- Joined
- Apr 28, 2018
- Messages
- 10,882
- Points
- 113
- First Name
- Jakko
The fun never stops …
My M4/M4A1 manual says there are different types of gunner’s controls in the Sherman: electric or hydraulic. Photos I found of a restored M4A4 show the electric type, but would my subject have had the same? When I showed my father the last photo I posted of the turret basket and mentioned the different turret drives, he said, “we used to turn a handwheel” — referring to his playing in this exact tank in his youth, when it was on display outside the war museum (see the start of this thread). However, he couldn’t remember if this wheel was vertical in front of him (as per the electric drive) or horizontal on the right (the manual controls for the hydraulic drive).
Then I decided to check the M4A4 tech manual that is available online, and happily, that only shows the electric type. Great, because that probably answers the question and it’s the easier one to scratchbuild. Here is what it looked like:
But how big is it? The hands in the photo don’t provide enough of a clue, but the manual also included the following illustration, a bottom view of the turret drive and how it meshes with the ring gear:
I photographed the ruler with it because that provides almost all the information needed to work out the size for your own model, if you’restupid enough crazy enough in a mood to add it to your own model.
It may not be immediately obvious how, but notice the two bolt heads drawn on the turret ring … because there were 32 bolts on the ring, you can work out what the distance between two bolts should be on your model:
This because the sine of an angle in a right-angled triangle can be found by dividing the length of the opposite side of the triangle by that of the hypothenuse — thus, if you know the length of the hypothenuse and the angle, you can work out the length of the short side.
Since there are 32 bolts, the angle between them is 11.25 degrees; we need half that angle, though, to get a right-angled triangle of which one side is half the distance between the bolts and the other important side is the distance from the bolt to the centre of the turret. You can just measure that last one on your model — on my kit, the diameter turned out to be almost exactly 50 mm, so halving that gave me 25. Multiplying that by the sine of half the angle results in half the distance between the two bolts, so it just needs doubling to get the full distance. In this case, that’s 4.9 mm.
Measuring from the top of one bolt to the top of the other in the drawing found that this was nigh on exactly 20 mm, meaning all I needed to do was divide measurements I took in the drawing by 4 to find how big all this needs to be in 1:35.
But we’re not there yet! How tall is the thing?!
That’s where the left-hand photo in the manual (page 330) came in. From photos, I judged that the handwheel’s left side is pretty much even with the left side of the gearbox. Other illustrations showed its axle to be offset to the right a little, so more measuring now that I knew the width of the gearbox, gave me a diameter of about 9 mm in 1:35 scale. That, then, let me work out sizes in the photo by measuring vertically using the wheel’s size as a reference. The gearbox, according to that method, is about 13.5 mm tall and the motor housing (the round bit at the top) about 7.5 mm excluding its pedestal.
This is the basic shape of the gearbox, built from 2 mm square plastic rod and some 1 mm card. I quickly decided against trying to build it hollow, because getting everything square would be a nightmare. Much simpler to build a solid block and file and cut that to shape:
The motor housing is two diameters of tube one inside the other (the outer is 7.1 mm) with a unched disc for a top and a bit of sprue as the basics of the pedestal.
There still needs to be plenty of detail added, as well as some basic shapes, well, shaped, but I’m getting there, I’d say
My M4/M4A1 manual says there are different types of gunner’s controls in the Sherman: electric or hydraulic. Photos I found of a restored M4A4 show the electric type, but would my subject have had the same? When I showed my father the last photo I posted of the turret basket and mentioned the different turret drives, he said, “we used to turn a handwheel” — referring to his playing in this exact tank in his youth, when it was on display outside the war museum (see the start of this thread). However, he couldn’t remember if this wheel was vertical in front of him (as per the electric drive) or horizontal on the right (the manual controls for the hydraulic drive).
Then I decided to check the M4A4 tech manual that is available online, and happily, that only shows the electric type. Great, because that probably answers the question and it’s the easier one to scratchbuild. Here is what it looked like:
But how big is it? The hands in the photo don’t provide enough of a clue, but the manual also included the following illustration, a bottom view of the turret drive and how it meshes with the ring gear:
I photographed the ruler with it because that provides almost all the information needed to work out the size for your own model, if you’re
It may not be immediately obvious how, but notice the two bolt heads drawn on the turret ring … because there were 32 bolts on the ring, you can work out what the distance between two bolts should be on your model:
This because the sine of an angle in a right-angled triangle can be found by dividing the length of the opposite side of the triangle by that of the hypothenuse — thus, if you know the length of the hypothenuse and the angle, you can work out the length of the short side.
Since there are 32 bolts, the angle between them is 11.25 degrees; we need half that angle, though, to get a right-angled triangle of which one side is half the distance between the bolts and the other important side is the distance from the bolt to the centre of the turret. You can just measure that last one on your model — on my kit, the diameter turned out to be almost exactly 50 mm, so halving that gave me 25. Multiplying that by the sine of half the angle results in half the distance between the two bolts, so it just needs doubling to get the full distance. In this case, that’s 4.9 mm.
Measuring from the top of one bolt to the top of the other in the drawing found that this was nigh on exactly 20 mm, meaning all I needed to do was divide measurements I took in the drawing by 4 to find how big all this needs to be in 1:35.
But we’re not there yet! How tall is the thing?!
That’s where the left-hand photo in the manual (page 330) came in. From photos, I judged that the handwheel’s left side is pretty much even with the left side of the gearbox. Other illustrations showed its axle to be offset to the right a little, so more measuring now that I knew the width of the gearbox, gave me a diameter of about 9 mm in 1:35 scale. That, then, let me work out sizes in the photo by measuring vertically using the wheel’s size as a reference. The gearbox, according to that method, is about 13.5 mm tall and the motor housing (the round bit at the top) about 7.5 mm excluding its pedestal.
This is the basic shape of the gearbox, built from 2 mm square plastic rod and some 1 mm card. I quickly decided against trying to build it hollow, because getting everything square would be a nightmare. Much simpler to build a solid block and file and cut that to shape:
The motor housing is two diameters of tube one inside the other (the outer is 7.1 mm) with a unched disc for a top and a bit of sprue as the basics of the pedestal.
There still needs to be plenty of detail added, as well as some basic shapes, well, shaped, but I’m getting there, I’d say