Intro: 3D Print ABS on a Cold Bed and Onto Any Material
This a two part Instructable.
The first part is about BuildTak and the second about using plastic primer to print on any surface you like.
BuildTak? Never heard of it....
No wonder as the product is quite new and most manufacturers of 3D printers won't include it when you buy one.
Some don't even list it as an option so I thought it is time to give you a little showdown on BuildTak.
What is it?
BuildTak is basically a plastic sheet with an adhesive back.
You get it in all standard print platform sizes and if doubt you can cut the excess off.
It usually comes in black and has either a logo or the BuildTak name printed on it.
Looks in the surface texture almost like a kitchen bench top.
Where do I get it?
There is the official website: BuildTak official website
But I sourced mine from a local supplier in AU, you can also find them on Ebay and Amazon in various sizes for most platforms.
How do I use it?
Instead of using tape, ABS juice (slurry) and other tricks to make your parts stick you simply print directly onto the BuildTak sheet.
No extra tape, glue or anything required and it works for all common printing plastics.
If you do have a heated bed it will tolerate up to 150°C before it gets a bit soft or the glue on the backing gets into troubles, so you should not have any problems here.
All your print settings can be left as you always used them but you might no longer have to print with a brim around your parts to make sure they stick - but that is a claim for PLA, using ABS I still print a 3-4mm brim around my parts, just to be sure...
Being plastic you should not use knifes or other sharp objects to get your parts off.
Usually a nice tap with the handle of a screwdriver or similar lets the parts pop off.
For bigger parts that won't come off that easy it helps to be able to remove the build platform to put it in the freezer.
After about 30 minutes the different expansion rates have seperated the parts and they pop right off.
Sounds good, but how do I get it onto my platform?
1. Make sure the sheet won't cover any holes for mounting screws!
If in doubt make the shett smaller or puch the holes you need out of the BuildTak sheet before you continue.
Once the sheet is on IT IS ON!
2. IMHO the best option is to have the sheet mounted on a seperate glass plate or onto your heated bed.
3. Clean the surface properly with methylated spirits to remove any leftovers from prints, glue or tape.
4. Check if the sheet will fit properly or if it needs trimming as it is easier to trim before you stick it on.
5. Peel the white "paper" off the back to reveal the glue on the BuildTak sheet.
For bigger sheets it helps to only remove about a third so you can your the area with the paper still on to properly align the sheet.
Another helping idea is to place the BuildTak on a table with glue side up and to "fold" your removed build platform over it.
There is no try here, once the sheet touches the surface it sticks like hell, if you put it on at an angle you won't be able to correct it!
The good thing it that it is quite hard to trap some air under the sheet when applying it, just start on one side and due to the stiffness it basically rolls onto the surface really flat with no bubbles.
Although it is recommend to press the sheet firmly onto the platform I apply them from one side and wipe over the touching area while letting the sheet down.
Ok and how does it perform compared to the normal way of printing?
You know the way you prepare your platform better than I do so I will just show you some pics and a video to compare for yourself.
First we have the sheet as it was delivered:
The cover sheet on the back is surprisingly sticky when it comes to dust, pet hair and other tiny things.
It has a slight rubber feeling, good that it wll be removed for installation anyway.
As you can see nothing special about it at a first glance.
Installed on my print bed is this 30x30cm sheet now:
The difference to normal ways of printing comes visible when you see how well the plastic sticks on the sheet and how well defined the lines are.
As I have no heated bed for my old printer I will try to print ABS directly onto the cold sheet:
And a bit further into the print still no peeling off or any of the usual problems.
Printed with a 4mm brim around the object.
Bit tricky to work with one hand so forgive the bad video, but here you can see the removal of the part:
It really is not easy with one hand, but after some tapping on the outside of the part it breaks off the brim.
I had troubles holding the platform and the cam, so I cheated a bit with a plastic scraper.
Last but not least some close ups from the underside of the print to show the surface quality, my print settings are still not 100% but still it looks nice:
It was clear ABS and only 3 bottom layers, so it might be a bit hard to see the surface properly.
