Hey First of all Thanks to +Daniel Norée for sharing the OpenRC Truggy and

First of all Thanks to +Daniel Norée for sharing the OpenRC Truggy and parts. I finished printing and assembling my Truggy yesterday. My problem right now is that the differential gears were broken after I accelerate. I printed all with PLA.
So my question is, is it enough to print these gears with ABS insted or should I buy some aluminium one?

Aluminum. I tried every plastic I had. All fAiled miserably.

Do you know if sth. like this http://www.conrad.de/ce/de/product/236525/Reely-6538-T002-Tuningteil-OP-Metall-Differenzial-komplett/?ref=detview1&rt=detview1&rb=2 will fit?

@Fabian_Schurig check this - http://www.thingiverse.com/thing:162810 there was an info about that in wiki but it’s deleted unfortunatelly…

I haven’t broken my differential’s gears printed in ABS. I used Nylon for the joints. But Daniel recomends polycarbonate for every gear as the only way to make them last enough.

Sorry the section on the wiki got lost. Those bots crashed the site. But I made a new section which is located here.

http://openrcproject.com/tiki-index.php? page=Truggy_Metal_Drive

It does not say much now, but if anyone actually goes through the build I would love them to document it in more detail.

@Fabian_Schurig Congratulations on finishing the Truggy, it´s looking good.

As for the the drivetrain i have tried many variants of plastics and combinations of plastics. For the gears i found ABS works the best. And if the casing and gears are printed right they won´t brake.
There is one problem though, you need to get it PERFECT or it will brake. I have tried a few printers but i have only managed to get the gears exactly right on ONE printer, my old 1st gen Replicator.
When you assemble the diff it should feel as if it´s slightly too big. It will wear in.

I use Polycarbonate for the internal driveshafts. I have done the diffcasing and the axle shafts in tritan.

The problem with the diffs are friction between the gears and the casing and the axle shafts and the casing. The friction heats up the parts and they wear into each other and brake. To solve this problem i have added thin metal washers (0.15mm) on the in and outside of the casing and so they work very well.

Every time i go for a test drive i do my best to brake things and during two years i have broken every singe part on the Truggy atleast once.
The drivetrain has been a real pain but now i can go out and have fun with the car till the battery dies and to be honest that is way more than i could even dream of when i started.
I posted this video a while back and this it is with the printed drivetrain and diffs: http://vimeo.com/105538084

could this be scaled up to fit a 30cc weedeater motor?

Conrad seems to have complete differentials, do you know if these will fit ?


I tried and tried to print with Colorfabb’s XT Polyester filament but I cnanot get them right, the small gears. The big ones are pretty fine but those called sun gear and planet gear are impossible to get right on Ultimaker2.

Daniel how did you manage printing it on Makerbot as it has slightly less resolution than Ultimaker?

@Boris_Tekaty ​ Nothing special really, just slowed it down plenty and reduced the extrusion multiplier slightly. I always print the gears at 100% infill.
I starting to think I should do a video showing these stuff and maybe also explain some of the hurdles and solutions I’ve come up with (that works and why).

That would be great @Daniel_Noree if you can make it. Jag försökte med extrusion, hastighet och infill och att sänka temperaturen. Få inte de små kugghjulet att blir bra. Jag ge upp nu :slight_smile: och börjar kolla vilka färdiga diffar går att beställa.