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Printing on Glass

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I did a big experiment today using the UM2 and printing on glass. I learned a lot. I tried at room temp (21C) through 75C. I only researched how well parts stick to the bed. I did *not* research how temp affects warping/shrinking issues. I only printed PLA on glass with and without gluestick.

 

I would print the bottom of the UM Robot (first 4 layers) and then remove it with a screwdriver pushing horizontally. I pushed the screwdriver with a scale that goes up to 30 pounds which was barely enough for one of the prints. Here are my conclusions:

 

You can print on freshly cleaned glass no problem - you need the filament to stay hot long enough to fill in the gaps and make a good surface if you want it to stick. So for example 220C nozzle, 30C bed was not enough - 1/2 pound force was enough to remove. Wimpy. Yet 30C/240C nozzle took 14 pounds force. At 220C printing, the bed needs to be at least 45C to stick well (14 pounds). If you lower to 40C it only took 5 pounds force to remove.

 

If you add gluestick you don't need any heat (but it helps a little). I printed at bed temp 21C (room temp) nozzle at 210C with glue stick and it took 19 pounds force to push the robot bottom off. With 45C bed, 220C nozzle, and gluestick it took 30 pounds force! Thats enough to put holes in the base of the robot print.

 

The other thing I discovered is bed temps at 60C and higher were bad. The part was still soft and it didn't take much force to remove it and when you did it wrecked the part. 220C/60C no gluestick took 11 pounds but it destroyed the part. 220C/75C took only 1 pound of force and it folded the robot base almost in half as I pushed.

 

Also if you use gluestick the amazing thing is you can soak in warm water for just a few seconds and pry it off slowly and the water disolves the gluestick nicely and the part comes off with only 1 pound of force even if otherwise would take 20-30 pounds.

edit: I also printed on plain fresh blue tape and it took over 30 pounds force. I couldn't push hard enough and had to turn the screw driver sideways to pry it off (then it came off with 30 pounds force). With alcohol it sticks much more - probably over 100 pounds force but I would probably damage my bed.

 

So here are my recommendations. 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.

 

All of this ignores warping issues! I want to do warping/overhang tests at some point but I'm not yet sure how I will test this in an easy, repeatable, objective manner.

 

Here are some of the results in photo form, lol:

PLA sticking to glass tests

 

I cleaned the glass with windex and a rag before every print!

 

Here's all the raw data:

bedtemp/nozzle temp pounds to remove, notes

220C/50C 11

220C/65C 5

220C/75C 1 (part just kind of folded up - much too soft - see photo)

220C/50C .1

220C/50C 1

Above tests were with putty knife that sometimes slipped under part too easily so I kind of threw that data out. Remaining were with screwdriver and blade vertical

220C/50C 10

220C/40C 5

220C/60C 11 (but part was wrecked - see photo - part with notch)

220C/50C 14

220C/30C 0.5 (part had warping/lifting on corner before I started to remove)

240C/30C 14 (hotter filament helped a lot!)

 

remaining are with gluestick

220C/45C 30 (bottom right in photo - part has 2 notches - first notch was only 20 pounds force)

240C/21C 16

210C/21C 19 (even at room temp - wow)

220C/45C 20 (mostly repeatable, yay!)

220C/45C 1 (soaked glass plate in water in sink for a few seconds while pushing/lifting lightly with fingernail)

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Great stuff George.

Worth trying PVA - dilute 50% with water.

Paint on clean glass and allow to dry clear.

PLA prints really nicely on it, and leaves a nice underside to the print.

Easy to wash off and re-coat.

Colorfabb XT does not stick unfortunately :( but I have not tried varying the bed temperature and will do that next.

James

 

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Yes I want to try PVA/wood glue and I want to try hair spray but most important was to try the glue stick that comes with the UM2 to help future UM2 users (and me). Glue stick cleans up very easy with water: wet sponge or wet rag. You also don't have to wait for glue stick to dry as far as I can tell. And glue stick is very fast to apply (don't need to unscrew a jar lid).

 

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I use hairspray on glass for both PLA and ABS. HBP to 60 for PLA and 90 for ABS unless it's a tall print and I need the heat. Has never failed and it pops off as soon as the glass drops below 40 deg or so.

 

That above quote was from clinton over on google groups.

