itself, and the operator even when unplugged.

[–] [email protected] 4 points 1 year ago* (last edited 1 year ago) (3 children)

Sorry for my terms. I am fairly new to 3d printing, so I often get them wrong. I'm glad to hear you don't think it's a problem, and I only thought the issues were related as they happened consecutively. Thanks for your assistance!

Edit: the confusion with terms is because I was having trouble differentiating between the thing that heats up, and the thing on top of that that I print on.

[–] Hazdaz 4 points 1 year ago (2 children)

To be clear...I DO think this is a problem, but I do not think it is connected to the other issue.

Your nozzle should never touch the bed.

Look at your limit switches. Did one break or disconnect. Use the slicer to move your nozzle close to the bed. Like really close. Amd then see what the coordinate it THINKS it is at. The distance should match the physical distance you can measure with a ruler or calipers. If the nozzle is like 10 mm above the surface, but the software think it is 30 mm above the surface then clearly you have a zeroing problem (usually a limit switch issue). If you hit Home, the printer is going to continue to drive thag nozzle down until it smashes into your bed again... what prevents that is the limit switch.

[–] [email protected] 1 points 1 year ago (1 children)

There's a sort of sensor next to the nozzle on the printer head that triggers when it's pushed into the bed, is that the limit switch you mean? When it triggers is when the printer stops when it's homing itself.

[–] Hazdaz 2 points 1 year ago (1 children)

Maybe.

Printers work in different ways. The convential way is literally a simple switch that's screwed into the Z axis (most of the time aluminum extrusion) and when the carriage lowers enough it hits it and triggers it.

What you are describing sounds like it might be part of the auto bed leveling function of your printer.

I wonder if your printer is combining the limit switch function with the bed leveling function with one sensor. That would save money in manufacturing. I don't have a printer with auto bed leveling so I can't tell you if that is common to merge both functions with one sensor. Maybe someone here has experience with that and can answer your question. Maybe search the printer's website for information that explains that part.

I guess one way to test it is to see if you can trigger that sensor and see if the printer then thinks it is at a height of 0. I wish I could help more,but I'm not familiar with that specific model of printer.

[–] [email protected] 2 points 1 year ago

Ok, thanks for the help you can give, I'll do some research.

[–] [email protected] 1 points 1 year ago (1 children)

The only thing other than the temperature change I changed between the previous print and the fateful one was I pressed the auto level function on the printer. Then I homed the printer again, and printed.

[–] [email protected] 2 points 1 year ago

Okay, so by running the auto-levelling routine, you will have reset the printer's coordinate system. Sounds like it maybe ended up thinking that the bed was lower than it actually is, and therefore plowed into it. If the bed wasn't at the absolute limit of the allowed z-axis travel, the limit switch might not have engaged.

On the model of printer I have, plowing the bed is usually a sign that the sensor in the print head has gotten displaced before or during levelling, so check to see if yours looks crooked or pushed back, or if any wires that should be stuck to it have come loose. It might be useful to know what kind of sensor it is—the one in my printer triggers on metals, so it's possible to test it with a coin and see if the attached LED lights to indicate that it's working.

I suppose it's also possible that the autolevel data is somehow not being correctly saved. Your printer may or may not have some method of inspecting the saved data (and it might be anything from a neat GUI to "pass this gcode through a serial console").

Inspect the gcode of the print you attempted for weird z-offsets if you know how, just in case it was telling the system to start printing at -10Z or something.

Manually leveling the thing might be worth a try if it offers that option.

[–] [email protected] 3 points 1 year ago (1 children)

The vibrating that you saw was probably the X or Y axis trying to move, but the head was locked in place by the hole it was now sitting it. As you've just witnessed, the stepper motors have quite a lot of power and will normally drag the head right through any obstruction (even if it's your 27-hour print job that was nearly complete). This is why you see a lot of pictures with deep scratches in print beds.

[–] [email protected] 1 points 1 year ago (1 children)

Thanks, that makes sense. In the pictures with deep scratches in print beds, did the people have to replace the beds, or did they continue to print onto an uneven surface?

[–] [email protected] 2 points 1 year ago

Everyone works around their first mistakes until they feel comfortable enough with their printer that they can justify replacing the bed. You actually want to get in the habit of making prints outside the center of the bed anyway, if you always print in the same spot you'll basically wear out the 'adhesive' properties of the bed until it starts requiring hairspray or glue sticks to make prints stick there.

[–] [email protected] 2 points 1 year ago (1 children)

A build plate commonly sits on top of the hotbed, but people frequently just call the whole thing the bed.

[–] [email protected] 1 points 1 year ago

I edited the terms in the post, thanks!

[–] [email protected] 2 points 1 year ago (1 children)

I had a problem with my Kywoo Tycoon where under some circumstances the printer would just dig right into the build plate when starting a print. Like the reference for the z-offset was completely out of whack. It had to do with the order in which I did bed leveling, homing, etc. I couldn't pin down the exact steps but it would usually happen on repeated prints. For me the issue was entirely fixed with one of the later firmware updates and I have never had the problem since.

[–] [email protected] 1 points 1 year ago (1 children)

When was the last time it happened to you?

[–] [email protected] 2 points 1 year ago

Before I updated the firmware to 2.1.3 which must have been well over a year ago.