I will print some gears in a different color later on and when done add some more images.
How long does it last?
My first sheet was abused quite a lot by my prints and the way I got them off, so read on for a long life span of your sheet.
A good estimate would be around 50-60 prints with ABS on a cold bed.
On a hot bed it can be more but also less depending on the print settings.
The estimate is based on printing on the same spot, if you arrange your prints over the entire platform instead of always using the center the sheet will last much longer.
Of course this does not apply if you use the etire build space for your prints anyway ;)
If mainly printing smaller, single parts that cover only 20-25% of your build platform you can get well over 200 prints per sheet.
Can I make it last longer?
As I found out the hard and expensive way, you can!
I already mentioned to arrange your prints so they cover a different spot each time your print.
But even more helpful is to use proper print settings for the first layer.
Every printer is a bit different, so are the thermistors and temperature readings, but I will give you a good way to get it right.
You usually start your first layer of ABS at 240°C so it does stick well.
The rest is printed at 220°C.
If your print fuses well at 220°C this would be the starting temp to try for your first layer on BuildTak.
Just do a simply test print like a long and slim bar.
Print the first layer not thicker than 0.25mm and check if the part starts to peel off once you printed about 4mm in height.
If all is good till now it is unlikely the part will start peeling later on.
Repeat the test with a lower temp setting for the first layer but don't go under a temp you consider the lowest for a proper print quality.
In case the part does start to peel off increas the temp by 5° and repeat until satisfied.
The worst abuse however happens when trying to get a part off!
Don't use knifes or other metal objects to pry your part off!
A little tap with a tiny hammer or the handle of a medium size screwdrive should be enough to get the part off.
Remember in most case you won't need a brim anymore ;)
If you want a good tool for the job check "bump keys" on the net, people use a flat piece of plastic (often just a ruler) with a little blok on one end to "tap" on the key - this works as great on your printed parts, only the door won't open once they come loose...
Step 1: Ok, But I Only Do a Few ABS or Nylon Prints a Year - Alternatives?
As mentioned earlier the common way is to use a tape suitable for printing ABS on, usually Kapton tape.
The obvious downside is that you still can't really predict if a larger part starts to warp off the build platform if not heated.
I can buy another can of primer to upload some images of the process if required but if you can use a spray can you should be fine.
If you do have a heated bed all should be well and fine by using Kapton tape, for those printing on cold beds there is a really nice alternative:
What you need:
1. A suitable build platform, copper circuit board, aluminum sheet or simply a pane of glass (might not be be perfect and can require a layer of Kapton tape).
2. Plastic primer ;)
Yes, that's right!
Use a spray can of your favourite plastic primer spray and cover your build platform with a thin layer.
For obvious reasons this should be done with a removable platform and outside.
Once the primer is fully dried (should not take too long) and you can't smell it anymore it is time to print.
I am trying now the BuildTak sheet and ran out of primer for pics but I can assure you this trick works with every material the primer sticks to properly.
3. Acetone or fine sand paper for cleaning.
How to apply properly:
Most plastic primers dry within 10 minutes, some even faster.
This means there is no real need to rush things and you should take your time to apply the primer properly.
It is best to put your plaform against a flat surface so the other side won't get the spray as well.
Start the spray outside your platform and then make nice sweeps over the area from the left to the right - always spraying over the edge to the outside (otherwise you can get too much primer on the outsides).
You should overlap each stroke a little bit.
Do a quick visual check against the light if you covered the entire platform evenly, if not repeat but turn the platform 90° so you cross the previous spray pattern.
How to print on it?
Simply start your first layer with about 60% of your normal print speed and have the temperature for this layer 10-15°C higher than for the other layers.
Is it hard to get the parts off?
If you use a plastic print bed it can be quite hard but other materials like copper, aluminum and glass make the parts snap off quite easy.
Bigger parts might need a slight tap around the base to break off.
Can I re-use it?
Of course you can!
