M4 (Tamiya) Build #6 – Finishing the Engine, Engine Bay, and Discovering That Another Clever Idea for the Turret Simply Will Not Work, and Then Figuring Out What to do Instead

One thing modelers should get used to is after developing a build plan, being able to modify or abandon that plan selectively when events show that the original intent is just a dumb idea or simply cannot work. When I fitted the rear engine access hatches, I got the clever notion (proving that once again perfection eludes me) to have these doors operational. So I did that. Having done the work and spent the time to do that, I then decided that “operational features” is a 60s gimmick that I shouldn’t do. In the following photos, the hatches (which I wish I’d seen weren’t exactly accurate before I superglued the hinge pins in place) aren’t quite accurate. But, having already pulled that trigger, I dug out my Big Boy Knickers, donned them, and kept going:

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Once the hull is painted, I’ll glue these hatches open. I’m leaving them as they are for now because though putting masking tape on the inside to keep the OD Green off the engine could be done now while this subassembly isn’t attached, getting the tape out once the part is glued on and the exterior is painted would create a problem I don’t care to deal with. So once it’s painted, these hatches will be glued open and bugger the “operational feature.”

Before gluing the engine in, I added stains and wear using pastels, enamel washes (supplied from the bottle of contaminated thinner I keep for just this purpose for its glad-I-don’t-have-to-match-this-color hue). Some of the wear was done with Humbrol Steel, some with silver pencil.

It’s at this point that the engine is glued in. There are more bits to add, but having the engine out where these bits are exposed would mean that they’d break, I’d do a lot of cursing, and they would have to be repaired and reattached…often. Gluing the engine in place now will create new challenges but the new challenges will be easier to surmount than riding the install-break-fix-break-fix carousel while my blood pressure spikes. Glue the this thing in (FINALLY) now:

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There a several really small, thin, DELICATE, lines and hoses that get added now before the rear hull is glued on. (Later there will be more bits added that require the rear hull to be in place first…and my goodness ain’t I looking forward to that!) This little…gem…is comprised of three STD parts (no, not a dose of spirochetes but small-thin-delicate), one of which had broken (and fixed…twice) before I even removed it from the sprue. And since each part needed the two other parts in place before it could be added…where the hell to start?! (This is one of those times when four hands…all under my direct “control,” would have made this quicker and a lot easier):

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While I was waiting for glue to set up, I adjusted the carburetor intake ducting to meet with the air filter housings. I was very surprised at how close they did match, though some bending (with the requisite entreaties to My Big Friend in the Sky) (known as “prayer” to you believers). Once I had them as I wanted them, I glued the ducting to the carburetor (the rear plate to which the air filters are attached to is just held in place with tape because this is the opening salvo of what turned out to be several days worth of work):

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The exhausts and mufflers are prominent features in radial engined Shermans (and derivatives that also used the radial engine) and sit directly under the access hatch. Fortunately, styrene tubing of 1/8″ (3.18mm) is a perfect match for the diameter of the exhaust manifolds. I used a couple of lengths for that, relying on my Mk I Eyecrometer for length. As subsequent work showed, it’s spot on (a novelty I found refreshing):

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Around these tubes I needed more tubing for the mufflers. What would be perfect is if I had a tubing that would just slip over these so that I didn’t have to go through the machining process to get the parts accurate. I was most pleasantly surprised to find out that 3/16″ (4.76mm) worked if I drilled out the center to allow sufficient room to slide over the smaller tubes. I attached the smaller tubing to the manifolds temporarily with white glue:

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Dry-fitting the upper hull showed me that there is a large opening between the top of the rear hull and the underside of the upper hull. Well…ain’t that interesting. The question became, what the hell did they use to fill that gap? Many fruitless hours were spent online trying to find a reference photo. Okay…fine. What would I use to fill that gap? (That gap has to be filled. It’s large enough that an enemy infantryman could easily drop a hot grenade into the engine bay and that’s never a good thing for the tank or its crew.) I decided that I would extend the rear armor up to contact the upper armor, but that’s not what was done. Okay, let’s use a piece of PE screen, with cutouts for the air intake ducts and the exhaust pipes:

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At this point I decided to dry-fit it and see how it fit…which it did not. The air filter housings plug up both sides of that gap. ::bangs head on desk:: Okay, let’s use a template this time:

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And that seemed to work fine (please note “seemed to”…):

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I don’t remember why I was online looking at M4s (maybe because I was building one…I don’t know) but I found a photo, a lousy photo, but a photo nonetheless, of that area of a Sherman and how about that! There’s a screen there! Since every silver lining has a dark cloud wrapped around it, the dark cloud in this case was the orientation of said screen. As you have seen, I oriented my notion vertically. ::sound of raucous buzzer:: Nope. That screen is supposed to be horizontal. (More banging head on workbench followed.) So I made another one, using Archer’s resin rivet heads (not that anyone will freaking notice, y’know) on the added plastic strip:


The screen goes under the mufflers with just the turned-down exhaust tips protruding beyond it. That will require me to cut the opening for them, but that’s a task for later on.

