Since you cant get 84-85 door pull cups anymore and the last ones I got didn't last all that long I decided to see if I could make something reasonable as a replacement. The pull cups seem to fail the same way. The lip splits and then breaks off on the side towards the rear of the car on the inside. This is because when the mold was made the edge of the lip on the inside corner is thin and this is where the most stress is applied when the door is closed.

My plan of attack is to make a mold of the visible side of a good cup. I happen to have a new in bag red cup for the drivers side. I have a good one for the passenger side on my GSL-SE in black but these are fragile enough that I won't try to remove that until I have to. I made a good right side cup by putting together good pieces of two cups. In the photos the black piece is the right hand cup in black from the GSL-SE and the red piece is from the GSL drivers side cup. This way I get a pretty good lip all around to make a mold from. I have quite a few hours of sanding and measuring and filling to get the red piece to fit well. It isn't perfect but is good enough for a first attempt at making a mold. I have mounted the cup on a piece of clear polystyrene. To eliminate clearance issues at the lip I added a fillet of clay. And to prevent the mold from sticking I have waxed the heck out of it with Partall mold release wax. I need to apply two more coats of wax and then a coat of PVA.

Hopefully I will be ready to try to make a mold from this repaired part in the next couple of days. Once I have the mold I am going to try to make one out of carbon fiber 2x2 twill for the outer most visible layer and several layers of 2x2 twill glass underneath that. If the Carbon surface looks good I will leave it like that. If the surface does not come out good then I will paint it with the SEM paint color that matches the interior. The fiber reinforcement should prevent it from splitting at the lip.

I will have an update in a few days.

 

You're a man after my own heart, Doug. Best of luck with the project!

 

I would imagine the cups would be unstable with out all the little clips that came stock.

I can probably find a spare cup for you. I have had more luck lately with finding them intact. They do interchange from side to side, only problem is the mounting screw in the bottom, they wont match up when mixed.

 

Thanks. We will see how they turn out.

 

The one way "clips" on the outside of the cup don't actually hold it in place very well. And the clips are the hard thing to mold. You need at least a 3 piece mold in order to mold those in.

I have a new LH side shown in the bag and there is a new RH one in the drivers door of my GSL-SE. So I am probably good for ones I can take castings from. At the moment this is a grand experiment in learning how to make a mold.

If this works out I will make a mold for each side so the original base mount will work.

I put two more coats of wax on it tonight. Supposed to let it dry a few hours before you use it. So earliest I can start is tomorrow night.

Doug

 

Also seems like a good 3d printing project for someone with a digitizer or good 3d design skills.

 

I would be interested to see how this would hold up. The stuff I have looked at had a poor surface finish and was not too rugged. It was also kind of expensive for what it was.

 

Are you sure they aren't available? My recent Black Dragon magazine shows the cups available. Albeit the RH side is $13 and the LH side is a whopping $60.

 

At this point I am a little discouraged. I have been unable to remove the mold I fabricated from the repaired part. I have a few more things to try but I suspect the relief is not enough to let me de-mold the parts. And if the problem exists in making the mold it will also exist when trying to pull parts from it.

I have removed the clear polystyrene piece and that was easy so the waxes and PVA did get applied. Ive tried heat and I will try cold next. Maybe my resin/fiberglass matrix shrinks more than the plastic.

Here is a photo of the mold curing in the repaired part.

 

It is possible Black Dragon has some left in inventory. Mazdatrix is showing all colors and both sides now discontinued. They note that they have one black right hand side still in stock.

I will try to order the ones I need from Black Dragon and then I can still try to make some. I wont pay $60 though so I guess I still need to make the drivers side.


Doug

 

yeah, the top is on the door panel, and the bottom is attached to the door, so everytime you use it, you're trying to bend it, and they don't bend! i leave the screw at the bottom loose, kind of hoping it adds a little flexibility down there.

i also use the door pull :P

i think both are true, its a good 3D print job, because you can't see much of the surface, so surface finish isn't as important as it could be.

cost is an issue still though.. oh and its green

 

Try air from an air compressor - turn it up high.

 

I managed to pop it loose with some persuasion (yes you can see the persuader.) Not perfect but I think I can touch up the problem areas and see if I can pull a part. I am most concerned about the lip area. It is pretty clear I didnt get a heavy enough tooling coat (black layer) down as the glass reinforcement is showing through.

 

I'm impressed.

 

Sanded on the mold and filled the big flaws. Nothing to see here. I will take another photo after the next sanding session tomorrow night.

 

Good to see you got the cups removed from the mold. I've done a fair number of molds in the past, and I know the frustration of having trapped a casting inside of a mold. Any reason you didn't use silicone rubber for the mold? It's a lot more forgiving with undercuts and the only thing that sticks to it is silicone. It is expensive but the costs are more than made up if you sell a handful of door pulls.

fm

 

I am probably going to vac bag the parts to get the cloth (Carbon or Fiberglass) to conform to the mold and I think silicone is not appropriate for vacuum bagging. The mold will change shape. But I could be wrong about that. It might have been a simple solution.

 

Good point. Although there are different hardnesses of silicone that you can get from places like Smooth-on that may hold up to a vac molding setup. But it sounds like you've got it under control.

fm

 

Continued cleanup on the mold. Looks like I will sand it smooth and then I will add another tooling coat and then another final sanding session. Will try to pull a part off of it later this week. My mold is going to end up with a smooth surface. The original parts do not have a smooth finish. I believe this was part of my demolding issue. The slight pattern on the surface was part of the clearance issue. Photos when the mold is ready to use. It looks a lot like the above photos still.

One thing I am dealing with is air bubbles in the cured resin. If I want good parts it is clear I will need to remove the air from the resin after mixing it up. This can be done by placing the mixed resin under a hard vacuum where the air appears to boil out. It is an interesting process.

I will probably get some silicone rubber and see how that might be used in making small molds.

 

Do you have a vacuum chamber? I still have one from when I was doing this all the time...a vac chamber is a must when working with resin.

fm

 

Not yet. I am looking for a serious vacuum pump as well. The one I have will only pull about 10inhg and I want something that will pull more than 24, 26 would be better.

Doug

 

Still cleaning up the mold. May try to pull a part this weekend. Not sure I can clean up the lip the way I would want if I was going to sell them but as a test I want to get this to the good enough to try stage.

 

awesome, thanks for doing this

 

Quick update. I have obtained a vacuum chamber and pump and I am playing with silicone RTV to make the next mold from. The vac pump was necessary to do the sun roof mold from anyway so one step closer to that as well.