Epoxy won't stick to....

[greenLED]

Epoxy won\'t stick to....

Hi, everyone,
Is there a material that epoxy won't stick to? I'm thinking about making some sort of a pill for a minimag and would like to encase it with epoxy (the regular 2ton stuff I got from the hardware store). I'd like to keep the pill's shape cylindrical (of course), but I don't know what to use as a "mold" without having the epoxy stick to it.
Thx!

 

[BayMoe]

Re: Epoxy won\'t stick too....

Try applying a thin layer of oil or tape to the underside of the mold, then sand off the layer of tape when the epoxy hardens.

 

[gadget_lover]

Re: Epoxy won\'t stick too....

The tape peels right off the epoxy. The tape's glue keeps it from sticking.

Daniel

 

[Wingerr]

Re: Epoxy won\'t stick too....

Maybe you could try using those flyweight poly plastic bags from supermarkets; you can use it in a mold as an isolation layer, since it'll conform easily to any shape, and either peel it off or just leave it in place-
I usually do that with silicone, but seems like it would work with the epoxy too.

 

[Zackerty]

Re: Epoxy won\'t stick too....

Any mass produced Blank CD holders, clear plastic, 50 for $10-00 type... or clear 35 mm film canisters.
Just in case you did not know, epoxy has very little peel strength on smooth objects, so if you make up a cylinder from the plastic, peel it off after the epoxy has cured, and sand the " overlap" bit!

Stuart

 

[Nutabegga]

Re: Epoxy won\'t stick to....

If you are going to use a plastic, then go to any plastic supply store and ask for either Teflon (PTFE - polytetrafluoroethylene), LPDE (low density polyethylene), or nylon (PA - polyamide). Nothing should stick to these types of plastics. Though, if you are making a deep mold, you may want to put a slight draft (outward taper) on the walls so as to prevent the part from sticking (due to an undercut). You can also spray the mold with something like PAM to help prevent sticking.
If you want to get fancy, you can incorporate ejector pins for easier part removal if you want to make lots of parts.

 

[knifebright]

Re: Epoxy won\'t stick to....

i've used black electrical tape very sucessfully for about a dozen sammies now. After about 15 minutes i just peel off the tape and your good to go.


jimmy

 

[Lynx_Arc]

Re: Epoxy won\'t stick to....

polypropelene is a hard plastic to glue to also.

 

[greenLED]

Re: Epoxy won\'t stick to....

Wow! Thank you everyone for all the suggestions. I think I'll go low-tech to begin with, but will also look for a plastic supply store around here. Have a merry Christmas, everyone!

 

[Trader55]

Re: Epoxy won\'t stick to....

Hey greenLED

I posted this on the thread for 4AA battery holder...Hope it's of use to you...

When I wanted to run 7AAA in series {like a gun cylinder}, I fabricated my holder using Devcon epoxy. 2" clear postal tape around the batteries to keep from sticking [sticky side out], then used the tape around the batteries to keep it nice and uniform [all available at wally world]. The tape will easily peel away from the outside after the glue dries, and the batteries will push out...You may want to put "play dough" on the bottom to hold the batteries in position while the glue dries, but put a thin plastic wrap between them.

Trader55

 

[mrsinbad]

Re: Epoxy won\'t stick to....

My vote is for UHMW (Ultra High Molecular Weight) plastic that is slicker than Teflon. I bought a piece of UHMW tape from a wood working mailorder company that is about 4" X 3'x 1/16" thick to stick to my table saw fence to make things slide better. They were also selling chunks of this stuff that is about 1/2" thick 4" high and forgot how long. If you just drilled out the slab to the right diameter, all you need to do is pop your pill in there, let the epoxy cure, and then tap it out. You could have several pills in this chunk and go into semi-production at a moderate cost.

 

[3rd_shift]

Re: Epoxy won\'t stick to....

A small wax block may work for molding epoxy into.
Nothing I know of sticks to candlewax.
It can then be broken/cleaned off of the molded, finished epoxy product. /ubbthreads/images/graemlins/smile.gif
Then sand down any rough spots on the epoxy.

