[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!

Luke, the 3D printer will print where there is a pin and nothing where there is a gap. Of course filament doesn't hang in mid air but the areas where the pin plastic sags and contacts the track segment below do not bond well and are broken loose after printing.  It's somewhat magical, but you'd be amazed at what can be printed in place!

I've attached a few photos from Tinkercad of the track as I modified it and there is another photo of a 20 segment track that I just printed. I turned Dean's segments right-side up, aligned them together via the pin holes, added an undersized pin as well as the segment tooth ( what I call it) that guides the track through the wheels.
This one comes up a bit stiff, but with a little 'working' it frees up nicely!

I've concluded that the reason the track segments are breaking (as you saw in my video) is that i am drilling them slightly in order to fit the 1.5 mm wire I am using as pins.  I have now ordered some 1.3 mm stainless rod that I will use for the pins, hoping that I won't have to drill out the segments and thus weakening them.

[LukeZ]

Ok, I understand now. There is of course no way to print the pin in free air, but I gather that it is "attached" to the tread segments only at a very small point which can be broken after printing such that the tread segments then move freely. I can see there is some trial and error involved in getting it all to work but you are making good progress!

[JPS99]

I've been questioned on the 'print-in-place' tank tracks I have on my tanks so I thought I would bring a few details into the picture.

I'm on version 7 of my T35 tracks. Originally Dean Rauch made them as individual segments, but I had problems with my tracks breaking, probably because I had to drill them out slightly to insert the 1.5mm pins I was using (actually soft steel wire cut into ~32 mm lengths.  It was also a LOT of work assembling the 132 segments per side, so, being a lazy cuss I instead fiddled with them in Tinkercad and came up with a printable version of 20 segments. I join the sections of track using a 1.3mm stainless steel pin now, and hopefully that will be more robust, since I don't have to drill the segments to fit the steel pin. I've also printed up 12 segment lengths as well as a few 1 and 2 segment pieces for repairs.  I have also modified the track so that the road wheel guide pins are printed as part of each segment, instead of having to glue them together.

I made a short video of the tracks and a test I did yesterday. They are slowly becoming more robust.  Right now I have a mix of probably 4 or more versions on the T35 and have become quite proficient at replacing broken segments!

Here's a comparison video 

and here is a video of the outside testing. 

[JPS99]

Codewarrior expressed an interest in seeing a time lapse video of a track being printed.
I don't think this shows too much as it's pretty small, but here it is!

[CodeWarrior]

Joe-   Thank you for posting the video showing the tracks being printed in place and your other updates.  It's clear that it takes a bit of time to print even just two track shoes.  I'd like to understand the track assembly process a bit better.  Can you clarify the process of inserting the pins?  I'm assuming that you remove the tracks from the printer plate,  drill out the holes for the pins and then insert the pins? 
     I'd like to ask a few questions about the track/pin design if you don't mind indulging my curiosity for a bit:

• What is the actual failure mode of the tracks?  I'm assuming the plastic fractures at the hinge joints (or knuckles as I believe they're called), is that correct?
• If the failure mode described above is correct is it possible to make the hinges thicker at the hinge knuckles?  Once again I'm assuming that is what your design iterations are working on.
• Can you use thinner wire to effectively increase the knuckle thickness?  I suppose the limitation here might be the small diameter of the drill bit itself as too small a bit will break easily.
• Any idea why the original designer chose to print the guide horns separate from the track shoe itself?
• Is it possible to use an acetone vapor-bath to help fuse the individual printed plastic extrusions together?  I used this on several of my ABS prints to help smooth out the rough surface texture inherent in 3D printed parts which I believe Luke once made reference to.  Perhaps a full-on vapor bath wouldn't be required but maybe "painting" just the track hinge knuckles would strengthen the joints. 

      I likely got way ahead of myself or you've probably considered all of the possibilities I described above but my curiosity has gotten the better of me.
      In the video of the T35 running outside its performance on the brick, and even the larger stones, was impressive.  I found myself holding my breath a bit somewhat expecting the tracks to break or slip off the road wheels.  I would think that, if you could run the tracks for a number of hours without breakage you would have a successful design. 

[JPS99]

Joe-   Thank you for posting the video showing the tracks being printed in place and your other updates.  It's clear that it takes a bit of time to print even just two track shoes.  I'd like to understand the track assembly process a bit better.  Can you clarify the process of inserting the pins?  I'm assuming that you remove the tracks from the printer plate,  drill out the holes for the pins and then insert the pins? 

