Heavy Mod - 1/18 21st Century Toys P-47D Razorback

[A-10LOADER]

Blown away by all this, simply AMAZING !! You sir, are a true craftsman.

 

Steve

[JayW]

Well I have just closed out alot of stuff!  Big milestone - the cockpit floor and instrument panel are final installed.  Take a look (BTW - cockpits are really hard to show well in pics):

 

 

 

 

 

 

First let me show you the coolest part - the rudder cable.  This picture of a real live P-47 shows a rudder cable running diagonally in front of the main circuit panel:

 

 

Now here is my 1/18 replica (half of fuselage removed so as to see better):

 

 

That is 10 lb test fishing line spray-painted silver.  Some of the other pictures show the pulley wheel on the floor that it routes through.

 

Other items to note - look for the clap trap behind the instrument panel including the support brackets,the pneumatic lines, wiring, and the can portions of the instruments themselves.  It's a bit of a mess, but I think that is how it was.  And that is why I took the trouble.  Also some small springs, and hydraulic or fuel lines on the floor.  All that the cockpit lacks is the engine choke panel just to the right of the IP, and a cable for the tail wheel lock lever to the right of the seat.  Some things, like the other rudder cable, must wait until the fuselage halves are glued together.  OH!  And of course the Mk VIII gun sight.  Here is the lathe turned part, resplendent in its brass sheen:

 

 

Next post I will show it completed and installed along with the choke panel.  Then the IP area will look alot more complete.

 

Although I want to button up the fuselage, which can only happen after a good bit of work on some of the other fuselage items, I think I am going to go to the main landing gear for a while.  Stay tuned, that is going to be quite a project.

 

BTW - those of you who are wondering what that silver bar is just aft of the windshield, that is the windshield defroster pipe. 

Edited February 12, 2018 by JayW

[Guest]

.....Harv

[Shawn M]

that pit is a masterpiece!

[imatt88]

Holy crap, looks real...

[Thunnus]

Incredible work!

[Trak-Tor]

Really great stuff! 

[KiwiZac]

That is stunning, how have I missed this thread?!

[JayW]

I declare a milestone!  The cockpit is complete.  And not a moment too soon - I was getting really tired of it after months and months hammering away at it.  The latest additions are the canted engine choke panel and the gun sight.  The engine choke panel also has a silver pull handle for the cowl flaps, and has an additional panel for ID light switches.  Here (in front of the oxygen unit):

 

  

 

With the instrument panel:

 

 

And what has been glaringly missing the whole time is the gun sight.  Not anymore - here it is:

 

 

 

Needless to say I have lots of work to do on the windshield to get it worthy of the cockpit.  That comes later.  I will only revisit the cockpit when the fuselage halves go together.  At that time I can hook up the oxygen lines and the RH rudder cable (both will be really tough to do).

 

Next is a really exciting and challenging project - main gear tires (with diamond tread) and wheels including brake drums.  A lot of lathe turning.  Stay tuned! 

Edited February 18, 2018 by JayW

[TorbenD]

Veeeeerrrrrry fine piece of modelling going on here - worth every second of time spent to my eye.

 

Looking forward to seeing how you tackle the next stages.

 

Torben

[DonH]

If you get rid of some of the modelling clutter in the background, you could fool me that it was a real cockpit.

That is absolutely stunning, great job and well worth all the time and effort.

[JayW]

Enough with the fuselage for a while.  Here is a feature of the 21st Century Toys P-47 that doesn't do it justice - its landing gear:

 

 

The kit has retractable landing gear, but with the heavy gauge plastic wing skins, the only way to fit the tires in is to skinny them up.  These tires are just over half the width they should be if they were to scale.  The diameter is close.  The gear strut itself is also full of inaccuracies as one would expect.  The folks at 21CT (in the day) did try to emulate the 3 deg kink in the lower strut - good for them.

 

Well, those of you who know me will not be surprised that I intend to give this thing entirely new landing gear, as realistic as I can make them.  For this model, I will salvage none of what you see here, instead scratch building everything.  To do this I make heavy use of my Unimat mini-lathe which can be set up as a drill press or end mill.  I did this for my other 1/18 efforts, as some of you know.

 

So what I will do in the near term is build the tires and wheels and possibly the lower struts - all big involved projects.  Then I will go back to the fuselage and finish it.  But for the LG, I will try something I have never done before - diamond treads for the tires.  That will require an elaborate jig that fixes the angular position of a modelling saw relative to the tire, and also controls the depth of cut.  I started a thread on LSP a couple years ago, looking for ideas on this, and got some good ones.  That combined with some of my own imagineering gave me a good idea how to get it done.  We shall see soon.  If it doesn't work, I will lathe-turn a new tire (which takes all day BTW) and use the block tread that I know how to do.  It will be a disappointment, but not the end of the world by any means.

 

Let me show you the first tire.  I used 2.0 inch diameter clear acrylic for the material, rough sawed to about .75 inch wide, to make a tire that is 1.861 inch diameter and 0.556 inch wide accepting a 1.00 inch diameter wheel.  In real life that is a 33.50 inch diameter, 10.0 inch wide tire, and an 18.0 inch diameter wheel (rim diameter). 

