My 5 year old son and I took on the Truggy as a project. He loves building stuff and I enjoy the time I get to spend with him. I would pre-assemble the differentials and then take them apart, bag up the pieces we needed for that build and the next day I would let him put it together. I would set the pdf of the exploded view in front of him, hand him a screwdriver, and sit back and watch. Doing it like this he was able to build all 3 differentials and their housings.
It took us a couple months to complete it since all we had to start with was the printed parts and we made the mistake of going to a hobby shop for screws that I could have gotten from mcmaster carr. All in all in was worth it though and now we are enjoying driving it.
The Truggy is printed in PLA at 30% infill with the differentials printed at 100% in ABS. Driveshafts were printed with PLA at 30% as well and my printer was tied up so I vacuumed out the air and replaced it with an acrylic lacquer. I waited 24 hours but that wasn’t enough and the front driveshaft broke at the front pin. I’ve since printed a set in ABS and ordered some metal dog bones but for now it is still running the ABS driveshaft in the front and the PLA driveshaft in the rear. I ran it pretty hard in some tall grass for about 10 minutes before the first driveshaft failed though.
The next thing to fail was the Center differential gears. I happened to have a spare set of gears sitting in a bag so I replaced them and this time I left a gap in the differential gear housing. After the next 10 minute run the front differential failed in the same way. I will re-build that one and leave the gap there as well. Since I smashed all of them shut before reading here that they need a little gap, I’m expecting the rear to fail next lol. I also drilled out the pin hole on the gears ever so slightly because the gears were next to impossible to get on the pin.
So, here is my question… Why the gap in the gear housing? What was the reason behind designing it this way?
Thanks for making this available to all of us and all the hard work that went into this.
Not sure about the gap, but if your front diff fails before the rear one then you have too hard brake mode on your ESC.
Thanks, yeah this thing will lock up all 4 when I brake. I guess I need to get the programming module and adjust that or just not get on the brake so hard 
Absolute most of the escs have throttle programming ability. Check the manual. It is a bit tricky but fairly easy.
Will do. I got the one from hobby king listed in the BOM. I’ll look tonight and see if it can be programmed without the USB module. Back in the day with my RC planes and my old castle creations speed controllers you could do it with the transmitter but was a pain.
@John_Seaton thank’s alot for the report, it’s the best reward to read about you and your son building the car together!
I’m sorry for coming in late with an answer.
About the gap in the housing, I’m not sure I understand what you mean. There should only be no gap once finished.
Sorry, I thought I read somewhere that when assembling the differentials there needed to be a small gap and I assumed it was to not put too much force on the gears. Maybe I didn’t read it right.
It’s all about the meshing of the gears - the correct gap between them.
Usually, if you can run a strip of a really thin paper, like from some newspapers or the packing of burgers there they’re good.
@John_Seaton Ah, ok i know what you mean. Here’s the gap thing explained and why I mentioned it. When gears and casing are printed, put the gears in place and put the half’s of the casing together. Here’s when the gap comes into play. When you put the halves together and tighten the two screws you get the feeling that things are a little two big and there’s a little gap between the two halves. If this happen everything is like they are supposed to be. What you need to do now is to either move the parts by hand or slowly with a hand drill. This is because the gears need to wear in. At first everything will move with a good bit of resistance but after a while you will notice that things will move a lot easier. This is when you tighten the screws again and close the gap between the two halves.
@Daniel_Noree Oh ok, that makes perfect sense now. Yeah, I definitely did that wrong then lol. I worked them by hand but not long enough because I still had to add a bit of pressure to close the gap. I did work them quite a bit after too so that might have helped a bit too.
Thanks for the explanation.
Really, many thanks for making these available. I had been racking my brain trying to come up with a project for my son and I to do when I ran across this. We have really enjoyed putting this together and I have the pictures, videos, and memories thanks to you.
My son can be watching his favorite show and see me pick up the car and a screw driver and he is instantly by my side saying “Daddy I want to help work on the car”
i’ll try and post some pics of us working on the car.
Thanks
You should also mention that this is due to the non-perfect shape of the printed gears.