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Discussion Starter #1
A while ago someone asked about casting in resin, and asked specifically if I would post pictures once I started this project. The stuff has been here since Monday, but I've been sicker than a dog the last two days and just started feeling reasonably human today. Being bored out of my mind with CSI reruns, I decided to do this in between naps.

The problem: The key heads available for our cars suck. They're made of wimpy plastic that might look like the real thing, but they tear and scratch and I'm on my fourth key head. I'm sick of it.

The solution: Use a pristine flimsy key head as a mold and cast a new one, with the key firmly embedded in it. Cast it using high strength epoxy resin, so it won't break easily.

I started with my valet key. Yes, I got the valet key to my car that no valet will ever be trusted to drive. I got it because the car originally came with one, and that was reason enough.

First, you make a box out of whatever. I used molding clay, because I have it and that's what it's made for. You can use a cardboard box and that will work just as well. The box should be just barely bigger than the key. Next, figure out a way to suspend the key. I found that toothpicks do a beautiful job. Two on the bottom, set well away from the head of the key, and another that will hold the key down - it's top-heavy and wants to throw itself deeper into the box than it should be. Then mix up your first batch of RTV Rubber. (Room Temperature Vulcanizing Rubber) and pour it in until you've got the key about halfway buried. Don't panic, this stuff doesn't stick to anything but itself. It'll wind up looking something like this:
Pic1.jpg
Then you go back to the couch, unpause the TIVO and fall asleep watching as the dauntless CSI team solves another murder. In four hours you'll be ready for the next step.

Pull the key out of the mold and liberally apply the Rubber-to-Rubber Mold Release. This is an important step. Remember back when I said this stuff doesn't stick to anything but itself? This keeps it from sticking even to itself. Skip this step and you'll be creating a little rubber tomb for your key instead of a mold. After you've done this, pull the toothpicks out, reinsert the key firmly - make absolutely sure it's solidly fitted down into the impression already there. Then mix your next batch of RTV and pour it in so the mold is filled and the key is covered. Sorry, no pictures of this step. Go back to the couch and fall asleep. Four hours after that, go back and take apart the box and carefully pry apart the box. It'll look something like this:
Pic2.jpg

Remove the key and take apart the flimsy plastic head. This will leave you with just the metal blade of the key. Don't get excited, you're not ready to mold just yet. Take a razor or sharp knife and cut a slot (or two) into the top of the mold. I used a syringe to inject the resin, so I just needed one. If you're going to pour it you'll want two, one to pour into and one for air to escape. Mine looked like this:
Pic3.jpg

OK, now take the key blade and once again, insert it firmly into the impression made in the mold. This way the blade will be part of the new key head and it won't come out.
Pic4.jpg

Because this is very soft rubber, you'll need some reinforcement to make it hold shape when you secure it. I used a wooden ruler and a couple of stir sticks. When I got it secured and ready to inject the resin, it looked like this:
Pic5.jpg

I used a very high strength resin to do this, and those typically take longer to cure. I just put it out into the garage, where it'll sit for the next 16 hours (at least) and I won't put any major stress on the key head for at least 48 hours. However, once the 48 hours is past I'll have a durable, rigid, long-lasting molded key head that looks just like the MB original and will last like the MB original. No more replacement key heads in my future. The valet key is my Proof Of Concept. Next is the real ignition key.
 

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Outstanding Contributor , Bob's Your Uncle!
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Nice job. I wish I had that kind of time.
Could you do me a favor? Could you mold me a new soft top?
Thanks a lot. I'll PM you with my shipping info.
 

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Great. Now Scott's gotta go out and buy all new hats. Again.

After the Best M-B award, you should have realized that hats would never fit the same again.
 

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Discussion Starter #5
Yeah, yeah, yeah. Like I need any shit from any of y'all.

I just separated the mold for my valet key, and it looks like it worked. I had the bright idea (not sure it was so bright) to make my valet key very distinctive, so I don't have to look at vaguely rounded corners to tell it apart from the regular key. I didn't dye the resin and left it the natural white. I'm not sure I like the look, but maybe I'll get used to it. I'll take a picture tonight before I trim and shape it, so people will know what to expect if they decide to do this themselves.