 

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I have experimented a bit with the dilute PVA aka glue solution and a non heated bed with very good results. I personally tried three different concentrations of glue to water. Albeit I'm sure it varies due to the formula of glue, but I didn't find a noticeable difference between a 30% solution and a 50% solution (disclaimer: I wasn't too scientific about applying the solution to the glass, just kinda smeared it on).

Either way it's worth a shot, and the pva solution also dissolves in water too for easy removal and cleaning. And the finish on the bottoms of the pieces are absolutely amazingly flat and shiny. Super jealous of the UM2 owners with their heated glass beds!

Also, how do these force readings compare with standard blue tape minus the alcohol treatment?

 

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Also, how do these force readings compare with standard blue tape minus the alcohol treatment?

 

Ah! Of course I should have done that! I will do that when I get a chance. Maybe tonight. Probably not (I play volleyball thursday nights).

 

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I've never needed any glue stick when printing directly to the glass and the build sheet is at the standard 75C. The models come away cleanly I find if you use something with a very thing edge like a pallet knife. Even better if you file the edge to be really sharp.

 

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I also printed on plain fresh blue tape and it took over 30 pounds force! I couldn't push hard enough and had to turn the screw driver sideways to pry it off (then it came off with 30 pounds force). With alcohol it sticks much more - probably over 100 pounds force but I would probably damage my bed.

Of course if you are printing something that is warping and you keep it above 60C, the part will be too soft to pull very hard at the corners. So that is probably why a heated bed works better for very large parts that warp.

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A few days ago I didn't even know that you could print on (cold) glass. I've now tried it a few times and I like what I see. My main motivation is to get rid of warping. I've got no heated bed, and do not intent to consider one until UM offers it as an upgrade; so I am looking into other options. My roomtemperature is now low (around 14 degrees C).

If you print on glass alone, the object hardly sticks, and will come loose.

Diluted wood-glue works, but I found it a bit messy, and hard to apply an even layer; and it takes forever to dry. The result is very smooth, but dull (not shiny). Warping is minimal however.

A glue-stick is easier, you don't have to mix a solution, it is dry instantly. Warping is nearly absent (when there is enough glue), but the finish is not smooth, you can see where the glue is 'imprinted' in the object. And you have to wash the glue away after the print, which is easily done with tap-water. With most of my objects, the bottom of the print is also the bottom of my object, so looks are not that important, but it is a pity that they don't look as smooth as with wood-glue, or no glue at all.

I will continue with my experiments, and I will print mostly on glass in the future I think, because of the minimal warping (much less than with the blue tape, which is lifted of the bed by the warping-force).

 

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I will continue with my experiments, and I will print mostly on glass in the future I think, because of the minimal warping (much less than with the blue tape, which is lifted of the bed by the warping-force).

I've tried the diluted PVA glue printing with PLA and thought that the adhesion was less good that with blue tape degreased by wiping with Isopropyl Alcohol.

Have you been using the Alcohol?

Are you printing in PLA or ABS?

What's the glue in the glue stick?

 

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With the blue tape, the problem is not adhesion of the PLA to the blue tape, but the blue tape itself comes loose from the bed. I can't get 15 cm wide tape here which would help a lot (maybe). I use PLA exclusively. I've got no idea what glue is in the glue-stick, but is dissolves very easily in water, and does not smell or burn when it comes in contact with the hot PLA.

I've made a support piece for the glass, that will hold the glass in place, and push down the bed so the head is at the correct height for the glass bed (no need to re-level the bed).

https://www.youmagine.com/designs/glass-support

 

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I like your support piece maurice! clever clever.

If I didn't have an imperial piece of glass I would definitely use your very clever device. instead I'm using something like:

https://www.youmagine.com/designs/z-material-add-on

to good results

As far as your experiments are concerned could you post some pictures? I'm awfully curious about your warping issues and the finish you are achieving on your glue stick on glass parts. With the dilute glue I have achieved nearly mirror finishes (some lines are present still). I guess the glue stick must make thicker layers of glue, but I would love to see what it looks like :)

 

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The finish is very difficult to photograph, but with the glue-stick, it is quite rough (only suitable for invisible surfaces). I'm still looking for a method to distribute the glue more evenly on the glass. I've printed a regular pentagon with sides of about 8 cm, and the warping is about half a mm at the endpoints.

