2x Studio Scale Falcon Gun Turret- Scratchbuild

[swgeek]

If you're going to cast parts in a pressure pot, you have to vacuum degas your rubber, otherwise you'll get warts on your parts. Some times you won't even be able to see the bubbles in the rubber but with the pressure, the resin will find them. Also, did you say you were running your pot at 60 psi? That's way more than you need. The most I'll do is 40 psi and 30 is probably all that you need. One more tip for making a brush up rubber mold. After you apply your first layer, use an air nozzle to spray your rubber to pop bubbles. You want to use enough pressure to get through the rubber and pop bubbles but not so much preasure that you blow the rubber off of your master, if that makes sense?

 

[Bondo Fett]

If you're going to cast parts in a pressure pot, you have to vacuum degas your rubber, otherwise you'll get warts on your parts. Some times you won't even be able to see the bubbles in the rubber but with the pressure, the resin will find them. Also, did you say you were running your pot at 60 psi? That's way more than you need. The most I'll do is 40 psi and 30 is probably all that you need. One more tip for making a brush up rubber mold. After you apply your first layer, use an air nozzle to spray your rubber to pop bubbles. You want to use enough pressure to get through the rubber and pop bubbles but not so much preasure that you blow the rubber off of your master, if that makes sense?

That is good intel, thank you. I have been making new casts at closer to 25psi, that seems to be plenty. Obviously I didn't need to be crushing the resin down so hard. Again, live and learn (also share and learn!).

 

[Bondo Fett]

So, third times the charm. I made a third rubber mold, urethane this time, and poured. Not my preferred way, because it forces me to use release for castings that are to be painted later. Its material I have on hand at my shop and it just never gives me trouble with bubbles. Polytek 74-45. I didn't take any pictures this time, just crashed through it.

Got four nice castings out of it, still using Smooth-On's Onyx. I really like that resin, it is super hard.

I washed the finished casts in Krud Cutter, then TSP substitute, then Dawn detergent. I'm pretty sure I got all the release (Mann 205) off. I wrapped some styrene sheet around the vents, it gives better sense of scale, and I didn't think I could reproduce detail that fine with a cast.

One or two little bubbles to deal with, but I'll wait for a coat of primer so I can see 'em better.

Epoxied them together using a jig. This is as square and true as I can get them:

And used another jig to drill the pivot axis:

Next its back to the drawing board to design the mounting/swivel frame and find out if this contraption will fit the rest of the turret already built.

 

[joberg]

Looking mighty good

 

[Bondo Fett]

Starting to fit together. I can't believe it I'm able to keep it all square and true. Not bonded yet, just a dry fit for now.

Now on to the mounting bracket arms, or whatever you call them. Using the drill press as a lathe again. This time trying to form my model out of urethane foam instead of balsa, its what I have to hand. Unsure if this is a good idea or not.

 

[joberg]

Looking real good; eager to see your next update