[JPS99]

I'm well  into printing my copy of Dean Rauch's very cool T-35a.
I first came across it on Youtube where his superbly edited and 'aged' video really grabbed me!  I was working on my 1/10 scale 3D printed IS-1 at the time, but now that it is complete (except for the TCB) I am relieving the Covid Lockdown woes by starting on this project.

At this point I have completed 265 hours of printing on my two Ender 5 printers. Still lots to do, although most of the rest of the parts will be smaller pieces.
I have all the tracks, road wheels, skirts, deck lids and the main superstructure printed. Printing the Main Turret tonight.
I have about 5 feet of track assembled so far (there's a fun job!) and have refined the assembly process to about 90 seconds per track link.

I'm also working on Kim (Heclo)'s TCB Hat project. I've had the PCB's build and have ordered the parts to complete. At age 68 it's a great time to learn how to solder surface mount components!

I have attached a few photos of my progress and will try to update here from time to time.
Cheers,
Joe/JPS99

[LukeZ]

I will be watching your progress with interest, and I hope Dean stumbles across this as well! I'm sure it will be flattering to see someone else follow in his footsteps.

The possibilities with 3D printing are really tremendous, but I have always been put off by the rough surface texture that seems like it would take an eternity to sand smooth especially on a scale model tank with lots of small parts and difficult to reach corners. However the printing quality seems to always be improving and the parts you are printing are looking worlds better than what people were doing several years ago. It's great that this method could allow us to realize some of the less-popular models the manufacturers are never going to produce but that we might always have wanted.

[JPS99]

Thanks LukeZ.  I didn't sand anything on my IS-1 aside from a couple of joints.. the mating surface on the two turret halves were quite large, but mated quite nicely after just a little work. Also, a lot of the surface detail like rivets and panel lines is printed on so you really can't sand in most cases.  Clever choices of cuts in the model can make a big difference. Lubos did a really nice job in his design I must say.
I am beginning to get excited about the T-35 build after seeing some of the nice deck and turret pieces. It really is a beautiful beast!

[Dean Rauch]

Glad you liked the video! It pays to have friends in film school.
Interesting that you just completed a 1/10 project, as my next one will be in 1/10 scale also.
Be warned my T-35 is more of a show tank than a driver! It hates grass and mine now has so much wear on the sprockets and tracks that I cant drive it anymore.
I may fix this and update the files in the future, but making all those track links a second time is much less appealing to me than starting the new project.
good luck and I cant wait to see the end result, as of right now I have only seen one other T-35 completed.

Dean

[JPS99]

Glad you liked the video! It pays to have friends in film school.
Interesting that you just completed a 1/10 project, as my next one will be in 1/10 scale also.
Be warned my T-35 is more of a show tank than a driver! It hates grass and mine now has so much wear on the sprockets and tracks that I cant drive it anymore.
I may fix this and update the files in the future, but making all those track links a second time is much less appealing to me than starting the new project.
good luck and I cant wait to see the end result, as of right now I have only seen one other T-35 completed.

Dean

Hi Dean, yes, the video is great as is the tank.  Yes, tanks printed from plastic will wear out. At my age I probably won't wear it out. ;-)
I can understand how completely rebuilding the tracks would be a daunting task.  The tracks on my IS-1 are printed in place in sections about 20 cm long, then the sections are glued together with the final joint being a 1.5mm pin. Much easier to  replace indeed.

I will be using Krasi50's transmission unit, any idea what size motors would be appropriate?
Also, as I'm working on the road wheels now I'm wondering what type of metal did you use on the bogeys as the 'return spring'? I've tried a couple of things, but they were too soft and had insufficient spring to them.

I lived many years in Canada, spent about 50 years in Ottawa. I have retired to Erie, PA (after some years in Phoenix AZ and Ann Arbor MI.
Erie is great but a little isolated. Can't seem to find any Tank activity in this part of the state.

Anyway, thanks for responding. I appreciate your help with my questions. You built a fine model and I look forward to completing it. You did a great job with the details and extra goodies for the tank.  I'm hoping I will be successful in building Kim's TCB hat and employing it to bring the T-35 to life!
Best regards,
Joe/JPS99

[JPS99]

I made some progress on the T-35 lately and wanted to share it.

I'd been really stalled on the suspension as Dean's design used a leaf spring on the road wheel bogies and I was unable to find a suitably springy metal. I'd seen another build on another website where the builder went with a coil spring design for the suspension.  I'm not sure if he used coils on all the wheels or just one on each side, the photos weren't clear on that, however it looked like an easier way to address the problem. I started my search on Amazon.com and eBay and finally located a 1/4" x 2-1/2" spring that looked promising.
I ordered them and once they arrived I fired up Tinkercad to design a way to mount them.

