Jerry Feather

Hans has been giving me some good ideas by PM including his own drawing of a mold very similar to mine, but with the **** being cast the way Factory did these 90 degrees different. Thanks Hans, for your input. That always helps to keep the creative juices flowing.

One of Han's ideas is to cast some kind of weight into the head of the **** to give it some kind of "heft" I think. I am giving that a bit of thought, but I have doubts about just being able to feel the difference in how the car shifts, but also just how to suspend any kind of weight during the casting process. Also, the space within the head of the **** is actually pretty limited which would require a very detailed casting, in lead probably, to make much difference in feel. Any thoughts on this idea?

Jerry Feather

Here is the fourth mold piece, the form for the shifter core. I made it out of aluminum bar stock in the mill and kind of polished it so it will hopefully pull out of the molded rubber compound when cast. The two notches at the upper end, as with the original, is for forming the corresponding bumps in the channel that sort of lock the shifter **** onto the stick.

You can see in the last picture I have also glued the hole piece into the first half of the mold body. I have it clamped in place and then after a while I took the clamps off and put it in the oven for a while. That set the epoxy pretty well rather than waiting overnight for it to cure.

I also cut a kerf at the other end of the mold body for the shifter stick piece; so now when I get the GTS **** I will be ready to pour the first half of the mold.

Jerry Feather

To pour the first half of the mold, when I have all the pieces together, the mold half must pretty well be level. First, I was going to assemble the mold half and the two metal pieces, both stuffed into the **** to be reproduced, then pour the mold compound into the small void between the **** and the wood. Then I am afraid that with the shallow channel that will be on the bottom of the **** for that pour I might capture an air bubble. Too, I am not too sure just how freely the compound will flow around and inbetween the wood and the ****. So I think now I am going to first put some of the compound into the channel in the bottom side of the ****, then I'll pour some of the compound into the bottom of the wood cavity. Then I'll carefully place the assembled three pieces with the **** in the middle into the puddle and sink it down into position hoping that just enough compound in the puddle will ooze up and around the **** to the top or maybe just short of overflowing. If it overflows I'll just let it sit to set. If it is short I'll then pour some additional in to fill to just above the surface of the wood.

When that all sets then I'll see if I can take it apart and have a proper mold cavity. Then I'll sand the top surface flat in my belt sander.

The second pour for the other half will be a little different.

GlenL

Impressive work, Jerry, but I gotta suggest that the "old fashioned' way would involve whittling. Or using a bone.

Jerry Feather

After I routed out much of the cavity in the wood I actually sat here watching TV and used a small chisel to whittle out the cavity to its final depth. I haven't gotten to the bone part yet.

Mark R.

So with the original approach from the factory, how were they able to split the mold?
They must have had removable sliding inserts in the mold to form that groove for the leather seam.

To encourage flow through a mold, you can add risers and flues to give extra volume for material flow.
Air bubbles and shrinkage due to cooling, can be managed to occur only in those areas.
Obviously, additional trimming steps would be required to remove these "arms".

IMHO, trying to encapsulate an extra internal weight is not worth the additional effort required.

Good stuff Jerry...

Jerry Feather

Thanks Mark. I'm not sure what their mold consisted of, but the compound the **** is made of is rubber-like and probably the same as I plan to use. It is probably flexible enough to pull out of the mold even though it is kind of captured after curing. The mold joint is clearly formed right in the bottom of the seam allowance grooves, so I don't think they had separate pieces for those.

Those "arms" are called sprues and vents, Mark. I don't think I'll need those, but thanks for the suggestion.

That's about what I am thinking about the added weight. Thanks for that also.

Jerry Feather

Rob's GTS **** arrived today. I didn't remember nor count on it being as different from the earlier ones as it is. It is shorter than the early ones and significantly different in shape. And, the top recess for the shift pattern insert, although about the same size, is canted 18 degrees to the rear/aft.

What that means is that the mold as I am developing it wont really be adaptable to it without almost completely remaking it. Rather than do that I am going to simply make a separate one and then complete both of them. That's probably better in the long run anyway.

