Making Mould blocks or Plugs for Turtle Decks

[Mike Griffin]

I ran a preliminary search on the forum for a tutorial (with pictures) of the step by step process of making molded turtle deck shells but could not find one.  I have carved a few canopy plugs and I would guess that carving a block to mould a turtle deck over would be similar except you would use  2 pieces punk 4 lb  1/16th wood and laminate them one on top of the other instead of heat forming plastic,  and wetting it and wrapping it with an ace bandage around the block.  Does anyone have anything like this in their library that they could post for those of us that would like to do this?

thanks

Mike

[Avaiojet]

Mike,

Here's 1/16" sheeting I used on the turtle deck for The New American. Tiger Shark also. One piece wrapped. Commonly done this way without mold blocks or a foam jig, just formers. That's why they call them formers.   

Hope this helps some.

Charles

[James Mills]

Mike,

Bob has a good DVD with Bill Werewage doing balsa molding, worth the $ and time.

James

[Matthew Cosier]

If you want the lightest way, hot wire cut the turyle deck using  foam, and two pieces of light 1/32 balsa
.
Depending on the amount of curve, with the right balsa, slightly damp, press it with the foam turtle deck into the block that the foam was cut out of, as this makes the perfect "form press", once fully dry the wood is now removed from the foam and the two pieces can be laminated together (don't use too much epoxy) and placed back into the foam press again with plastic wrap so it won't stick to the foam.

Allow plently of time for it to completely dry.

The balsa is now in the shape of the deck and can be fitted without too many formers.

[Bob Hunt]

Hi Mike:

Funny you should post this; I'm just now finishing up the photos for such a tutorial. It will include a way to make a fuselage crutch on which the molded shells will fit perfectly. It's all part of a complete new fuselage building system that I've developed over the past few years with my son, Robby.

So far there are over 350 photos in this tutorial, and I've yet to write the step-by-step instructions. Will start on that this week and put the photos in the text to illustrate the process. This one will be a for-sale item as it has consumed well over 100 hours of work already!

Later Bob Hunt   

[Avaiojet]

Mike,

Almost forgot!

Here's my scratch built 28%, 80.5" in span, Staudacher from Bruce Lund's plans. Yes, it's absolutely a scale model.

No kit. Plans only, glass parts and a great canopy. Gotta scratch build it or you don't get one. 

Sheeted foam wings, tube in a tube, "and a one piece sheeted turtledeck." No foam in the turtledeck, just a few formers.

"Roads? Who needs roads." Name the movie.

The actual aircraft was flown by a woman no less, Diane Hakala, and she became the U.S. National Aerobatic Champion in 1997. I think?

Yes, I've had this model a long long time. I built two actually. Yes! Of course they aren't finished. 

Believe it or not, the second model, I haven't sheeted turtledeck yet.   

Charles
 

[john e. holliday]

Hey Bobby I would very interested in the dvd  of molding and the new fuselage build.   All I have is the cassettes that I got from you years ago and nothing to play them on.

[Randy Powell]

I usually cut formers for the length of block. For full length shell, probably 6 or 8 of them. Glue them to a base (I have some 1/2 inch balsa stock just for this occasion - maybe 20lb stock). Then I glue some blue or gray foam in between the formers. Block it down using the vertical shape I want and finish sand it. then I glass the whole thing, sand it down and use this as a molding block. It works for me.

[W.D. Roland]

Mike
Somewhere is posted the how to.
1- center profile/top/firewall/formers from wood paneling or such.
1st pic is these parts test fitted to wing/engine mount.

2-blocks of foam cut to fill in sides and carved/sanded to shape.

[W.D. Roland]

somewhere is picture of finished wood foam plug. took about 8-10 hours to make sand shape plug. Could have been less.

this pic is first layer(inner) on form after drying and 2nd layer being formed but not laminated.

[W.D. Roland]

One file at a time!
inner layer 1/16 6lb balsa on form with outer layer 1/16 6lb removed.

[W.D. Roland]

both layers next to form(center)
The balsa sheets grain has 20deg or so bias between layers. No formers needed from cockpit back with high
torsional rigidity.
finished and sanded shell weighed under 2 oz from memory.