I use Tinkercad because it works with my brain.. I'm a visualizer/hacker not a designer. I've tried Fusion360 and was blown away by its power, but the learning curve was too steep for my old brain.  I guess if I actually had to design a large project, Fusion360 would be the way to go, but my needs are more for hacking out a part or two based on a picture in my head and Tinkercad, which is shape based cad, works for me.

I designed an upper spring holder with a swivel end and modified the lower suspension mount to handle the swivel. I then modified the bogey crosspiece to incorporate a lower spring holder/guide that would hold the spring and align it with the upper spring holder.

I printed out a test mount and spring holder assembly and found that with a couple of extra millimeters extension on each part, they would work well. I assembled one set and mounted it on the tank hull to see how it looked.  To see how this works please check out my Youtube video: 

Breakthrough #2 -  I have most of my track assembled, but wondered how durable and repairable it would be in the long term and wondered if it would be possible to print lengths of assembled track on my 3D printer with the joints built in.  I fired up good old Tinkercad, imported a track segment, duplicated it, then aligned the two sections together and then created a joiner pin.
When I had a two segment section that looked good, I printed it for a test, and it worked and hinged quite well.  I adjusted the pin size a couple of times to have the largest, strongest pin, yet still have a working hinge. Once I had that nailed, I printed up a section of 19 segment, about all that would fit on my print bed, and did a test print.  Luckily, it worked great!  I was able to flex all 19 segments and after a couple of pivots, it freed up nicely.

With those two problems solved, assembling the T-35 will progress much better.  I will try to update the forum on my progress.
Cheers,
JPS99/Joe

[JPS99]

Now that I have the suspension components figures out, I've begun the assembly of the lower hull. I've attached some photos for your perusal.

I'm waiting on some 5mm brass shafts to start building the transmission with. I'm using the "Krasi50" gearbox that was added to Dean Rauch's files on Thingiverse. It looks like an interesting design but I only have a single photo to work from for the assembly. Things will probably start to make sense once I begin fitting the gears in. I'll upload the photo for those interested.

I recently made a 'reflow oven' from a toaster oven and did a small board in it today.  It worked out pretty well, but I need to be more sparing with the solder paste it seems. I had to fix a few solder bridges, but the process appears doable.  I'm not ready to attempt Kim Anderson's TCB Hat yet, but I'll have to eventually if I want to get this tank moving! 

[LukeZ]

Hey Joe, it's looking good. It must be cool to see an actual "thing" start to materialize in front of your eyes from what were just spools of filament to begin with!

It's definitely true that less is more when it comes to solder paste, I seem to have to learn that lesson over and over. This is especially the case on ICs with small pins located close together, or on chips with multiple pads underneath (too much paste and the pads will bridge, and there is no way to fix it after the fact). Using a stencil greatly helps with placing an appropriate amount of paste, though it is possible to overdo it even then. I would suggest getting one for Kim's design. Occasionally for some packages it ends up being easier to just hand-solder, I found this to be the case with the ATmega processor on the original TCB, but I reflowed everything else.

[JPS99]

Hey Joe, it's looking good. It must be cool to see an actual "thing" start to materialize in front of your eyes from what were just spools of filament to begin with!
....... Using a stencil greatly helps with placing an appropriate amount of paste, though it is possible to overdo it even then. I would suggest getting one for Kim's design. Occasionally for some packages it ends up being easier to just hand-solder, I found this to be the case with the ATmega processor on the original TCB, but I reflowed everything else.

Thanks Luke. Yes, getting all those wheels mounted and working well is a big step.
Next is figuring out the transmission.
Next big hurdle is the TCB.   My drag soldering is not bad and fixing solder bridges is no problem either. The motor driver package is something rather intimidating. They will almost certainly need to be done in the reflow oven. I should look into getting a stencil.

[JPS99]

I just did the first test of my 1/16 scale 3D printed T35a tank drive and suspension, (STL files by Dean Rauch https://www.thingiverse.com/thing:3064387 )

I've incorporated a few mods in the form of the coil springs for the road wheels and (for the most part) print in place tank track vs individually linked segments.  In the video the suspension is working fairly well, but is still stiff and needs a lot of running in to free up the bogies and coil springs.  I now have the considerable job of making it look like a tank. There are a multitude of parts yet to assemble - the tank has 5 turrets and a crew of 11, so is quite a beast!  I will keep updating my channel as work progresses.

