Ze FrankenShtooka. 1/32 Trumpeter Revell Kitbash

[Gazzas]

I've come to the unhappy conclusion that I need vac-formed canopy parts. 

 

The Trumpeter clear parts are too tall, with radii that are too sharp.  The Trumpeter fuselage is also 4mm wider at the top than the Revell fuselage.  So, I cannot use the Revell clear parts as no clear plastic can be stressed that much.

 

Therefor I am contemplating buying a dental vac form machine.  I don't want to build my own as I don't have a spare vacuum and the MRS. would have a fit if I did anything with the one we do have. 

 

A couple of questions for those who have traveled down this road:  Is there a certain height that my buck should be?  Is balsa sturdy enough for the buck, or should I use something like pine?  Is there a best thickness for this scale?  And finally, which material is both easy to get and will do an adequate job.   Gonna watch some videos and see if I can get any more useful info that way.

[Rick Griewski]

Look through builds by Frank Mitchel. He smash molded canopies over modified kit canopies, reinforced with dense clay or resin filler. Modifications include sanding off all the canopy frames.  
 

I have just finished resin patterns (bucks) for my Bouton Paul canopies and turret.  I have included 0.040” at the base so the edge wraps around.

[Greif8]

9 hours ago, Gazzas said:

I've come to the unhappy conclusion that I need vac-formed canopy parts. 

 

The Trumpeter clear parts are too tall, with radii that are too sharp.  The Trumpeter fuselage is also 4mm wider at the top than the Revell fuselage.  So, I cannot use the Revell clear parts as no clear plastic can be stressed that much.

 

Therefor I am contemplating buying a dental vac form machine.  I don't want to build my own as I don't have a spare vacuum and the MRS. would have a fit if I did anything with the one we do have. 

 

A couple of questions for those who have traveled down this road:  Is there a certain height that my buck should be?  Is balsa sturdy enough for the buck, or should I use something like pine?  Is there a best thickness for this scale?  And finally, which material is both easy to get and will do an adequate job.   Gonna watch some videos and see if I can get any more useful info that way.

 

Ouch!  4mm is a whopping difference.  I am sorry I can't help you Gary as I have never vac-formed anything and I am completely clueless how it works.

 

Ernest

[easixpedro]

9 hours ago, Gazzas said:

A couple of questions for those who have traveled down this road:  Is there a certain height that my buck should be?  Is balsa sturdy enough for the buck, or should I use something like pine?  Is there a best thickness for this scale?  And finally, which material is both easy to get and will do an adequate job. 

Balsa does work, but I wouldn't use it for clear--the grain of the wood will show through.  I've used Bass wood before (on my Prowler build). Soaked the wood in thin super glue then it's rock hard.  Used the balsa wood to make my jammer pods and wasn't too concerned about super smooth.  There's a difference in the materials (don't remember which is which, but certain ones do form bubbles due to humidity)

Whatever you do, looking forward to pictures!

[Gazzas]

Guys,

     Thank you for the helpful replies.  I appreciate them a lot.

 

After a week to ruminate on a process, here is what I have decided to do:

1.  Make the Revell parts fit the Trumpeter fuselage, even if they are ugly.

2.  Fill them with resin...   so they become solid and strong.

3.  Sand them and make them pretty.  Here I am aided by the fact that the bracing for the Stuka's canopy is on the inside...  more on that later.

4.  Attach them to bases which will be hopefully be conducive to vac-forming.  Got some good ideas from Paul Budzik's Scale model Workshop for how the bases should be.

5.  Cover them with aluminum foil, just as if I was foiling a model.  The PETG shouldn't stick to the foil as it stretches over the part.

 

...  and after Christmas, get me a dental vac forming machine.

 

Anyway, that's the basic lazy-man's idea.  I really didn't relish trying to carve and shape all four parts from wood.  Although I'm retaining that option if necessary.

 

so...   let's talk about now...

 

I began cutting plastic to make the parts fit.  On the windscreen, I added plastic card to the outsides and then filed it down to make it right.

 

On the center two pieces, I split them in half and added card to the middle to get the correct width.  Then I had to let them dry.  They'll need to sit at least overnight to get hard enough to handle latter.

 

 

Fit is a bit sloppy for a number of reasons.  Notice how low the second segment is compared to the rest.  Revell did this so that the canopy could be posed open.  On the Trumpy kit, if you try to pose it open, you'll be sorely pressed to make it fit without either removing (a lot of) material or applying a mallet.

 

 

Once everything hardens, I will raise the section up making it taller.

 

 

But since I am posing it open, nothing has to be absolutely perfect.  The Revell Gunner's mount piece is a bit taller than I think it should be.  But I'll think a bit on what I want to do there.

 

  Now here is a comparison between the Trumpeter and Revell parts.  Once you see a completed build of the Trumpy bird, these things jump out at you.  Like somebody parked a double-decker bus on top of a small hill.

