Glue

[PlainName]

Bit of a long shot, perhaps...

When I first got my printer (a Flashforge Dreamer) I spent quite a lot of time and effort sorting out the issue of having parts stick to the bed. I tried tape, glues, special pads, etc. Eventually I found the solution that worked every time: UHU purple glue stick.

But now I've run out, and it seems the purple stuff hasn't been available for quite some time. So long that there are no sources at all any more. UHU do a blue glue stick which is supposed to be the same, but it isn't - things barely stick at all, and even a slight draught can move prints in progress. By contrast, with the purple stuff I have to wedge a sharp knife under the part and then lever it off.

Anyone know of anything as good as the purple stuff? Or even the source of a few sticks?

[Just_another_Dave]

Some people use cyanocrylate for that purpose, but in my case hair lacquer has always been enough. I also tried kapton tape once, but it didn’t work well

Additionally, activating brim or raft in your slicer might also help sometimes

[PlainName]

Raft helps but is a pain to get rid of afterwards. Brim used to work but is no use at all now.

Cyanoacrylate sounds rather expensive and could be annoying in the case of accidents! Don't have hairspray but will brave the pharmacy and try some. I'll just say I need it for my beard.

[james_s]

Cyanoacrylate is cheap if you look in the right places. I buy Superglue at the dollar store, 2 bottles in a pack. It's the same stuff you can pay several times more elsewhere.

[PlainName]

I'll keep an eye out, but the only stuff I've seen is in relatively small bottles which don't look like they would last long. Still, if the hairspray doesn't work I could well be more receptive!

[Just_another_Dave]

I'll keep an eye out, but the only stuff I've seen is in relatively small bottles which don't look like they would last long. Still, if the hairspray doesn't work I could well be more receptive!

If you’re going to try with hair spray, remember to let it dry before using the printer to ensure that it is sticky. You can also apply more than one coat

[PlainName]

Thanks, will do.

I am wondering what made the purple stuff so good at this. None of the various glue sticks I've tried since have been any use once dry, and the purple stuff did dry since it went white quite quickly. Didn't seem awfully sticky to the touch, but it wouldn't let go of the PLA once introduced. Maybe it just took longer to actually dry, and by that time the first layer was down.

[jpanhalt]

Perhaps a wild thought:

Maybe that glue stick was a PVA adhesive.  That can be reactivated with heat.  There are lots of PVA adhesives on the market, i.e, almost any "white glue."

Here's a discussion: https://www.finewoodworking.com/forum/reactivating-yellow-glue-with-an-iron  (NB: I didn't search very hard.  There are probably better references.)

EDIT: Could the thin layer of adhesive from your glue stick be removed (slowly) with water?  Unmodified (i.e., uncrosslinked) PVA adhesives are slow to dissolve, but are not stable to water.  You can also add water to PVA adhesives to get a nice think coat.

EDIT#2:  Rosin (like for soldering and violins) and shellac are soluble in ethanol, and once dry can be heat activated too.

[james_s]

Maybe the manufacture would be willing to tell you what the purple stuff was? They may not be aware that their product had found the use you were using it for.

[jpanhalt]

Maybe the manufacture would be willing to tell you what the purple stuff was? They may not be aware that their product had found the use you were using it for.

My guess is that the TDS, SDS, or MSDS has/had that information, if the manufacturer is willing to share.  Otherwise it will be a proprietary secret.  In that case, it will be limited to relatively non-toxic stuff, like library paste or PVA.

[Whales]

Aside: I have been using masking tape on my glass bed of my super-cheap prusa clone $300 kit printer and it has been working really well across hundreds of prints.  There is a secret that makes the difference between it being perfect and useless: soap and water.

If there is any hand grease on the tape (eg from assembling the tape or rubbing the centre print area with fingers) then the prints do not stick.  A paper towel, a little bit of water and a drop of dish detergent work wonders.  If the bed is heated then you don't even have to wipe it off.  Alcohol does _not_ work anywhere as well as soap and water, that's what I used to use and it often required multiple cleaning cycles + frustration.

