CMR WM chopnose geep shell

[wm3798]

I picked this shell up at N Scale Weekend, and am working on marrying it to an old Life Like GP18 lead sled drive.

I don't plan to put a decoder in it, as I will be running on the Retro Rig when the mood strikes.
It fits the drive well with an adapted weight in the cab replaces the original high hood weight.
I have rerouted the pick up wires, and still need to install LEDs fore and aft.
For $25, it's not a bad rendering.  I'm not sure if it's 3D printed or cast some other way.  It doesn't have any evidence of print in striations, and there is a fair amount of flash to contend with.
The shell is one piece, including the cab, car body and sill, as well as nicely rendered pilots and steps.
It appears to be dimpled to facilitate drilling and installing grabs and railings.
One thing that concerns me is the cab roof, which is cad very thin.



You can see here that it is nearly translucent, and it flexes dangerously when manipulated.  I'm going to try to reinforce it by brushing some matte Mod Podge to the inside.  I don't want to use .CA or MEK for fear that surface might craze.

I know CMR has done similar shells for Canadian choppers and other Paducah-builts,  so I'm wondering if this is a common issue or if I got a bum casting that should get replaced?

I want to paint it soon, but I don't want to put out of warranty!

Lee

[Missaberoad]

It's actually not a bad looking shell... I've been tempted by their products on ebay but have been hesitant up till now...

As far as the roof goes perhaps laminating some .005" or .010" styrene to the top, then sand and fill to conceal the edges would provide sufficient strength to withstand "manipulation" 

Excited to see it all dressed up! Black or circus?

[davefoxx]

It's actually not a bad looking shell... I've been tempted by their products on ebay but have been hesitant up till now...

As far as the roof goes perhaps laminating some .005" or .010" styrene to the top, then sand and fill to conceal the edges would provide sufficient strength to withstand "manipulation" 

Excited to see it all dressed up! Black or circus?

I'd try laminating styrene on the inside of the cab.

DFF

[wm3798]

I have 25 in black, so I'll probably do one in Circus again.  @peteski helped me get the right sized lettering, so it's ready to go into the paint booth once I get it cleaned up and procure the lenses/windows etc.

Laminating something on the inside will be tricky on account of that circular blob that's in there.  Won't get a clean bond, and no practical way to clean it up.  I'm starting to lean toward cutting the whole roof off and bending a new piece of thin styrene over it.  I just want to be cautious of raising the profile too much.  The windscreen already looks small compared to the brass fronts I did years ago...

Lee

[MK]

Laminating something on the inside will be tricky on account of that circular blob that's in there.  Won't get a clean bond, and no practical way to clean it up.  I'm starting to lean toward cutting the whole roof off and bending a new piece of thin styrene over it.  I just want to be cautious of raising the profile too much.

Then how about laminating on the outside and filling in the seems?  A THIN piece of styrene shouldn't raise the profile too much, say 0.005" or 0.010", that Missaberoad mentioned.  Certainly easier than cutting off existing and gluing back on a thicker piece which might arrive at the same end thickness.

[davefoxx]

Laminating something on the inside will be tricky on account of that circular blob that's in there.  Won't get a clean bond, and no practical way to clean it up.

Ah, I see what you're talking about with the circular blob on the inside of the roof.  Is there something you could pour in there that could harden, like, say, epoxy?

DFF

[thomasjmdavis]

Ah, I see what you're talking about with the circular blob on the inside of the roof.  Is there something you could pour in there that could harden, like, say, epoxy?

DFF

Beat me to it- although I was thinking casting resin.  If you opt for pouring epoxy or resin, clean the inside of the roof well beforehand to get rid of any mold release from the original casting.

Actually (re-reading before I hit post), the OP had this from the beginning...

I'm going to try to reinforce it by brushing some matte Mod Podge to the inside.

I've never used mod-podge- does it dry rigid or flexible?

[wm3798]

It would be flexible, but being water base it would bond fairly securely without attacking the plastic...  but epoxy might be a more sturdy solution.

Lee.

[Angus Shops]

If it's a resin kit I would up vote the idea of adding additional resin. I do this regularly with my own projects. Works 100% of the time. However, if you're not already into resin casting you'll have to go out and purchase the resin (I suggest Smooth On Smooth Cast 300); the smallest kit goes for $30.00 or so in Vancouver. You'll use about 2 grams of material and have about a million grams left over. So epoxy may be more reasonable. Either way, prop it up roof down and pour in a few drops of your choice in product and let it set.
Geoff

[bman]

CMR casts their shells from a mold. I've purchased a couple shells and 1 GP35 high nose/cab casting to mess around with. They are decent castings and all one piece. I starting working on them but never finished. Long story. I've also been given a few of their high nose GP30 castings also to see what I can do with someday when the motivation strikes me. The roofs on all of these are not translucent as yours is. I'm thinking it's a defective casting. It wouldn't hurt to contact them to see what they say about it. The most you could loose is a few minutes writing and reading an email.

[wm3798]

I've gone ahead and contacted them and sent the picture with the thin roof with an inquiry about replacing or reinforcing it.  I'll keep you apprised of the response.

Lee

[Angus Shops]

I don't know how 'high tech' their mold making and casting technology is, but mine is definitely 'low tech'. My molds consist of a female mold, the outside of the car body, and a male mold which is the inside of the car body. When I cast I fill the female mold about 1/2 full of liquid resin and insert the male mold. Then I press the male mold down into to the female (wink, wink,nudge, nudge) and squeeze out the excess resin. If I use too much pressure on the press down I'll end up with a too thin roof. It's tough to throw out a casting that's perfectly good other than a thin roof, so I add a little extra resin to thicken up the roof.
Geoff

[MK]

That has so many different connotations!    

[wm3798]

Reply received:
Aric Hartle <arichartle@gmail.com>

You can use superglue on the inside of the shell to reinforce it.  sometimes they get thin towards the end of the mold life as the mold doesn't hold as stiff as it use to.

So there you have it.  I'll flood some CA into it and let it set.  Will post results when it's cured.

Lee

[davefoxx]

Reply received:
Aric Hartle <arichartle@gmail.com>

You can use superglue on the inside of the shell to reinforce it.  sometimes they get thin towards the end of the mold life as the mold doesn't hold as stiff as it use to.

So there you have it.  I'll flood some CA into it and let it set.  Will post results when it's cured.

Lee

Great!  If he's not worried about CA crazing the shell as you were yesterday, then that's a good solution.

DFF