A genuine Zimmermann. :-) Great. Markus
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A genuine Zimmermann. :-) Great. Markus
Thanks Markus!
Well, I'm not totally ready with the carbs: I tried to install one under the manifold assembly; it's almost mission impossible to turn the bolts as the space is very tight for one bolt. Maybe studs and nuts could help, but I prefer the following set-up: the carbs will be attached with a central screw from the exhaust manifold when the intake manifold is not yet installed, plus dummy bolts.
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After the carbs, I had to decide with what to continue. The choice came on the tires. There are very nice reproduced tires for those antique cars with an intricate thread. Unfortunately, my equipment is totally inadequate to reproduce most of the treads. I saw that there is a Firestone with a zig-zag thread which will be easy to do as it's very similar to what I did on my other models.
Last week, I ordered a large piece of brass (about $ 40.00) to make the tire pattern. As you can see, the stock I got is really the maximum which can be handled with this machine. The outside diameter is 70 mm (2 3/4") and the weight 1.47 kg (3 1/4 pounds)! There will be hours removing material and almost so much waiting time as the electric motor cannot run for hours without cooling from time to time.
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It took two afternoons to get the large piece of brass to the shape it's now. Too deep a pass or higher rotation speed caused strong vibrations so it was a balance between low speed and moderate cutting deep.
This rough element will be refined to look like a tire.
My deepest concern was about the dimensions. The original tire was 7.50-18; those tires are reproduced as I stated earlier, but their dimension are strange. I found nowhere the correct dimensions from the thirties and the tires produced now are like overinflated with an exaggerated width and overall diameter. Why tire manufacturers are doing that now? I have no answer. Anyway, I was the "victim" of those practices when I was building the Mark II: I took the dimensions from my own 8.20-15 tires installed on my '56 Biarritz and reproduced the tires according to the dimensions I recorded. As a result, I was unable to fit the spare wheel into the trunk; I had to cut away a good portion of the thread to install it. Sure, it could also be that I did some errors and the space allowed for the spare tire was too small.
Some years ago, a friend of mine discarded a restored spare wheel and the new tire installed over it because it could not fit the wheel well in his 1960 Corvette! Obviously, he got the same issue with an oversize tire. Strange.
As I noticed on several occasions, it's better to have parts a tad too small in scale model construction, I will do something similar with the tires: a compromise between the theoretical dimensions and the ones I saw on various advertisings.
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Roger, did you super glue the tire brass to a steel shaft for machining purposes?
Paul
30 minutes time of Try & Error to log in the Forum and this thread !!!
Since weeks poor horror
nice work again Roger I think Your late is with this pece of brass near some end ??
No, Paul. I just remove the unwanted brass from picture in post 740 to get what you see at the picture in post 741. Makes a lot of chips!Quote:
Originally Posted by PaulPK
I too have the same problem. For the moment, this forum is rather unfriendly!Quote:
Originally Posted by happyfreddy
Sorry, I don't understand what you are saying at the end of your message. I suppose it should say that my lathe could not accept a larger piece of metal to be machined. I could not do a tire pattern on a 20" rim!
Roger,
I tried to correct the written word "pece" to correct PIECE but the forum software did not accept this.
The meaning of my last sentence is that Your lathe will come to a limit in proceeding to machine this tire.
I suppose in result this brass tire will look like the others You made for the Toronado
As I see there is no glueing at the axle of brass tire.
The tric is to work between the tips and using a drive plate
That's correct. I could not machine a larger piece of metal! The process is the same as for the other tires; I will publish more pictures.
The rough work is done on the tire pattern. The face towards the rear of the lathe will be refined with an hand held tool. This is the best way to get a smooth and regular surface. Because of the white wall, the other side will be handled differently.
Pictures will be published when the forum is running correctly. For the moment, it's not possible.
Edit: Today is not so bad...
A third picture is added, showing the rear of the tire almost ready.
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Hello Roger! -I guess all of us have been having trouble logging on? THANKS FOR THE FIX !!!
Regarding your lathe and it's limitations? I should remember, (I used to sell them) but is the lathe head attached to the bed? -If it's not you could create spacer blocks to increase your turning capacity. Remember a spacer of X thickness will add a capacity of 2X to what you can turn.
Also, instead of Brass, you could turn Acyrlic, (PlexiGlass), or a cylinder of any number of other material. Automotive body filler? Plaster? Ren board. , . . . .
Very nice to see your work again! I was afraid the forum was going to be down for a long while.
Very happy to be wrong!!!
This is correct, Don: the lathe head is attached with two screws, easy to remove. However, the spacer alone will not solve all problems: the tail stock must also have a spacer for my application and suddenly, there is not enough space between the rotating part and the tool post/saddle!
With my tire pattern design, I must attach the band for the thread. With the main part in brass, I can soft solder them, even if it takes a very long time. With another material, I can glue them, but I'm not comfortable with glue.
Anyway, the forum is now functioning the way it should; maybe this will increase the traffic!
The tire pattern main element is ready. Most probably, by looking at the attached picture, you will not understand why the front of the tire has this strange shape. This is my way to add the large white wall: it will be a separate element pushed into the black rubber. I did the same with the Mark II's tires with one major exception: the tire's name will be on the white wall. For the Mark II, I did a negative mold and I could directly do the white elements. As I cannot engrave the tire's name into the brass, I will to make a positive form; with that done, a negative mold can be created. It's just one step more...
For the moment, the next step is to add the profile on the thread.
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