PLA @ bed 55degC: works perfectly, I only ever have bed detach if there is hand grease on there.  Cancel the print, peel old off, clean bed with soap+water and re-run; so far this has always worked with once cycle.

PETG @ bed 70degC: sticks so hard I often tear bits of the tape during removal.

EDIT: take these bed temps with a grain of salt, in my design the bed thermistor is not really reading the top surface of the glass (it's on the bottom of the PCB element instead).  My actual resulting bed temps are probably (?) lower.

Photos below show a variety of marks on my tape: small (very tall) repetitive part marks in the centre, scratches around the edges from z-height getting knocked, several little tears all over the place from removing PETG.  I have replaced the centre tape line recently, so it might look a bit neater than the rest in places.  "It used to be nice and flat"   luckily the tape is soft and extra forgiving.

[PlainName]

Could the thin layer of adhesive from your glue stick be removed (slowly) with water?  Unmodified (i.e., uncrosslinked) PVA adhesives are slow to dissolve, but are not stable to water.

Yes, but the stuff that doesn't work is similarly slow to wash off.

Rosin (like for soldering and violins) and shellac are soluble in ethanol, and once dry can be heat activated too.

Now there's a thought! I'll see if I have the right stuff - got some liquid flux that is super-sticky and almost impossible to remove if you spill half of it over the bench.

Maybe the manufacture would be willing to tell you what the purple stuff was?

I will try and find a contact, but I have to say I won't be holding my breath

I have been using masking tape on my glass bed of my super-cheap prusa clone $300 kit printer and it has been working really well across hundreds of prints.

Ah, I wondered about doing that and should give it a try. That will mean a bout of bed-levelling though, and it's pretty spot on at the moment.

PLA @ bed 55degC: works perfectly

I'm using a thin mirror (for flatness) and 50C for PLA seemed to work well, which is pretty close to your figure.

[Whales]

Could this be the purple glue stick?

https://s3-ap-southeast-2.amazonaws.com/wc-prod-pim/Asset_Documents/Gloo%20Glue%20Sticks%20Purple%20SDS.pdf

(also attached, in case that link ever goes away.  MSDS are generally publicly available documents in Aus anyway)



ie:
 - PVA glue
 - common soap
 - glycerin (probably to thicken it?)
 - coloured dye
 - water

[PlainName]

Thanks for looking! I doubt if it's the same thing. The one I am after is this:


https://www.fishpond.co.uk/Toys/Uhu-Glue-Stick-Purple-860ml-Saunders/9999660083438

I just tried a BIC purple for no other reason than that it might be the colouring:

https://www.amazon.co.uk/dp/B01N9B1QEA

Same uselessness as all the other sticks.

[PlainName]

Googling around I found this:

https://www.reddit.com/r/mildlyinteresting/comments/26fwcu/my_purple_glue_stick_wasnt_used_for_a_while_and/

The stick sweated, and I wonder if that's the reason it was withdrawn. So, anyway, you know how Googling goes and eventually I would up here:

https://all3dp.com/2/what-s-the-best-glue-stick-for-3d-printing/

Hmmm, Elmers. Clearly (ho ho) a USA thing but blow me if the link didn't take me to Amazon UK, whereupon I ordered this:

https://www.amazon.co.uk/dp/B08PCHSL7Y

Should be here before 10pm...

[Whales]

I initially doubted it would be the colourant, but given that the MSDS I linked claimed that colourant could be a few % of the final composition I might be wrong.

Found as MSDS for UHU Color Glue Stic, but they are completely troll with the ingredients.

