M41 Cargo Tractor (1/35)

[apophenia]

... in the meantime, I printed out some seats, radios and bits...

That is one hell of a print-run! And amazing detail on those smaller parts 

[Frank3k]

I paid for that build plate! Surprisingly, I didn't completely fill it.  Adding more parts doesn't take longer (just uses more resin).

[Frank3k]

This one went on the back burner for a while, for a stupid reason - I couldn't figure out the best interior layout, the floor and the back wall. So after a lot of faffing about, I decided to just print both cabin styles and the doors.

In the picture below, the supports are off and the parts are fully cured but they still need cleaning. The discoloration is from not thoroughly mixing the resin in the vat (it's been sitting there for a while). It's just cosmetic. The LED light covers were too thin and didn't print properly and the external AC units were literally printed microns too high and luckily, they just popped off in my hands (and not in the vat). I'm using a slightly different CAD modeling workflow, which makes it easier to modify the design, but it also means I have to be more careful before I save the file, so i don't miss objects... like one of the windshield wiper posts:



I still have to remove the support nubs. This is a slicer detail - I can make the support contact points smaller so they don't leave these nubs (or leave craters), but there are pluses and minuses. Since the cabs are heavy/large, I went with the larger support contact points/depth. This is a door - inside and outside. The nubs on the inside look like bolts, but They'll have to come off:



The inside, where all the heavy lifting (or supporting) is done looks bad. The AC units took some damage when I removed the supports:



Doors on both:



I used the FDM printed floor and placed it on the M41 lower hull. The hole on the lower rear of the cab may be the hold to swing the cab forward to access the engine compartment:



Same with the LED version:



Here I reversed the lower hull, so the drive is right next to the engine. Shorter transmission distance:



Here's Nigel modeling the seats I printed earlier:



It's both a roomy and cramped interior:



As much as I liked the LED light bar version in CAD, I like it a lot less in reality, so I may just stick with the regular cab.
I may also just reprint the regular cab with the doors closed. It solved the issue with ultra detailing the interior, but still allows the interior to be seen through the windows.
I may just print the floor on my FDM and print some of the details (like the engine cover) in the resin printer. I may do the same with the rear wall of the cab.

[Story]

How about the cannisters & such for an NBC Overpressure system, since this thing reeks of being in the support train of an Atomic Annie?

https://www.warhistoryonline.com/cold-war/atomic-annie-cannon.html

https://taskandpurpose.com/history/army-nuclear-tests-desert-rock/

[Ramba]

The cab came out great!

[finsrin]

Liking this one already.  Can tell its gunna be good.

[Jeffry Fontaine]

Drive sprocket at the front = double-plus good. 

LMK if might want to try using the lower hull from the Academy 1:35th scale M551 Sheridan.  I have some that are gathering dust/taking up space. 

[Kerick]

I would have to try and make snow cat style tracks somehow. Sounds like research might take me up to Alaska! Or at least the Rocky Mountains.

[Buzzbomb]

Working very well, the seats look great

[Frank3k]

Thanks, guys. Jeff - let me think about the Sheridan lower hull. I think it's wider than the M41.

I decided to reprint the cabin with fresher resin and a different orientation, but with the doors "glued" shut. I also printed the back wall and floor flat on the build plate. Doing this has some issues since there tends to be an "elephant's foot" where the model meets the base, caused by the longer exposure required to stick objects to the build plate. The effect was minor in this case, although the floor parts warped slightly after I cured them - I made them too thin. Expanses of thin, flat resin will warp.

Here's the cabin. I wanted to leave a small gap between the door and the cabin. I didn't properly support the thin window frame and it peeled away. I may just putty and rescribe or cut the doors out. I haven't removed all the supports at the rear of the cabin and they almost look like they belong, but I'll remove them.



I supported the cabin with the front facing straight down into the vat (vs the previous prints, where the roof was facing the vat). It meant fewer supports in the interior. You can see one of the floor prints to the right (and one of the back wall prints):



Cab with the back wall. I still need to sand the back wall edges down a bit:

[Jeffry Fontaine]

@Frank - you are right about those support nubs.  They certainly do look like they belong on the rear cabin wall.

