Check out these knobs! (dash knobs)
 

My dash knobs were all cracked and warped, and rather than do the sensible thing, and buy new ones, I built a compression mold to make new rubber parts. Here are the results.
http://forums.pelicanparts.com/uploa...1092899008.jpg
http://forums.pelicanparts.com/uploa...1092899050.jpg http://forums.pelicanparts.com/uploa...1092899063.jpg

I put some on ebay to see if I can get a little to justify the time I put in. http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=7917231855

very clever - thats way beyond my capabilities.

amazing.

did you use the originals as plugs?

What material is the mold? and the final product?

neat work!

The original knobs are 3 or 4 pieces. There is a plastic threaded knob, a plastic icon part, an outer rubber, and some have a plastic light pipe.
http://forums.pelicanparts.com/uploa...1092929343.jpg


I just made the rubber part that slips over the original plastic parts. The rubber is 50 Duro EPDM.
The mold is CNC machined out of aluminum, with a removeable aluminum core. You can see from the cross section that there is heavy undercuts in the part. This makes it tricky to get the part off the core.

As we say here down in Maine... "ain't you clevah "

John

nice job. what knob is that with the warning? and what does the warning say?

Wow that is awesome. With engineering like that, you could make spark plugs and oil filters and... oh, wait, never mind, I got carried away.
Question: how much time did it take you to do this? Was there a huge cost avoided by buying them or do you like to diy everything?
Can you create a custom AL spacer for a 930S wheel for me? PM me and if you can to get details and cost.

I painted the knobs red on my red targa and think they look "way cool". And no, I don't have a "Type R" sticker!! I would have just bought your red ones had I seen this sooner.

This board never fails to amaze..... the abilities and desires of some people is boundless!!!!

Really great stuff.;)

Thanks. That is the NOS injection knob. :D

No actually it is the emergency flasher switch, and it says something like "Do not mis-use."

ingenious work!

aligator arms?

Nice Knobs!

I am impressed. Nice stuff.

JP

There is a "how to" article for a similar method of doing this in the September 04 issue of Car Collector magazine.

Rather than constructing a mold from CNC aluminium, the article describes how to do it with the original knobs, even when they're cracked as bad as shown in the original post.

Good work, I am sure I will there will be a p.m. when I am ready to do the interior.

Midlife,

I sent you a PM about these knob surrounds. I'd be interested in buying a set from you if you have any ready.

Also, do you know where one can get the little icon plastic inserts?

Thanks

Very impressive and NICE work!

How about some walnut, oak or camel browns, and gray to match factory leather colors???

Good idea. A pair of NOS early sun visors just sold for almost $1,400 on ebay. Good replica knob rubber should be worth a bit ;)

rswannabe,
I didn't get your PM. Maybe the spam filter stopped it.
I'm all out of knobs right now, but I hope to make more soon.

You can get the emblem inserts from Pelican.
http://www.pelicanparts.com/catalog/shopcart/911E/POR_911E_interi_pg10.htm


ubiquity0,
I'm toying with some concepts for sun visors. (Like most targas, my visors are pillowy).

the last time i used the phrase "great knobs" i got slapped... so i'll just say "nice work" ;-)
are we going to see more of these anytime soon ?
okay... DAMN nice work!
cheers
jerry

I prefer a polished knob.

midlife,

Any progress? I'm sure there is a market. Will Pelican pick these up?

Can you make knobs in silver?

Jerry,
Thanks.


Norm,
Not a chance.

Aaron,
So far I've been able to sell every knob I make on ebay. I've programed a four cavity mold, but haven't got around to cutting it yet. That would enable me to quickly saturate the ebay market, and I would need to find other outlets like pelican.
It's been a good way to finance some of my parts needs.

Austin,
It may be difficult to get the raw rubber in silver.

I'm impressed! My originals still looking good, but I gather replacements are NLA?

Mid,

Can you elaborate on the injection process. How is the rubber introduced to the mold...you say compressed.

Thanks for satifying my curiousity.

i thought i saw them listed somewhere @ ~ $20 each (?) maybe midlife needs to give us his ebay ID ;-)
best
jerry

Rick,
Some rubbers like silicone can be almost liquid in their uncured form, and can be injected into the mold. Rubbers like the EPDM used for the knobs are "rubbery". They are almost as hard as the cured rubber, except if you stretch it it won't spring back. These rubbers are usually compression molded or transfer molded.
For compression molding weighed out chunks of uncured rubber are placed in the mold cavity. The mold is then closed, and the rubber cures under heat and pressure.
With a transfer mold, the slug of rubber is placed in a pot in the top mold half, and a piston squeezes the rubber into the cavities.


Yes, the parts are still available elsewhere for $26.00. I don't know if they are the original OEM, or reproductions like mine.

Thanks for the info, Midlife. If you ever take pics of the process please share.

My limited experience has been with RTV Silicones for creating molds.

EPDM, those ought to last forever! I used to make a lot of EPDM parts for a thermal sight/missle guidance system that I used to build. We had some pretty extreme environmental requirements.

Regards,

Jerry Kroeger

Midlife,

Do you still make these?

midlife,
how the hell do you do that. Man.. so many handdy people here. Oh.. can someone make $100 dollar bills? :D

Dam...a 2 yr old thread resurrected.

...and for a damn good cause! :D
now... if we could all just find out where these things are available and how much they cost...
Midlife ? ...are you there ? SmileWavy

jerry

Yes, I am still here, and still have knobs. Occasionally I make a batch of knobs and put them on eBay. I also make ’72 oil door hinges. I have had so many other projects going that I have not done much with these for quite a while, but the Porsche funds are low, so I need to get busy again.

Midlife,
I need four rubbers. I live in South Florida 33027. How much including shipping. Black please.
Thank you,
JLC

PM sent.

I ordered a pair yesterday. They arrived today, I swapped out the old ones for these new ones and they look great.

Some threads are too good to die.

If you look around, there's a thread on this board titled "admit to your stupidity." I've been subscribing to that one for a long time!