Custom Center Caps for Porsche Wheel [from CAD, prototyping to finish]

[tommy583]

Fred I'm in for a pre order of a set in silver. Um throw me in for a super upgrade plenum as well

[Nine8Six]

Well, success RE the wife going shopping I have fresh and imported Cheddar Cheese to put on my toasts tonight and the dogs have their weekly cow-bones to finally get busy with. Hmm sharing with you what a typical Saturday night looks like here in Shanghai (loll we're getting old).

Not so much success on the rendering of the parts however. Not sure what's happening but the rendering PC I use here is blowing its life out of the cooling fan each and every time I switch it ON. Fear the CPU will melt if I use it - Hopefully I'll be able to fix that later myself :/

In a meantime, I have those which I think is sufficient for now. Surely gives a good idea of where this is going. Another good news is the kit only weight 77grams. Ultra-Light if you ask me.

I think we've done an amazing job so far. More to come on the wheel hub adapter in a few days. Cheese Toasts first

[911monty]

This thread is fantastic! Not often you get to see the inner workings of a master artist at work. Guess a Cheese Toast will have to do...

[Anker]

Originally Posted by Nine8Six

Not so much success on the rendering of the parts however. Not sure what's happening but the rendering PC I use here is blowing its life out of the cooling fan each and every time I switch it ON. Fear the CPU will melt if I use it - Hopefully I'll be able to fix that later myself :/

Bring the Task Manager up and check if the Windows Antimalware Executable is hogging the CPU. If it is, google on how to prevent it from doing that. I had exactly the same issue and had to take care of it.

[Nine8Six]

Originally Posted by 911monty

This thread is fantastic! Not often you get to see the inner workings of a master artist at work. Guess a Cheese Toast will have to do...

Do not get hypnotized by these modern and expansive software/tools man. The "true" masters are those who fabricate with their hands, and using tools that everybody has. If you want to know my version of true (genuine) ingenuity!

But thanks for the compliment, well received!

Originally Posted by Anker

Bring the Task Manager up and check if the Windows Antimalware Executable is hogging the CPU. If it is, google on how to prevent it from doing that. I had exactly the same issue and had to take care of it.

Sorted. It would have been a tad more helpful for me if the main-board would have beep'ed letting me know what it was. My neighbor's son disconnected the E drive and all came back to normal. The HDD was an old style WD and basically died. Not sure why this HDD was left in there anyway, been using SSD since a few years already. Thanks for trying to help bud, too kind

Originally Posted by Troy.Boxster

Damn you Fred! I'll take four.

haha Troy! ah for you its local pickup only. Always good to hear from you brother

[Nine8Six]

The part below will be the wheel hub adapter.

It threads & secure itself inside of the cap and meant to clamp the whole cap assembly onto the hub geometry of the wheel. As you can see I am using the traditional clamping style that, well, Porsche and many other automakers are using already. I’m guessing there is a reason for this widely used concept so no point going all creative RE hooks, clips, or new ways to get this to clamp. Let’s stay focus lolll

I won’t lie, I’ve already tough up this part quite a while ago. Often I’ve heard complains about how difficult it was to install the previous CGT style caps and many said “it got to be a better way”. So there, I’ll finally comply with this and provide in the best of my capacity.

The material we’ll be using for this part alone is Acetal (Polyoxymethylene, or Delrin if you prefer). Acetal is possibly ranking Top 1 in its group of engineering plastics and for many reasons (you can read about it). Not exactly cheap, in fact The Most Expansive in its class, but at least we’ll be 100% sure that the part will last for minimum half a century and perform in literally any environments. E.g. whether you roll my cap in Alaska at below 40deg Celsius or Texas at above 40, The Great Center Cap is going to stay on your wheel and perform its task without any complains.

I personally love Acetal because it is magical to machine. If you are familiar with its thermal expansion behavior, you can achieve tolerances of 1~5micron on this thing without much efforts (not joking). Something I’ll need to do for the matting of the threads with those of the cap, you’ll see why later.

I’ll soon explain the method I’ll be using to “thread lock” Acetal with the aluminum cap using its thermal expansion properties. That’s right; thermal expansion is occasionally an “advantage” for engineers, not all negative!

Nuff blah, it’s all about visuals (and Cheese Toasts in between)!








And off to the part validation (CAE). Lot of work there :/ The ring in front of the adapter represent the exact same geometry of the Porsche wheel hub. Same shape, size and tolerance (0.05mm) and used for non-linear clamping analysis.

[Nine8Six]

Acetal is “snappy”.

Here I’ll share with you validation procedures that the part will undergo. In general terms, we need to ensure a few things for this to work. 1) Ensuring that the part does not exceed (in any ways) the Ultimate Tensile Strength(110Mpa) anywhere in the clamping process i.e the ultimate TS is when the part shatters in little pieces, or the moment when you get mad at me loll. We also need to ensure that it stays below its Yield Strength (64 Mpa) when in operation. We don’t want the part to be living under excessive stress during all of its life. Within the range is perfectly fine, but not above!

Lastly, it need to provide a good clamping pressure so when the wheel rotate and X and Z velocities changes, the cap remain where it should. Keeping a pressure above 100Mpa is the target here so watch your fingers when you snap them into place, it’s going to hurt-a-little if you get your skin trapped between the wheel and the cap Although, for a light 77grams cap, I think that 50 would be more than sufficient – but let’s not take any chances!

Side note: for anyone familiar with CAE, I am solving this with SOL 601,106 Advanced Nonlinear Statics (using a 0.2 as coefficient of friction, 2D CQUAD4 mesh and a RBE2 connector for the enforced displacement). Nastran 11 Solvers, what else better




^ Not 100% completed but going into the right direction! Nasty work I tell ya but still fun to do. Sometimes I think my fellow Chinese friends have the right way of doing things = "looks good, then its okay lolll"

[Nine8Six]

Decided to become a VJ for one day loll

Did this vid to show the ‘behind the scene’ of CAE and how design (or feature) changes are validated. In this video we’ll be lowering the height of the clip and wall by -0.5mm. We’ll then clone the solution and see how stresses compare to the design changes.

When I say ‘nasty job (but fun)’ I really meant that. It can take quite a bit of time to come up with a proven concept – weeks sometime.




Next: I'll be showing how to balance a part assembly using Multiphysics Simulation tools and sensors. Think some of you will love that episode. I'll try to vid those over youtube for you guys to see.