Jerry Feather

I have the air bubble and the small crack in the early **** mold repaired and still have one other tiny defect to try again to fix. I think I got some mold release into that one and the compound did not stick in it. It is not a big deal though since I think the rubber can be carved off if the defect ends up showing in the final cast ****.

Now I am changing my plan about the final casting procedure. I have been thinking all along that I would make a pour opening at the bottom of the ****, set the mold with that at the top, and try to simply pour the rubber compound into it. Given the small size of the opening I would have for that and the slow rate at which these compounds seem to pour, I am now thinking that I will be better off trying to inject the compound, probably just like the factory ***** were cast.

That will require me to simply drill a small hole into the mold cavity somewhere and, using a large syringe, inject the compound thru the hole and into the cavity until it appears thru a vent hole, probably at the top of wherever or however I have the mold sitting. I'm not sure yet just where to put the injection port, but I'll be working on that in my mind for a while.

I think I'll order some inexpensive syringes from the far east to use for the injections, and I'll probably end up throwing them away after each use, unless they can easily be cleaned up after the compound sets in them. 100 ml syringes are only less than a buck and a half, so that is not a big deal. If they can't be cleaned up I can get two *****, one of each style, out of each one.

Randy V

Am I the only one who thinks this looks a high tech *****?

Jerry Feather

Many of us have seen pictures of you in your fisherman's shorts; so the answer is probably YES!

Jerry Feather

Here is a picture of how it will be configured prior to closing and pouring/injecting.

The blue line is where I was originally planning to put the pour opening.

Randy V

What's the purpose of the solid shaft extending out of the top of the shifter?

Jerry Feather

That's something to hold that metal piece of the mold in place, both during the process of making the mold and then molding a new ****. Think about it. How else would you accurately hold that piece where it needs to be, in both phases.

Randy V

I would hold it with my dainty little fingers.

Jerry Feather

Randy, I think you still have ***** on your mind.

Jerry Feather

Perhaps I shouldn't be so flippant and poking fun at you, Randy, about your question, but sometimes such a question leaves me with little or no answer. Not because of the question, because it is actually a pretty good one, but because the purpose of the 3/4 inch rod extending out the end of the mold is just something that really just came naturally to me and I didn't really think about why it might need to be there.

After thinking about it some I conclude that it has a few purposes. First in order to make that part of the mold, the purpose of which is to mold the cavity in the top of the ****, I needed enough material in the aluminum bar I used to hold it in the lathe and then later in the mill. Since I can bore holes up to about 3/4 inch fairly easily in my mill that is how I came up with the 3/4 inch diameter. Actually I was originally going to make it 1 inch in diameter until I realized the tooling convenience of the 3/4 inch hole.

I could have made the shaft of that part much shorter, (and then I too might have had cause to think of it briefly as a high tech *****), but working with a piece of aluminum about 3 and a half inches long seemed to me quite natural. (Maybe the same reason?) Again 3/4 inch was convenient to both bore the hole in the mating wood blocks for the mold and for boring the hole in the aluminum bar that I used to make the holding fixture to mill the three "ticklers" on the upper end of it.

Next, at least for the pour of the first half of the mold, there needed to be a way to hold both ends of the **** and this mold piece suspended in the mold cavity while I poured the compound in around it. The compound takes up to 16 hours to set or shorter in the oven, but holding it there by hand, dainty fingers or not, was out of the question, both for 16 hours and/or in the oven. However, it could be much shorter in length even for that purpose.

Now that the piece has been cast into position in the mold the shaft part of it could probably be eliminated completely, but it is still useful as an indicator about the position in the mold after the mold is closed and ready for the final pour. I have even put a heavy mark or scratch around it at the surface of that end of the mold in order to tell me that it is still in the correct position after the mold is closed. Too, that could be done with it much shorter, but why bother at this point.

It also helps largely in the function of registering the mold halves together correctly at the final molding stage. One thing I hope to eliminate in the final product is any offset of the mold halves, as I find with the factory *****. They are all molded off about 20 thousandths. That's not enough to be noticed in the final leather covered stage, and it is only noticed in the bottom of the seam allowance groove, but off is still off.

Now that I think about it I am actually molding that "offness" into my ***** since I am using a factory **** to make the mold, (and I didn't cut one in half to correctly line the original halves), but I still don't want any additional offset at my mold mating line.

Finally, I think, when a new **** is cast in the mold, when it is removed the 3/4 inch shaft will be a convenient handle to pull that part of the mold out of the new casting. Otherwise it is going to be fairly well captured in the new **** and might be quite difficult to remove without something like this to grab and pull on. (Pardon the pun.)

I hope that helps explain it.

Randy V

Sure, that all makes sense.

So I guess you'll cut that rod off flush with the top of the **** as one of the final steps?

You'll then have a round aluminum surface at the top of the ****. How will you then install the shift pattern insert, or will you engrave it into that circular piece?

Jerry Feather

Randy, the metal piece with the round shaft on it is a part of the mold, not part of the ending ****. When the molding rubber compound is poured or injected into the mold it will form around the three fingers on the big end of the aluminum shaft. Then the rubber as formed will be removed from the two wooden parts of the mold with the aluminum pieces, including the other flat bar-like piece of the mold, both stuck in it. Then both pieces of the metal parts of the mold then stuck in the molded **** will be pulled by force out of the molded rubber leaving on the small end a rectangular hole for the shift stick in the car and a recess at the top of the big end of the **** where the leather will be formed over its edges and into the recess and then the plastic shift pattern insert will fit into the recess with its three fingers sort of locking into the three finger-holes as then formed. The aluminum pieces will then be put back into the other mold pieces and will be used to form the next ****. The aluminum pieces will not remain part of the new ****.

Jerry Feather

I think I have decided about the rubber compound injection. I'm going to drill a hole about a quarter inch in diameter through the wood mold pieces at the mating line and right about at the middle of the large part of the **** at the top.

I have ordered several 100 ml syringes, most from the far east, which will take a couple of weeks to get here, but two from CA which I expect in about the middle of the week. I'll wait to get them to decide about the final size of the injection port in the molds. With those I think I will be able to inject the rubber compound carefully so as not to create any air pockets in the final ****. I'll inject it with the injection port at the bottom and go slowly so as to keep the air moving toward the small end of the mold. I'll also cut a couple of vents in the mold at the small end to let the air out and so that I'll be able to see when the mold is full.

100 ml is about 6 cubic inches and I think the ***** are about 3.5 to 4 cubic inches or less in volume. I'll have to wait and see for sure with the first injection, but if I do both molds at the same time I should be able to get the volume just right so as not to waste any of the fairly expensive rubber.

Now, I'm going to finish up the GTS mold with the pour of the top half, so I'll post some pictures of that when I get to it.

I hope Randy finally got the picture about the aluminum shafts.

Randy V

You can determine the exact volume by doing a simple water displacement test in a graduated container.

Science!

Jerry Feather

Murphy's Law, Seventh Corollary, says that when starting out to do something, something else must be done first. It might be simple to determine, but first I have to go somewhere and find a graduated cylinder large enough to accept the shift ****, and that is more trouble than I think it is worth, since I'll find out the volume in the first two injections. But, thanks for the suggestion.

It's the Law!

Bertrand Daoust

You can also use a scale to do this.

- Put a bucket with water in it (at half maybe) on the scale.
- Tare (0) the scale.
- Then suspend the part in the water without touching the side or bottom.

The weight shown will be the water displacement (volume).

Use the smallest wire you can find to suspend the part to get as precise as you can.
If you don't have a scale you can tare, just take the weight with the part suspended less the weight of the bucket and water et voila!