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bsilverwood

Bed adhesion for larger PLA parts - UMO+

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So - with most of my initial build issues of the printer resolved over the past week I have been experimenting with different prints (useful items and toys) in the PLA that was supplied with the printer.

What I have found is that on larger prints (hight or bed area) I tend to loose adhesion.

I'm printing at 210 degrees and a bed temp of 60. I am using just a glue stick on the glass. Should I do more? I have heard for PLA I should consider 70 degrees for the bed temp. I have head using AquaNet might be a better option.

Any advice would be greatly appreciated.

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Try to take the glass out and clean it with soap. After drying it clean it with window washer (they are mostly alcohol and isopropyl alcohol). I never had a problem with my glasses, except the first glass I got long ago that I damaged it iver time by pulling the prints before it reached 30C. For hard materials I use a paper towel with windowwasher + 1 puff of hairspray. But pla sticks way too much with this method and I did chip one or two bed glasses, so don't overdoit :D

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Follow neotko's advice. In addition to making sure the glass is perfectly clean (don't touch it with your bare fingers), you can apply some gluestick and spread it around evenly with a wet cloth until you can barely see it anymore.

Also try using a brim on troublesome prints. You can increase the width of it in Cura if the default (8mm?) is not enough.

As neotko said, the disadvantage with getting the part to stick to the glass really well is that it can be hard to remove it. I'm usually too impatient to wait until the bed cools down and I bent my removal tool. Fortunately I have not damaged the glass bed (yet).

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Follow neotko's advice.  In addition to making sure the glass is perfectly clean (don't touch it with your bare fingers), you can apply some gluestick and spread it around evenly with a wet cloth until you can barely see it anymore.

Also try using a brim on troublesome prints.  You can increase the width of it in Cura if the default (8mm?) is not enough.

As neotko said, the disadvantage with getting the part to stick to the glass really well is that it can be hard to remove it.  I'm usually too impatient to wait until the bed cools down and I bent my removal tool.  Fortunately I have not damaged the glass bed (yet).

 

I will do a thorough cleaning of the plate tonight. I might play with the brim too.

Does the bed temperature matter at all? 60 degrees should be enough?

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Like Neotko I also use hairspray on glass. I am not saying it is better than other stuff, just that it has worked faultlessly for me over the past 3 years.

Use a brim! That will normally solve your problem; I use 10-20 lines depending on geometry.

Plus do not forget that your temp sensor may be measuring the bed temp not the glass temp. On my printer there is about an 8 degree difference.

Plus if you are printing something with a big bed area, if your heater is placed in the centre of the bed then your perimeter areas will not be 60; it may take the perimeter areas 10 minutes to reach 60 once the centre is there.

Failing the above you will do no harm in using a higher temp unless the piece is really small. I use 60 but used 65 for a long time. 70 will not damage anything, worth a try if all else fails, but surprising.

Are you checking that your 1st layer is going down really well?

Use .300 for your first layer and make sure your fans are off for the first 2 or 3 layers

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I only wipe the glass plate with salt water prior to printing. For PLA, this gives a very strong bonding when hot, but no bonding at all when the glass is cold (so you need a heated bed).

For a full description and photos, see the PDF manual at:

https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/#

For colorFabb and Ultimaker PLA this works excellent: I could print anything without corners lifting, except upside-down prisms and pyramids. No brim or raft are required. I have printed more than 500 parts in this way without failure (except those inverted prisms as test parts).

However, recently I got another brand of PLA (ICE) which was more brittle, and which bonds a bit less: it is still okay, but no longer perfect.

For ABS this method does not work. For other materials, I don't know.

And yes, the bed temperature does really matter: if too cold, parts may warp due to lack of adhesion, or they may even pop-off suddenly, with a "pop" sound indeed. When too hot, the model stays too flexible, and then it may peel off the bed, like you would peel a layer of tape off something. So you have to find the exact spot in-between, where bonding is best. Not necessarily perfect, but better than higher or lower temps.

For most PLA filaments, 60°C seems to be a good starting point for trials in my experience. I got a lesser bonding at both 50°C and 70°C.

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I have done a thorough cleaning of the glass plate, spread a nice layer of glue, and also raised the bed temperature a couple degrees. It appears that I am maintaining my bonding to the build plate now.

