TOPIC:

The print lasted about 14 hours for 3 wheels that I intended to test to validate the work. This morning, the print was finished, and I could see the results.

First thing I noted is the requirement to review the slicing to go for tree support rather than normal support, as the normal support are difficult to remove between the rings... That being said, I'm not sure the rings are required (I'll probably let them in the final design possiblilities, though)...


Next was to do some tries. I have two obvious combinations to test:

1. Kyosho Scorpion re-re rear tire at rear and Schumacher T693 at the front.


Here is this set on the Samurai. This is the most approaching combination in spirit from the original Samurai wheels set




2. Hotshot tires. This could work with any 2" tires combinations with narrow front and normal size behind


Here is the combination on the Samurai


I'm not decided yet on what I do at the end for my Samurais. Ultimately both set works. I still need to do some fine tuning on my rims design, but it's already in very good shape. I will review and finalize my design before printing a full set...

I like those Schumacher tyres but I have a few sets of the block tyres in my box so I wont be needing any for a while.  When I have printed a wheel I get a mark at one point where its starts each layer, I have found a setting in my slicer to start at random points which should eliminate the mark in the print, I have printed a couple of wheels for some road tyres / slicks 50 x 25 and there's no mark which is great. the supports on mine gather in the rings but I make them a little thinner, 1.5mm instead of 2mm and they are easier to clear out, I use a dremel with a burr type bit to smooth them out. The inside of the rim is fine and if you have smoothing/ironing/polishing option for the top face that will also give a nicer finish. 

Was thinking tires again...
There is some STLs for the tires in Thingiverse. And yesterday I come across an interesting post on one Facebook group about tires printed with Varioshore foaming TPU. It's a TPU with foaming agent inside, and it results in different density depending on the temperature you print it. And it have some advantages compared to standard TPU: in particular, it could be printed with a bowden extruder. Another one is that you could potentially target the right shore for tires including (and that what's interesting) infill which would remove a lot of the support issues... I may want to try that for Samurai tires. I'll probably have to order some Colorfabb Black Varioshore Foaming TPU at some point within the next months...

Very interesting Marc I will also take a look. 

There is another possibility, but it would require a resin printer: I saw some rubber resin, and they exists in the proper shore grade (target would be about 60A).

 I launched a final printing for my Samurai wheels. I've opted for on set of oval blocks at the moment (I could always change my mind if I find something better later). I did a few change in my cura settings :
- Infill 30%, Grid (which I think should be ok, as some are using Lunchbox with printed wheels and an infill at 20%)
- Monotonic Top and bottom
- Ironing, concentric
- Support in tree mode, everywhere
- Layers of 0.12 at the exception of the first one. The wheels are grown up from their rear face.

For a set of 2 rear and 2 front in 50mm diameters, it is going for about 23-24 hours print. The current progress is about 61%. And the result in terms of quality appeared to be promising as per what I  can see already on the spokes of the front wheels (and yes, there could be always ways to have better quality, but this will be probably good enough).

Here are the new printed rims. The quality is really better than previous set.


I may want to adjust the retractation as there traces of under extrusion in the areas post a move, but beside this it is quite good.

I will try with tires on a Samurai  next

Four wheels, oval blocks




Two minor details to review in my stl and they are good to go...

This got me thinking the whole night. It's good, but it doesn't respect one thing of the Samurai design. Something disturbs me when I look at those pics.
The rim diameter size difference of the original wheels is about 4mm. Front tires are lower profile than rear ones. That gives a very specific look to the buggy (it would be the same with a Kyosho Progress, I believe).
4mm is nothing and a lot, ultimately.
Yes I could choose original diameter and squeeze smaller tires on both Front and Rear (aka Dadio's method... But I won't be able to do that with the oval blocks which are the closer in spirit from the Marui Hyper Traction tires I can find... I can't do that but what about adding a millimeter to the external ring of the front rim so it looks bigger?

Let's see... I still have the front wheel originally printed. it has a bigger external diameter, but I found it too big, so I reduced it for the second set... I took them in pictures, and here is:


I think I got my perfect solution, now :-D

Added one parameter, reviewed the slot internal diameter and it should be perfect now...



Edit : tweaked it so it become less obvious that the external ring is bigger...


I think I'll need to reprint those