[apophenia]

@Frank - you are right about those support nubs.  They certainly do look like they belong on the rear cabin wall.

Agreed. Somehow that line of nubs make it look as if the Cargo M41 will just go faster 

[Jeffry Fontaine]

@Frank - you are right about those support nubs.  They certainly do look like they belong on the rear cabin wall.

Agreed. Somehow that line of nubs make it look as if the Cargo M41 will just go faster 

Speed Bumps? 

[Frank3k]

Third time's the charm, I guess. There has to be a 3D printing equivalent of "measure twice, cut once". I played with the previously printed parts and came up with a better orientation on the build plate. I made the floor thicker and attached the engine cover and back wall to it in my CAD program. The exterior of the back wall stays the same. The slots on the floor are for the Pantsir style seats I printed earlier.
I was careful with the cab supports, so it minimized external and internal support nubs. Same with the doors, which I printed vertically.

Parts:



With one door tacked on. The M41 looks small (the cab is big - twice the length of the HEMTT's cab, about 25% taller):



With the door open. The other door (with no support marks) is on the mat. The white residue is from wet sanding the visible supports:

 

[Buzzbomb]

This is so cool. The design work on the 3D elements is first class.
Build is ok too. 

[Old Wombat]

 

[Jeffry Fontaine]

@Frank -- Why bother removing the tiny bumps?  I think they do a great job in suggesting that the cab is assembled from multiple components and retained in place by fasteners to allow quick removal of each component if it needs replacement due to damage, etc.  That way the "speed bumps" from the support structure can remain and be part of the model back story description. 

That said, it looks great! 

[Frank3k]

Thanks, guys!

Jeff - the support bumps look ugly to me - the exterior is supposed to just have the plate armor? bolts holding them in place (or as bolts for additional armor).

Next, I'll come up with a cargo area and start building the cab.

[Buzzbomb]

Agreed frank, the support points are small but in most cases just don’t look right. Can be aright pill to remove as well if in out of the way places

[Frank3k]

Supports are a battle between getting the print to print correctly (or at all) and an ugly mess of pips or craters. I have to play with the support heads - size and depth. The supports I've been using peel off easily in warm to hot water (after the parts have been cleaned but not cured). This isn't always possible, since curing can warp thin parts and leaving the supports in helps reduce warping.

While looking for parts for this build, I came across the partially built hull of the 1/35 M270 NATO MLRS. It had been rattling around in my stash since the early 90s. I eventually parted it out, with the rocket parts going to Jeff and the cab to another project. I have the wheels and track and some other parts in one of my spare parts boxes. so I decided to put one of the cabs on the hull:







The cab fits perfectly. If I remove the engine box, I can move it back and allow the forward tow hooks to be used. I don't think I would have gotten this good of a fit if I'd done it intentionally. I guess I have to print another cab.

[Buzzbomb]

Good call. Double the load capacity space already

[Ramba]

Looks much better on the MLRS hull.

[Frank3k]

Currently printing another cabin and the walls for the M41 cargo section. I started to scratchbuild it, but I realized that the CAD + Printing time would be much less. Here's what's cooking on the plate:

I looked at images of M1078 trucks and "borrowed" the cargo wall details and the taillights:



The floor of the cargo area and the front fenders were printed on my FDM printer. I may have to reprint it to make it slightly longer, or adjust the cab position:



Hopefully it'll look like this on the M41:



Tomorrow it's time to don the meth lab resin printer PPE and wash and cure the print.

[Jeffry Fontaine]

No barrier at the front of the cargo bed?  It looks unsupported without some kind of connection to the opposite side walls.  Other than that, I like it a lot!  Nice, Nice, Baby!  See what I did there? 

[Frank3k]

The wall at the front of the cabin is basically a blank, fat U shape (flat wall, two uprights at the ends), so I'll either print a flat slab on my FDM printer or cut out some styrene to match. Printing thin flat pieces on a resin printer can be a pain. I also have to figure something out for the machine gun hole over the cabin.

I was thinking of ways of disabling/defeating drones - especially fiber optics drones - that could protect a large area. Hmmm... maybe EMPs or microwaves? it turns out that the Epirus Leonidas is making one. I may make that an option for the MRLS version.