The next task, because finishing the engine bay is the driver, now, is making both intake ducts for the air filter housings. Those ducts look like they were constructed in the same manner that home clothes dryer vent ducts are; spiral wrapped with something that looks like fabric. Yes, I’m pretty sure it wasn’t fabric (heat, petrochemicals, etc.) but that’s what it looks like so that’s what I set out to replicate.

I started with more 3/16″ (4.76mm) tubing and bent them using heat (and anatomically impossible threats). Only having two hands, sometimes one must be creative about holding something in place to be able to mark it:

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Having accomplished that seemingly impossible task (which could be any modeler’s epitaph), it was time for the application of heat. It took a couple of tries for me to consider using the tubing’s propensity for straightening out (don’t ask me how I found out that you canNOT anneal a styrene tube) in my favor by bending it seemingly too far, applying heat (another thing I’d rather you did not ask was how I figured out to use tape to hold it…but don’t worry, as if you would, the blisters are just about completely healed), and letting it cool resulted in just the amount of curve I was after (also…use a hairdrier, NOT a heat gun):

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With the blanks formed (and all the melted styrene off the bench, floor, AND MY LAP cleaned up), I used 22awg wire for the spiral wrap. If you try this method, use a drop of superglue for each loop and then you can run a bead of superglue the length of the wire (this time I annealed the wire after I rediscovered that the wire won’t stay wrapped long enough for the superglue to even be applied):

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With the spiral in place, I cut textureless paper towel into a strip. For the first one, I applied diluted white glue after I’d wrapped the paper towel around it. For the second one, I applied the diluted white glue with a brush as I was doing the wrap. The second method is MUCH easier and resulted in a better looking finish (these photos are from the first one I did):

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A hairdrier dried them quite quickly (and didn’t result in more puddles…with paper…needing to be scraped off anything). You can see the difference between the first, awkward, method and the second, much cleaner, method. The first one is on the left:

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With the glue dry, I used my “gun metal” paint mix, Tamiya X-18 Semi-Gloss Black (5 parts) and Tamiya XF-20 Medium Gray (4 parts), to paint them:

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I set those parts to the side and went back to the tedium of gluing the STD lines back together. Sometimes one must get inventive aligning things:

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And you can see below how well that didn’t work:

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So I tried again, this time off the sprue:

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It worked about as well as the first attempt didn’t:


So why did I waste so much time on this minutia? Because I liked the fittings that were molded onto these STDs. By the time I got to the point where I realized using these parts wasn’t going to work, I realized that I should have just used solder and replace them all…which is what I ended up doing. Near the top right of the photo below, you can also see where I added the tips of the fire suppression system:

2023-02-10 01

Earlier variants of the Continental R975 had a breather/filler cap sticking up from the top of the crankcase. I forget where I’d read it, but after about 200 hours these engines were pulled out and replaced. I figured by the Normandy Invasion (the parameters of this build), the original engine would have been several engines ago. So I modeled this engine after a later variant. Instead of the breather neck, later engines had PCV lines between the air intakes and the crankcase. Those lines can be seen below as copper lines. Once I had the PCV lines in, I added the air intake ducts to the air filter housings:

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The cat’s cradle lines assembly that needed four hands to do easily was added as were two descending lines to the left, and I mixed ivory black and white oil paints to create a color used to dry-brush the highlights onto the engine (which you can also see in the previous two pictures, just not quite so evidently):

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I again wanted to see how much of the engine would show with the hinged engine cover open. Not much. But I know that at some point at least one person will take out their flashlight, bend down nervously close (for me), and look under the bolted-down engine cover:

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Now that most of the engine parts have been added, it was time to add the exhausts pipes and mufflers. References have shown me that the mufflers seemed to rust more than the pipes leading into them were. I wanted to add the rough texture to the mufflers that I have seen while spending far too many hours on my back under a car wondering what broke (and wishing I could afford to have someone else under there instead of me). I wanted to coat the mufflers with superglue and roll them in baking soda. I really don’t like supergluing my fingers to each other (no matter how many times I manage to) so I made an armature/axle from a solid 18awg wire, rolled the mufflers in a puddle of superglue, and then rolled the gluey mass in baking soda. It’s not evident but at the top of the aluminum foil I used as my pallet there’s a puddle of superglue with the baking soda below it in the photo:

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It was at this point that I realized that the two rings that go on each muffler had been forgotten. I used solder (I forget what size) to add them. The ends of the exhaust manifolds that these will attach to aren’t exactly square which required me to trim the smaller tubing to fit properly. So that I got these added correctly, I marked the top of each one with an “L” on the bottom of the one that doesn’t go on the right:

