Author Topic: Cosworth V8 1:12 scale  (Read 7039 times)

Offline Art K

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Re: Cosworth V8 1:12 scale
« Reply #60 on: December 04, 2021, 02:57:05 AM »
Steve,
It looks like you've been up to some very intricate work, twice. Looks very good.
Art
"The beautiful thing about learning is that no one can take it away from you" B.B. King

Offline steamer

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Re: Cosworth V8 1:12 scale
« Reply #61 on: December 04, 2021, 10:24:33 PM »
That's coming along beautifully Steve!!!

Dave
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Damned ijjit!

Offline Steve Crow

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Re: Cosworth V8 1:12 scale
« Reply #62 on: December 06, 2021, 03:13:13 PM »
One of the most fiddly things on this build was hand fettling the bearing blocks so the camshaft turns freely with a minimum of play.



The cam shafts are supported by a sort of shell bearing. These were made by turning down brass bar to 2mm and boring out to 1.6mm.

These were then trimmed down to a semi circular C-section and burnished/work-hardened into place using a polished steel 1.6mm rod.

They are now held firmly in place by there own springiness.



I'm making all this up as I go along but it seems to be working fine.

Steve

Offline crueby

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Re: Cosworth V8 1:12 scale
« Reply #63 on: December 06, 2021, 05:02:19 PM »
Quite impressive!!

Offline Steve Crow

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Re: Cosworth V8 1:12 scale
« Reply #64 on: December 07, 2021, 11:02:01 PM »
My next challenge is to finish the cam gear train. The principal gears are in place and running smoothly, I just need to sort out the idler gears.



Here are some sat in their final position.



Steve

Offline Admiral_dk

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Re: Cosworth V8 1:12 scale
« Reply #65 on: December 08, 2021, 11:22:49 AM »
Very nice progress  :ThumbsUp:

You are not doing things the easy way ...!

Since you have very small tollerances on the placement of these gears - are you placing the axels on excentrics so you can adjust them ?

Offline Steve Crow

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Re: Cosworth V8 1:12 scale
« Reply #66 on: May 28, 2022, 05:23:10 PM »
It's time I resurrected this thread. I've had a couple of months off metalwork but I'm back into it now.

Yesterday, two years to the day from the first idea and drawing, I finally finished making all the major components.

I've completed the task I dreaded most. The valves, guides, tappets and springs - 32 of each.

The valves took the most time as they are rather small with quite tight tolerances. Each one needs 8 machining processes.



Here's 16 of them on a penny.



And a close up of one so you can see the slot.



At this magnification, you can see bits of paste from when I ground them into their seats.

Offline Steve Crow

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Re: Cosworth V8 1:12 scale
« Reply #67 on: May 28, 2022, 06:37:43 PM »
Here's how the valve parts fit together, open and closed.



The valve guides are brass and reamed with a 1.026mm carbide reamer (Jurassic Tools - great price). They are a friction fit in the cylinder head and the springs keep them seated.

The tappets are adjustable using the 3 holes and the slot in the valve using a tool that I have not finished yet.

Here is a tappet and an untrimmed spring. And a penny.



Steve

Offline A7er

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Re: Cosworth V8 1:12 scale
« Reply #68 on: May 28, 2022, 08:16:23 PM »
A great piece of work! I haven't read through the whole process to see if you have already covered this question, but why 1/12th scale?

Offline Steve Crow

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Re: Cosworth V8 1:12 scale
« Reply #69 on: May 29, 2022, 10:37:59 AM »
A great piece of work! I haven't read through the whole process to see if you have already covered this question, but why 1/12th scale?

It's the smallest I could get away with! Also, it's easy to scale from the imperial measurements of the original. The block fits nicely into a 1 inch square bar, look at my earliest pictures.

Offline Steve Crow

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Re: Cosworth V8 1:12 scale
« Reply #70 on: May 29, 2022, 10:44:41 AM »
Here is one cylinder head with valve gear installed and a cam carrier behind it.



Valves, tappets and springs (and spares) for the other head.


Offline Admiral_dk

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Re: Cosworth V8 1:12 scale
« Reply #71 on: May 29, 2022, 10:14:34 PM »
Very impressive work and scale  :praise2:

I can't remember, but you are getting close to first run, aren't you ?

Per