Jerry Feather

I'm anxious too, Tom, but I'm trying not to get in a hurry. I have all the short pieces beveled on the ends and ready to have the guide slot cut in them. I'll make a new "guide bump" for the slot cutting jig later today and then try the trimmed down slot cutting bit on some scrap then try to work them all up.

I have the jig or simple guide block made for the finish of the long pieces and have been measuring the original handles and the mold carefully to be sure where to cut both the mounting screw holes and the cross bore for the short pieces. But first I need still to mill the flat on one side of the long pieces. Maybe I'll get to that later today also.

Jerry Feather

Well, that turned out to be kind of an interesting operation. I set up the mill and started cutting the guide slot longways into one side of the short pieces. First, I found that I have ground the mill cutter too narrow. Then, I decided I could just cut them twice to make the slot wide enough for the guide tabs. That seemed to work just fine, until I sat down with a few of them to deburr them and found that even though I had set the mill correct to widen the first cut, it did not get very wide. I finally figured out that what is happening is that when I make the first cut it cuts the slot about .068 wide. (It should be about .085) Then, when I move the mill table about 20 thou to recut the slot it is only cutting about an additional 5 thou. The reason is that the work piece is heating up with the first cut and then when the cut opens up the side of the tube it expands and opens up the slot about 15 thou.

Now I need to recut all but one of the first small group of pieces. One did turn out about right and I find that the shift button works just fine in it, and that the size of the hole is just about right. I had been thinking it was going to be a bit big.

Here are some pictures of the ones I have cut so far. I have marked all of them so that I can tell just about how much more to cut them. They also show how these will be set in the weld jig and approximately how they fit with the long pieces. They also show again how the short pieces fit in the mold and how the long pieces will relate, sort of.

Jerry Feather

I see now that my welding jig needs some more work. The way it is milled for the short pieces it is not letting them rest at the bottom of the slot milled for them. I guess my previous measurements were a bit off.

I had already decided to do some work on it anyway because since it is aluminum and since the brazing rod I am going to try flows so well I am afraid that it might braze the workpieces into the jig. So, I am going to mill out completely the area under the joint so the workpieces will not be touching the jig where the melted rod might want to flow.

I think that also might close that small gap you can see in the third picture above between the flat on the long piece and the cross bore on the short one. I don't think that should be there if I have my offset measurements correct.

Jerry Feather

I fixed the welding jig and now the pieces appear to fit just about perfectly. The tiny gap between the pieces appears to be closed, and much moreso when the long pieces are milled to fit.

I am still trying to figure out how best to solve the slot issue(s), but think now that it will be best to simply grind the other spare cutter I bought and try to get it to the correct width so I can make only one cut. I found that trying to recut the ones I have already cut too narrow is a problem for some reason. They do not want to sit in the jig the same way as with the first cut and then cutting them again is destroying them. Well, one of them so far. I'll work on that some more.

One of the previous short pieces that I somehow got the slot correct in works perfectly with the button shaft.

Then I have received the Primer to paint these aluminum pieces with before casting them in the rubber compound. Getting closer.

However, time for a break since the wife and I are going out of town for the weekend for a wedding about 2 and a half hours away. We will be staying overnight. I might get to some more of this Sunday afternoon after we get back.

Have a nice weekend.

hernanca

Following with interest, Jerry. Thank you for including us along on the journey!

Jerry Feather

Thanks Carlos. Doing this there is always a question about how much interest there is in something like this, but doing it online seems to help keep me focused. Too, when I find myself getting directed to something else mid project, which seems to be often, going back to these kind of threads give me a good review since I don't take many or any notes along the way and sometimes my memory isn't very good for getting back into a project.

We got back earlier from the wedding today, than I had thought, so I got to redo some of the work on the guide slots. First I ground another of the slot cutters to a better width and then put it into service with great success. I also didn't dull it on the bolt holding the guide bump, like I think I must have done with the first one.

Then I started using some cutting oil in my cuts and that, plus the better sharpness is making my cuts with much less burring. I have about a third of them cut now, including the first dozen or so that I have recut, and will spend a little while in the house watching TV and deburring these to see if the button slide is going to actually slide in them. I also found the sweet spot for the slot since I think I was cutting them about 20 thou off. It wont matter much since the slot will always be correctly aligned in the welding jig - - it will just put the cross bore in the short pieces off a bit, but it is slightly oversized anyway.

Overall this is good progress; and I'll try to finish up these short pieces later today or maybe tomorrow.

Otto Mechanic

Jerry I wanted to say I've been following along on this thread with great interest, not just because I need to replace my original 1985 T handle, but also because I bought a mill/lathe a few years ago with the idea I might be able to do exactly what you're doing here for NLA parts on my 928 and also my recently restored '89 944 S2. It's a bit humbling to read (and even see) the detailed work necessary to make something like this project happen.

My hat's off to you. I hope you begin selling these parts, I'd like to get in line

Best Regards,

Jerry Feather

Hi Scott. Thanks for your comments. Actually you might be surprised to learn that my own concept of these T-handles, as I ran them thru my mind on the highway about a month ago, was probably pretty close to what your original concept might very well be. It is only after getting started with the process and finding smaller issues along the way that need solutions, that the project seems to have grown to a point of more complexity.

