Well it seems that FR4 only lasts for about a week. The grip slowly fades making the parts very easy to remove. In fact they all pop off as the bed cools below 60°C and slide about due to the fan and the bed's final movement to the front. The odd small part falls down inside the machine.
If I mounted my machine so it was inclined at 45° they would all fall out the front and could be directed by a chute into a hopper and the machine could then build continuously unattended. Who needs a conveyor belt! The only problem is the grip is now not enough to hold the bigger parts during the build.
I have tried cleaning with acetone but it doesn't seem to help. I suspect the high temperature is making the epoxy more brittle and less sticky. I will be able to prove that when the FR4 without copper on HydraRaptor fails. If I then turn it upside down and it still works on the under side then it is not a temperature ageing effect. If the other side is still working then it must be a reaction to the ABS or the acetone that is the problem.
It is shame because I much prefer a solid substrate to tape. Something like polyimide and fibreglass laminate would probably be ideal but it is hundreds of dollars for a piece big enough.
Wolfgang has posted a mystery material to me that sounds promising, so back to PET tape until it arrives. My friend Tony found that Farnell sells it in wider rolls. It seems to be a bit thicker as well, so is easier to apply, but a lot more expensive than the stuff from BestOfferBuy.com.
If I mounted my machine so it was inclined at 45° they would all fall out the front and could be directed by a chute into a hopper and the machine could then build continuously unattended. Who needs a conveyor belt! The only problem is the grip is now not enough to hold the bigger parts during the build.
I have tried cleaning with acetone but it doesn't seem to help. I suspect the high temperature is making the epoxy more brittle and less sticky. I will be able to prove that when the FR4 without copper on HydraRaptor fails. If I then turn it upside down and it still works on the under side then it is not a temperature ageing effect. If the other side is still working then it must be a reaction to the ABS or the acetone that is the problem.
It is shame because I much prefer a solid substrate to tape. Something like polyimide and fibreglass laminate would probably be ideal but it is hundreds of dollars for a piece big enough.
Wolfgang has posted a mystery material to me that sounds promising, so back to PET tape until it arrives. My friend Tony found that Farnell sells it in wider rolls. It seems to be a bit thicker as well, so is easier to apply, but a lot more expensive than the stuff from BestOfferBuy.com.
have been using the greem tesa pet tape (5060) for a while. works well for abs, but couldn't get pla to stick well yet (but this could be just me). it's pretty thick and has silicone glue. much more resistant to close encounters with the head than the thin kapton.
ReplyDeletewe actually got the tape for free from the local tesa representative. supposedly it's designed for protecting areas you don't want sandblasted on your car...
Thats a shame it was looking like a neat solution.
ReplyDeleteStepping back I think I saw someone with an Up printer using the 0.1" perferated PCB maybe adding a surface finish ie a fine etched grid so as to keep a smoth finish still into FR4 double sided will retain the idea a little longer?
What a pity.... I was getting all excited by your findings so far. I have been using the Heated Bed Platform PCB with Kapton on top and found that I have had to heat the bed (the PCB) to at least 100 degrees to get the ABS to stick. However, once the build is finished, a drop in temperature to about 80 deg. allows for the item to be easily removed with a sharp tap with a hobby hammer.
ReplyDeleteBTW great blog. I have been reading it with great interest. Keep it up and thanks for your great analyses.
Another material down, plenty more to try.
ReplyDeleteHave you or has anyone else tested heated acid etched glass with ABS?
No only plain glass. I find shiny surfaces work but matt or textured don't. I think the grip is not mechanical, it is chemical, so requires the materials to come in very close contact.
ReplyDeleteYou also get atmospheric pressure helping if the seal with the bed is airtight. With PLA on glass you can sometimes slide an object about when it has cooled but it is still held down by suction.
@Bodgeit,
Veroboard works by mechanical grip, but it needs a raft to avoid pimples on the object.
I believe that someone mentioned in the forums within the last week or two that he was able to regenerate the surface using a steam cleaner on the surface.
ReplyDeleteMaybe you could try that to see if it helps.
I saw a machine that makes FR4. It deposited some sort of waxing release on the metal that formed the bed of the machine. I wonder if this material was clinging to your sheet of FR4 and use removed this coating? Just a random thought...
ReplyDeleteIf we do find the right coating, can't we just use the same coating on a plate of glass, since it seems to be sticking more to the coating than the FR4?
ReplyDeleteI doubt there is any lasting coating from manufacturing as I cleaned it with acetone before using it. I suppose there could be something that the use of acetone slowly removes.
ReplyDeleteIt works well for about a week and then the grip falls off a cliff. Turning it over got a little more life, but nowhere near the same as the first side, so I think the surface changes due to the heat.
I haven't tried rejuvenating it with steam as I don't have any spare machine time for experiments at the moment. I don't think the ABS deposits anything water soluble on the surface, so the only explanation for steam working I can think of is that water is lost from the epoxy and the steam puts it back. It would be odd for it to take a week to dry out at 110C though. I would expect it to dry much faster than that at such a high temperature.
We desperately need some surface chemists in reprap!
Well, let's hope the new mystery material from Wolfgang (that he has from Philip) appears to get even stickier over time and you need to use the acetone so it doesn't stick too hard.
ReplyDeleteI got my pieces finally yesterday (one week in the mail from north Germany to south Germany) and have been testing PLA w/o a heated bed.
So far it looks really good.
Yes it appears to stick well but is too thin to hold things flat.
ReplyDeleteYesterday i glue the unnown Material onto a sheet of FR4 but it needs time to harden. So i give the FR4 an other try and sand it with fine sandpaper. Now it glues again... but i dont know how long.
ReplyDeleteHave you tried a granite tile as a bed?
ReplyDeleteCrazy?
No, but if ABS does not stick to hot glass, I doubt it would stick to granite.
ReplyDeleteI use an fr4 like material. Try sanding it down with 600 grit and clean with acetone. Works well for me to rejuvenate the surface.
ReplyDeleteWat a pity, that it didn't work.
ReplyDeleteWould have been a great way to avoid the issues of a belt.
If you put a little bit ABS into Acetone and brush this onto the FR4 then it works... now since 3 Weeks.
ReplyDeleteUntil now it works very well. Only 10mm ABS in 100ml Acetone. Bush very thin on the FR4... works... it must be very thin on it.
ReplyDeleteHow long does it last before you have to do it again?
ReplyDeletei do it every 2-3 prints, i see when i must do it again. But someone in the German forum tryes the same with Glas and say it works too. I didnt try this. FR4 works well for me .
ReplyDeleteUnder the assumption that the grip is not mechanical, perhaps an additive would help fix the fr4. Someone mentioned the waxing procedure and I seem to recall various types of ski-wax (cheap) offer different types of friction based on heat. You may want to give it a try.
ReplyDelete