Intro: Sticking Coat for FDM 3D Printer Heating Bed Glass
For less than 10 € with a little training, get a life time lasting solution for heating bed glass sticking.
This sticking coat is:
- A natural and renewable material.
- Very cheap and cheaper at each print !
- Reusable eternaly.
- Easy to set (and clean, after many prints).
- Leaving a flat and glossy surface on prints.
- Free of residues left on prints.
- Sticking so well that you can't remove your print unless bed cools down.
- Releasing prints under 35°C with a "click".
- Environment and user friendly, free of chemicals.
Easy to find in online stores.
This is performed by the use of a natural polymer, called Shellac, on your heating bed glass.
Shellac is produced by an insect, the kerria lacca cochineal. It soften with heat and dissolves in alcohol (among others). It is known by humanity since more than 4000 years. It is used to varnish old and fancy wood furnitures and music instruments.The first 78 turns records were made out of it, the isolation of electrical wires in coils were first made with it, and I can't quote here all the uses made out of that incredible material and are still done nowadays.
"Necessity is mother of invention"
As I was born 30 years BI (Before Internet), and because I've always been a hand worker, modules boards, numerical machines, electronic projects or 3d printers appeared to me as alien stuff... I believed one had to study many years and to be good in math. to enter that world.
Then last year, I entered the next door Fab-Lab, ("SquaregoLab", Perpignan, south of France). Meeting people playing with all theses funy things changed my mind. I then soon dared to buy a cheap 3d printer kit and put a dump scanner glass on it.
The machine was ready to print, but this (*) PLA was not sticking !
Mr Google told me it was a very well known problem, but no blue tape, no glue stick, and not even hair spray at home...And my very first print could not wait, I had to find something within the next ten minutes to enter the new era ! I'm sure you understand what I mean...
The solution came by intuition, out of my dusty workshop, from that old pad varnish technique (called "french polish" out of France). It took me some time to understand why and how it worked so well at the first time, to be able to renew this at will.
In this instructable, I give you the tricks I've found to get constant good results, and beg your pardon in advance for my english being ...so french :-)
This works for PLA. ( I'm new in 3d printing and I don't even have any ABS roll yet, it could probably work, but I have not tryed, but if you want to, remember shellac sticks well between 50 and 60°C)
On the picture above, the full set that I have next to my printer since last year. (It's still the same...)
Step 1: Different Qualities of Shellac !
Depending of what kind of tree the insects lived on, the season, the cleaning, etc, the quality is different.
Globaly, there is 3 qualities. brown, orange, and clear/golden
Among theses, there are 2 other choices: plain, and unwaxed
The shellac I use is the Orange Unwaxed ("fine orange décirée" or "blonde décirée"), the one in the middle on the picture.
It's the most used, at a good price around 24€ /Kg but, relax, you just need less than 10 grams...
The brown is too "dry" and breaks too easely, and the Astra, (the golden one on the right) is supposed to work too, I have not tryed, but it is much more expensive and because it has almost no color, you won't feel the thickness of the coat applied on the glass.
So, Orange Unwaxed shellac is a good choice for what we want here...
Also, you should know where it comes from, the people and the forests you support if you choose to buy ans use shellac.
(Thanks Vijay for your very interesting video:-)
Step 2: Things Needed
These are first (and second) choice ingredients.
- 8/10g orange shellac unwaxed.
- 100ml of alcohol from drugstore (or alcohol to burn).
- 10cm² of linen fabric (thick cotton is ok but could leave fibers in the coat without to be a problem).
- Few grams of cotton wick ( or tousled cotton rope or thin DIY cotton stripes)
Cabinetmakers, or luthiers, use this to make the famous french polish. It can be an opportunity to visit such a workshop and ask for ingredients that you could not find. But all of this is easy to find ... Don't despair finding that in DIY supermarkets, (in furniture polish area)...
We will also need:
- A small plastic bottle with a tiny hole under the cap. (because one use only few drops each time).
- A small plastic or glass pot that can be closed hermeticaly. (fabric with alcohol shoud not dry in it)
- A new large cutter blade.
And eventually, in a second time, a ceramic scraper to clean your glass after many prints because it's safer than cutter blade for this operation..
Step 3: Let's Prepare the Varnish
First, remove the tiny hole plug from the plastic bottle.(using the edge of the cap, not a knife)
Pour the 8 grams of shellac into it (with a piece of paper, it's easyer).
Add 100ml of alcohol, put back plug and cap, check that it's well closed.
Wait 10 minutes and shake it energicaly (if you don't, the flakes will stick all together to the bottom of the bottle and it will take much longer to dissolve)
Then wait 1 to 3 hours, shake it again , check if everything is well dissolved, it's ready !
