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I have a general interest modeling question

I have a general interest modeling question. I have a slot in a piece of plastic, which might be polystyrene or ABS or something else. It happens to be a Life-Like Proto-1000 model. This slot is approximately 1/4 inch (6.35mm) wide and 3/8 inch ( 9.53mm ) long I need to fill it with something like body putty. After it is filled, it has to be shaped and drilled to accept and hold a section of plastic tubing approximately

1/4 inch in diameter.

I can do this without any trouble, but I was wondering what is better to use than auto body putty. Is there something better? I have thought of using epoxy resin. I thought I would smear a bit of resin on the backside of the hole and embed a little slip of gauze or glass cloth, then, later apply some more resin from the front. I also thought of doing something similar with body putty and brass screen. Another idea was to use some lo-melt plastic, put a backing plate on the backside of the hole, and pour in the molten plastic. I have some from a craft store that melts at about 200 degrees F. I've used it to cast things, but not this way. It is quite dense and hard when at room temp. Thought about JB Weld Thought about talc and cyanoacrylate cement I want to try something that will give me better results than plain body putty. Any ideas?

..................F>

Pondering, GA

Reply to
Froggy
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A lot military and airplane modeler folks swear by Squadron Putty. Can the tubing be cemented through the backing plate? How deep is the cavity after a backing plate is put in place?

See

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about Squadron White and Testor's Red Putty:

"Testors Red Putty is somewhat new to the hobby, but it quickly found a home on my painting desk. Its attributes are basically the same as Squadron Putty, but with two differences. The first (and most important) is that Testors Red Putty does not shrink. This means it can be used on larger gaps than the Squadron can be used on. The second difference is that it fairly coarse, so it may need some minor sanding depending on its application."

Reply to
E Litella

"One word, Kimmay! - Milliput."

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Seriously, this is a better alternative for filling than body putty, if afterward you wish to drill holes, or attach parts with screws, as it can be drilled and tapped.

Easy to work, doesn't smell bad, and may be shaped and smoothed with a wet finger.

Cheers,

Mark.

Reply to
Mark Newton

Use either Squadron Green or Squadron White Modelling Putty.

Reply to
Slingblade

BINGO ! That's it. I can't get Milliput, but there are other brands here that will serve. That is what I shall try first.

Thanx all...............F>

Reply to
Froggy

Hi Froggy:

Most ANY of your suggestions will likely be better than (non epoxy) body putty.

You have two issues, the strength of the material, and it's ability to bond to the surfaces (body and tube).

In any case, get the surfaces to be bonded really CLEAN ... no grease, oil, mold release, or fingerprints. With most of your suggestions, it would be a good idea to roughen up the bonding surfaces of the plastic so the epoxy (or whatever) can get a better 'grip'. One way to do this is to drill a number of small (1/16"?) holes in the surface ... these form tiny 'pegs' when filled with the bonding resin.

JB Weld is a 'filled' epoxy material. There are many other 'filled' resins, with fiber, glass fiber, or metal dust fillers. Some are very stong. Unfortunately, usually you have to buy at least a pint or quart of the material from an industrial chemical supply house. Your idea of providing your own 'filler' with a mesh of some form is a good one.

I think the epoxy-glass cloth solution would likely be the strongest. The gauze, cheesecloth, or nylon pantyhose material will work, but not be as strong. The brass screen would also be a good reinforcement, though harder to form to odd shapes (if that's an issue). All these assume a good bond is formed with the surfaces being joined.

Epoxy should be no problem, but some of the 'Bondo' type products and glues are polyester or similar resins. Epoxy is slightly flexible. Polyester is glass brittle, so this is an issue if the item is subject to flexure. SOME resins will also attack common plastics. You might want to experiment with a small drop on some non-critical surface of the model before making a large scale application.

Good luck,

Dan Mitchell ==========

snipped-for-privacy@thep>

Reply to
Daniel A. Mitchell

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