spinnetti

Thanks Bob. Way I look at it is, 1/6 scale is ideal for me for both Tanks and planes but I'll never have the space or money for the dozen or so each of the airplanes and tanks that I want. 1/16 is just too small for both tanks and planes for me, and bigger than 1/12 for my airplanes is just a bit too much storage and transport hassle, so 1/12 it is and its just half of 1/6 - I'd say 8th and 10th are more odd! (I can also fly that size out of the back yard). I also like treading new ground that others haven't already gone down. I do build fully scale and scale working landing gear for Luftwaffe birds in 1/6 scale including lately the Do-335, Ta-154, He-111 and Ju-88 with both machined and printed components. Nick, I had no idea you could get action figures in 1/12, but that makes things a lot easier! I'll post another pic when I get the steering brakes figured out, no doubt this weekend.

RC_BobM

spinnetti,
I agree - I love my 1/6 stuff, but they are monsters to move, store and take anywhere. 1/10-1/12 is ideal. Not to mention a home equity loan to finance. Check out Monkeydepot.com for 1/12 figures. You can find STL's and print your own scale figures too - that's something I'd like to do. I like the 1/16 scale, much easier to store and collect, but just don't quite have that "big tank" look and feel.
Post more as you make progress. Are you planning on printing at home or outsource? Shapeways is expensive for printing large parts - I priced one of Tomas Fudor's 1/6 Hetzer parts at over $800 in their basic Nylon plastic. That was just one large hull part. Simply not feasible.

Bob

spinnetti

Thanks for the feedback Bob. I had shapeways print once, but was not happy with the result. I'll do it all myself. I've got both FDM and resin printers (and used to have and will have again a machine shop for that matter). I'll check out Monkeydepot.

RC_BobM

One last note about Shapeways - I do like their metal printed parts. I've had great results with steel, brass, and aluminum. Their prices for small metal parts is high but not horrific. But only for small parts --the cost is exponential w respect to volume of metal (ie size of part). I like to print the hard to machine small parts in brass especially.
Bob

spinnetti

Got the Differential install figured out and fully mounted properly, driveshafts sorted as well as the brake drums. Still need to finalize how I want to do the brake bands. First Diff I bought had a bad ring gear, but the replacement is good. The diff barely fit and I had to clearance the front hull plate to get it in there. Total gear reduction is about 1:32 (1:4 in the diff, and 1:8 in the final drive) so it will have monster power, but a low top speed with a brushless outrunner. I haven't done all the math to figure out the motor KV, but pretty soon. I'm printing the diff cover as I type this, and will section the hull soon and trial print that - it will print in 2 parts.

Crius

It says above that you'll print the lower Hull in fdm, but from that fantastic print quality in the photo I'm guessing that you printed the prototype in resin? It looks really great, you're getting a most excellent print quality.

spinnetti

Sorry to mislead - that's the CAD model post processed in imagining software, not the actual print. Prints look like Prints look unfortunately! I've printed some of the bits here and there, but getting close to printing the lower front hull section to test the drivetrain fit. Just calculating gear ratios now - I might need to redo the final drive ratio.

spinnetti

Making steady progress... Happy to figure out the driveline brakes finally.. will be fun to see how they work.

herrmill

My jaw hit the floor with that last photo before I read the follow up post. Some very nice work, there!

I have to agree with Bob that 1/12 is an odd scale but then it appears the market is pushing more in that direction. FMS recently released their latest Willies MB in that scale & all of HG's releases have been the same. Even KY Model is following suit & is soon to release their upsized Schwimwagon for Torro in 1/12. When I asked why not 1/6 or even 1/10 to fit in with the crawler crowd I was told it was too big! Not many 1/12 figures on the market to dictate vehicle decisions so figured Torro simply wants to make a killing on their accessories as they always do.

spinnetti

Well, if you look at R/C cars, 1/12 scale was the defacto standard since the 70's from the days of COX... Doesn't matter really. I just like doing my own thing to suit my purposes. What I really hate these days is RC plane makers making them all the same wingspan instead of the same scale. Easier for manufacturing, but horrible if you want a scale combined arms fleet like I do. I'd definitely go all 1/6 scale if I had the space and money, but 1/12 is next best thing for me. since even a 1/8 or 1/10 scale bomber for instance is just too big to fly from home and store in the house.

