1/48 P-38F-15-LO – Mediterranean Theatre of Operations

[Crimea_River]

With my Hurricane now done, I'll see if I can get this Lightning done before the deadline without rushing and despite the setback. This morning, I prepared a mold for a new resin part thusly:

Lego blocks, saved from the days from when my kids were still young (really, I don't play with them, really I don't) made an ideal container for the mold.

The above trial fit of the mold revealed to me that I would need to add a dam to stop the mold material from oozing into the inside of the nacelle so I made one of sheet styrene.

After mixing a batch of molding compound, I poured it into my container, installed the part that I will duplicate, moved it around a bitto make sure that all the nooks and crannies are filled, and left it to set.

And that's how she now sits. Later today, I'll strip the the form and mix up some casting material and make my new piece. Hope all goes well.......

 

[Airframes]

Looking good on the moulding front so far. Looking forward to seeing the result.

 

[Wurger]

I'm second in that.

 

[T Bolt]

Good to see you back at it Andy. Looking forward to seeing how the resin turns out.

 

[Airframes]

No sign yet - Andy must still be playing with his Lego ....................

 

[Wurger]

Whatever that means..

 

[Crimea_River]

Alright smarta$$es....

The mold survived the removal of the nacelle and I was fortunate that a few bubbles, seen just below the surface, didn't break through.

The resin I used is actually clear as I could not find any that was a solid colour when I was looking for some. No matter as it will be painted anyway, though it will be a little harder to see the surface details. I toyed with adding some talcum powder but I did not want to risk messing up the mix.

The resin was poured into the mold and I tapped the sides for a few minutes to make sure that no bubbles formed in places that I did not want them

This was done last night and the recommended curing time is at least 24 hours. I just went down to check it and the resin has hardened nicely. I think I'll leave it over night just to make double sure before I break it out. I'm a little concerned now that the resin may have stuck to the mold as I did not buy the casting materials together as a kit. Time will tell......

 

[Airframes]

Good stuff Andy. If the part has stuck to the mould, ease it gently from side to side, and back to front, which should free it without much problem.
The only times I've ever moulded resin parts, all I had to make the moulds was 'Plasticine', and of course the parts stuck to this. But by moving the part(s) as described, they broke free easily, and with minimum distortion to the soft mould.

 

[Crimea_River]

Cheers Terry. I'm a bit concerned that the mold shrank quite a bit. Hopefully there won't be too much of a fit issue with the new part, assuming I get it out alright.

 

[JKim]

Brave new frontier! I like seeing new things like this... hopefully your "aftermarket" piece comes out well!

 

[Wurger]

Nicely done Andy.

 

[destrozas]

great job with that mold andy, I Resin I use is tanning in 15 minutes

 

[Catch22]

Great job Andy, hopefully it goes smoothly.

 

[Crimea_River]

great job with that mold andy, I Resin I use is tanning in 15 minutes

The mold I made hardened in 15 minutes. The resin casting material takes 24 hours.

 

[Crimea_River]

Attempt 1 is a fail.

As I suspected, the mold shrinkage was just too much and the resin piece came out too narrow. The picture below has the rough casting sitting on the underside of the nacelle I used to make the mold. The opposite faces have been lined up and, as you can see, the casting is a good 2mm too narrow and also a bit short. I could have dealt with it being short by adding some styrene sheet as a spacer but there was no way to deal with the width.

Blame for this went to the fact that I used a cheap mold making kit designed for making crafty things. I decided to go out this afternoon and see if I could locate a proper silicone molding compound and eventual found some. For the price I paid for it, I could have picked up a new model but, hey, I can use this for a long time for many other needs, hopefully. Here's the new stuff with the nacelle placed in again.

This stuff takes 2 to 4 hours to dry and,, with my shop being on the cool side, it hadn't set after 4 hours so I'll have to wait before adding the resin. Things will have to go without a hitch now if I'm going to make the deadline but I won't rush the build. We'll see how it goes.

 

[fubar57]

That sucks. I know nothing about resin casting but good luck with this one. Is there mention in the instructions of using some sort of release agent between the mold and resin?

Geo

 

[Crimea_River]

Yeah, but the first one release fine so I took a chance.

 

[JKim]

Good luck Andy! Fingers crossed for cast #2!

 

[Airframes]

Glad you mentioned the shrinkage Andy, as I very nearly bought a similar 'cheapo' casting kit.
I know now to get the proper silicone mould material.
BTW, when I've used 'Plasticine' to make moulds, no shrinkage was experienced, but of course the number of 'shots' are limited to one, two if lucky, per mould.

 

[Catch22]

Good luck!