Printing on Glass

[gr5 2,172]

Joergen speaks truth. Although I think I already mentioned this. On this very thread. So simmonstrummer. Read all the posts in this thread please! You certainly didn't read all of my very first post.

 

[joergen 2]

Joergen speaks truth. Although I think I already mentioned this. On this very thread. So simmonstrummer. Read all the posts in this thread please! You certainly didn't read all of my very first post.

It can't hurt to repeat it occasionally... for all UM2 users, pour the watered-down wood glue onto a clean glass bed, spread it, and set your bed to 70C until the PMA wood glue is nicely dried.

 

[donmilne 2]

When I first got my UM2 printer I saw the gluestick that came with it, and assumed I was supposed to use it every time. I lathered it on. You may remember that my first few posts was about the difficulty of getting the finished print off the glass. Everything else about the print at that time was default PLA settings, so the bed was heated as well.

Then one day I started a print after forgetting to apply the gluestick. I was surprised that the print went perfectly, and popped off the glass much more easily once it cooled down. Ah! I thought, the gluestick must be for ABS only.

Since then I didn't use glue and the part has become easier and easier to remove... until yesterday, a tall PLA print separated from the glass while it was still printing. I applied glue and it went fine... and was noticeably better stuck to the glass at the end.

So, now I'm thinking that PLA does benefit from a thin coating of glue, but you only need to treat the glass every now and then, not every time. I.e. when you notice that the print comes away a tad too easily.

I've skimmed this discussion. I was surprised about the bit about temps over 60C being bad, but it makes sense. I'm not sure why wood glue is being suggested. Surely you must be talking about white PVA glue, which is basically the same stuff as the gluestick. I can't immediately see why an optically perfect film is necessary, though it'll certainly be elegant. Obviously you don't want lumps of the stuff, but IMHO the heated bed will smooth it out anyway, within reason.

 

[DidierKlein 729]

Hi guys i've read the whole thread.

I'm having more and more trouble getting my pieces from the glass plate.

I got my UM2 Thursday, read the manual and applied some gluestick on the bed, then i applied it on the bed with a wet cloth to make it more uniform on the plate.

The robot came off quite easy by hand. After a couple of prints i tried a raspberry case which has a big surface in contact with the plate. It was stuck to the bed, i had to use a lot of force to pull it off and a bit of material stayed on the glass resulting of the case to have a bad finish.

I was using the default temp for the buildplate which is 75°c

I tried with 60°c and i have the same problem.

Should i lower the temperature?

Should i clean the bed? If so how?

It seems that more i print more it sticks... if a wait a lot for the plate too cool down it doesn't change anyting.

 

[burki 1]

Didier, i don't have a UM2, so i can't help you much, but:

the glass can be cleaned with water only, or with a dish washing detergent. At least that's how i clean mine.

I don't know about the bed leveling for the UM2, but i found that if the bed is too close to the nozzle, the plastic sticks like hell.

so maybe trying to increase the gap betreen nozzle and glass a bit could help you?

Do you print PLA or ABS?

You should be able to print PVA on a cold glass plate, meaning: no heating of the bed at all. Since my UM1 doesn't have a heated bed, that's how i print my PLA prints.

Does that help you a bit?

 

[jameshs 42]

Likewise I don't have a UM2.

But from UM1 Experience;

Scrape off the remainder with a window scraper (with a razor blade) but do it gently as you can score the glass.

Then wash the glass - the glue under should mean that it all washes off.

If you are using PLA to print then only a slight bed temp (or none at all) and a light coating of glue will work well - trial and error to work out what works - and taller prints tend to need more as they can warp a bit - also things where you have a large infill and the nozzle is rattling around - then I go really Sloooooow and only a light amount of glue is needed.

If you can get some spare glass that is good too (I run two sheets and use dilute PVA glue solution which when dry helps stick)

Lots of experimenting!

James

 

[DidierKlein 729]

I print in PLA.

I have to check my bed level again. When i print the first layer i hear the feeder making a tock noise once in a while and i almost see nothing on the plate.

I level the bed with a paper and when i feel that the paper begins to be stuck between the nozzle and the plate i assume it's correctly leveled... The paper can still move. Maybe there is a more efficient way to level the bed?

I'll try this again, maybe wash the build plate also, and put the temp at 60°c max or maybe lower?

How often to you level the bed?

 

[donmilne 2]

Apropos of nothing much in the above discussion: I've discovered that a broad wood chisel - 30mm say - provided it is very sharp, makes a perfect tool to get semi-stuck PLA prints off the bed without damaging either the glass or the print. I expect it would work on non-PLA prints too, I haven't needed to try yet. Now I don't worry about using a little too much glue. You just give the edge of the print a rap with the chisel, bevel side up, and the print pings off.

 

[gr5 2,172]

I have to check my bed level again. When i print the first layer i hear the feeder making a tock noise once in a while and i almost see nothing on the plate.

