PLA does not stick to glass anymore?

I've been printing PLA to sanded glass for a while now with no problems getting it to stick. Now all of the sudden it doesn't stick anymore. I've been cleaning the glass the same exact way I've always done. I've got several colors of Ultimachine PLA and none of those stick better than the others. This has become very frustrating.

The only change I can think of is the weather. It is winter in the midwest now and very dry. Could humidity be the issue?

I've also tried printing to etched glass and kapton covered glass and I still can't get it to stick very well. Any ideas?

Edited 1 time(s). Last edit at 11/26/2012 01:01AM by tosjduenfs.

Have you checked bed temperature? What's the temp in your room compared to back in the summer?

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Experimenting in 3D in New Zealand

I'm using the same bed temperature as before. The temperature in the house is the same as the summer as well.

Well it looks like I've found a "solution". I dissolved a 5mm length of 3mm PLA filament in 10ml of pure acetone, I then added 1 drop of superglue. I spread the solution on the sanded glass and now everything is sticking again. I'm still not sure why it wont stick to the plain glass though.

... sure you have PLA and not ABS? - AFAIK PLA is not so easy solvable with Acetone

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Viktor
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No, PLA takes weeks to dissolve in Acetone!
nophead has some examples in his blog.

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

I agree. PLA does not easily dissolve in acetone. In any case, printing to glass is not hard at all, if you follow the correct advice. You don't need to sand it, or add kapton, or buy special glass, or anything like that.

1. Make sure the glass is securely attached to the bed. You can use kapton around the edges, or a couple of binder clips. Use glass that is at least 1/8" ~3.3mm thick. You can use borosilicate glass, but any kind should do as long as it is not treated with any special coatings. You can use mirror glass also.

2. If your bed is a MK1/MK2 (These are the red ones), put some cardboard on the bottom for insulation. Three sheets should do it.

3. Clean the glass with glass cleaner, or 70%+ Isopropyl alcohol. If you ever touch the glass surface, do yourself a favor, and clean it again.

4. Don't put your thermistor in the center of the bed. Instead, put it half way in from the edge.

5. Make sure your bed is level.

6. Make sure your bed is level.

7. You guessed it... Make sure your bed is level. When I say level, I don't mean level to the ground. Level refers to the distance from the glass to the nozzle tip in Z at any given position in X/Y.

Home your Z-Axis over the front/left corner of the glass. The nozzle should touch, but not move the glass.
Level the rear/left corner to this position in Z. Check the front/left again and make any adjustments.
When the left side is level, move to the right side/center edge of the glass, and turning the Z-stepper on that side, bring the nozzle down to the surface of the glass.
Check the front/right and rear/right corners against this center position, and make any adjustments to the leveling screws of the bed on that side. Do not try to adjust corner leveling by turning the Z-motors at this point. That would defeat the whole process.

8. Make sure that your extruder flowrate is adequate to keep pace with the feedrate across the glass. This is interdependent with the thickness that you set for the first layer in your print.

If your filament comes out 0.6mm wide, and your initial height above the glass is 0.6mm or greater, it's not going to stick.

If your filament comes out too slowly relative to the speed of the nozzle across the glass (flow versus feed rate), you will notice a distinct curling of the filament, coming off the glass at the beginning of the print.

To remedy this, you can try bumping up your extruder steps per mm in the firmware settings. These may be in the source code, or in the EEPROM settings, depending on your particular firmware.

9. Temperature of the bed is very important to stick. Too cold or too hot are both going to cause the plastic not to stick. My experience is that 110°C is the right temperature for ABS. This has been verified using a FLIR SC-8300 HD camera, so I'm pretty sure the reading was accurate, taking the glass emissivity into account as well.

I'm sure I'm missing something, but that should cover most of it.

for PLA add some water to PVA Glue.

Heat up the glass to 62C (bed temp sensor sould measure glass temp not heated bed temp)

When up to temp brush on the pva giving a nice coating it will dry very quickly.

i use slic3r to slice up my stls and set the 1st layer to 0 and set my nozzel height at what ever layerheight im printing at

should stick okay then

after print leave to cool to room temp and should crack off okay

i find i can normally get around 2 - 3 prints before i need to give the pva another coat.

pva easily cleaned off the glass using glass cleaner

if you find prints are lifting from the pva then you have too much water not enough PVA (i use something like 5 part pva to 1 part water)

hope it helps

Ditto my experience with the PVA glue. I mix mine 4:1 and it works great. I clean the bed with nail polish remover which seems to dissolve the glue just fine. Further, if the printed object shows too much PVA residue, I just wipe it with a paper towel that is BARELY moist with the nail polish remover, and it takes it right off.

I have been extremely happy with this solution.

BTW, PVA glue = white (or yellow) woodworker's glue, or, if you're in the states, elmer's glue.

just to warn i have used wood working glue and had bad results !

but it was evo stick wood working glue which is a bit up market (i had run out of PVA at the time)

i know 100% theres a difference as evo stick wood working glue sets a whole lot quick then stock PVA reason why i use it on model projects etc.

but most places will have 5L jugs of just strait PVA for very cheap will last for ages

i only wish i could find a nice water proof tube with a brush built in the lid save me keep having to clean brushes

I had a similar issue before - thought I'd changed nothing, and then realised I'd used screen cleaner to clean the bed (which leaves some kind of anti-fingerprint/anti-static chemcial).

I then cleaned the glass with acetone, and hey presto, back to sticking.

Again, I recommend the 4:1 PVA glue (Elmer's white glue) to water applied cold or hot with a paper towel. Once applied it is usually good for at least 5-10 prints with a bed temp of 55-65C. I've never had the issue with the PVA solution remaining on my prints. I always get a nice, glass smooth surface.

I use 4:1 PVA and it works well except I struggle to apply it evenly with a brush. How do you manage it with a paper towel?

Andy

I used dilute PVA for a while, and had issue getting it to apply with a Brush or a Paper towel, I figured the water was evaporating off as it dried anyway, to I've gone to squeeze some PVA on the cold piece of glass and spread it out as thin as I can with a business card or similar.
Once I have a thin layer I just heat up the bed.

It's white glue. Just use your finger.

billyzelsnack Wrote:
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> It's white glue. Just use your finger.

hehe then you end up with stickly fingers :| and the dreaded fake peeling skin effect

any one having problems applying with a brush im guessin you have too much PVA not enough water. Should apply on like paint and then dry quickly