Applying Kapton, the foolproof way

[CaptainObvious]

I always had trouble applying Kapton tape to the print bed, specially when using full width tape, now I think I have the technique down pat and thought to share it.

You need a large (at least twice and a half times the size of your print bed), clean and flat surface to work on, put down the print bed on one side, get the Kapton, a squeegee (or plastic card) and a bottle of window cleaner.
Spray the window cleaner on the table next to the print bed... hang on, there's method to this madness...
Unroll the Kapton tape, a little longer than the print bed, spray the sticky side with the window cleaner, then lay it down sticky side up over the wet table and cut it, the surface tension will keep it flat and the liquid on the sticky side will keep static electricity from sucking up dust particles in the air.
Now spray the print bed with the window cleaner, a sloppy job is a good job, then flip over the Kapton over the print bed, slide it around until if fits right and get the squeegee, squirt some cleaner on top to help the squeegee slide, and starting from the center squeeze from the center out, don't go back and forth, one stroke at a time always outwards and next to your previous stroke.

The edges may not want to stick because the Kapton sucks up liquid from the edge of the print bed under the film, so cut the excess Kapton, soak up the liquid with a paper towel and wait until the rest dries out, then you can squeeze down the edges down.

Done properly it takes only a few minutes and it leaves no bubbles or dirt under the Kapton

Hope that helps!

[Davo]

What do you print with that requires kapton tape?

[CaptainObvious]

What do you print with that requires kapton tape?

For ABS, it sticks like guilt.
The method I use is glue stick spread out with a wet paper towel for an even, thin layer, if the part sticks too well I just put water around the edges and let it sip under the print, after a while it unglues itself.

[CaptainObvious]

By the way, I use regular glass for the print bed, with the Kapton tape on top I don't get any problems of cracking due to the expansion/contraction of the glass and print.

[curious aardvark]

Sooo, if you're actualy printing on pva - why bother with the kapton at all ?
Just use pva directly onto the glass.
The tape wouldn't effect whther or not contraction cracked the glass - that's a function of how thick and strong the glass is.
When prints contract they pull upwards, the tape goes with the contraction, so has no effect on whether the glass flexes or not.
Were you to put kapton on the bottom of te glass, then it would help stop the glass flexing - but not on the top :-)

So throw away your kapton and stick with glass and pva.

[CaptainObvious]

Sooo, if you're actualy printing on pva - why bother with the kapton at all ?
Just use pva directly onto the glass.
The tape wouldn't effect whther or not contraction cracked the glass - that's a function of how thick and strong the glass is.
When prints contract they pull upwards, the tape goes with the contraction, so has no effect on whether the glass flexes or not.
Were you to put kapton on the bottom of te glass, then it would help stop the glass flexing - but not on the top :-)

So throw away your kapton and stick with glass and pva.

In my experience I get better bed adhesion on Kapton than plain glass; as for the cracking I'm sure it's not just a function of the glass properties, because I found that out when one of the glass plates I was using chipped under a print after a few uses, I turned it over and started using Kapton on top and haven't had any problems with it after over a hundred prints.

In any case the same technique for applying the Kapton can be used on other materials, like aluminium print beds.

[Geoff]

I'm with you Captain, Kapton has always proved for me the winner with ABS, nothing beats a fresh flat kapton surface and that nice shiny finish you get on the bottom of your prints.

I got Kapton when I first got my Flashforge - it worked for me since day one. The only time I have ever gone ABS on blue tape and glue is for very very large parts (like entire build volume) Hairspray is ok but it doesn't have that same stick like blue tape and a glue stick. The only problem with that is you have to have the blue tape on fresh aluminium, if you put it over the kapton the ABS can shrink and actually pull the blue tape of the bed, so yeah if I can I will always print direct on Kapton, and to be honest with fresh kapton you really should not need hairspray or anything.

I'll give your method a try, but I would recommend a warning to people not to spray too much window cleaner near the contacts or terminals on the bed - and do it with the machine switched off

[curious aardvark]

but you're still printing on pva.

[Geoff]

but you're still printing on pva.

I don't have any experience with PVA, I have no need or want for water soluble plastic! I can imagine a roll sitting in my workshop would go pretty bad overnight unless vac sealed.

[Marrrs]

PVA glue =/= PVA filament http://reprap.org/wiki/PVA