Macchi Castoldi M.33

[DMC]

Started this build off with the wing over on the modelling WiP page.  Got that wrong so I’ll start off again here with the fuselage.  I’ve done a little plunge moulding and I like to use balsa for my moulds.  Easy to carve and sand and tough enough for several “plunges”.

 

In the photo, ignoring the wing, I’ve traced the profile and plan view outlines of the fuselage onto the balsa, ready to be carved.  The plans were simple but pretty accurate, as far as I could tell.  I will have to do the wing over and I’ll explain why after I get into the build a little more.

 

Thanks for your interest 

 

Dennis

 

[Courageous]

And you're off the blocks Dennis. 

 

Stuart

[DMC]

8 minutes ago, Courageous said:

And you're off the blocks Dennis. 

 

Stuart

So it would seem, Stuart (awful lot of popcorn consumed on BM 😀)

 

Dennis

[Courageous]

 

That's why I'm always dieting 🐷. 

 

Stuart

Edited September 3, 2019 by Courageous

[DMC]

Moving right along, as the fuselage is mostly done, I carved the balsa to the plan and profile outline. Leaving a little overage for sanding.   The mould is actually in two halves, separated by a couple of slips of veneer.  After shaping, I’ll split the mould in half and prepare each half for plunge moulding.  More tomorrow.

 

Thanks for your interest.

 

Dennis

 

 

 

 

 

Edited September 4, 2019 by DMC
Corrections

[JOCKNEY]

Excellent, are you going to make multiples of this kit ?

 

If so can you put me down for one please.

 

cheers Pat

 

 

[Courageous]

A good start but I'm itching to ask. I see a side profile and a plan profile but what about cross sections like for boats? You do have a boat like hull after all.

 

Stuart

[DMC]

11 hours ago, JOCKNEY said:

Excellent, are you going to make multiples of this kit ?

 

Pat, I’ll be happy to get this one done.  The fuselage was relatively easy to do, the wing are a different story altogether.  There are a total of 50 ribs that will have to be depicted, top and bottom.  That’s 100 rib tapes in all.  Thinking about it now, I might have chosen something less time consuming.  Thanks, however, for your flattering request

 

10 hours ago, Courageous said:

cross sections

There’s one in the photo Stuart. Top left.  I used three or four but only one was really necessary.  Starting from, say, the cockpit and one cross section former the hull almost carved itself such was the flowing shape from nose to tail.  No bumps or humps, etc.  The planing hull is just a shallow  V shape. Watch this space, all will be revealed.

 

Dennis

Edited September 4, 2019 by DMC
Corrections

[jrlx]

Hi Dennis!

 

Welcome to the GB! You're another courageous scratch builder! I'll be following with great interest!

 

Cheers

 

Jaime

 

 

[DMC]

Apologies for drip feeding these photos in like this but there are 7 or 8 of them and it gives me a little time to work on the wing.  Here I’ve carved the hull and split it open.  Each side providing a male mould for plunge moulding.

 

Thanks for looking 

 

Dennis

 

[DMC]

Male moulds carved then and ready for the female moulds.  I use thick balsa for most of my female moulds.  This piece almost a quarter inch thick.  Anything less for a plunge this big is likely to crack.  Early on I learned that it was easier to split the wood lengthwise and then carve out the opening rather then try to do out it of one piece.   I’ve also experimented with clearances and, for most plunges, have settled on  1/16” or near enough.  Smaller plunges need less.

 

After gluing the mould halves together I made risers (?) thick enough to keep to hot styrene from bottoming out and spoiling the plunge.  On some moulds the risers are glued on but on this mould I only pinned them on so I could swap sides rather than make a mould for right and left.    That’s it for today, must get cracking on with the wing or I’m going to run out of photos and have nothing done.

 

Thanks for looking

 

Dennis

 

[greggles.w]

Appreciate the tutorial- there’s quite a bit of meticulous planning & preparation toward one melting moment!

[DMC]

8 hours ago, greggles.w said:

Appreciate the tutorial- there’s quite a bit of meticulous planning & preparation toward one melting moment!

No problem , Greg.  I realised early on that the more time I took with with the moulds, usually, the better the results.   Logical I suppose but sometimes even best efforts get it wrong.

 

Here is the first fuselage plunge.  I use bulldog clamps to clamp the styrene to the mould and heat it in an old toaster oven.  A large kitchen oven really wouldn’t do.  Madam doesn’t care for the fragrance of cooking plastic, not to mention the electric bill if you do a lot of plunging.  Takes about 5 minutes to soften .040 styrene to plunge ready.  The balsa stops on the male mould keep me from plunging too deeply.

 

Hmmm, Village Photos not working for me this morning.  I’ll try again later.   Ah! There it is.

 

 

Thanks for looking

 

Dennis

 

[Courageous]

1 hour ago, DMC said:

The balsa stops on the male mould keep me from plunging too deeply.

Having never done anything on this scale, would you not make it a little deeper to allow for the thickness of the plastic? 

 

Stuart

Edited September 6, 2019 by Courageous

[DMC]

4 hours ago, Courageous said:

would you not make it a little deeper to allow for the thickness of the plastic? 

