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Construction of a Continental Mark II model, scale 1:12


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While I was waiting for the brass to turn the forms for the wheelcovers, I decided to begin another pair of interesting parts: the valve covers. For those who don't know how is looking a Mark II valve cover, the first picture is showing a dirty real one.

How to do that? An aluminum casting like the original parts? Unfortunately, I'm unable to cast something except silicone rubber...

I imagined two ways. The first one was to do a valve cover with a sheet of brass, then cut grooves to insert thin brass pieces to form the fins or ridges. Unfortunately, I had no tool of the proper shape for that task. Therefore, I had to turn to the second solution:

I cutted 31 pieces of .8 mm brass with a hole in the middle to fix them during the rework. (second picture)

Then after some hours of filing with rather high tempereature (should be a winter job), I got the definitive profile of the cover. (third picture).

After that, I cutted 32 thinner pieces of brass, again with a hole in the middle and assembled one thin part with a larger one, then a thinner one, and so on, like a sandwitch. (fourth picture)

The shape was done again with a file (due to the odd shape, machining is not a solution) and then the assembly was brazed. (last picture)

The next step will be to finish the shape to the correct dimension and braze the assembly to the base.

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Incredible, Roger!

Not quite: it's mostly inspiration or imagination and right now, perspiration!

When the available equipment does not allow to replicate the way it was done originally, you have to be a little bit creative!

By the way, thanks to your pictures, I was able to dertermine the proper dimensions of these parts. Again, thank you.

Edited by Roger Zimmermann
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Roger, enjoy watching you work. How many hours do you think that you have in that one valve cover so far?

Me too, on your Avanti! You are publishing pictures I would have love to get when I was doing that model!

You are asking a difficult question...Never count the hours, just the years...I think I had up to 10 hours for what is done now. Usually, the second piece is done quicker; anyway, as most is done manually on this kind of part, there will not be a great difference with the second valve cover.

To Barry: I'm using a rod with 45% silver content and a propane torch. Is that what you had in mind?

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We call that soldering. What we call brazing is using brass to weld metal parts together.

It's what I'm doing, with a brass/silver rod. The bonding agent is called "Castolin 1802"

I wanted this morning to get the specification of this product; unfortunately, the site is not working.

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Learned something new today.

Found another site. The material is getting liquid by 1200 degres F or 630°C.

What you are calling soft solder is liquid at about 400°F or 220°C. This art of fixing parts together will be used for the remaining parts of the valve covers for practical reasons.

Edited by Roger Zimmermann
completing the text. (see edit history)
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Today, I finished both stars going on the valve covers. As you may imagine, the most time spent was to do the 4 holes into the star. Both pieces were soft soldered together; the irregularities on one are to be found on the other.

Before to solder them on the valve cover, I will attempt to improve them a little bit. On the other side, I have not to forget that the parts seen on a computer screen are X times larger than reality, rendering the irregularities more obvious.

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It took a long time to mill the recess for the emblem, but at least I was more or less satisfied. I corrected a little bit the star; not too much as the danger is more to harm as to do good.

I then soft welded the star on the cover. Unfortunately, it was offsett by 0.1 or .2 mm. Maybe the next one will be better (but usually worse)!

I noticed also that the star on the valve cover is not symetrical; it is in line with the attaching bolts. I had to shorten a little bit (.2 mm) one leg of the star to be more or less in line with the original design.

To finish the covers, I have to do the end caps and solder them to the main corpse.

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Thank you for all for your positive comments! The second valve cover is progressing slowly; I did a measure mistake by drilling the holes at each end too near from one side. Fortunately brass is a wonderful material and I could rescue the part by brazing a cap and drilling again. Oh! the error was not significant: 0.4 mm (0.016") but at this scale is almost catastrophic!

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Now that the valve covers are done, I'm beginning other covers: the wheelcovers. The cover itself will be done in 2 pieces: a small one, like a cheap hubcap and then the outer ring. Both will be welded together.

However, I have to do first the forms to press the brass. Here are the first step for the hubcap. One picture is showing the form almost ready, the form is ready on the second picture. The next step will be to do the negative form, also in brass.

