Molding JB Weld

[sbosecker]

I want to do a repair with JB Weld. I would like to like to put a flat piece of material behind the hole that I'm filling in with JB Weld and after the epoxy has cured, remove the flat item.

I am assuming that the JB Weld would have a tendency to adhere to the flat piece. Is there a suitable parting agent/wax that would allow the flat piece to be removed easily?

I see there are products to help unmold fiberglass and such... would any of these work?

Scott

 

[Stuart in MN]

I did some fiberglass work a while back, and I simply covered the mold with clear packing tape. It worked pretty well, I was able to release the fiberglass part from the mold easily and it had a nice smooth finish.

 

[CJM8515]

vaseline.

 

[four.cycle]

I use masking tape and/or wax paper, BUT: I don't use just JB-weld to fix the hole:
I put a piece of masking tape over the hole on the side that is going to be seen, cut a piece of fiberglass cloth a bit larger than the size of the hole, apply the JB Weld (or steel epoxy) to the side that is NOT seen, lay the fiberglass cloth onto that, and then apply another layer of JB Weld (or steel epoxy) over the fiberglass cloth.
Easy fix for small holes on lawnmower decks that have rusted through, but you need to get out the wire wheel (cup brush or angle grinder) and clean the surface up first.

After it's cured I remove the masking tape (and/or wax paper.)

 

[mtnkid85]

Really about any lube will work. Do a quick search for "rifle bedding release agent" and you'll get all sorts of ideas for products to use. Really no reason to purchase a dedicated product for what your talking about.

I use a wax based boot water proofing product that I have which gets rubbed on with a rag or if its not as critical just a quick coat with an aerosol can of no stick baking spray.

 

[sbosecker]

Thanks guys!

Best regards,

Scott

 

[rlitman]

Do you have baking parchment paper in the kitchen? That would be ideal.

I've had epoxies stick to wax paper, but only the liquid kind of epoxies. Putty epoxy doesn't tend to.

The best non-stick backer I've used for epoxy was an old teflon coated cookie sheet retired from the kitchen to the shop.

 

[Ohmthis]

OP, I made a repair like this some years ago on a outboard motor. The crank bearing was shot and let the rod cap bolt pop a hole in the intake. I put masking tape on the outside, thoroughly cleaned (with acetone) the inside, and put the JB on. The next day while it was set up completely, I took the masking tape off and mixed up more JB and applied that to the outside. Once everything had plenty of time to cure, I took a burr and cleaned up the inside to make it smooth and to not interfere with anything. After a rebuild that outboard ran perfect for several hundred hours when I sold it. I have a tig now, my fix would be to weld now.

 

[ghost68]

I used jbweld to fill the holes in a Lincoln AC225 where I wanted to make the leads removable. I use a piece of wood wrapped with plastic wrap from the kitchen. Used clamps to hole it in place on the inside and it came off with no problems. I also sanded it after I was sure it had dried.

Ghost

 

[theoldwizard1]

Fiberglass mold release (which is basically wax) or wax paper. Make sure the hole is clean and that it has some "tooth" to it.

 

[sbosecker]

Thanks guys!

I'm waiting for a couple of items that will become the "mold" for this project. This will be an attempt to repair the drain hole in a 60 year old stamped steel enamel porcelain sink.



I've acquired a flat washer for a 2-inch bolt (4-1/2 inch OD - 2-1/8 inch ID) from a local Fastenal outlet and I'm waiting for a muffler pipe adapter

After dealing with the corrosion, I hope to use these two components to act as the form to build up a solid "flange" and drain hole for the drain spout assembly to interface with the sink.

Scott

 

[four.cycle]

^ that little piece of swedged exhaust tubing may not be the ideal material - that stuff is just mild steel and might corrode awfully fast in a sink drain. a lot of those aftermarket exhaust adapters are coated with a shiny plating, but whether or not that will prevent them from rusting out in that application is an open question.
just tossing a few pennies out there.

 

[PoorOwner]

JB also make a JB quik that you knead with fingers and push in.
It is better for filing flat or shaping.