But, after doing the solutions to each issue, I expect that the end result will be just about what I conceived in the first place - - just more difficult to get there. That is just the nature of this kind of development and fabrication, at least as I find it.

Otto Mechanic

Jerry;

And of course, thanks for your well considered reply.

That's what I was getting at; it is much more complicated than I had understood. You're doing a great service to our community just by documenting the attempt. Of course, I wish you only the best of luck, though from what I've seen you're one of those rare people who make their own luck.

Best Regards,

Jerry Feather

I could tell that was what you were getting at, Scott. You might be right about luck. Although I am by no means rich, good luck in many ways seems to find its way here.

I have finished the mill work on the short pieces and have only to hand finish them now. Then I started on the first of the last three steps on the long pieces. That step is to put a flat on one side. I decided to keep it at the 50 thou that I had originally planned which I think is about right since the wall thickness of the tubes as bored and reamed is about .078 in. That leaves plenty for their purpose and enough space for the rubber to cover fairly well around that part of their outside. I have about half of the long pieces milled flat. I'll finish them up in the next day or two; then all I have left to do with them is to drill the two holes in one end and mill the cross bore to mate to the short pieces.

Here are three pictures of the fairly simple mill process I'm in now. I first milled across at about .030 depth then back the other way to a full .050. This allows me to eyeball the first cut to be sure it is cutting the same width which tells me that the piece is level in the vise and not cocked some way.

Jerry Feather

My analysis about the bubble is this: As stated above, it starts in the syringe when sucking the compound out of the mixing cup, and then it stays at the front of the syringe piston while the syringe is filling and the plunger is pulling upward. Then, the syringe is reversed so that it is pointing up and it is then inserted into the injection port pointing up since I want to fill the mold from the bottom upward.

In this process, when the syringe is reversed the bubble then starts to migrate upward through the compound so that at some point it gets injected into the mold. When in the mold it tends to migrate up through the compound, but not immediately since the compound is pretty thick, but only after the compound has reached the top and has come out the vent holes which signals to stop injecting.

Then as the mold sits to set the bubble finds its way to the top, but since the compound is so thick it does not find its way out the vent holes but rather stays right below them. Too, there is not enough compound in the mold at that point to take the place of the bubble.

So, I haven't figured out just how to deal with the bubble, and that is why I have one in just about each of the manual ***** I have cast so far.

With this new auto handle mold I have put the little trough at the top with the vent holes, and will likely make it a bit larger hoping that I can pause in the injection process long enough for the bubble to migrate up to the top and then inject some more compound and maybe even suck some of the excess compound out of the trough at the top so I can see when the bubble comes out.

The main problem in all of this is that the compound it setting up the whole time and getting much thicker, which make it much more difficult to work with the longer it goes.

Jerry Feather

Another small step backwards. I finished milling the flat on one side of the long core pieces, then decided that it might be prudent to see if they will in fact fit over the shift shaft in one of the cars. The shaft measures .590 in. or right at 15mm in diameter, so I assumed that reaming the long core pieces to 19/32 in, which is barely under .594, they ought to fit just fine. However it seems that at the top of the shafts where they have a guide slot cut in them they seem to be flared a bit and measure .595 in. The long pieces do not slip over the shaft and, although they might be driven over them they would not likely be removed without much trouble.

So, I am going to re-ream the bores first to .595 which is the size of a re-ground reamer I found on eBay, but more likely I'll end up reaming them out to .600 with a larger more expensive reamer that I'll have to order from one of the machine tool suppliers.

Jerry Feather

The .595 reamer is supposed to be here Saturday and my mail comes about 1:00 pm, so I ought to be able to see if that will be sufficient to fix the long pieces. If not, then the .600 probably won't be here until about Monday. Then, in between there is a .597 reamer on eBay that I might want to try next, but I am going to wait until after I try .595 first, and maybe the .600 on one or two pieces before I spend the extra money for the one in between.

In the meantime I'll probably cross drill the holes for the mounting screws; but I'm going to wait until the bore is the correct size before I do the cross bore for the joint with the short pieces.

Jerry Feather

One odd thing I am finding with the four of the long pieces that I have tried to fit onto the shift shaft, is that I have kind of re-reamed them with one of the 19/32 inch reamers (.5938 in.) that seems to measure maybe a thou or two over the others and that reamer measures .596 across the opposite cutting edges. However, even though it fits smoothly now into the holes reamed with it the holes measure only .590, using the same measuring instrument. If that holds true with the .595 reamer I am waiting on I won't be getting anywhere with it, and maybe not even with .600. So, there is a .6050 reamer on eBay that may end up in my tool chest and it might very well be the one needed.

Jerry Feather

Right after posting the post just above I took a very very careful look at the inside measurement points of my dial caliper and discovered a very tiny burr where it has probably been dropped or bumped against something. I gave it a light swipe with my trusty file and then tried the inside measurements of a couple of the long pieces and find now that they measure much closer to the outside measurement of the .5938 reamer. Mystery mostly solved!