Marui Hunter - My first buggy... Found one to restore :-) - and a Galaxy RS too :)

[silvertriple]

Last week-end the Marui Hunter run, and my daughter was there with her phone...


She took the first lap, unfortunately... I ran it faster during the following laps... At least there is a video of it...

[silvertriple]

After the Super Wheelie yesterday, today it is the Hunter who gain the new transmission with a metal idle gear...




Same adjustment than for the Super Wheelie, it seems that this is on the right path... And should be the same on the Big Bear (which is basically the same as the Super Wheelie diff and gearbox wise).

I did a quick run, there is no more cracking sound, and I can open full throttle with no fear. For the small story, the nylon idle gear was still in good state with some superficial wear for the smaller part of the gear... This is also good indication as the part of the gear in contact with the motor was not worn at all...

So I'm now happy as I have a Hunter and a Super Wheelie able to run powerfull motors

[silvertriple]

The ball bearings were a bit loose (8.3mm for a target of 8.05 mm) on the first printed SLM version. The designed was updated to 8.2mm. And while at it, I also included some holes to try reduce as much as possible the weight of this thing...


I mounted it this morning, and it was a bit more complex than expected :
On the small side, the fit is still a bit loose, but nothing to what it was before (before it was required to put a paper around the ball bearing), and when I say loose, it is actually fitting...
On the bigger side, although the same measurement is on the design, it is tight. I had to improvise a press to get the ball bearing in...

And since I increased a bit the clearance on the smaller gear, it is now perfect for runs...



I have now a very proper transmission for my Hunters and Galaxy, and this lighter version will get uploaded to replace the V2 i made to cope with the minor improvement required...

[silvertriple]

My first attempts to print Hunter tires were unsuccessful. The resin looked nice at the end, but I never succeed to print a second rear tire, and the front looks to fragile to survive a run...

While I had still some resin in the VAT of my printer following success with the Super Wheelie tires, I printed a rear and a front at the same time for the Hunter... And it worked like a charm...


Soon my Hunter will run on printed tires as well...

[Dadio]

Recon you could be taking orders soon

[silvertriple]

Recon you could be taking orders soon

See, I'm sure about one thing : it's good enough for me... But the rear face of those tires is just awfull which means that for a customer's standards, no way it would work... This is a hobby and I want to keep it this way... I'll get full explanations in a document and this document will be attached to the STl files archive I'll put on Cults3D for everyone willing to try this for themselves, because for me, it is just not realistic to make a business out of this...

[Dadio]

For running those little extra pimples might help grip and they can all face the inside anyway

[silvertriple]

For running those little extra pimples might help grip and they can all face the inside anyway

For some reasons, I just cut one of the printed tires for a checking of the inside... The surface is even cleaner inside... What if we could print it the outside face inside?

[silvertriple]

And here is the Hunter with the new set of wheels...




I'm quite sure one looking in the details would say the rear side of the tires are not good, but this is to run the car, and I know from what I did with the Samurai and the Ninja it will work...

[silvertriple]

There is no secret I love the Marui Hunter. Few months ago, I scored a cheap Hunter body in very nice state. Yesterday, I got it in hands as a friend leaving near by the seller got it for me...


And somehow this acts as a trigger, as I intend to do the Hunter/Galaxy family in CAD, with the firm intention to work out the prototype model as well... Watch this space

[silvertriple]

I have few Hunter awaiting rebuild, I pulled a chassis and few parts to start this activity...
When puting a car in CAD, each chassis has its own characteritics. Here the chassis include the gearbox definition, and it is quite long.
I decided to work part by part and I tackle the center first.


Next i focused at the rear, with the idea that the idle shaft position will define the differential position, which is by design on the bottom plan of the gearbox. And the main difficulty is that the chassis has a lot of angles here and there, very small but highly impacting when you are trying to measure them... And again the chassis is not symmetrical.
This is where I am currently. The shock towers will be taken during next session, before taking care of the front end for which the complexity is high, because of the angles.


In short it is a lot of fun...

[silvertriple]

I defined shock towers next... The definition is in one single sketch, and I'll did in V2 version first. For V1, the plan is to reuse the exact same sketch as it already includes V1 definition


After that I focused on the front side. I defined first the overal footprint, then used some surface definition to define the sides. The power switch support will be added later, as it only require extrusions perpendicular to the top plan.


The rest of the definition, at the very exception of the angle at the bottom of the front end will be managed with simple extrusions (my principle do it the easiest way possible to obtain what you need to obtain)...


I'm stopping here for today, next will be continuing to focus on the front end...

[silvertriple]

After my day of work, I took my second shift
After a little of work the front end is defined. That was clearly quicker than what I thought initially (again, boolean mastery is very helpful to work fast in Fusion360).


Few minutes later, only the the ribs a very few details remained to deal with...


You may noticed that I did not add the switch support yet. This will come next. This is considered my master, and I'll work by diff on some derivatives of this one...


The reason I did not put the switch is that I want to model the prototype, and as per my analysis and the format of the bodyshell, the prototype had no room for the switch at that place, plus the fact that it seems the switch support was added after the main conception of the mould...


After that, I had only to create the prototype, V1, V2 and Galaxy derivatives...




That's all for today

[silvertriple]

Before moving to the other parts, I decided to do some chassis validation.


I've done an adjustment as the idle shaft was positionned slightly to far at the rear, and reprinted the quick print after the modification to validate the modification (8 minutes print).


Next step will be to validate the bottom layout: I prefer to check as i have a theorical value for the diff-idle gear center to center distances, but it may happen there is a bit of backlash, so I need to verify. A partial print of the bottom layout should allow me to check this, as all the definition is within the bottom plan.

[silvertriple]

The bottom profile is right as per the similar test I after the previous one. But I'm not happy and this has turned in my mind the whole night after the test. I've always thought the 4 holes on the side of 4 corners of the gearbox are actually going thru the chasis and are lined up with the motor mount and gear cover holes. And I found a bit of discrepancy. I'm also seeing the holes are being symetrical around the diff axis.
In short there is two option to explain what I see in CAD :
- holes are not actually set symetrically around the diff axis (very unlikely)
- the diff axis is wrongly placed (around 1/10 mm of backlash) or I did wrongly positioned the idle shaft (around 1/10 mm) or a combination of both

At the end, I decided to print the gearbox area in full to make sure about my work, and while there is some good stuff, I'm now conviced I have just one thing to modify, it is the motor mount holes position (quick modification to do)...



While the gearbox was printing, I added the motor mount and the idle shaft...



Having already almost all the transmission content (my Marui 2WD set is ready for the Hunter, while the original diff is already modeled and I also have a original idle gear modeled somewhere, with ball bearing sleeves), I'll focus next on the bottom gearbox cover, and the front train...