You can print quite a few parts just by changing the print position for the part.
E.g.: Instead of always printing in the center, print the next part far away from the previous print area.
You can also apply another quick spray of primer over the area used for the previous print.
After a number of prints the platform starts to look a bit uneven and unclean, use some acetone or fine sandpaper to clean it an apply a fresh layer of primer.
Are there any other good uses for it?
If you adjust your print height you can directly print on anything.
Ever wanted a personalised Zippo lighter? Apply some primer and print your own logo on it.
Print directly on your cell phone cover.
Whatever surface is flat enough and fits into your printer can be printed on.
Are there any dangers?
Apart from the usual when working with spray paints not really.
Only when printing on certain plastics, paper, leather and other materials that can absorb the primer you will have a problem getting the part off.
Printing on leather this way means the parts stay on and won't go off until they break.
Nylon can be a problem as much more heat is required and Nylon does not really like to stick to anything.
Here it can help to apply an additional layer of primer and to start the print very slow with a layer height as low as your levelling allows (0.1mm is good, 0.5mm better).
I got an old scanner from the hard rubbish, sanded the surface milky using a diamond sharpening block (300 grid) and applied some ABS juice to the surface.
The prints stick really well and to get them off all that's needed is a a slight cut somewhere and to add a drop of methylated spirit - the part pops right off.
Using the plastic primer gave similar results although it was a bit harder to get the part off, probably a polished glass surface would be better here.
PLA sticks quite well to it too :)
Step 2: Printing on a Cold Glass Bed
A glass bed is almost perfectly flat anyways, but it can be improved for printing.
Adhesion is our biggest problem on a cold bed as parts tent to warp and if the forces are too hight the part starts to peel of.
I think I really tried it all, tape, BuildTak, benchtop liner (quite good actually), sugar and lemon mix (makes a good lemonade if it does not help with the sticking)...
But in the end all these "solutions" still kept peeling off the bed when printing big or just long and thin.
I wanted a surface that is as flat as possible, easy to clean and provides at least half decent adhesion.
My solution for this was to use a scanner glass plate as they are really flat already and heat tolerant.
After sanding the surface with a diamond sharpening block using the 300grid side the first test prints with PLA were a disaster.
ABS was no better, instead of sticking to the surface it was more of a repelling thing LOL.
A few tests with molten plastic (the light it up and let drip down method) two problems emerged:
a) the material was cooling down on impact
b) the material was shrinking badly while cooling down and lifted off
After applying some wood glue mix on the glass I also realised that this did not wet the surface evenly, it tends to form drops - a few drops of lemon juice in the mix solved that problem.
Now PLA was sticking good after the drip down test.
ABS was doing ok with ABS juice but of course not perfect.
Back in the printer with the glass...
Ok, combining all my previous priniting exeriences I decided to use the sanded glass surface as the replacement for the tape.
Tests with lemon juice and sugar mix were really good with PLA, some so good that I had to use water to dissolve the glue to get the part off.
The stickiness is superior and the adding water trick only takes a few minutes extra.
If you use a brush right after the print surface is back to good after drying.
This way it is possible to print PLA without warping and without a brim - something that comes handy for certain parts.
ABS did cost me some nerves and near breakdowns.
Small parts were no problem with ABS juice, even if applied on top of the sugar coating.
The bigger the part and the more solid the first layers, the more I experienced the usual warping off the build plate.
Against common "rules" I decided to now go the other with the first layer: print it thin instead of extra thick!
So instead of going to 0.2mm or more I started the first layer with just 0.1mm.
The speed was reduced as well and the line thickness increased to 120%.
This made the first layer stick fine but the second peeld off later in the print :(
A cold blonde gave me a brain storming experience and I played with the layer temps.
I already started at 250° for the first layer but went down to 235 right after.
The new settings started at 260°, 255° for the second and third layer and after that 245°.
Now all was sticking fine :)
Big parts require a brim of up to 30 lines wide but they print ok.
Oly problem I noticed is that after you got them off the plate they still warp a little bit.