Mike
FW 190 finally flight ready!
Plan to go to B.R. or N.O. for test flight when good weather returns( Global Warming)

[Mike Griffin]

Thank you all for some great input and instructions.  I appreciate it very much.

Mike

[steven yampolsky]

I usually cut formers for the length of block. For full length shell, probably 6 or 8 of them. Glue them to a base (I have some 1/2 inch balsa stock just for this occasion - maybe 20lb stock). Then I glue some blue or gray foam in between the formers. Block it down using the vertical shape I want and finish sand it. then I glass the whole thing, sand it down and use this as a molding block. It works for me.

My approach is even simpler than that:

1) cut formers the length of the block about every 3 inches or so
2) cut the base from any 1/2" scrap wood you can find at the Home Depot. shape it so it is flush with the former sides.
3) a bunch of years ago I bought a sheet of thick insulation foam. Cut the chunks to fit between the formers. Hot glue them in(5 min epoxy is an overkill but will work as well).
4) carve foam with #26 xacto wittling blade to rough shape
5) rough sand to shape with #60 paper. fine sand it with 120 or 150 grit. Make sure to use long blocks to make sure you maintain the overall shape. If you make an accidental divot, you can use regular white Balsa filler. It will not dissolve when wet balsa sheet is wrapped around the buck.
6) cut a 2" wide strip of wood to be glued perpendicularly to the base. It will act as a holding handle.

That's it. you're done. you can mold balsa over it! It usually takes me about 15 minutes to make a mold.

Soak sheets in a mix of hot water and ammonia for about 5 minutes and wrap it around the mold by wrapping it with elastic bandages with clips they used to wrap sprained ankles or knees. Like this: http://cvs.com/shop/product-detail/CVS-Elastic-Bandage-With-Clips-3-Inches?skuId=160093

I usually do it before going to sleep. the whole thing is dry by the morning and the mold is ready for the next set. These molds will last you forever. I've been using this approach with leading edge sheeting, top and bottom blocks and bottom sections of engine cowls. The approach is SO simple and the results are SO consistent and good, I pretty much stopped carving.

[MarcusCordeiro]

Very good thread!!

Marcus

[Tim Wescott]

Any feel for how much compound curvature you can put in and have it still work?  Or do you have to strictly simple curvature?

[Randy Powell]

You can do complex curves. There's a practical limit and it depends on a lot of factors, but you can certainly do compound curves.

[steven yampolsky]

Member in good standing of P.I.S.T
(Politically Incorrect Stunt Team)
AMA 67711

Randy Powell

I just saw your signature. This is AWESOME    ! Can I join the PIST club!? I am totally slapping this on my next model, right next to the PUTZ and Henry Reese logos!!!!

[EddyR]

I did this with 3/32 sheet. The only block is the 3/8 sheet nose ring. Even the cowl is sheet balsa.
I have rebuilt a couple of old models cutting off the blocks and mounding new parts. It is much faster than carving blocks.
Ed

[john e. holliday]

Now that I remember, I shouldn't mention that Al Rabe shows on his CD's how he mold the shells for his Bearcat and Mustang. 

[Steve Helmick]

Haven't tried this, but if your turtledeck needs a curve (Silhavy's Gypsy?), you could either carve/sand or hotwire the foam form straight, and then bend the foam form to suit the curve you desire.  I'd bet that Bob Hunt shows this in his video.  Steve 

[W.D. Roland]

compound curved sections in one piece requires kurfing at or on one end.

mental image the following;
I have 6-8 different size and shape Mag Speed Pans that make good canopy shapes
and top nose block replacements.

Fit and mold balsa of the largest section then cut line down center of short section
and mold while letting one side of cut overlap other. when shape is as close as possible
cut through center line through overlap part and the part that is down. Remove the
2 small triangle pieces this makes and the joint will be nearly perfect.

Usually just a heat gun and sometimes a little help with a damp paper towel for wetting the balsa.

[EddyR]

Like Roland says cut down through the overlap and remove the bottom piece and the part now has a perfect fit. In the wall covering business we called that double cutting. Silkspan can be done the same way to get rid of the overlap.
Ed