 

 

There are still a lot of things to consider, but I feel like I have made a major step forward by deciding to vac-form and deciding on a process that I hope will save me some time.

 

Thank you for looking!

[Greif8]

I admire your perserverence in correcting the canopy issues Gary, and I think you are taking in intelligent approach towards doing so.  This whole issue would really be testing my patience on a build.

 

Ernest  

[thierry laurent]

You can easily use balsa if you cover it with CA glue and sand the grain as soon as each layer of thin glue dried. However, this asks for a lot of liquid glue as initially balsa will react as a sponge.

[Gazzas]

So...   after quite a few days, here is a tiny little update.

 

After hacking and re-sizing the Revell clear parts, I wrapped them in blue tape to hold in the resin I was about to pour into them.  Alas, my tape dams were not leak-proof and some resin leaked out.  So, I had to add more a day later.  And fortunately it peels off the Revell clear parts with some not-too-gentle persuasion. 

 

I dyed the resin green by tinting it with a drop of grey green paint.  I sometimes wonder if using acrylic paint causes some molecular change that keep the resin from getting rock hard?

 

 

After peeling off the blue tape, I attacked the raised area of the Revell clear plastic with an aggressive rasp normally used for wood working...  you know, the kind that are about 14 inches long.  Amazingly it took a lot of strokes to get rid of all of those raised canopy details.  The Revell molds must have been highly degraded, because the tapered edges all had gaps and other faults needing filling.  I mostly used CA and baking soda to be my filler when I needed it.   It's so nice not to have to wait overnight to sand away the excess.  But still there was a lot of filling, sanding, ...  and more and more...

 

I'm a bit nervous about the gunner's piece.  Because of it's complex shape, it was easy for me to decided to cut open mounting hole to allow the vacuum to suck the Petg into that area.  I hope it works. 

 

 

You may notice through the three angles in the photos, the pieces probably wouldn't fit perfectly in a closed-up situation.  But that's ok as I don't want to do them closed up.  It's not that I'm keen to show off my cockpit interior.  But I think the modeller has more options to make a nice looking diorama or simple display with a couple figures. 

 

So, what's next?  Foiling.  Then I will REALLY see where the faults are.  I will start to work on the aircraft body, too.  Then getting a dental vac form machine.  I think it'll be a one-use thing as I can't imagine doing it often...

 

So...   there you have it.  Comments and questions always welcome!

[MikeMaben]

You're  a brave man Gary 

[Wouter]

1 hour ago, MikeMaben said:

You're  a brave man Gary 

I'll second that, way above my patience limit!

[Rick Griewski]

Hi Gary,  The patterns came out great. And you now have very sharp/angular patterns, all have steep sides.  All patterns should be relived so the plastic pulled/stretched down over more gradual, rounded pattern.  This will prevent thin edges with potential wrinkles The parts cannot be removed from the vac plastic.  Epoxy putty “pillows” on the steep sides will do the trick.  You are transforming the sharp angles into a vertical pull for the vac plastic. The pillow surface needs to meet up and just slightly away from the edges of the parts. This will preserve the nice edge so it is obvious where to cut out the part.  Each pattern should have 0.030 or so thick sheet plastic spacer on the bottom.  Cut each so that they are slightly smaller so the bottom edges of the vac part will be evident.  
 

I hope this helps. 

[Gazzas]

18 hours ago, Rick Griewski said:

Hi Gary,  The patterns came out great. And you now have very sharp/angular patterns, all have steep sides.  All patterns should be relived so the plastic pulled/stretched down over more gradual, rounded pattern.  This will prevent thin edges with potential wrinkles The parts cannot be removed from the vac plastic.  Epoxy putty “pillows” on the steep sides will do the trick.  You are transforming the sharp angles into a vertical pull for the vac plastic. The pillow surface needs to meet up and just slightly away from the edges of the parts. This will preserve the nice edge so it is obvious where to cut out the part.  Each pattern should have 0.030 or so thick sheet plastic spacer on the bottom.  Cut each so that they are slightly smaller so the bottom edges of the vac part will be evident.  
 

I hope this helps. 

 

Thanks for the advice Rick.  I'm not sure if I understand completely.

 

Lemme know if this crude illustration of two views of the canopy section are what you're saying.

 

[Rick Griewski]

Close and I needed to say a more gradual sloping pillow.  You will not need a tall “base”. 
 

 I should have included the following for sample diagrams.  These are 1/72 scale.  You should vac your parts individually due to the length of the whole canopy and the small size of your proposed machine. 
 

Google, “ clear prop vacuum formed canopies“

 

 

[Greif8]

You are getting into some uncharted waters for me Gary, I admire your courage and skill to sort this issue out.  It is certainly well above my skill level to do so.

 

Ernest

[monthebiff]

You are moving this build on to a new level Gary, I'm super interested in what you are doing here and your next steps on the canopy.

 

Regards  Andy