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I used Italeri Flat Rust #4675AP thinned to something substantially less than the putty-like viscosity it came with and used a brush to apply it (because after wrestling with the Vallejo Aged White, I didn’t feel like cleaning my airbrush for another hour). It looked good before it dried, whereupon it became more red than I wanted. I’ll mute that color with pastels later after I’m done handling things. After this photo was taken, I painted the pipes before the mufflers Tamiya X-18 Semi-Gloss Black:

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I used the jeweler’s tweezers (self-locking and on a pedestal) to align the exhausts and hold them in place while the glue set up. The second photo below shows how RED these things turned out:

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After the exhausts were set, I added the exhaust tips. I was pleased that the fishtail exhaust tips that came with the kit were good enough to use without much modification. They were molded with the intent that they would be glued to the underside of the upper hull where it overhangs the rear armor plate (and y’know…Tamiya never did supply a part to deal with the gap where there’s supposed to be a screen…but then again, they also didn’t supply any sponson bottoms, either). I cut them apart, removed the mounting stubs where they would glue to the underside of the upper hull, and after testing for fit relative to the upper hull (just right), glued them to the ends of the mufflers:

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And with that, I think that I’ve done everything I needed to do to the fighting compartment and engine bay! ::trumpet fanfare:: Next I puttied and blended the additions to the rear ends of the sponson bottoms, and spent a LOT of time getting the upper hull fitted to the lower. I got it as close as I could manage without destroying everything. It’s close. When it comes time to permanently attach the upper hull, I can see I’m going to have to get creative with clamps. But that’s a headache for another time.

The next headache is the turret.

My usual build order is to attach the upper hull to the lower at this point. But have you forgotten I want to add clear sections to this? The upper hull will have the clear section on the right side and the turret will have the clear section on the left side. I figure inserting a flat piece of clear styrene will by much easier than doing the same thing to the left side of the turret. Since this was the challenging part that I wasn’t sure how to do (not having done something like this before), I wanted to work on the deal-breaker that failing to pull this off would be. Masking the clear turret to leave a portion of it unpainted would be sort of tedious. I had NO idea how funny that notion was.

I found out.

The turret as it was delivered:

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And of course I had a clever plan! I had intended to delineate the section that was to be clear. My first warning that Loki and Eris had…again…involved Themselves in my plans was when I had a difficult time even getting the Sharpie to stick to the turret:

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Plan A was to cut out an area of the turret, fit it snugly to replace the kerf (that’s the slot a saw leaves behind as it cuts…sawdust has to come from someplace), and then use that as the buck to vacuform a piece of clear styrene to replace what I’d cut out. Lots of tedious and fiddly work. That gave rise to Plan B.

For Plan B, I was going to polish masked off the area inside the outline on the clear turret, paint everything but that area, and bam…clear panel in the turret without any fiddling involved and still a PERFECT fit.

I have tape. I have regular, tan, masking tape, blue painter’s tape, duct tape, 200mph duct tape, house sheathing tape, packing tape, electrical tape, and of course Tamiya tape. I wish I had as much money as I have tape. Well…that was before I tried masking that outline. It wasn’t as if it just slid off, but just about! NOTHING stuck to it. Nothing. It would simply move (or fall off) if I so much as touched it. Cut it? BWA hah hah hah. Well, if I can’t mask it, that torpedoes Plan B. Looks like Plan A it will be.

It was much easier to make the outline on the kit’s turret:

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Even if I did bobble the cut a bit. (I haven’t used a coping saw since 1994.) You can see on top right of the cut where I missed the line:

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I used a different saw to cut away the part I’d left behind during the bobble and glued it back where it belonged, and then started playing styrene scrap Tetris to refit the plug I’d just cut away. Once I had that done, I added little wings to increase the strength of the gluing process:

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Since the inner edges of the hole would be visible, I needed to thin the plastic to scale thickness. As it was, that’s about 6 scale inches (152.4mm) thick:

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The armor on top of the turret was 1 1/8″ (about 25.58mm) thick, so I kept at it until it was the correct thickness (yes, I have a 1/35 scale ruler):

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The sides of the Sherman’s turret were about 2″ (about 50.8mm) thick, so I thinned the sides to the correct scale thickness while I was in a plastic-scraping mood. With that done, I set about setting the buck on the vacuum molder:

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The thickest sheet styrene I could find is .015″ (0.381mm) so that’s what I used:

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When I cut the plastic from around the buck, the wheels didn’t exactly come off the cart, but they were wobbling like crazy:

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When the wheels come off the cart, the cart becomes a really poor sled. This is where that happened:

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I’m sure you can see how thin that clear part is. Since I just had to know, I took out the digital calipers and tried measuring the thinnest section. My calipers will not measure anything smaller than 0.001″ (0.0254mm). Only one point measured that thick, everything else read 0.000″ (approximately 0.000mm). Yeah. Right. That’s going to give me a lot of gluing surface, not to mention great resistance to any pressure against it (sarcasm…probably the most used service I don’t just offer, I insist upon). Those of you who are old enough to remember cellophane know how thick this part wasn’t.