Dries almost immediately

 

[sbosecker]

^ that little piece of swedged exhaust tubing may not be the ideal material - that stuff is just mild steel and might corrode awfully fast in a sink drain. a lot of those aftermarket exhaust adapters are coated with a shiny plating, but whether or not that will prevent them from rusting out in that application is an open question.
just tossing a few pennies out there.

four.cycle,

The tubing and the flat washer will be used to act as a "mold" for the JB Weld. If the parting agent acts correctly the flat washer and the tube will be removed and the sink's flange will have been rebuilt to accept a Kohler 8820-CP Sink Strainer.

Best regards,

Scott

 

[sbosecker]

JB also make a JB quik that you knead with fingers and push in.
It is better for filing flat or shaping.

Dries almost immediately

PoorOwner,

Thanks! I think for my purposes a longer set time would be desirable.

Best regards,

Scott

 

[four.cycle]

^ in my humble opinion I think you are correct. I've had poor results with the "quick set" and the "putty" formulas with both JB Weld and other aftermarket "epoxy putty" products.


on the "mold" thing - I get it. I misunderstood your post above. we sold those little exhaust adapter too - first from Fenton and then later from other companies - they were all pretty cheezy no matter who we bought them from - Walker/Goerlich/AP didn't offer anything better, either.

 

[yhprum]

A good release agent is to rub a bar of soap on the areas you need the release from.

 

[shepherd]

Spray some "Pledge" or other wax based dusting spray on the mold...also, makes a good quick shine for motorcycles! mmm, lemon-y.....

 

[sbosecker]

After the boys and girls at the Post Office gave one of my "mold" components a tour of the South Atlanta Metro area - it spent a couple of days at the wrong post office - it arrived yesterday.

Rather than cross post, I'll provide a link to the information that I posted in my build thread: HERE.

Scott

 

[Tig Master]

Min wax paste wax is about the easiest and well proven mold release you can rely on.I use it when bedding the action to the stock on target rifles. Done that way for years.When the gun is worth a couple of grand and it is a customers it needs to work.Kiwi neutral shoe polish Johnson floor paste wax as well.These will work with epoxies resins fiberglass just about a universal release agent and easy to apply just use your fingers wait a couple of mins and you are good to go. Forget about tape Vaseline and all those others mentioned it works.

http://www.westsystem.com/ss/mold-release-pva-and-hairspray/

The pic is one done with floor wax

 

[Jcrapola]

If you have access to the backside of the hole, use masking tape. Works like a charm

 

[sbosecker]

Min wax paste wax is about the easiest and well proven mold release you can rely on.I use it when bedding the action to the stock on target rifles. Done that way for years.When the gun is worth a couple of grand and it is a customers it needs to work.Kiwi neutral shoe polish Johnson floor paste wax as well.These will work with epoxies resins fiberglass just about a universal release agent and easy to apply just use your fingers wait a couple of mins and you are good to go. Forget about tape Vaseline and all those others mentioned it works.

http://www.westsystem.com/ss/mold-release-pva-and-hairspray/

The pic is one done with floor wax

Tig Master,

Thanks for the information!

One thing that concerns me is the exhaust pipe part of this mold. It was formed in such a way as to have left some ridges in the pipe. I will probably try to chuck it into a lathe and work on smoothing those ridges out with some emery cloth.

Best regards,

Scott

 

[sbosecker]

Today I think I accomplished the repair discussed above. I have posted the operation in my build thread. Links to same may be found below.

Scott

Start of the "Molding"

Finish of the "Molding"

 

[jhelrey]

I know this is late, but epoxy won't stick to blue painters tape. Could try that in the future.

 

[shedfullatools]

Was the drain hole in the other tub of the sink still usable?? Or did both sides get this treatment..Just curious, the one you showed turned out great I always wonder about building things up and molding things from J.B weld and similar epoxies, glad to know it does work well. Might prove useful in the future

 

[sbosecker]

Was the drain hole in the other tub of the sink still usable?? Or did both sides get this treatment..Just curious, the one you showed turned out great I always wonder about building things up and molding things from J.B weld and similar epoxies, glad to know it does work well. Might prove useful in the future

shedfullatools,

Yes the other drain hole was intact.

I'm hopeful that the repair will work. I guess when the plumber shows up and starts laughing I'll know for sure.

Ha!

Best regards,

Scott