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Again another Marui project : Super Wheelie and Big Bear! 1 year 4 weeks ago #75342

Your wife will be happy with the rc on the sofa

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Again another Marui project : Super Wheelie and Big Bear! 1 year 3 weeks ago #75388

The sixteen cars I went with in Montluçonnaise 2023 all made at least a few laps of run during the event...



And this included the Big Bear, the Super Wheelie and the Hunter (I still need to mount a video of the runs :-) )...

The Big Bear ran a lap and about 2/3 of a second one, and then stop and did not move anymore.
Upon inspection, the 9T on the idle gear did not survived the run.


It clearly needs to see a dentist :-). I replaced it by another one, and will try again during next event or before...

For the Super Wheelie, on Saturday, i put it on the track, and it made about 3 meters... What a success! I opened the gearbox on the next day, and I was able to run it for quite a good 7 minutes and the transmission is still alive. I will do more tries next event. For the Hunter, it ran quite nicely with a Tamiya Sport Tuned motor. I made a 7 minutes session with it, and again the transmission is still alive at the end. That being said, there was some transmission noice probably due to diff skips. Something I did not have with the Super Wheelie. I've planed to open it for inspection before next event...

Beside this, I've modified my 3 parts printable chassis to ease printability. The best way to print those part is with a quite unconventional orientation, and it happens that elements in the air (on top of supports) are not always perfect. Adding walls to join them to the other side shoul make this easier to print. I did it when I thought it would bring improvements.


- at the rear of the center part : a top bar with the same thickness as bot side of the chassis, and a wall of 1 mm which can be removed afterwards easily.
- on the front part, I bridged the parts

The better orientation I found for the print is on the antenna post for the rear part, angled on the battery pod and rear for the center part and on the rear top upside down for the front.



I've checked holes and nuts dimension : holes need to be drilled to the right diameter (I won't change the tolerance as in case one wants to print it in MJF it is fine while it may be tight for FDM depending on the printer), and nuts are entering in their position when force is applied which means they won't move to much if the chassis needs to be tear down for maintenance, unless you really want to get the nuts out...

Still a few checks to do, but soon this will be published. I'm considering as well putting chassis, gearbox and arms on Shapeways...
I buy kits to built and ru(i)n them :-)
The following user(s) Liked this: stingray-63, EddyCH

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Again another Marui project : Super Wheelie and Big Bear! 1 year 1 day ago #75539

I ran the Super Wheelie and the Hunter during the vintage event last week-end...


Both cars have now some run time, as they both got run time during the event in Montluçon as well... I'm not going to bet on Super Wheelie's idle life span, but for sure the wheels on the Super Wheelie are easier to entertain for the transmission than the big and fat Big Bear wheels... And considering that both Hunter and Super Wheelie differential are still working, i'm going to try a metal print this time. Ordered idlers for both Super Wheelie and Big Bear in metal print (SLM) to do a test. I had to try. Hope to see this in a week or two...
I buy kits to built and ru(i)n them :-)
The following user(s) Liked this: stingray-63, Al, EddyCH

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Again another Marui project : Super Wheelie and Big Bear! 11 months 3 weeks ago #75580

SLM prints arrived today...


The hole for the shaft seems good, next will be to test those inside the Big Bear and the Super Wheelie gearboxes...
I buy kits to built and ru(i)n them :-)
The following user(s) Liked this: stingray-63

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Again another Marui project : Super Wheelie and Big Bear! 11 months 3 weeks ago #75582

The Big Bear is upgraded with the new metal idle gear


Now we will see if the diff is resistant enough...
I buy kits to built and ru(i)n them :-)
The following user(s) Liked this: caprinut, stingray-63

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Again another Marui project : Super Wheelie and Big Bear! 11 months 3 weeks ago #75594

I asked my son to take a video while I made the gears spinning with the Big Bear...


This is just an extract. About 15 minutes of run, quite bestial, and the motor was really hot at the end (Marui 480 RS - hopefully I did not killed it). The diff is still alive and smooth at the end of the test run....

Looking at what it supported, it seems I'm on the good path. I will have to test more, but it is definitely different from the test with the Nylon idle gear which required a dentist after a lap on the track :-)
I buy kits to built and ru(i)n them :-)
The following user(s) Liked this: caprinut, yogi-bear, stingray-63, AndyAus, Ducksnuts

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Again another Marui project : Super Wheelie and Big Bear! 11 months 3 weeks ago #75600

A bit of disappointment today after yesterday's success...

I took the Super Wheelie and mounted the SLM printed idle gear...


Shaft hole is perfect, and the movement seems fine until I close the gearbox. When the gearbox is closed, the shaft is in the right position and it's too tight. I suspect the root diameter is too large of .1 or .2 mm.... It would be still in the specs of the printer, but too big for the use... It worked perfectly for the Big Bear this is not the case for the Super Wheelie, they were in the same print batch, and the conclusion is that the result might be unpredictable...

This need more work again :-)
I buy kits to built and ru(i)n them :-)
The following user(s) Liked this: stingray-63, Al

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Again another Marui project : Super Wheelie and Big Bear! 11 months 3 weeks ago #75602

Oh sucks! Same batch "same" gearbox same gears and it doesn't work.

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Again another Marui project : Super Wheelie and Big Bear! 11 months 3 weeks ago #75606

See if you can find a thinner washer or shim to put on the idler. It might be too thick in that application 

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Again another Marui project : Super Wheelie and Big Bear! 11 months 3 weeks ago #75607

It's not the width, but the diameter. 19.4mm measured for the outside diameter for an expected diameter of 19.2mm. The big Bear idle gear is in the specs, the Super Wheelie one is slightly too large (diameter), making it too tight once the shaft is in proper position...
And as matter of fact, the printer specification says "+/-0.3 mm OR within 0.4%". In this case, 0.2mm is actually 1% but I can't file a complaint because it is OR and not AND. Conclusion SLM printing process is having variability, and it is not proper for printing gears (at least with this provider).
I buy kits to built and ru(i)n them :-)

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