 

I prefer a thicker first layer - usually .3mm so that my bed levelling doesn't have to be perfect. With many printed piecs it's *good* to have it crazily stuck. You can try printing with no glue at all if you want. All these glues wash off with water just fine - it's easier to do it in a sink as you need a lot of water. But you can do it in place if you let the water soak in for 30 seconds each rinse cycle but you may need to rinse 10 times. Sink is much easier.

 

I level the bed with a paper and when i feel that the paper begins to be stuck between the nozzle and the plate i assume it's correctly leveled... The paper can still move. Maybe there is a more efficient way to level the bed?

 

This is recommended. The software assumes your paper is .1mm thick which is typical. It should be pretty gently "stuck" or not really stuck at all but more friction than when the nozzle is farther from the bed.

 

I'll try this again, maybe wash the build plate also, and put the temp at 60°c max or maybe lower?

 

There's no difference in stickiness from 30C to 75C. Many people noticed that 75C causes problems because the part warps a bit and is quite ugly (doesn't cool fast enough) for the bottom 10mm. This has nothing to do with sticking to glass. 70C is cool enough that this problem goes away for me. Most people prefer 60C for PLA. I usually print 65C PLA which is plenty cool enough. For very large parts that warp enough to lift corners, 70C is better than 60C as the part is too soft to lift the corners.

But again this has nothing to do with stickiness.

 

[gr5 2,172]

If you read my original post above, in bold I said:

 

For medium/reasonable stickiness print at 45C-50C bed temp and use no glue stick. If you want it to stick like crazy use 45C with gluestick but beware it is hard to get off without soaking in water.

 

So for many parts you can print with no gluestick as long as the bed is above 45C. (again 60C is recommended for other reasons).

One more piece of advice. For getting parts off I have changed to a new technique (months ago) and now my favorite is a putty knife sharpened to a razor blade sharpness.

I used a metal file to get it very sharp:

I usually have to hit the rear of the knife with my other hand palm to get the knife started, then I can be very gentle and slow and the part pops off a section at a time.

 

[DidierKlein 729]

Many thanks for all the advises (i love this forum)

I will try all that but first thing to do is wash my buildplate correctly relevel it and get my putty knife sharp as a samourai blade

One last thing: do you need to relevel the bed often?

 

[gr5 2,172]

I went a whole month without releveling my UM2. It doesn't change. My UM Original I have to relevel every week. Minimum. When it was new I had to relevel it every day.

 

[DidierKlein 729]

So yesterday i cleaned my glass plate and i noticed a little "hole" in the glass. It seems that i have damaged the glass while attempting to get a part off... it's very small something around 1mm or 2.

Anyway i washed with water and i used the other side of the plate. At first i tried to print at 60°c with nothing on the glass and the two attempts failed, the print was ejected from the plate by the nozzle.

So i applied a little glue made it uniform with a wet cloth. Tried several prints but very small parts. Seems to come off without to much force. Will have to attempt to print something with more contact on the plate to see how it sticks.

Thanks for all the advice

 

[gr5 2,172]

You can buy a new piece of glass - it is ordinary glass except that it is very thick - so it should be very cheap - probably only 10 euros. Any glass store will custom make this for you - they do this kind of thing many times per day.

 

[Titus 170]

Googling because I couldnt get it right. Gr5, your topic helped me a lot, I didn't figure out it would stick better at 45 than at 20 degrees. I thought it had to reach glass state for it to work.

Mixture of glue, water and a heated bed of 45C, and I can Auto print from glass, giving me that smooth surface Thanks!

[LePaul 321]

This was a great re-read

On my Ultimaker Original, with the blue tape wiped down with rubbing alcohol, I have to remove the build plate to remove the parts. I have to use a sharpened scrapper to remove them. That usually tears the tape up :(

I wind up using a lot of tape and of course, re-level the bed.

I have my heated bed upgrade kit though, once I have some time to record the installation, it goes in!

[LePaul 321]

I've gone through and re-read this thread, since my heated bed has been a challenge.

One thing that struck me...wow, 240C for PLA? I'm using ColorFabb PLA/PHA and those filaments prefer the 190-220 range.

Some good tips I gained from here...

1) Large prints (for me, over 2 inches wide), 70C seems to be good at prevent curling/lifting. In other threads, people mentioned lowering the temp after a few layers to 60C or lower.

2) Diluted wood glue is great if you don't want to print on a very warm bed.

3) Prints with overhangs and high bed temps don't mix (actually they droop...) Lower temp after first layer is on

4) Bed leveling is a bit more challenging with heat, but when done right, can last for quite some time!

[chorobe 0]

I am also trying to print straight on the glass so I can have that glassy shiny surface. I typically have used a glue stick which works great for adhesion but the glue marks are on the ugly side. Some of you here have said the PVA wood glue solution is just as shiny while some say it is more of a dull or matte finish. I don't have wood glue on me now, but I have tried with regular school glue (diluted to about a 2 to 1 ratio) and that did not adhere well at all plus the surface was matte. If I want matte, I'd just as well print straight on to the painter's tape without any glue.

So those of you who do use the PVA solution are you really getting mirror finish with it? I just wanted to make sure before I buy some of the glue.