flanging a multi piece and semi perming the plug?

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#1

So here is the deal

I’m prepping a plug and it will have to be a multi piece mold (3 pc).

I’m not sure what to use as flanging for the part lines, up till now I have been using some thin Al sheeting, but cutting this stuff is a bit of a pain since I have to use some tin snips/side cutters and getting a very nice smooth cut is not possible(partly due to the serrated blades of the snips and the fact that it’s hard to cut curvature into the sheets)

Also I am not sure what to use to seal the gap between where the flange and the surface of the plug will meet to form the part line.

Ontop of all this I am not sure what to use for a release agent. I don’t want to hassle with PVA for this job. I’m considering using either a semi perm or waxing the enitre thing. I’m a bit hesitant in using the semi perm or the wax as a release (each alone as the release agent) since I have never done that before. I’m worried about sticking the part or damaging the plug (which is actually a mint motorcycle tank).

Suggestions and tips would be great! Thanks.

#2

Well, as I always say. I’m a full believer and user of release agents such as Frekot. As long as it is will coated, and done as per the directions, all is good. If you are really scared, use wax, and THEN semi-perm!

#3

Hmmm, so I lay down a few coats of wax and then wipe on the semiperm on top of the way? I wouldn’t have thought that the semi perm would go over the wax…wouldn’t it disolve the wax?

#4

Hi RC, Make a paper or thin cardboard template of where the flanges will be then trace that perfected template onto your flange material.

I know what you mean about cutting radii into sheetmetal with tin snips. I use a pair of 12" scissor type metal hand shears, it works better than regular tin snips but still it’s somewhat difficult to make a turn in the cut.

Perhaps you could use masonite board or MDF wood for the flange material. Use a low temp hot glue gun to temporarily bond the flange to the plug/fuel tank. Do a hot glue gun test on the bottom side of the fuel tank first. See if the glue will hold, then peel off once done without damaging the paint. Just an idea.

I use Walmart modeling clay and epoxy won’t really bond to it. You’ll have a clay clean up job on your hands when your done with the mold though.

#5

I’ve used white formica (about$40.00 sheet @ Lowes) and trimmed it out on a inexpensive router table. The formica is pretty flexible to conform to some slight bending,and the release agents added allow a “no stick” smooth finished surface.

Backside support can be achieved by using strips and pieces of wood and CA(super)glue. Kinda like a bridge built up behind the formica to hold it in place. Use accelerator for the CA glue to speed up the process. A hot glue gun would work too.

The seam can be filled with regular modeling clay. The wood handled shaping kits available at the arts & crafts stores,work excellent for molding the clay in the gap.

After all of that work to create a “masterpiece” tank, I wouldn’t
skip the PVA step. Yea… you probably didn’t want to hear that did you.

Good luck…

#6

Unfortunately I don’thave access to any shop equip to cut mdf and the like…

I am using Al flashing for the flanges around the perimeter and I have decied to do something very different for the flange.

I am going to make a “channel” along the length of the plug a few inches high, and into this channel I will pour urethane plastic and let it cure, then i will remove the walls of the channel and I will have a very nice one piece plactis flange that I can caulk to the surface of the plug, this way I will have no clay or other crap to mess around with to seal a gap between the part line flange and the plug. it should be a perfect fit to the surface of the plug… I’ll let you guys know how it turns out, I am confident it will be just right.

#7

ya lol, I can’t stand spraying pva, it’s a bitch…

thanks for the advice!

#8

Cool. I’d be interested in seeing photos of the flanging.:cool:

#9

hmm i dont think semipermanent over wax would work… semiperm tend to have a strong bond with the surface… unless you dont want that, and just want a film to form , in order to protect the plug surface…

i’m starting a two piece mold of a rear bumper tomorrow, and i’m gonna use 1mm cardboard covered with aluminum tape, and stick it on with either hotglue, or tape on the backside and some clay to fill the gaps. I will use semiperm on the surface.

#10

I’m begining to hate using aluminum tape on mold flange surfaces, it creates lines in the completed mold surface. I hate those lines. I still have to use that method at times though.

polyethelene plastic sheet could be very nice for making flanges. It comes in thickness of 1/32" up to an inch thick.

#11

I hear what you are saying. but it’s a small price for a decent and quick method, are you needing smooth flange surfaces?