JB Weld Casting

Intro: JB Weld Casting

If you need a small part and you have access to the original then use some JB weld to get 'er done.

JB weld did the trick on a missing piece for my airsoft gun.

UPDATE - Make sure you check out all the awesome comments about how to go even further and reinforce the epoxy.

STEP 1: Playing With Playdough

Take some kind of casting medium, I stole some playdough from my son. I think this would work even better if you used modeling clay or something made specifically for such an application. Who knows.

STEP 2: Your Part

Here was the part that I wanted to copy. It is the selector switch off of an airsoft gun. I'm sure you can buy these parts but I didn't feel like paying $10 + $10 shipping on ebay for such a silly part. Luckily I had a spare part from a buddy's gun that I could use to make the copy. Notice that there are some pretty finely machined areas of this part that were essential to fitting on the gun.

STEP 3:

This stuff isn't rocket science so I'm sure you could probably figure it out on your own. I just wanted to prove that it does in fact work. Or maybe you hadn't thought of it.

One trick I did learn was that for the really deep parts that it helped to fill them with the clay so that it would then adhere to the rest of the mold when you remove.

Also, try to make sure the top of your mold is even with the top of your piece to avoid too much excess.

STEP 4: Mix It Up

Mix up your jb weld and dump it into the mold. I had the quick setting type laying around. It would probably work better to use the slow setting, just leave it in the mold longer until it is hard. The original recipe is supposed to setup harder than the kwik version.

STEP 5: Final Result

Here you can see the final result. It turned out fairly well and most importantly it is fully functional. I can't wait to need to duplicate other things because I am really impressed with how it turned out. JB weld really does turn out pretty hard and durable.

Comments

[MarinaG14]

One quick and easy way to make a mold is to use hot glue. Just make sure whatever your going to make a casting of is well lubricated. I use cooking spray since it gets into any little groves without a problem. Just melt the hot glue and press whatever your taking a casting of into the hot glue. Let it cool and then remove. Now gou have a silicone mold that you can reuse ;)

[Meglymoo87]

Question: if you put this JB Weld into the hot glue mold you made, will it need to be lubricated first? Will it adhere to the hot glue mold?

[Eric T]

Can JB Weld be made thinner so it will flow into crevices better?

[rrichards4]

According to the jbweld website you can thin with acetone or lacquer thinner. Refer to their website for exact quantities

[PKM]

If only I'd known this when those igganunt fools in the drama department broke my prized Beretta all those years ago... do you know how strong the finished product is? I guess your switch isn't going to be under great mechanical strain, but could you cast a new trigger out of it? Or some part that takes a lot of local pressure?

[jammin0]

I'm sure you could use this for a trigger as well. I used the quick setting stuff and it is probably about as hard as aluminum. If I gouge it with a screwdriver it will dent and scratch. However, I've heard that the regular JB weld is considerably stronger. Or do like kenbo suggests and add something. I'm thinking like metal shavings or something really fine. Dremel up some metal so that you get a fine metal powder to add.

[sarkozykal]

I'd suggest using one of the additives from West System Epoxy (http://www.westsystem.com). They're experts at this sort of thing. Offhand, it seems either West System 404 High Density Filler (http://www.westsystem.com/ss/404-high-density-filler/) or West System 406 Colloidal Silica (http://www.westsystem.com/ss/406-colloidal-silica/) would do the job.

[maruawe]

You can take aluminum foil and grind it in a coffee grinder, it will take a while to get it to a fine powder , I needed aluminum powder to make thermite and this worked quite well. cut or tear foil into strips for best results Grind and regrind several times to get a 400 grit on the aluminum .

[imthatguy1125]

whats thermite

[maruawe]

Thermite is a combination of aluminum powder and iron oxide usually a one to two mixture that will burn through most anything. It is dangerous to use , i have a hole in my patio as evidence , before using thermite do a lot of research.

[Pazzerz]

Don't pressure contain it either. Makes a devastating bomb and throws incendiary particles everywhere that will burn through your hand, etc.

[maruawe]

What do you mean by pressure contain it .I have been working with thermite for over a year and never ever thought about pressuring it. Are you referring to a powder compression in an explosive or air compression.. Please clarify

[Pazzerz]

What's to clarify?? I suppose I should have added the extra ingredients on the last comment, but I really don't want to blatantly tell everyone how to make a bomb. Obviously you are working with it in the way that it is supposed to be worked.

[maruawe]

Bombs are good in their place, But the components that make bombs are useful in many ways and I kinda like to have me around in case I need me. So I am very careful about how I use chemicals......having had the training in explosives that I have been fortunate to get through out my life give me the knowledge to work with chemicals . My motto is: if you don't know ask questions till you do know and then be real careful. (See above statement).
research is the key to longevity.........

[imthatguy1125]

where can i get iron oxide

[PKM]

Leave some steel wool half submerged in slightly salty water, stir it every couple of days to break it up slightly. Add more steel wool when you can't see much shiny in the brown powder, and when you have enough rinse the salt out and crush with a pestle and mortar. You can then get residual iron out with a magnet.

[Vermin]

A quicker way to oxidise steel wool into Iron IIIOxide is by using Clorox bleach (or any bleach that contains NaOCl).

[maruawe]

Thanks I'll try that .The way i do it is very time consuming

[curecreator]

Stuff that burns at about 4,000 degrees Fahrenheit and was used to do welding until recently. They still use it to weld railroad tracks and large metal parts. The military uses it as an antitank weapon and for busting up locks (with the help of a little explosives). It is composed of Aluminum (400+ mesh) and iron oxide (rust). For every gram of aluminum you need 2 grams of iron oxide. You don't need to do anything other than mix these two powders.

[maruawe]

In the tutorial he mentioned that you could mix in aluminum powder to strengthen the piece that you were molding . rather than buy the powder I usually make my own, true that when mixed with iron oxide it will burn,but you have to use magnesium to get it ignited or a very hot igniter. Thermite does not self ignite..