Warning, this thing sounds like a rock crusher!

[CodeWarrior]

Joe- That is a very impressive build that you're doing.  It's an interesting choice by Dean to model a fairly complicated tank. If I were even to attempt to create the models for an RC tank I think I'd opt to make something like a Stridsvagn 103 (turretless!). 
      Are you using ABS or PLA filament?

[LukeZ]

Good progress Joe. But I have been quite stumped about your "print in place tracks" and have tried to figure it out for myself, to no avail, so now I will ask. Are you not using a metal pin to join each track segment? I saw the picture you posted earlier of a series of track segments being printed at once, but that was early in the process, after only a few layers, and as yet there is no hinge-pin visible.

It is beyond my ability to imagine how you could print a "pin" inside a floating hole to link the segments. Can you explain your wizardry further? It might help some others who are printing tracks!

[JPS99]

Joe- That is a very impressive build that you're doing.  It's an interesting choice by Dean to model a fairly complicated tank. If I were even to attempt to create the models for an RC tank I think I'd opt to make something like a Stridsvagn 103 (turretless!). 
      Are you using ABS or PLA filament?

Sorry to take so long to reply.  I guess I need to turn on notifications.
I do most of my printing in PLA.  I've had good success with ABS in printing track segments, but was never drawn to it beyond that.

[JPS99]

Good progress Joe. But I have been quite stumped about your "print in place tracks" and have tried to figure it out for myself, to no avail, so now I will ask. Are you not using a metal pin to join each track segment? I saw the picture you posted earlier of a series of track segments being printed at once, but that was early in the process, after only a few layers, and as yet there is no hinge-pin visible.

It is beyond my ability to imagine how you could print a "pin" inside a floating hole to link the segments. Can you explain your wizardry further? It might help some others who are printing tracks!

I have had good success with 'print in place' objects. I have a printed motor, 3 cylinder with pistons rods and crankshaft that all rotate as you would expect, all printed in one piece in PLA.

I first learned of Print in Place tank tracks on IS-1 project. Lubos Hort had created them for his rendering and they worked perfectly. 
After laboriously assembling the individual segments for the T-35 Dean created, I started thinking life would be simpler if entire sections could be printed.
I just imported a segment into Tinkercad, duplicated it, then aligned them so the pin holes lined up and created a pin and put it in place, allowing for a few tenths of a mil clearance, then exported and printed it.  Takes about 30 minutes to print a two segment track which i then evaluate for swivel motion.  If too tight, I just shrink the pin another couple of tenths and keep trying until it works well. in places the pin will bind to the segments, but if the clearance is reasonable, it will break loose and allow movement.

I will try to attach a sample file in case anybody is interested. Also a link to a Youtube video showing some interesting 'print in place' items I've printed.

Cheers,
Joe

[JPS99]

Forgot to add an update to my T-35 project!
This is a paste from the description on my Youtube video. Sorry, I'm Laaaaaazzzy!

This is the second test of my 1/16 scale 3D printed T35a Russian Tank.
I now have 2 ESCs so I can test the turning ability of the tank.
I am controlling the tank with the open-source 2.4ghz micro transmitter designed by TheDIYGuy999 as well as his own design micro receiver. Both of these designs and more are available, please check his Youtube channel for more information at https://www.youtube.com/user/TheDIYGuy999
The tank itself can be found on Thingiverse   https://www.thingiverse.com/thing:3064387
My testing today revealed a weak point in the tread design. The tread on the right side of the tank was printed as individual segments joined by 1.5mm wire pieces while the tread on the left was my hack - I imported one track segment into Tinkercad then duplicated it and joined it together with a 1.5 mm rod and duplicated into sections that would fit onto my 3D printer bed. I created different lengths of segments to assist with the final total tread count and to have on hand for replacement. My goal was to have as few metal pins as possible.
I anticipate problems with the pin joining method so I will endeavor to  increase the size of the joining surfaces to make them stronger. I will also attempt to add the segment alignment tooth that sticks up from the track and is what guides the track between the wheels. Currently these are glued on individually and are a real PITA!   
The track segments were designed to print upside down so I  will have to see if it is possible to print them successfully right side up so I can  print the alignment tooth along with the tread. The T-35 is such a long tank that the treads are incredibly long and because of the large surface area  invite problems. It does not help that they are somewhat spindly as well, compared to the IS-1 and T-34 tank.
This has been a fun project and once I can get my chassis rolling along reliably I will complete the superstructure and turret detail.