Hmmm…Plan A ain’t off to a stellar start, methinks. That’s when Plan B-1 arose. CUT WHAT I NEED FROM THE CLEAR RESIN TURRET!

All I can say (no…not really, there’s lots I could say) is Plan B-1 was a pain in the ass. Righteously so. But if I couldn’t get the clear section into the turret, there would be no clear sections at all, and dammit I want clear sections.

This time I didn’t use the coping saw. I made a bazillion shallow passes with the smallest burr I have for the dental drill. To accomplish that, I used white glue to attempt to attach the cellophane part to the surface of the clear turret. This is when I found out that there a subtle difference between the curvature of the clear, donor, turret and the intended recipient of the transplant, the kit’s turret. You can see where the white glue failed to harden even though it sat all night to do just that:

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Knowing when to quit is still an arcane skill I’ve yet to even become conversant with; forget mastering it:

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Then came the fitting process. I spent took two days to get to this point. Since I just mentioned it above, you’d better remember…er…I’m sure you remember when I said that the shapes were subtly different? The gaps below…after taking two days…are the best I could do with it at this point:

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Gaps can be adjusted and filled, resin can be heated and recurved. But it’s all for naught unless it’s clear, so the grinding, sanding, and polishing commenced. Resin doesn’t melt as plastic does which allowed me to use a Dremel for the initial shaping. Files followed. Then I started with 220 grit sandpaper, to 320, 400, 600, 1200, and 2000 grit:

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I was just about to go to Novus #2 plastic polish when I saw this little tiny scratch; tiny but deep, requiring me to go back to 320 grit to excise it (the needle tip is pointing at it):

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It was at this point that I tried fitting the clear plug to the turret. No, resin doesn’t melt like styrene does. As I have just learned, this resin became warm enough to change its shape:

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I decided after a few days of this, I needed a break. Behind the clear plug above, you can see a U-shaped depression. This is where the pistol port goes. Tamiya never thought anyone would need it open so the pistol port itself is a single piece. As ever, I have other plans.

When I did the M4A3, I encountered the identical situation with its pistol port. My solution was to take a surface mold of a Dragon turret that was not only molded open, it had the correct flange around the opening. I still have the surface mold and I tend to try to use the left over resin whenever I do a pour and I had cast a pair of pistol ports from that mold. I used one of them here.

I’m familiar with the physical properties of the resin I use (Smooth-On’s Smooth-Cast 322, a polyurethane compound). It becomes very flexible from just the warmth of my fingers which renders it quite flexible. This is a small, thin part, and I knew that it would be challenging to thin it out enough. I put the casting back into the mold so that my hands wouldn’t warm it and the entire surface of the casting would be supported before I used the Dremel with a burr to thin it out as much as I thought practical. Since the turret has no opening for the port, I held the part in place, traced the opening onto the turret with a pencil, and then cut a hole for the port. I checked alignment by dry-fitting the casting. It works:




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Frankly, I was never content with the area I’d thought to make clear, it just took me a bit to figure out what I didn’t like about it. I didn’t like the area on the top of the turret. What that area would allow seen can be seen through the commander’s hatch. Being an earlier turret without a loader’s hatch, this turret didn’t come from the factory with the vision cupola seen on later versions (though they were frequently fitted in the field), it had the old split hatch which allows a larger view of the turret’s innards. I made my decision, cut the opaque plastic from the buck, and refitted it to the turret. Having thinned out the periphery of the roof opening, I filled the resultant depressions with 0.010″ (0.254mm) scraps and then 3M’s Acrylic Putty (the deformed plastic near the opening was where I had glued the plug to a bit of styrene tube to support it on the vacuum molder’s platen):

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Then I puttied the outside:

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I like this opening much better.

Since the opening is smaller, the clear plug had to be as well:

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After letting the putty sit overnight, I scraped it down. Sanding it would make the surface too smooth. These things came from the factory with very little, if any, finishing. Yes, scraping it would make it smoother than it should be, so I’ll try using the Mr. Surfacer 500 to replace the rough-cast surface texture:

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That was the easier part, next was the interior. I scraped, sanded, and muttered imprecations and realized I would need another application of putty to fill in minor depressions (sort of what happens when I look at my checkbook balance, only without the “minor”):

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Next month I hope to finish the installation of the clear plug. I consulted a fortune teller who told me that I have much polishing in my immediate future.

Next time I have my fortune told, I think I should consult someone who reads tea leaves instead of someone who reads my entrails. I just don’t have the guts to do that again.

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