RC_BobM

Spinnetti
That is really cool and thanks for sharing the details. You'll prob want a metal gear servo for the braking action. I'm curious how well it will work. It definitely models the real tank.
Bob

Kear-Skof

To further water down the soup, some "1/10 scale" scale trucks/crawlers measure in at 1/8 scale for stuff like the Tamiya Hilux, while a lot of others range from 1/10 to 1/12. Crawler scaling is a very interesting mess.

herrmill

Agreed, it is what it is. My HG Humvee is supposedly 1/10 but more closer to 1/12. We have a 1/10 D90 crawler from a local Chinese manufacturer but its closer to 1/8 & looks YUGE!!! sitting next to the Hetzer. Gave up on trying to find suitable figures so we stick with the Marvel Comics line for now.

spinnetti

Lots of details this eve. Printed the diff cover, brake drums and brake covers. Finalized component placement and put fasteners bosses on all the bolt on parts and holes in the hull to mount them (very tedious!). Designed the track tensioner and refined the brake bands and mounting. Did lots of other little tweaks all over too. Bearings and driveshafts on the way, and I think I have a motor in my airplane stuff good enough for a trial. Split the hull, and am printing the front half now to test parts fits - it BARELY fits and fills the entire build plate, which I guess is perfect really lol. Print quality is turning out excellent. Even at 1/12 scale, this is a pretty itty-bitty tank. When I eventually get to the Tiger, that will be something else to break up for printing.

RC_BobM

Spinnetti,
Good to see you use a Prusa. I've got one too, I'm just now getting it running. Great project for the Prusa!
Bob

spinnetti

Its a really great printer, with lots of potential ahead, particularly in software. This was just a trial print for general settings, and even in draft mode I was impressed. I used scale thickness for the hull, but the bottom is a bit too thin for scale; will need to make a bit thicker which means I have to tweak .... well dang near everything lol. Differential fits well though.

RC_BobM

spinnetti,
Glad you like the Prusa. I'm looking forward to making lots of tank parts with mine. What material is the hull? You may be surprised by how strong it is - even at scale thickness. I have Tomas Fudor's 1/6 Hetzer to print - although I cannot print all the hull parts with Prusa.

How are you joining front and rear hulls?
B

spinnetti

Bob,

This is just PLA. Studied lots of materials, and given stiffness is right up there in my requirements PLA has a great mix of properties. I'll add some stiffening ribs here and there and it will be good. I'll probably both glue and "bolt" the hull halves together and have an interlocking mating flange. Just tweaking a few of the fits then will add those features and reprint here in just a bit, but overall really pleased both with the results and the design process. I don't enjoy all the fussy little exterior details because they are really just decoration, but really enjoyed designing the suspension and drive system. Gun mount will be fun too.

spinnetti

Steady Progress.. Printer running pretty much non-stop, trying, fine-tuning, and adding more detail. Hopefully the bearings will be here shortly, and all the other hardware today or tomorrow. Soon I'll have to quit stalling and print out the umteen track segments lol.

RC_BobM

That's looking slick. Great work on the CAD! Excited to see this one printed and put together!
B

Biasphere1

Wow! Now I see how I can make STL files I had been previously buying them and making RC models.
Awesome thread guys.

spinnetti

Thanks! Definitely more fun being a designer and maker instead of a consumer, but some engineering skill helps. The overall design/build is really going well. This is my first tank, but I think I've got the hang of it - very little rework or adjustments have been required, mostly just running a little looser fit tolerances due to the impreciseness of 3d printing. Quite happy how its going. I got the hardware, but still no bearings. Keeping that printer humming, trying various printer settings and orientations to get the wheels to come out acceptably. I've got a very novel way to join the upper and lower hull that should make it super stiff - I won't spill the beans until I prove it out first but won't be like any other.

spinnetti

So, one big experiment worked out better than I hoped. I took a gamble and made the springs exactly like the real thing - Same number of leaves (16) and exact scale thickness and camber of the springs. I individually modelled each spring printing each separately and assemble them in the full scale way. Much to my delight, they feel just about perfect, giving supple articulation and looks like just about the right amount of support.

RC_BobM

Looking good! Looks like your tracks were resin printed? I've printed quite a few 1/6 resin links - they fit together wonderful. Not sure if they'd hold up to powered RC use however. The resin parts seem strong, but brittle. I've had decent luck mixing a toughened resin with an ABS like resin.

Will be interesting to see how the "springs" hold up over time and use. Really cool project -a real gem.
Bob

spinnetti

Thanks Bob. I wonder at longevity too. Given how little it will actually get driven around I suspect it won't be an issue, but we'll see - I did use the "ABS-like" resin. I can FDM print them but I liked the look of the SLA ones better. Spring are a good question too, but the combo of thinness and number of springs leads me to believe they will work pretty good. I've got all the springs printed now - all 64 of them! and need to get some metal rod for a couple things including mounting the leaves, and mounting the pack to the bogeys. Of course, testing and refining is half the fun, and I can always print more! Even making all my own stuff, this ain't cheap to build. I've used more than 40 bearings already plus $100 worth of fasteners and more stuff to order still.