Step 4: Setting the Pad
Why to use a pad and simply not a paintbrush?
On glass, the liquid would retract himself and make spots and drops, because of alcohol.'s behaviour.
A pad leaves a very thin and shooth coat that you can control.
Now, take the cotton wick, the piece of fabrik and your shellac varnish.
Once compressed, the cotton wick should not be bigger than a walnut nut for our use.
Soak it with the previous shellac preparation and knead it. If you press it, it shoud not lick.
Place it in the middle of the 10 cm² of fabric, close the fabric around the cotton wick.
You shoud see shellac passing slowly through the fabric making an orange spot.
It should be damp, not wet.
Understand that a new dry pad fabric needs more preparation to be damp...
Your pad is ready.
Remember : Shellac or alcohol should always be added to the cotton wick, not on the fabric!
If you don't use it now, put it in the hermetic pot !
As much as possible, it should never dry because it hardens.
If it happends, put a few drops of alcool on it and let it 20min in the closed pot before to knead it !
It will then recover it's softness by itself.
Step 5: Set a First Coat on the Glass.
It's a 10 minutes operation to renew every....15/30 prints maybe...
You may wear gloves or not. Personnaly, I don't. Shellac doesn't stick very long on flexible materials like skin, if you forget about it, it goes by itself from your fingers but not from nails. At the end, one can clean his nails and hands with alcohol if needed.
Clean the glass with alcohol ( remove grease), and preheat it at 60°C. on your heating bed.
Once heated, remove the glass from your heating bed (or not), it's just question of being at ease drawing on 8 shapes with your buffer. Glass has to be warm to catch shellac...It's my trick.
The pad slides. If not it's too dry, add some varnish preparation. (this is the only thing to always check)
The pad arrives on the glass like a plane landing. When it touches the glass, it's in movement. Same when it leaves the glass. Otherways, the pad will stick and leave the mark of the fabric, and fabric fibers eventualy.
By drawing 8 shapes, the pad never pass by the same area. It leaves a very thin coat behind, of a few microns thick. If it passes by the same area, it removes the previous coat before it dryed.
Cover your glass with theses movements until your glass looses its gloss. If the pad begins to stick, put some more varnish in it.
If you cannot cover the glass gloss, your preparation has too much alcohol, put more shellac in it or heat the glass again..
You can't see any glass gloss? That's it !
Put it back on your printer, let it cool down and level your bed properly.
This coat works like a primer. It won't stick anything, not even dust. You can leave it on your printer.
Step 6: Let's Print !
In your slicer, as usual, set the heating bed at 55°C or 50°C even, for a large bed, it saves energy.
Send a print, let the bed heat, and during the nozzle heating, take your pad out of the pot, draw some 8 movement 2 or 3 times on the area where the print will happend, and it's ok. Don't put more than this !
To check if it's ok to print, touch the bed with the back side of your fingers,( it's not greasy, more sensible) and If you feel it's "in love", I mean if it sticks softly without gluing, like tape, great !...
Watch the first PLA layer to print and everything is now ok, it will stick until the end even with long prints (I've tryed up to 9 hours print).
It's hard to wait...
Once your print is finished, wait for the bed heat to decrease under 35°C and hear this lovely "click" that tells you that it doesn't stick anymore. Take your print without any effort...I love it !
In hurry? Then put your glass in the fridge...
Step 7: Before a New Print
Prints leaves a mark on the coat. Especialy after a few prints and pad coats. .
To always have a clean surface, I pull a large cutter blade to remove any asperity.
This has to be done on a cold bed.and before to add a new sticking coat with your pad..
The dust removed by the blade can be cached by the cotton wick...And will be reused into the pad whith a drop of alcohol.
Proceeding that way, your shellac will never be lost and your print space always flat..
Step 8: Totaly Clean the Glass
By the time, the shellac coat can become too thick, glass becomes brown in the middle and nozzle digs into it.It still works great, but the finish on your print can suffer a bit from that.
It happends because one tends to always put too much pad coat.
So it has sometimes to be cleaned and renewed, and it is very easy to do.
Just like hoarfrost on your windshield, it's removed using a ceramic scraper on a cool glass.
(on the picture I use the cutter blade, but I don't recommand to do that of course...You could harm yourself)
Keep the shellac removed from the bed, put it back into the bottle, add a few alcohol...It's a closed loop.
I'm using the same material that I've prepared last year...
Warning ! Scraping shellac produces some static electricity, be aware of that disadvantage. This means that this operation should me made out of your 3d printer.
I hope this will be helpfull to many makers, to shellac producers and thanks for having read my very first instructable !