Where the AM sponsons attached was treated with 3M’s Acrylic Putty (because this was during Tamiya’s “Nobody will ever see under here” phase and didn’t bother to include sponson bottoms with the kit). The sponsons were welded and I’ve not seen any seam here so that gets puttied:

And Tamiya’s utter disregard for anything underneath the model continues to…well…anything underneath the model. Asuka has a good reputation for accuracy and detail (among other traits) so I took one of their DV (Direct Vision…Shermans originally came out of the factory with vision slits for both driver and co-driver) Shermans off the shelf and used the underside of that kit as my source for details and measurements, transferring locations from Asuka who has them onto Tamiya who does not. I know…it looks like the Asuka hull bottom is much shorter but that’s an illusion. The Asuka bottom is a flat piece without sides and it’s far enough from the camera lens to create that illusion. I used a divider (like a compass but with two steel points instead of one steel point and pencil lead) to mark where things are going to go:

Tamiya ends the differential cover too soon at the underside. I extended the underside of it using .020″ (.508mm) flat styrene. Once the glue sets up completely I’ll fair the forward edge the forward edge of the plastic I just added to blend it with the differential cover:

I punched out the appropriately sized discs to use for the drains (which are what those round bits on the bottom are). When I have to center a disc over markings, being able to see the markings makes things much easier (and accurate). To enable this, I punch out the first disc…the one that locates however many will follow it…out of clear styrene:

I wanted to add the lower engine access cover and escape hatch. With the locations marked, I drilled the corners of the intended openings to provide the rounded corners:

And right after I had all the holes drilled, I realized that the lower engine cover wasn’t recessed from underneath; it bolts into position and drops down when it’s unbolted. ::sigh:: I don’t know if those mistakenly drilled holes will be evident once the engine and upper hull are in place, but I do know that plugging those holes will be easier now than later. I took a piece of sprue from my extensive (and like the rest of us, growing) sprue stock, chucked it into a variable speed drill, and sanded and filed it to a taper so that I can glue it tightly into place(s):

And then it’s trim, file, sand, and putty where needed:

I also had to redo a couple of the saw holes for the escape hatch (switching to tea…which unfortunately has less caffeine than the kidney-flush coffee I make) (made):

The thickness of the plastic in this area is MUCH thicker, scale-wise, than it ever was on the actual Sherman:

I think it was something like an inch and a half (about 38.1mm). The plastic is about 5″-6″ (126mm-152.4mm). The escape hatch sits above the opening, has a flange larger than the opening, and pulls upward to open. Rather than try to scrape the plastic to a more correct thickness, it was easier to open the hole and make a plug, pushing the plug to get the inch and a half (about 38.1mm) recess I was after (I think I used .030″ (.762mm) as the plug but I forgot to make a note):

I puttied over the plug on the inside so that the AM resin hatch would fit flush to the floor:

I copied some of the engine bay details from Mini-Art’s M3 Lee (Early). When I cast the floor, somehow I failed to notice that (what I think is the oil reservoir) has a substantial bubble:

I cut the hole to a relatively even hole, trimmed pouring block resin to a tapered fit, glopped a generous portion of superglue into the opened hole, and stuffed the tapered pouring block resin into the hole. I let it sit overnight so that the superglue was well cured (in the third photo it looks as if there’s a gap around the plug but there isn’t…that’s superglue). Once painted, shaded, and with a radial engine stuffed into the same area, I doubt anyone will ever see it, much less be able to critique my patching job:

I used Squadron Green putty to make my first pass and blend the added plastic to the diff cover:

It was okay, as far as it went…which wasn’t quite far enough, so I used 3M’s Acrylic Putty to finish blending. Later I will add bolts because the differential cover, whether three piece as this one represents, or a solid casting, all bolted to the upper and lower hull (I should also probably get my mitts onto some Mr. Surfacer as well so I can replicate the as-cast texture):

I used .020″ (.508mm) styrene for the lower engine access plate (which will also get bolts added):