[jpanhalt]

I didn't find Saunders SAU99601 (your link), but this link calls the UHU glue stic "purple" with a different product number, SAU99653:
https://www.usaofficemachines.com/sau99653-uhu-stic-permanent-purple-application-glue-stick-1-41-oz-stick-by-saunders-mfg-co-inc.html

That number brings up this safety sheet:
http://content.oppictures.com/Master_Images/Master_PDF_Files/SAU99653_MSDS.PDF

As expected it is useless, except in addition to phenolphthalein (dye --> clear), it lists polyvinylpyrrolidone ("povidone")(https://en.wikipedia.org/wiki/Polyvinylpyrrolidone), but doesn't give a composition range.

If one clicks on the glue stick link in the Wikipedia article, you get this: https://en.wikipedia.org/wiki/Glue_stick


Edit: Sorry, I took a long time referring to post #14 and didn't see the more recent posts.

[PlainName]

The USA Office Machines place apparently has stock (but shipping costs make it worth more than its weight in gold). Hmmm.

[PlainName]

https://www.amazon.co.uk/dp/B08PCHSL7Y

Should be here before 10pm...

Not a success

A bit sticky but the test print warped and lifted an edge, and the whole thing came off quite easily.

[jpanhalt]

That's research.

Have you tried PVA glue (white or yellow wood glue) or rosin alone?  Polyvinylpyrrolidone is really quite similar to PVA.  Shellac may bond a little to well.  It can be used to attach irregularly shaped objects to the faceplate on a jeweler's lathe, but I have used it on a 3" hobby lathe too.

[PlainName]

Not yet. I thought I would work my way through the least messy first, hoping I don't get to the really messy solution. So hairspray next.

[PlainName]

Photos below show a variety of marks on my tape

Forgot to say earlier: that's a nice little setup you have there 

[Whales]

Photos below show a variety of marks on my tape

Forgot to say earlier: that's a nice little setup you have there 

Thankyou   Screwing the shaped board to my bookshelf to fit it has been perfect.  It's now "ready to print" any time, rather than requiring me moving it, wiring it and re-levelling it every time some small printing takes my fancy.

This printer design has a fatal flaw in that the left and right steppers for the Z axis go out of sync if you apply outside force to the gantry (eg when changing filament).  Until I worked this out I was constantly recalibrating bed levelling to suit the crooked gantry.  Now instead I use two high-precision calibrated german manufactured length standards (read: two flat AAA batteries) to fix this problem:

1. Home
2. G0 Z40 (raise the gantry 40mm)
3. Place the two AAA's against each vertical threaded rod
4. G0 Z0 (lower the gantry until it crashes into the AAA's and skips several steps)
5. G0 Z10 (relieve pressure off the AAA's)
6. Remove AAA's
7. Home again.

Voila, everything is straight and reliable now.  I do not have to re-level the bed anymore (unless my dodgy Z-top wiggles, but then I wiggle it back).  I literally do a few prints, leave it for a few weeks, come back and print some more without having to worry about levelling (or buying auto-levelling devices).

When I printed directly onto the glass I had to change the Z-stop (or re-level) when changing between PLA temps and PETG temps.  I have not had to do this at all for a long time, I think a combination of a fatter first layer (0.35mm, even when doing the rest as finer layers) and the soft masking tape has helped me here.  Again, avoiding the fiddly stuff means I can just print whenever I want now

EDIT: Said length standards can be seen stuck to a magnet on the top-left of my printer in the earlier photo.

[PlainName]

The Dreamer is three-point manual adjustment, so a bit of a faff (although it's actually reasonably quick and simple).

Hairspray is a no. Not just because it didn't work but also because it stunk the office out.

So, on to masking tape which worked very well indeed! Didn't need to prise the model off at the end, but it didn't fall off either. If it works like this every time my search is completed 

Just remains to see how long it will last before needing to be resurfaced.

[Whales]

Never tried hairspray.  I didn't remember that the stuff stinks, thankyou for testing it for me 

Recently someone suggested I make some skins over 3d printed frameworks using crepe paper and hairspray.  Might rethink that, try and find out what else I could use.

Glad you found something that works.  I've read claims that different brands/types work and others don't, but it might just come down to cleaning the human grease off vs not.  EDIT: I wonder if plain A4 paper works if you clip it down...