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Marui Big Bear tires - lets CAD :) 1 week 5 days ago #72274

After some feedbacks and further checks on the pictures, I decided to review the model slightly to make the chevron profiles different...

I also included some lettering (a plan under the surface, a text, an extrusion, shaved with a revolve at an offset of .5mm of the surface of the tire).


I added colours in order to make it more realistic


When discussing yesterday with a memeber of another forum, he reminded me about the support issues I had the only time I tested flexible filament on my own printer: they are a mess to remove, which means it is definitely not going to be easy to print in flexible material using FDM. This turned in my mind the whole night. This morning decided to have a look at few options.

First, I went to I.materialise.com to price the STL in MJF rubber like. Very simple : definitely too much. That won't work.
Then I had a check to see if there was other providers doing similar Rubber like printing online, and it seems that only few printers actually print flexible material.

Ultimately, this tire maybe printable with dual head printer and soluble support materials... Not the usual printer most of the people do.
Maybe printing two halves, integrating the sleeves to act as support could work. I may have to create STL for this...

Next element I thought about is a mould. I decided to do an attempt to create stls for a mould. Printing moulds should not be an issue, and won't require any supports in the important side. Which also means proper finish...
I used the tire model as cut in a mould, and made few parts for this.

The mould would be composed of two parts for each halves.
An external side, with the chevron, and the lettering and the tire side


An internal side


Each halves would be moulded separately, and the center part would be removed before assembly of the two halves.


I believe the external mould would help into this assembly, and I created some elements to make sure the two halves would be oriented properly (one of fixations attachement is bigger to make sure it is proper).


Printing those parts should be easy. a release agent would likely allow for multiple tires from the same mould parts...

I received some feedbacks from a friend with moulding experience and I'll review the moulds slightly, but the general idea is there....

(and while I may not try to print Big Bear myself as I have none, I may want to try to print or mould some buggy tires, and I may try that on some of the other tires I modeled recently)...
I buy kits to built and ru(i)n them :-)
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Last edit: by silvertriple.

Marui Big Bear tires - lets CAD :) 1 week 5 days ago #72279

After yesterday's various discussions I had with different people, I reviewed the mold.

First, I modified the centering cone.


The idea is to put the compound in the exernal mould, and then add the centering part inside, ideally with pressure.


No change in the principle to assemble the two halves after removal of the center parts of the moulds


After that I rethought the FDM printing topic. Main issue to print something without support is to remove all overhangs or to reduce them under a certain threeshold. I thought about printing the tires in halves, and to glue them after wards. I integrated the sleeves and used them to remove most of the overhangs of the side wall.  I believe Chevron could print easily, as long as the mid plane of the tire is the printing bed. I have created the files for the two sides...




Still thinking about possible improvements (have many ideas flowing to my mind currently :-D)
I buy kits to built and ru(i)n them :-)
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Marui Big Bear tires - lets CAD :) 1 week 4 days ago #72284

Someone sent me this video


I may need to rethink my mould to allow injection the way it is presnted in this video. For this I believe I must close the mould, and have some holes at the top level to allow the end of the process.
The injection hole must go thru the cone, and the cone would be a separate part, or 2 parts, fixed by the central part...

Need to think about it, but is looks like it is possible to do something :-)
I buy kits to built and ru(i)n them :-)
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Marui Big Bear tires - lets CAD :) 1 week 4 days ago #72285

Very interesting. Some events and "sous vide" before injection. 

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Marui Big Bear tires - lets CAD :) 1 week 4 days ago #72288

Those tires are running in my brain the whole night... On one side, I can see there is a lot of people awaiting for this.

First action this morning was to contact the guy from the video to get some details on how he was avoiding air to be captured in the his tire mould. There should be a way.. I also contacted a small company here in France. they are doing some vintage tires for 1/8. They are in holidays currently, they messaged me back they thank me for the message and they would contact me as soon as they are back from vacations... I believe they are not far, so I could eventually visit them to get more information on how to proceed and eventually more.

For those reasons, I decided to hold on the publications of the files on Thingiverse for the time being:
- I want to get the things right. It means getting additional feedback and informations from experienced people in the matter, even if it is for DYI mode
- if I can find an opportunity to have people doing tires for us, that would be super great news

At the end, be patient, my goal is still to provide a solution or a set of solutions for Big Bear fans...
I buy kits to built and ru(i)n them :-)
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Marui Big Bear tires - lets CAD :) 1 week 3 days ago #72291

Fantastic work so far my friend 

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Marui Big Bear tires - lets CAD :) 1 week 3 days ago #72295

Quick update. I'll put the Big Bear tire on the side for the moment. I need to do some testing. For this, I'll need a smaller tire. The main reason for this is that the Big Bear tire is big and that may lead to lot of spoiled material and desillusions even before having it right. I choose to work on another tire, smaller, and which I need for 2 cars. I have already the model done, added some lettering, and will proceed to build a mould, so I can experiment at some point.

I have a vacuum machine somewhere. I will have to find some pipes, accessories, silicon and pigments and to order some resin prints once the model is done... It put the Big Bear tire on hold for some times, but I'll come back on this later on.
I buy kits to built and ru(i)n them :-)
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Marui Big Bear tires - lets CAD :) 1 week 2 days ago #72308

As I said, Yesterday, I refreshed the melting brain and the cooling had some effect again...
I did reworked the mould


I designed a 3 parts center piece that serves the purpose of the injection, and allows to spread the injected material into the ring.



And this morning, while finalising this, I was thinking again to the next problem : assembly of the two halves. 
For this, I believe the best way is to extend the surface where there is contact between the two parts is the way to go. and as well, I thought there could be a way to make it in order to ease the assembly. 


I decided to remove a ring of a millimeter thickness and few millimeter deep and add it on the other side. I required to make the side mold rather différent...

After some work, I have completed a mould for each side.



Now that looks cool already. I'll add some marking on each distinct part to allow this to work and avoid user mistakes. 

And over the last two days, I contacted many people to get feedback and to see if there is opportunities to use those tires CAD model to decline real tires, in a very vintage way... With all those bottles I launched around, maybe one will have an idea to do something about this... I'll publish the files by early September the latest: I need to do some research first on the material to use, and will include this. THat means time without CAD, without building and just research... Time will come :-)
I buy kits to built and ru(i)n them :-)
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Marui Big Bear tires - lets CAD :) 1 week 2 days ago #72311

Update the design to make sure each part is properly marked with the useful information...



There is 2 elements still in my todo list for this CAD design:
- include tolerances for assembly. At this stage there is none in the design. Normally, to get the assembly air tight, one should used fine sand paper to make it nice and smooth. But I may want to add a tenth of millimeter between all assembly plans so it's not required.
- I want to inludes some elements to ease mold separation.

During this last night, it was a bit hold, I have a bad sleep, a lot of thoughts again, and I may have an idea on how to proceed for a smaller tire to get it injected in once... Need to work in CAD for that... See you in NInja/Coors/Shogun thread :-D
I buy kits to built and ru(i)n them :-)
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Marui Big Bear tires - lets CAD :) 1 week 2 hours ago #72322

Finalised the CAD model with what remained in the todo list




- tolerances for assembly was added
- features to ease the unmoulding

I've read a lot of things and searched for a lot of informations, up to a point some people are now contacting me to sell some products... Let's see if I can find someone willing to showcase their product for free :-)
I buy kits to built and ru(i)n them :-)
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