Back into the crew compartment, I started working on the canisters of the fire-suppression system. This starts with cutting away the pouring block and putting back the detail lost. It also entails reattaching the valve/gauge assembly that got knocked off (using my traditional pin and glue method):

I get to do this again because there were two canisters (and you can see where the gauge has already been knocked off the valve…or it simply didn’t pour):

I used the punch/die set to knock out three discs to make the gauge and before I add the conjoined canisters into the interior I will add the Mystery Bit (seen on top of the other gauge):

With most of the details added to the belly of the tank, I used Vallejo’s Acrylic Putty to fill in the alignment marks and mistakes. Since I’ve brought up the subject of mistakes, gimlet-eyed readers have no doubt noticed that I have extended the resin sponson bottoms all the way to the back of the sponsons. Yep…correct for an M4A3…incorrect for an M4. (This also explains why the AM set has abbreviated sides…Tamiya actually provided the parts that would otherwise go there, so both the sponsons and the upper sides of the engine bay will get trimmed. Later):

Since it isn’t the 60s anymore (and I am not a kid) (substantially), I am not a fan of “working features.” Having said that, I again remind y’all that I am a creature of mood and whimsy. Not understanding why myself, I have decided that the engine covers must open and close. (Well, doesn’t THAT simplify things! Having had Covid last month, I blame Covid-brain.) I started with the rear engine doors. I held the doors in place and drilled through the hinge parts in one pass, thereby making inserting the wire I’m going to use as hinge pins even possible, much less easier:

That worked well, so I tried it on the top engine covers. That didn’t work worth a rodent’s rectum. That so didn’t work that I bitched up the kit’s front engine cover (very thin drill, too far to go to reach the areas that had to be drilled, which caused the bit to bend and the hole to be drilled as a curve, and that utterly screws up a hinge). Okay. Since it has become evident that I cannot drill out the hinges with them in situ, the end result is that to have the top engine cover open, I have to scratch-build it.

Lovely idea! Let’s DO that!

::insert eye roll here::

The upper engine covers are three parts, of which two bolt into place. The front engine cover (which is the one I bitched up) has the air inlet for the engine’s cooling fan (obviously, Shermans with the Continental radial aircraft engine are air-cooled), as well as a couple of armored fuel cap covers.

Step one is to cut three pieces of .015″ (.381mm) styrene to replace the kit’s covers. I used the thickness I chose for scale thickness. Once I had all three parts cut (which for simple rectangles took me far too long) and fitted, I noticed that allowance had been made by the kit engineers for the out of scale engine covers to sit flush with the surrounding surfaces. That meant that the scale thickness covers were recessed and should not be:

My first attempt used .015″ (.381mm) shims to raise the covers:

That didn’t exactly do it, as the center cover in the photo below shows:

Since both for forward and rear covers are typically bolted down, I shimmed the covers and not their seat, which is why in the above photo they sit even with the surrounding hull. I added .020″ (.508mm) strips to the shims already glued down and that brought the middle cover up to where I want it:

The rear and front cover will have bolt heads added later. For now I have to get the missing details added to the front cover. That started by sawing off the bullet-splash lip:

You can see that it wasn’t my cleanest excision. I cleaned up and leveled the U-shaped part (on the right in the above photo) and then glued it down to a flat section of .015″ (.380mm) styrene to replace the kerf. Once glued onto it, I could see an area where the plastic of the excised part didn’t meet with the plastic of the kerf replacement. I added a couple of pieces of .010″ (.254mm) and .005″ (.127mm) to fill in the gap:

I applied Tamiya Extra Thin cement liberally and once the plastic started to melt, I clamped it all into a vise to cause the squidge to flow and fill gaps and to make the gooey plastic a bit more level:

And what with all the cutting, fitting, fixing, and of course Colorful Invective (often applied while crawling around looking for the sodding small part that just tried to “tick” its way to oblivion), I never did do any work fitting that engine…