 

So bear with me.  Here is a pic of the raw cut piece clamped in the three jaws of the lathe chuck:

 

 

I have faced off the near side and drilled a starter hole so as to begin the turning of the inner diameter and its shallow counter bore (for the wheel rim), which when done looks like this:

 

 

I wanted to get the inner diameters just right so the wheels fit well.  To do that I lathe-turned a mock wheel out of brass that helps assure the right diameters within a few thousandths, and importantly the proper depth of that counterbore you see.  Here is the mock wheel machined part:

 

 

Note the big pile of brass shavings (heavy, and expensive) - I saw-cut the raw material too thick, which greatly increased machine time, and exasperation level of the lathe operator.  Not sure it was worth it.

 

Then came the true outer diameter of the tire (1.861 inch):

 

 

Lotsa shavings everywhere that must periodically get cleaned up.  Otherwise the work area gets buried!  Then comes rotating the head of the lathe so I can make angled cuts (not all lathes can do this; I love this feature).  These cuts, of course, begin to give the tire its shape.  It requires large scale layouts and some planning on which cut to do first, etc.  It can be a challenge especially large angles.  Here:

 

 

Once one side is completed, the part must be flipped 180 deg, rechucked on the ID, and machined the same way.  Here it is part way through the process:

 

 

And here is the end product (a full day's work):

 

 

And primed:

 

 

There is a prominent ridge, you will notice.  The other ridges have been sanded fairly smooth.  Well that ridge is there to help me when I start to cut the diagonal grooves that will give me the diamond tread.  I will cut to the ridge and no further (at least that's how it's supposed to work).  Once the grooves are cut, I will rechuck the tire on the lathe and cut and sand away the ridge.

 

Hope the step-by-step was not too boring - I have forced my followers through it before.  But for any new followers, it may be informative.  BTW, for those of you who don't know already, I got this lathe a few years ago based on work done by Paul Budzik who is pretty famous in modeling circles.  He makes tires and wheels too.  It is a great tool for all sorts of things.  But it wasn't cheap - and the electric motor breaks down from time to time, taking money to get fixed.  Also, cutting bars must be reground to keep the cutting edges sharp.  So if you want to get one, prepare to pay.

 

Next step, of course, is to fabricate and assemble the diamond tread jig, and try it out.  I am very pumped.  Stay tuned!

Edited February 20, 2018 by JayW

[brahman104]

Fantastic start on the wheels Jay! I have every confidence you'll make this work. I can appreciate the amount of time and skill it takes to do these sort of operations, which makes it all the more impressive

 

Looking forward to your next instalment.

 

Craig 

[Dan Paxton]

UHHHHH uhhhhhh ooooohhhh ahhhh ooooohhh

 

 

Cant speak, drooling here

 

Dan

[JayW]

Hello y'all.  Raining alot here, allows me more modeling time.  I fabricated my diamond tread jig and am in the process of creating a diamond tread on tire number one.  Here is the jig - first photo shows it unassembled (with the tire and its special wheels waiting to be placed in the jig):

 

 

 

Every part of the jig is made with common plastic or aluminum stock, except the wheels which are lathe-turned acrylic.  Note the axle has a cross pin that fits in a slot in the near side wheel.  One side of the pin (and the slot) is painted red to prevent me inserting the axle into the wheel 180 degrees out (which would mess up the angular alignment).The wheel halves are bonded into place, hopefully just enough to prevent rotation of the tire relative to the wheel (no, no, no - cannot let that happen!), but not enough that I have to chisel the wheel out.  Note also the toothed gear wheel, 28 slots.  This will control the incremental rotation of the tire in the tool so each cut is properly spaced relative to the other cuts (in theory).  The metallic uprights (0.125 inch diameter aluminum rod) are for properly orienting the saw blade.  They must be stiff and strong, as I will be making at least 112 cuts (56 per tire, 28 per side).

 

Here is a close-up of the 0.063 inch diameter brass fixed pin which engages the slots on the gear wheel:

 

 

 

Here is a shot with the tire in place, and the saw blade positioned to make a cut:

 

  

 

The saw is 0.025 inch thick, about right for the treads I think. 

 

And here is the historic first cut (111 to go):

 

 

 

I tried to make this jig very strong and stiff.  But it takes considerable force to saw through an acrylic tire.  So flexing occurs which can throw off the position of the cut. 

 

I researched the diamond tread pattern on P-47 tires as much as I could, just by looking at alot of period photos.  I concluded that there are longitudinal rows of three complete diamonds, alternating with rows of 4 where there are two complete diamonds and two half diamonds.  And there are 28 circumferential rows.  Please do not tell me if you know this is not right!  Once that geometry is determined, and once the width of the tread is decided on, then an angle can be calculated for the individual diamonds, and their width.  And once the angle is known, then the uprights are set up to give that angle cut.  It takes alot of layout work to design this jig.

 

Annnnd - I am off to the races:

 

     

 

It's OK, but not as good as I had hoped.  I am finding it difficult to control the cuts exactly, and because of that, some diamonds are larger than others, and/or a diamond is not symmetric looking.  But the more I do this, the better I get at it.  So the first (less accurate) cuts will be relegated to the bottom of the tire which will have a flat cut into it, and some putty added, to simulate weighting.  I will orient the tire so the best part of the pattern is the most visible.

 

Next post I will show a completed tire, maybe both tires.  Then I will start the spoked wheels and brake housings.  Until then....thanks for looking in!

Edited February 23, 2018 by JayW