1/32 scale torpedoes and casting materials

[subshop]

If this post needs to be moved to a different forum please do so.


In building a 32p fleet boat i decided to make operating torpedoes w/ counter rotating props. i am casting certain sections of these "fish" in alumilite to make them more buoyant. in casting the tail section i am having problems using the alumilite. the tail fins are real delicate. i made the master in brass and the fins are 1/64" brass . seems that when casting parts that are real thin alumilite leaves much to be desired ! i did not want to use 1/32" brass on th fins so as to keep the torpedoes looking as true to scale as possible. if anyone has any suggestions, for a different material, or different process, i would appreciate it greatly. neil
p.s. i am having the same problem with the props .

[sinkinpat]

I cast parts lots of

I cast parts lots of parts. mostly tank parts but also used to work full time in a resin casting company.

I have used alumilite. it should work for you. Are you preheating the mould? I have a toaster oven that I preheat my moulds in in the winter. I find in the summer everything is warm enough. also with thin parts you may need to let the part cool before demoulding as the part is still soft.

also are you using a pressure pot? for thin parts like this you should use a pressure pot and work fast or use a slower resin.

[JWLaRue]

I've been considering a similar

I've been considering a similar problem for the 1/32nd scale G7e torpedoes for my Type II U-boat.

Perhaps modify the afterbody master by removing the tail fins and leave slots in their place. After casting the afterbody in Alumilite, glue in four tail fins made from sheet plastic.

-Jeff

[subshop]

SINKINPAT, i do heat the


SINKINPAT, i do heat the mold and wait 30-45 minutes before i remove the item from the mold. i ordered a pressure pot from alumilite but returned it because to achieve a good seal i really had to wrench down the wing bolts and charlie from alumilite said that the seal or lid may be defective. so i am waiting for the placement pot and i will try again to cast the tail section. maybe that is all i would need and possibly a solution for the torpedoes props too. though they may still present a challenge in that not only did i have to form the blades by hand but the two hubs for the props were milled at the angle corresponding to the taper of the torpedoes aft section. we will see.

JEFF, i considered doing that either w/ plastic or brass but then what adhesive would you use that would not be affected by water submersion . or could some type of plastic weld product be used to make plastic fins and alumilite bond together .

neil

[raalst]

maybe (no experience here...)
you

maybe (no experience here...)
you could pre-insert sheet-plastic (or other material)
fins into the mold, with a bit protruding into the tail cone area,
so that the alumite only forms the tail, and fixes the sheet
plastic fins in place ?

[JWLaRue]

Hi Neil,

You can use a

Hi Neil,

You can use a CA adhesive. Once it's painted, you would have no problems with it.

...and I like Ronald's idea even better. It would not require that you modify your master. Just place the four fins into the mold prior to adding the alumilite. Make some holes along the root of the fins so that the resin can form a good mechanical hold.

-Jeff

[Guest]

Or perhaps keep the tail

Or perhaps keep the tail fins in brass and just make a cone in resin.

Andy

[subshop]

TO ALL: All great ideas

TO ALL: All great ideas . i think ill try the plastic fins w/ a spur sticking out then cast around it. might still need pressure pot to make sure no gaps around spur. will let you know and thanks again to all,
neil

[subshop]

1/32 scale torpedoes and casting materials

UPDATE
[color=blue]After considering all suggestions i decided to replace the fins on the torpedoes aft section w/ a heavier brass material. The new molds have improved the outcome of the castings. Although some spots will still need to be filled w/ bondo and sanded smooth the results are much better. The problem still seems to be my pressure pot. I spoke to Charlie at Alumilite and explained that i am having a problem w/ forming a good seal on the pressure pot quickly. I explained that i need to use a wrench to get a tight seal, and it is taking too long. Since i already returned one pot for the same reason Charlie, after examining it, agreed that it is a manufacturing issue. I suggested replacing the original hard gasket supplied w/ one made from silicone material they sell. It worked and they will be replacing all the gaskets on the pots they sell w/ gaskets made in house.
back to the torpedo, using the alumilite I was able to bring down the over all weight of the torpedo from 120 gm to 80gm. The parts that make up the torpedo are as follow]
HOPE TO HAVE PICS REAL SOON AND WILL TRY TO HAVE A WORKING TORPEDO READY TO BRING TO THE WRAM SHOW FOR ANY SC MEMBERS THAT WILL BE THERE. NEIL

[subshop]

HERE ARE THE PICS I

HERE ARE THE PICS I PROMISED:






NEXT ][/url]
EXCUSE THE MESS.
AND FINALLY THE FLEET. SOME DETAIL WORK AND THE LAST PHOTO SHOWS AFT STARBOARD TORPEDO TUBES. TOP TUBE IS CLOSED AND BOTTOM IS OPEN.

[cody]

Subshop....I would love to see

Subshop....I would love to see more of your progress on the sub!

I count 2 waiting?...Plus the one on the bench.
I have one which has been sitting in wait for a long time!
I never did like the "Basic Shape" of the dive planes....Or the way they felt "Flimsy or Weak"....Your build may cause me to "Pull mine out of the corner!"
Your 'Conning Tower' is absolutely gorgeous!
I planned on a "Late Conn",But yours.....Hmmmmm...
Please post more of this....I need an excuse for the wife...."Honey look at the way this guy is doing it!"


Thanks!

Jeff

[subshop]

1/32 scale...

hi jeff, thanks !
I have been planning to do an outline of the build for a long time now but like everyone else priorities have to be respected . I have pictures to go along with the descriptions when i get around to it. I can tell you right off don't bother with the directions you got with the sub ! I borrowed the slogan from Apple Computer , "THINK DIFFERENT " ! I try to take a different approach in doing the build. For example: in the directions that came with the sub it described building the WTC using thin plywood, glass and resin. Taking care not to miss any spots or leaks could develop bla, bla bla. I just used fiberglass board, simple solution !

The one thing i did do is that whenever i made any part i kept the template to be able to use on the other boats. BTW i plan on doing five different gatos. I also have a 32p type xxi I will be doing. One bit of advise i can give you is to set your goals as far as what you want the sub to be able to do, then plan out how you want to do it just like a flow sheet. Another bit of advise i can give you is do research, research, research !!! Enjoy the build, this is not a KIT. There are hardly any parts in 1/32 scale so MOST PARTS ARE SCRATCH BUILT ! And unless you needed the sub done yesterday so what. Using your hands to make something from nothing is quite satisfying. Don't rush, enjoy your build. Troubleshooting, experimenting w/ different techniques, trial and error make this hobby very different from other r/c hobbies. Anyway sorry for rambling on and thanks again for the compliments. Look for my build very soon. neil

[cody]

Thanks Neil for the response...
That

Thanks Neil for the response...
That is the main reason I stopped building!
As fast as things were changing in R/C subs,Technology wise I just decided to wait. It was 1995-1996 If I remember right when I bought the "Full Kit!"
I'm not sure how many books I have on the Gato/Baloa? With Revell's 72nd version my library grew a lot! Due to all the new releases'.
And yes...She aint' no "throw in a tube of glue and shake the box and out comes a sub model!" I only have the one..You lucky dog!
I understand the time constraint's that life put's on all of us...But I do look forward to more of your build. No matter how long it takes....



Jeff

[raalst]

Subshop,

Very nice work,

Subshop,

Very nice work, Brass is a beautiful material.
love the torp gears.

I saw your conning tower and it is beautiful.
Only, beware that it will not become too heavy,
otherwise the boat will topple, or list/rock heavily.

I am planning to take a course for amateur
jewelmaking, just to gain some experience with
casting, hard-soldering etc.
your brass work is inspiring !