 

Stuart

Edited 4 hours ago by Courageous

I would and do, Stuart.   In this example I only used the v-shaped bit.  You can see in the photo that the plunged bit is deeper than what I actually needed.  No formula for it, mostly trail and error.  Early days I sometimes made 3 or 4 moulds.  Getting a little better at it now, however.

 

Dennis

 

[DMC]

Next photo instalment: first fuselage plunge results.  Both sides turned out pretty good, better, in fact than I expected. Took me a couple of attempts to match the top half of the vertical stab to the fuselage but got there finally.  

 

This (Russian) link to a no longer produced resin M.33 has thumbnails of details that will be very useful when I get to the detail stage of the build.  http://scalemodels.ru/modules/myarticles/img_6736_1382300644_rrsrrrr.jpg.html

 

Thanks for looking 

 

Dennis

 

 

[DMC]

Next up, joining the hull halves.  On some shapes  plunging stretches the styrene enough to leave only a thin edge to join together.  Even .040 can be reduced to .020 in some instances.  Not really enough to get a strong joint.  One way to overcome this problem is to line around the inside of the thin edge with, say, .030 strip.  That usually works very well but compound curves can require a bit of fiddling around.  On this build I decided to just go ahead and line the entire front and rear hull tops with plunge moulded shells.  A sort of double hull arrangement.  The bow required a complete new plunge but for the stern I was able to use the top of one of the M.39 floats that didn’t make the cut.   This worked out very well although the bow shell could have been a little wider at the bottom.   Note the bulkheads of .060 styrene.

 

Thanks for looking

 

Dennis

 

[jrlx]

Impressive work! Shaping up beautifully

 

Cheers

 

Jaime

 

[DMC]

54 minutes ago, jrlx said:

Impressive work! Shaping up beautifully

Thanks, Jaime, very much appreciated.

 

Posting photos of the fuselage build has given me a little time to get started on the wing.  Cantilever wings are made a little differently than the method Woodman used to make fabric covered ones as seen on, say, WW1 biplanes.  The M.33 wings were very thick at the root and tapered in thickness out to the wingtips.  There were 25 ribs to a side and the wing was, I’m pretty sure, fabric covered.  I’m making the wing over because I read the plans wrong and started the dihedral a few ribs out on a flat center section.  Should have started at the Center of the wing.

 

After shaping the wing I trimmed a piece of .010 styrene to the fit the outline of the wing, leaving it a little oversized.   This piece is folded along the LE but not creased as it could split.  The trailing edge is matched up and taped.  This is then placed between a couple of pieces of balsa to make a sort of styrene sandwich.  It is then heated, I use a hair dryer, and the balsa is gently pressed together and then allowed to cool a minute to make the fold permanent.  Meanwhile, having had a generous application of liquid cement, which hardens the balsa, the wing has a couple of strips of double-sided tape applied to the top only.  The folded styrene is wrapped around the wing, bottom first, and the the top is smoothed over the wing.  There are several ways to do the wing tip but plunging them worked out pretty good before so I’ve done it again on this wing.  I’ll be using strips of .010 styrene for the rib tapes as I think that method is a little more flexible than other options.

 

Whew!  This has gone on a bit hasn’t it.  Tried to make it as succinct has I could but wanted to get it all in.  If you’re still here thanks for looking, and reading.

 

Dennis

 

 

[greggles.w]

1 hour ago, DMC said:

Whew!  This has gone on a bit hasn’t it.  Tried to make it as succinct has I could but wanted to get it all in.  If you’re still here thanks for looking, and reading.

If you merely showed us the outcome, that would be very interesting, but also revealing your process & the thought behind it is a gift - much appreciated!

[Thom216]

It's getting a peak behind the Wizard's Curtain.

[DMC]

15 hours ago, greggles.w said:

much appreciated

No problem, Greg, the pleasure is all mine (except, perhaps, when I have to do something over several times🤬).

 

3 hours ago, Thom216 said:

's getting a peak behind the Wizard's Curtain.

More like the wizards apprentice maybe, the wizard being Harry Woodman. 

Thanks Thom.

 

[Courageous]

I agree with what Greg and Thom says. Great stuff. Am I to take it that the balsa remains inside the plastic wing?

 

Stuart

[DMC]

13 minutes ago, Courageous said:

agree with what Greg and Thom says. Great stuff. Am I to take it that the balsa remains inside the plastic wing?

 

Hi Stuart , 

 

Thanks, pleased you like what I do.  Yes, the balsa remains inside giving the wing its airfoil shape and a solid core to attach LG, pylons and so on to, if required.  Woodman, in fact, would have left the balsa inside the fuselage also with a cutout for the cockpit.  

 

Cheers

 

Dennis

[DMC]

Wing is now fully skinned and while I busy myself with the rib tapes here’s a photo of the fuselage and simple cockpit.  Plunge moulded seat, Milliput belts and the stick.  That about it but not much will be seen anyway (maybe I’ll put a Porco Rosso pilot figure in there).  The bow hull bottom is plunge moulded to the step, the stern is a flat piece scored and bent.  

 

Thanks for looking

 

Dennis