However, I might have a secondary issue now of curling on the corners of the build. Not sure if this is because of the increased temps on the bed or something else.

More experimentation is in order I believe.

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OMO no heat, dilute pva on the glass - great adhesion and easy removal. Agree glass needs to be really clean, then paint on a thin layer of diluted PVA - dry withhair dryer or allow to dry naturally and off you go for 10's of prints - I only wash off and reapply when the surface looks bad. I have no heated bed and happily print anywhere and any size on the bed.

The only other aspect is to make sure you are only heating up the filament just enough for proper layer adhesion - too much heat in the filament can cause a bit more shrinking in my experience. I never use brim either :)

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Wanted to follow up on this for closure on the topic. I have been experimenting a lot over the past couple months looking for the best over all means of bed adhesion. My solution is actually simple, cheap, and shockingly effective.

Kapton tape (bitch to apply and expensive to use), Blue Tape (good for small prints, horrible for large ones), glue sticks (inconsistent spread over the build plate causing "pockets" of un-adhearable area), and AquaNet (messy to apply and runs the risk of gumming up the other mechanicals inside the printer) all have had inconsistent effects. Wider brims, anchors, and the like needed to be added to the prints in order for some of these to work semi-constantly.

The solution was simple after scouring messages boards. I will take no credit for this solution, but I will attest that it works:

1 part Elmer's Glue to 2 parts water. Mix and apply with a brush and/or rag to smooth it out evenly (found applying on a warm bed is easier and it dries quicker). Parts stick EXTREMELY well on this. Make sure the plate is COMPLETELY cooled before you attempt to take them off (I have actually broke parts I printed because I tried to remove them before the plate is completely cooled). You will sometimes hear a "pop" of the plastic releasing from the build plate when it is completely cooled.

Cleanup is easy. Elmer's Glue is water based, so hot water cleans it off. Of course it is recommended that you also clean your plate off with alcohol before and between applications.

I have so far successfully printed about 10 prints with one application of this (I think I can still do many more prints before having to re-apply the coating. I am testing this out, but at this rate I might go another week or two before hitting failure and I wanted to update this post first). As long as you let the bed cool off before removing the part and also "dust off" the build plate between prints (remove any other debris with a lint free rag) you should be good. pre-mature removal of parts, besides potentially damaging them as mentioned above, can mess with the coating and you will need to re-apply.

I hope this helps anyone coming across the same issues...

Edited by Guest

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How big are these prints?

As @yellowshark  points out, brim could help prevent the curling.

See my recent post about what I am doing for bed adhesion... I have found that the mantra "Make it stick like hell" to the build plate helps in the curling. The glue mixture I am using is a thing of the devil (just try removing a print while the bed is still hot) so I got that covered. :p

The other factors (which I am still playing with)

1.) limit the infill

2.) use a raft - let the raft warp and your print stays fine.

Other things I want to play with:

1.) Make the "open air" design of the UMO+ more closed in. I want to get some plexiglass and make sides for the printer to trap the heat inside. I have heard this can help a lot (drafts can cause uneven cooling which leads to warping).

2.) print slower and at a lower temperature. Personally, with all the other playing around I have been doing, I'm getting tired of all the trial and error testing I have been doing. This might be a "last ditch effort" if it gets annoying enough to me.

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Actually one area that none of us have mentioned is the setting of the nozzle to print distance. As a general principle moving the two closer together squishes down the filament and improves adhesion (sometimes dramatically, depending on what your starting point is). Only up to a point though, go too far and the reverse will happen.

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100% agree with the pva - I dilute it more like 5:1 and it works well - even after mould grew in the container I just took it off the surface, shook the jar and used as normal :) - if I am in a hurry I heat the glass with a hair dryer to speed up the drying. works for about 10-15 prints and then I wash and re-apply.

To make life really easy I have blue tape on the bed under the glass, so if I want to print XT I just take off the glass and take off a little 'end stop fooler'

and print the xt - and then do the reverse - often without a re-level :)

I have closed in one of my UMOs https://www.youmagine.com/designs/james-holmes-siedle for simple clips and some lexan. I would not say it makes a huge difference to the one I have not closed in.

James

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