Objects stuck too well - broken bed

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lesthegringo
Posts: 76
Joined: Mon Dec 26, 2016 9:41 pm

Objects stuck too well - broken bed

Post by lesthegringo » Mon Jun 18, 2018 1:38 am

I fitted a new bed assembly on Saturday, while I wait for a new PEI sheet to be sent on the old one.

Trouble is, the new PEI is too adhesive, and the print was so firmly stuck that the borosilicate glass bed cracked while trying to get the part off. I went from inadequate adhesion to too much! Is there anything I can do to counter this? I need to buy a new bed and replace the PEI layer on the old one but don't want to stuff up another bed after that.

Also, any advice available about transferring the heater from the broken bed to a new one?

Cheers

Les

Galadriel
Aleph Objects | LulzBot
Posts: 271
Joined: Mon Sep 25, 2017 10:23 am

Re: Objects stuck too well - broken bed

Post by Galadriel » Mon Jun 18, 2018 9:09 am

For your bed adhesion woes, what filament are you working with type/brand? What does your removal procedure look like? It could also be related to your first layer so attaching some photos of what the bottom of your prints looks like might be useful.
In terms of replacing the current bed, unfortunately you will need to purchase a replacement for the full bed, the heating pad isn't intended to be removed after application with our standard heat bed. It goes through a rather intensive lamination and baking process that isn't really achievable in a household environment. https://ohai.lulzbot.com/project/heat-b ... heat-beds/ (If you would like to see how it is applied)
There is a new Modular Bed System that we recently added as an alternative for Minis and Taz 3 and up printers which has a separate heating element. This is nice because it means with it you can replace just the glass/PEI surface not the full bed but it is also handy because it has a more consistent temperature range across the plate because of the sheet metal the heating pad is laminated to and you can flip the bed over to print directly on glass which is useful for certain filament types. Whatever route you go make sure to check out our OHAI guide for the installation instructions for your replacement.
Guide for installing standard heat bed: https://ohai.lulzbot.com/project/mini-r ... e-repairs/ (This shows a Mini but it's the same on a Taz)
Guide for installing modular heat bed: (Taz) https://ohai.lulzbot.com/project/lulzbo ... cessories/
(Mini) https://ohai.lulzbot.com/project/lulzbo ... cessories/

lesthegringo
Posts: 76
Joined: Mon Dec 26, 2016 9:41 pm

Re: Objects stuck too well - broken bed

Post by lesthegringo » Thu Jun 21, 2018 1:06 am

Thanks for the reply

I'm working with the Protopasta ABS. The bottom layer is actually quite poor, the first pass by the print head leaves a rather blobby inconsistent line. Subsequent layers are good, in fact very good, but that initial layer apart from adhering very well to the bed is a bit rough. I would say that until the third or fourth layer the print quality doesn't settle down. I'd appreciate any feedback on improving the quality of that first layer. Print temps are 275 for the filament, 110 for the bed.

I've ordered the modular heater and a couple of beds with PEI so will be replacing the broken item with that in due course. In the meantime, I need to get those adhesion and first layer issues licked. I print everything with a chamfer on the bottom edge in order to facilitate removal by getting something under the edge, but that first layer is currently obliterating it. As for the removal method, a large kitchen knife with a good thin edge is being used, I slide the blade along the bed surface until it catches under the edge of the print.

Cheers

Les

Galadriel
Aleph Objects | LulzBot
Posts: 271
Joined: Mon Sep 25, 2017 10:23 am

Re: Objects stuck too well - broken bed

Post by Galadriel » Thu Jun 21, 2018 7:24 am

What temperature is the bed at when you try to remove the prints? If you are removing the print at too high or low of a temperature it can cause issues with the filament adhering to well. You might also consider trying a wide putty knife instead of the included clam knife or a kitchen knife. Please sharpen one edge to a nice low angle. Then place the putty knife with the un-sharpened edge down against the PEI and against the base of the print. Then tap the handle of the putty knife with the handle of your blue knife. Please avoid any upward force, whenever possible. It is best to tap the tip of the tool in underneath the part using force parallel to the bed. This will cause the putty knife to slip under the print and lift it up while pressing the PEI down.

Tapping the sides of the print with the clam knife handle, carefully, can help shake loose some of the bonding between the print and the bed to make removal easier.

This will help with difficult prints.

bedhead911
Posts: 13
Joined: Thu Nov 02, 2017 8:34 pm

Re: Objects stuck too well - broken bed

Post by bedhead911 » Sun Jun 24, 2018 12:34 pm

Here are some tricks I use. You don't even need any tools.

PLA: after the print is done heat up the bed to say 70-80. Then turn the machine off and let it cool. Eventually the PLA will just pop off on its own.

ABS: pour a small amount of alcohol between the skirt and the part or any holes or gaps (the point is to get the alcohol go under the part). You will hear small crackling noise. The part will pop off on its own.

Hope this helps.

lesthegringo
Posts: 76
Joined: Mon Dec 26, 2016 9:41 pm

Re: Objects stuck too well - broken bed

Post by lesthegringo » Mon Jun 25, 2018 1:30 am

Thanks guys, will try those tips.

Cheers

Les

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