And Nobby, it really doesn't take that much time. Total time spent actually doing this was about 30 minutes, about 10 minutes at each phase, spread out over 9 hours.
 

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Yeah, yeah, yeah. Like I need any shit from any of y'all.

I just separated the mold for my valet key, and it looks like it worked. I had the bright idea (not sure it was so bright) to make my valet key very distinctive, so I don't have to look at vaguely rounded corners to tell it apart from the regular key. I didn't dye the resin and left it the natural white. I'm not sure I like the look, but maybe I'll get used to it. I'll take a picture tonight before I trim and shape it, so people will know what to expect if they decide to do this themselves.

And Nobby, it really doesn't take that much time. Total time spent actually doing this was about 30 minutes, about 10 minutes at each phase, spread out over 9 hours.
Given your woodworking abilities (I assume there's a set of woodcarving tools in that garage), I would have expected you to come up with a more distinctive key head.

 

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Discussion Starter #8
Given your woodworking abilities (I assume there's a set of woodcarving tools in that garage), I would have expected you to come up with a more distinctive key head.

That would have been kinda bulky. But I do have an MB logo keychain. Maybe I could adapt something....

Send me a key to your car and I'll experiment. ;)
 

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Why bulky? A wood billet just the size of a Sakajawaya...Sacagwea...a Kennedy half dollar and scoop out the bits that don't make up the star.
 

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Discussion Starter #10
Why bulky? A wood billet just the size of a Sakajawaya...Sacagwea...a Kennedy half dollar and scoop out the bits that don't make up the star.
But then where would the top of the key go? There's that big tab that has to be embedded in something.
 

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Always Remembered RIP
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I don't get it why didn't you get a key made at a key store. 2 bucks.
 

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Discussion Starter #12
I don't get it why didn't you get a key made at a key store. 2 bucks.
Because keys made at the key store are soft metal, and they leave metal powder in the locks of the car as they wear, accelerating the locks' eventual failure. MB keys are made of harder metal and don't wear like aftermarket keys do. And because I like the look of the original key. I just don't like how often I have to replace the plastic key head. This gets me the MB key blade and a much tougher key head. Best of both worlds.
 

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Outstanding Contributor , Bob's Your Uncle!
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Always Remembered RIP
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Because keys made at the key store are soft metal, and they leave metal powder in the locks of the car as they wear, accelerating the locks' eventual failure. MB keys are made of harder metal and don't wear like aftermarket keys do. And because I like the look of the original key. I just don't like how often I have to replace the plastic key head. This gets me the MB key blade and a much tougher key head. Best of both worlds.
Oh, I am on my 4th key now and had 6 more made.


PS I invested in that masterpiece.
 

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Discussion Starter #15
Oh, I am on my 4th key now and had 6 more made.
And I'm still using the key I got from the dealership when I first got my car - it still looks new. The only thing I've had to change is the key head and this will take care of that.

PS I invested in that masterpiece.
I don't know enough about art to invest in anything. The only original piece of art I've ever bought was because I like it and want to have it where I can always look at it.
 

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Discussion Starter #17
Replacement heads are available through Performance Products, I found out today.
Yeah, that's where I got my replacements, but they're the same flimsy plastic. I guess they have to be to be flexible enough to snap together.

That was after I made my own as well ...
That's interesting. Do you do jewelry work?
 

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Discussion Starter #19
Of course, you can just grasp the key head closer to the shank and it will last more than 25 years.
Nah. The original keys were a little flexible, but they were molded onto the key blade just like my resin one. It's these flimsy replacements that don't last for crap. I found two original keys (unfortunately not to either of my cars) when I was refurbing.
 

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hi

I have two keys that came with my 560 when purchased. They both look like
Scott's key, valet keys. What does the orignal key look like? My keys will open the
trunk does this mean my keys are not valet keys? Does anyone have a picture
of what the non valet key looks like?

Thanks
 
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