How do you apply the diluted glue? How long does it take to dry? I'm still considering using it because of the finish, although with me it was smooth and dull, not shiny.

 

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Hmmm, I thought that if you used a heated bed, no glue was necessary. I tried rolling the glue from the glue-stick with a hard roller (a piece of PVC pipe), it rolls out nicely but the finish is still not smooth and shiny. And I got my print very easily from the glass, so warping may be a problem again. Ik must try to print the first layer at 240 degrees again, that seemed to help with the bonding to the glass.

And what about the Kapton tape? I thought that needed to be on the glass plate if you used a heated bed, but apparently it is not necessary.

 

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I do not understand it! :shock: :eek: :eek:

 

1 / If you work on the plate without glue, you risk damaging the take-off of glass.

2 / If the gluestick is used, which result from not in use?

3 / If you do not warm up, you can use the blue band.

4 / If you mix water with acrylic adhesive, it can work well.

 

Please! Help me understand the easiest method. And especially the method that does not habime the tempered glass. :ugeek:

 

Thank you very much.

 

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This is a little worrying but I have not damaged my glass yet. Plus you get 2 sides so you get 2 chances. Also glass is not very expensive - you can get it cut to size from your local glass manufacturer.

Having said that - what is the most gentle and easiest is to print at 50C on glue stick for parts that don't warp too much and print on 70C glass plate if part is large (keeping it over 55C keeps the pla soft so it can't shrink/pull very hard).

Then to remove the part - the most gentle way is to wait for it to cool and if you can't remove it easily with your fingers, then soak it in water for a few minutes and the glue will dissolve.

 

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If you apply the glue stick fairly thinly, and then wipe it down with a damp sponge, it will get any lumps out of the glue, and spread it around more evenly. As the bed heats, it dries, leaving a uniform thin layer of glue that gives the print a mirror finish.

 

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We do not understand then!

 

I am looking for a simple solution which does not degrade the bed of glass during removal of the object.

 

If the glue used to hold the workpiece. If the towel (cloth) would spread glue evenly, then this is a good point.

 

However, it does not tell us why it is so difficult to use the glass.

 

I try to understand. :-P

 

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Many people get very different results with printing on glass.

So there doesn't seem to be a method that works for everyone all the time.

Results vary particularly with the shape and size of the model.

Other variables which we may not be aware of like moisture in filament, humidity and outside temperature etc. may all make a difference as well.

 

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However, it does not tell us why it is so difficult to use the glass.

 

It's actually very easy. It's so easy you can do 10 different things and they will all work. So for example you could always print straight onto the glass with the bed at 70C with no gluestick and for small parts this will work pretty well. If you don't want to wait for 70C you can also print at cooler temperatures with or without the gluestick. If you find your part comes off too easily you can use gluestick. If you are printing something that is artwork that sits on a table and you don't care about the bottom, you don't have to use the sponge to get the glue smoother.

The problem is: there are many choices and most of them work in most situations.

 

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Hi everybody,

I am also printing on glass, but have some troubles.

I need to print this: http://www.thingiverse.com/thing:45731/

It´s a large print and it matters how the bottom looks because this will be the outer visible part of the dose. I have an UM1. So I installed a heatbed this weekend. Wasn´t a great deal, had the parts laying around. I also changed the bed leveling system to 3 point leveling. It´s much easier and you don’t need tools for leveling. I can publish the files if anybody is interested. The heatbed works pretty well.

70°C is too much for my setup, I figured out. The first layer did not stick even after cleaning with alcohol. Was a mess. With 60°C and diluted PVA, it works. The bonding is very good. 12h print, still printing. We will see how to separate it from the printbed.

I leveled the printbed out with a piece of paper (80g). I needed a little force to pull it out under the nozzle. So the printbed was level. I heated it up and started to print. The first layer printed well on most parts, but in one corner, it did not print at all or very, very thin, almost invisible. Anybody had the same experience? It did not print on layer 2, but on layer three. So the surface in this area had gaps in layer three, of course because more material was needed to fill the gap of layer one and two. But what caused it not to print in layer one? Hope you understand what I mean. Anybody had this before? Any ideas?

This might be a leveling issue, but I leveled the bed before… Strange. Maybe if there is no distance between the nozzle and the glass, the extruder is not strong enough to drive the material out. I did not have this on blue tape, only on glass.

Cheers,

Philip

 

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