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Now, it's the turn of the female form. It's the most difficult part of the tooling as it's almost impossible to measure and use "normal" tools. Most of the job is done with a hand held tool like shown on the picture. Of course, the tool is held with both hands (and with the minimal turning speed), but I my third hand was not available to held the camera!

The part is far from finished...

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Yesterday, I spent almost the whole afternoon to do the female form. When I had the impression I cannot improve it any more, I did a test with a small band of brass to see if the inside profile was more or less like the outer profile...I saw on the test part that a small rework was necessary, which was done this morning.

Then, the great moment: how will the brass do between both parts? Well, I'm satisfied with the results. And I'm happy about my decision to do the dish in two part: on the picture below, you can see the first hubcap; the metal on the outside diameter is full of wrinkles. If I had a form for the whole wheelcover, I would have the same wrinkles. As my dies are brass, the wrinkles would imprint the brass, rendering the dies useless as well as the covers.

Now, I can do the ouside tooling...

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Thanks for the updates, Roger.

Do you heat the brass before stamping it like that? Or is it soft enough to press without heat?

It depends of the quality of the brass. Some is hard, some is soft. I suppose this properties is coming from the mix between cooper, zinc and maybe other metals.

The brass I'm using now is of the soft quality; I tried to press it without heating and the process went well. The thickness is .2 mm (.008") The outer ring will be a little bit thicker, .3 mm. As I did for the Avanti wheelcovers, I will heat it, but I'm not yet that far!

By the way, I noted that you are living in the UK...I have a very international audience!

Edited by Roger Zimmermann
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By the way, I noted that you are living in the UK...I have a very international audience!

I know of at least 1 Australian following this. You must have unbelievable patience.

It's fantastic to be able to follow your progress.

Thanks for taking the time and effort to post.

Danny

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Roger,

You have to know that there are a lot of people that find your skills highly interesting just by the number of views your threads gotten and I for one am amazed at the patients you have to scale/model and build these little pieces. It's still more impressive when you pull all these little pieces together into a wounderful piece of art. Keep up the great work. Scott...

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You got the whole world watching Roger. No pressure now:D Nice work my friend;)

Ah! Lou! Nice to see you here! Sorry for the trouble you got at the CLC forum; I don't understand this lack of flexibility. Why don't you publish here the restoration work you are doing on your '56 Biarritz?

I will have to rework the dies of the small hubcaps: if the first part went well, the other ones had inacceptable flaws...The wheelcovers will keep me busy for a long time!

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Roger,

You have to know that there are a lot of people that find your skills highly interesting just by the number of views your threads gotten...

Yes, Scott. I'm amazed at the number; what will be that number when a "real" part will be under work like the frame or engine or body? Fortunately, the cold months, which are not far away, are more productive as I'm less distracted by my own old cars requiring maintenance and nice weather which I enjoy as much as I can.

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Before I'm doing a new tool for the small hubcap (the center is not like it should), I did the dies for the outside parts. It went better than the forms for the hubcaps; it's simpler. This morning, I did the first sample with mixed results. However, after some rework, the form is acceptable.

The outer part is a little bit thicker: 0.3mm. To do the rework, I cemented it with a contact cement on one of the dies. With this unortodox method, I could turn the outside and inside diameter as well as eliminate a small wrinkle.

The last picture is showing the 2 parts pre-assembled. As more finish work is needed on both parts, it was just for fun.

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As the first try went well, I'm doing now the full serie of outer wheelcovers. As the picture is showing it, I have some plain sheet brass discs ready to be "stamped". On the left (and above), one prepared part; the hole in the middle prevents too much stress on the brass. In the middle, a "fresh" pressed brass part; you can see that the hole went larger. On the right, an almost finished part.

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Yesterday, I could assemble the first wheelcover with soft solder. The other ones are in the pipeline, they will probably be in the same shape at the end of the week.

My estimate is that I'm at the middle of the wheelcover's saga. The fins will be an heavy task. I have various ideas how to do them and how to install them on the dish (no, not with screws!); nothing is definitive right now.

One picture is with the flash, the other one without.

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Edited by Roger Zimmermann (see edit history)
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