Hi Eric, actually I print the segments (usually twenty at a time) and the first and last segments have open holes (no pin printed), so I don't have to drill out the holes.  I had been drilling slightly to enlarge the hole because I was joining with 1.5 mm wire. Now that I'm using 1.3 mm I no longer have to drill and this results in a stronger track hinge.

     I'd like to ask a few questions about the track/pin design if you don't mind indulging my curiosity for a bit:

• What is the actual failure mode of the tracks?  I'm assuming the plastic fractures at the hinge joints (or knuckles as I believe they're called), is that correct?

Yes, the rest of the track is quite sturdy. The knuckles were a problem when I drilled them out. The print-in-place tracks now break when the pins give out.

• If the failure mode described above is correct is it possible to make the hinges thicker at the hinge knuckles?  Once again I'm assuming that is what your design iterations are working on.

Yes, that's exactly what I was attempting to do, but I tried probably half a dozen mods and then tested by printing a few segments but they were not breaking loose at the hinge, so obviously I was doing something wrong. I may try again in the future.

• Can you use thinner wire to effectively increase the knuckle thickness?  I suppose the limitation here might be the small diameter of the drill bit itself as too small a bit will break easily.

As mentioned above, that's what i did. I ordered some 1.3 mm stainless rod and it seems to be working better now. I tried to make a crude measurement jig by suspending a section of track from the ceiling on a hanging scale and then hanging a gallon jug from the bottom of the  track. I filled the jug up and it still held together - 8.75 lbs!  I added almost 4 pounds of stainless shot to the jug and repeated the process. The track ended up supporting 12.5 pounds without breaking. That's quite a weight!

• Any idea why the original designer chose to print the guide horns separate from the track shoe itself?

Yes, he wanted to print the track on its flattest surface, which is the top, where the guide pin goes. He also printed individual segments and joined each with a fine pin.  He reports that his T35 is no longer in use because of track and sprocket problems.  I can understand how the track is a pain, the way he did it.  I am lazy and forsaw that I would grow tired of building tracks so I got brave and brought a segment and guide pin into TinkerCad,  flipped the segments over, added the guide pin and a plastic hinge pin, then duplicated 19 more to get my 20 segment section, which is close to what I can fit on my Ender 5 build plate.

• Is it possible to use an acetone vapor-bath to help fuse the individual printed plastic extrusions together?  I used this on several of my ABS prints to help smooth out the rough surface texture inherent in 3D printed parts which I believe Luke once made reference to.  Perhaps a full-on vapor bath wouldn't be required but maybe "painting" just the track hinge knuckles would strengthen the joints. 

I hear that works on ABS, but pretty much melts PLA, which I use.  I think it would also glue the segments together hopelessly. I'm pretty happy with my track now.  I think once I completely replace all the test sections with my V6 track it will be pretty reliable.  I will have to avoid carpet though as the tracks are extremely 'grippy' because of the fine filament fragments that are on the bottom because I am printing them upside down without support.  I've gotten rid of some of that by modifying the segment to leave less of a gap from the build plate. I think as long as I avoid carpeting which has loops I'l be okay as the segments work like velcro on it. I drove over a small mat on my shop floor and it picked it up and wrapped it up over the sprocket and had about 18" of it attached to the track before I got it stopped! It works great on cement floor, as I've done a lot of zooming around in my shop. It should be good on asphalt too. I need to avoid mulch and gravel as they will jam it, I'm pretty sure.

[/list]
      I likely got way ahead of myself or you've probably considered all of the possibilities I described above but my curiosity has gotten the better of me.
      In the video of the T35 running outside its performance on the brick, and even the larger stones, was impressive.  I found myself holding my breath a bit somewhat expecting the tracks to break or slip off the road wheels.  I would think that, if you could run the tracks for a number of hours without breakage you would have a successful design.

Yes, that's my goal.

I'm getting to be comfortable with the track, so now I'm playing with sound!