Jerry Feather

I made a step backwards to pick up the process for the GTS ****. I have the basic wood laid up with epoxy, the metal shift pattern insert piece made, and it's two pieces of wood bored. I also have the design made up which is a bit different from the other mold since the shift pattern insert is at an 18 degree angle to the shifter stick in the GTS ****.

I'll have to set the mill up a bit and then mill the three fingers on the metal piece, and when the glue sets I'll have to use the mill to cut the 18 degree angle into some of the wood.

Jerry Feather

I'm not sure if it is a good idea or not, but I think I'll make the GTS **** a little longer by adding about a 3/4 inch to the length of the shaft at the bottom. I'm not yet sure about how I'm going to do that; but I think it will involve simply glueing some small pieces of wood to the bottom and around the aluminum shift stick form when I get that made. Then I can shape it and smooth it to become part of the GTs **** for taking a mold off of. I'll probably have to wait until just before I do the mold pour to add the length since it will be fairly fragile for handling in the meantime.

Jerry Feather

I have caught up with the GTS **** to about where I am with the original ****. I laminated the halves of the mold and have carved out the cavity for the first half and have it fitting the GTS **** pretty well. I got the angle between the mold piece for the top cavity and the shift stick just about right.

Now I also have the upper half of the GTS **** mold nearly carved out and ready for the mold compound with only a little bit more carving. When it is completely carved out I'll be able to epoxy the top half together since it is still in two pieces, as with the other mold.

I have also glued two little blocks of wood onto the mold shift stick so I can shape them tomorrow to form the extension of the bottom of the GTS **** to make it a little bit longer.

Jerry Feather

I think I have both molds ready to pour the first half of each one. Here are some pictures showing the wooden extension I grafted onto the GTS **** and the status of the mold halves, both in progress and then with the last half routed out for the mold compound. They also show the final rounded bottom edge on the GTS **** extension.

Oh, one thing I keep forgetting to get done is to mill a small registration mark or slot in the two metal mold pieces that will form the recess for the shift pattern insert. To pour the molds themselves the ***** are keeping these pieces in place, but when the molds are complete and I'll be pouring the ***** in them I'll need to have these metal pieces oriented correctly, and the best way to do that is to mill a registration slot in them that gets captured in the finished molds.

Now I need to go to the crafts store and get some modeling clay to build some little dams at the ends of these molds so my compound wont run out while it is setting.

Jerry Feather

I got in a rush and went ahead and made the first pour on both of the bottom mold halves. Here is a picture as they sit to set. The marker scribble on the top surfaces under the mold compound is for registration purposes because when the material sets and is hard enough to try to remove the ***** being struck off, I will need to sand the upper surfaces flat in my belt sander. The marks will tell me when I have reached the original upper surfaces and I can't go any further or the upper halves of the molds will not fit correctly.

I went to the craft store and bought some modeling clay, but I forgot to take it out to the shop when I get involved with this, so I just cut some little pieces of wood to use as dams to keep the compound from flowing out of the low spots on the GTS mold.

The molding compound, by the way is Devcon Aluminum Liquid (F-2). It is a 2-part epoxy resin compound. I mixed up more than I actually needed, but I still have enough left to do the upper mold halves.

I also still forgot to mill the registration slots in the two aluminum pieces. I guess I'll have to put them on top so they will register with the upper halves of the molds.

Jerry Feather

I checked both molds this morning and the mold compound seems pretty hard, and I was able to pop the small end of each one free; so that gives me some relief about getting the ***** out of the mold compound. However, I put them both in the oven at a fairly low temperature to have them do a final cure. I'll try to pop the ***** out later today after they have heat soaked for a few hours. I don't think I'm going to be too thrilled about the finish on the molds since the mold release compound I put on the ***** seemed to create a pretty rough texture. I don't suppose it will matter much since they will be covered with leather.

Jerry Feather

Here is one of the mold halves that I had put in the oven for a few hours at about 168 degrees. The **** assembly pulled right out, so I guess the waxing and mold release worked fine. I did capture two or three air bubbles that I'll have to patch, but overall I think it came out fine. I have sanded it down to my registration marks and see that the heat apparently warped the wood a tiny bit. Not enough to be a problem.