 

[NewBie]

Re: Epoxy won\'t stick to....

Standard mold makers silicone should work well, it is what it is designed for.

Plop in something that is the dimensions you want, pour the stuff in, let cure. Pull out the "reference piece".

Mold is done.

It is very strechy, so it works well for molding complex items, and follows intricated details very well.

TAP Plastics carries it (Nationwide), and you can also order a wide variety of the material from Dow Corning.

 

[KevinL]

Re: Epoxy won\'t stick to....

Just to second the tape idea. I've used it on all the sandwiches I built - it's just normal packing tape cut to size with a hole in it for me to pour the epoxy in. I put the sandwich on its side (the tape prevents epoxy leaking if you do it right), pour, and let it level off. Works like a treat every time. I'm using Loctite's Quick Set mixed with Al oxide powder. I give it around an hour, although Loctite says much less but I'm not in a hurry, peel off a corner where the tape meets the PCB, then unroll the whole thing. Leave to post-cure for a while.

My first sandwich.. the tape is hard to see, but it is there. The hole is on top.

PS: If the epoxy does leak out of the small holes, use an small knife and scrape it upwards. Since it doesn't stick well to PCB either, sometimes you can peel off those bits without leaving any trace. If it sticks out the side, you can cut it off directly.

 

[Nutabegga]

Re: Epoxy won\'t stick to....

Actually, UHMW is typically associated to UHMW-PE. It's generally assumed, since polyethylene (for all intents and purposes) is either of the low, high, or ultra-high molecular weight polyethylene. Any lower than LDPE is essentially wax, which makes for a good mold material. As slick as the polyethelenes are, PTFE is even more so because it has a lower coefficient of friction. You can get into other types of plastics like Rulon J, which is a bearing plastic used with soft metals. I spent 2 years of my life in a Plastics Technology program and earned a diploma out if it.
But, the consensus is it sounds like there are many ways to skin your cat. You should have no probs making your mold.

 

[eebowler]

Re: Epoxy won\'t stick to....

Green, I know this doesn't apply, but the little rubber things in a keyboard under all of the pads, sticks to NOTHING. Heck I even tried crazy glue and it just peeled right off. Don't know what type of plastic(or rubber) that is...

With respect to your question, I've made AA to C battery adapters using paper and wood glue. In your case, use a little glue and when the epoxy is cured, just peel off the paper. (I guess you can do the same with paper tape... )

 

[3rd_shift]

Re: Epoxy won\'t stick to....

OIC...
Wax paper may work too. (grocery store item)

 

[Chop]

Re: Epoxy won\'t stick to....

I'm not quite sure of what you mean by "mold." When I build a sandwiche (I don't build many of them), I just use masking tape. After the epoxy dries, the tape peels right off.

 

[greenLED]

Re: Epoxy won\'t stick to....

[ QUOTE ]
KevinL said:
PS: If the epoxy does leak out of the small holes, use an small knife and scrape it upwards.

[/ QUOTE ]

Hmmm... it seems like I'm using a different "epoxy beast" than you guys. I've been using 2T "Do-it-yourself" (hardware store brand) 10 minute epoxy, but it's very thick and sticky. Its consistency is almost like thick butter and I can't pour it into the sammie; it stays where I put it. I end up with a huge amorphous and sticky blob that I have to put inside the sammie. I usually fill one side of the sammie and then fill the other side, but it gets messy trying to hold the sammie's edges while filling its "guts". If I lay the sammie on it's side the epoxy sticks to the surface; if I lay it "right-side-up", then the epoxy sort of droops down and makes a skirt... I was thinking a cast of non-stickying material will help ease the process.

You've given me great advise, thank you very much. My wife also told me about Ranger Mold n Pour. You mix the two parts and make a "rubbery" (that's what my wife said) cast for any kind of crafts. I know they have it at the local craft shop, I'll have to check it out. In the mean time, tape it is! I'll see if I can get some of the plastic you guys recommended too and do a trial run.

 

[Reptilezs]

Re: Epoxy won\'t stick to....

mix smaller batches so it wont harden up as quick and try using somthing that cures slower