[CodeWarrior]

Joe-
      Sorry it took so long to respond,  it's not for lack of interest!  This forum is the first one where I have been active at all, even to the small degree of that activity.  Anyway, I was checking back daily expecting that a response to a post that I had made would be flagged.  I know now that that only happens for PM's.  Live and learn, I suppose.
     It sounds like you have invested a lot of time, thought and effort into making a good track design.  If the tracks can support over 12 pounds I would say that you have succeeded in coming up with a very good track design.  It seems to me that it could make the T35 a viable tank for battle if that's the intent, and, at a minimum, worth the effort to print one up and tool around in.   I must admit:  The addition of sound really makes the tank come to life.  Hopefully you're now on your way to finishing off the superstructure, turrets, etc...
    Also-  thanks for your detailed responses to my slew of questions.   This helped to clarify some details about the tracks.  Please keep us posted on your progress!

Eric

[LukeZ]

Anyway, I was checking back daily expecting that a response to a post that I had made would be flagged.

Hi Eric, if you click the "Notify" button at the top of a thread the forum will send you an email when a new post is made, that way you don't have to keep manually coming back and checking. There are further user-specific Notification settings if you go to your Account Settings and under "Modify Profile" go to the "Notifications" section. 

[Hoover]

I too am making the T35, 90% of the body and wheels printed but still have the fun part to do( track links) also printed part of the gearbox parts but struggling with assembly as I’ve no reference photos

[JPS99]

I too am making the T35, 90% of the body and wheels printed but still have the fun part to do( track links) also printed part of the gearbox parts but struggling with assembly as I’ve no reference photos

Yes, it sure would be nice if this thing came with instructions! Are you building the Krasi50 transmission that was posted in the comments on Thingiverse?  If so I can give you some tips.  Also, if you want, I can post my STL files for the print-in-place tracks I'm using.
Good luck!

[JPS99]

Hello, I just finished printing a few small parts and I know how interested some of you are who haven't yet committed to a 3D printer.
I'm attaching a couple of photos I took of a Hatch for the T35 as well as some little hinges for another hatch.  I've photographed them beside a metric ruler so you can get an idea of how small these are.

For a NON-SLA printer I'm pretty pleased with how these turned out on my Creality Ender 5.  I didn't even make special effort to accomplish this. I printed using a 0.20mm layer height ( I could have gone to 0.12, possibly 0.07 if I'd tried) so I'm pretty happy.

You might not be able to tell from these photos, but the hinge pin holes are clear and usable on all of the hinges.
I'll post some more shots of other detailed pieces in the future.
Cheers,
Joe

[CodeWarrior]

...if you click the "Notify" button at the top of a thread the forum will send you an email when a new post is made, …. There are further user-specific Notification settings if you go to your Account Settings and under "Modify Profile" go to the "Notifications" section. 

Thanks Luke, now being notified.  There is a lot of flexibility that the forum settings offers, I appreciate your mentioning it.
      Looks like Joe may now have a fellow “Brother in Arms”!

[JPS99]

I've had some time to work on the T35.  I got the main turret rotation servo installed and working. It required cutting out some of the deck and hull to fit the servo, but not too difficult.  My servo pinion which engages the turret ring kept getting snapped off. I ended up adding a 2mm section of turret as a spacer to allow more clearance.  It's pretty simple in PrusaSlicer.. i just brought the main turret STL file into the slicer and dropped it until only 2mm was showing above the build plate, then printed it. It fit perfectly.

Here's a link to video of the turret test: 

I've also got the side skirts on and most of the superstructure now together and finalized along with working out mounting points for the superstructure sections. They need to be accessible for access to the battery and other electronics, certainly as long as I'm working out the details.  I plan to use Kim's TCB hat for the final control of the tank, but currently I'm just using an 8 channel receiver and the ESS Sense One sound unit as it requires a lot of volume to overcome the super noisy drive train. I know that Kim's design has a powerful amplifier, so I'm sure it will work out, however there's not much room in the hull for a good speaker, especially the Krasi50 gearbox takes up much more room than a Heng Long gearbox.

I put together a video slideshow of construction photos which may help others who embark on this project.  I'll add more photos and videos as progress wraps up.

[JPS99]

Okay, I gave it a good try, but  after 7 or more variants of the print in place track with poor reliability, I'm throwing in the towel on that idea.
On the plus side, I did modify the track segment so it could be printed with the guide pin in place, so that was a win, but  I am now assembling my segments with 19 gauge (1mm) steel wire and the wire pushes in quite nicely.  Since I'm no longer drilling the segments to accommodate the larger size wire I first used (1.5mm) the segment hinges will be stronger and the track should be much stronger. Definitely is more flexible.

[JPS99]

I made a Youtube video showing how I modified my turrets to rotate and elevate the cannon.