Brass tops (and bottoms)
Old 03-06-2017   #1
kshapero
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Brass tops (and bottoms)

I read this somewhere, "I thought some M6's had brass tops. I don't remember the details but I'm sure someone here does."
Don't all Leica M's have brass tops and bottoms. Can someone clear this up? or correct me?
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Old 03-06-2017   #2
Robert Lai
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The M6 and late M4-P have a zinc top, though there is a claim that some of the M6 had a brass top. Bottoms have always been brass.
More discussion here: http://nemeng.com/leica/042b.shtml
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Old 03-06-2017   #3
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M1, M2, M3, M4, M5, M4-2, some M4-P tops are brass. Some M4-P are zinc. M6 were zinc. I'm fairly sure they started going back to brass with some versions of the M6 TTL.
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Old 03-06-2017   #4
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All film M cameras have brass top and bottom plates, except late M4-P? and M6.
M6 and M6 TTL use zinc.
The M6 TTL Millenium and M6 LHSA have brass plates.
M7 and on have brass again.

Some digital M cameras, typ 262, do not use brass plates.
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Old 03-06-2017   #5
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I wonder why they decided to go back to brass?

Wouldn't the Zinc have a tendency to crack before bending/denting? Especially since it is cast?
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Old 03-06-2017   #6
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Impurities in zink casting show up as bubbles and are very unsightly.

It has happened with M cameras, never with R as far as I know.
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Old 03-06-2017   #7
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Quote:
Originally Posted by B-9 View Post
I wonder why they decided to go back to brass?

Wouldn't the Zinc have a tendency to crack before bending/denting? Especially since it is cast?
For the bottom plates, some early M6 ones were zinc, but it cracked at the point where they go over to bolt so they were later changed back to brass to be more forgiving.

Why did the top plates change back? Zn is a better material, and wasn't the cause of the 'bubbles', that was a layer under the chrome not the zinc. If it was the Zn, then all M6s would corrode like this but they don't, just some early ones do. As for Zn compared to brass; sure, Zn will crack rather than bend or dent, but on a top plate, the impact required to crack it would be pretty big, whereas the brass can dent with a relatively minor impact.

My best guess is they changed back to brass when Leica finally realised that the only way they were going to stay in business was to offer a 'premium' product that recognised its history, rather than a practical and more affordable product.
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Old 03-06-2017   #8
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In the early days the brass tops went thru several stamping dies to get their final shape. Today the brass tops are milled from a solid block of brass on a CNC mill. All the brass chips are recycled and the tooling will last a very long time. I suspect a mill fixture or two and a CNC mill with a standardized tooling package could be set up and running more quickly and easily than several dies or a die casting line. This is from memory so please correct me if I'm wrong. Joe
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Old 03-06-2017   #9
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What about the certain brass inserts in the bottoms (not camera related)
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Old 03-06-2017   #10
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This is all quite interesting to me, as most of this is new information to me.
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Old 03-06-2017   #11
michaelbialecki
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My standard M6ttl .72 has a brass top and as someone already mentioned, my Black Paint M6ttl Millennium also has a brass top (you guys already knew that).

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Old 03-06-2017   #12
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Joe - apparently M top plates are CNC milled out of billet (!!!) - this video shows a block of brass being loaded into a CNC mill and then a top plate emerges...

Presumably someone did the math and figured CNC milling was cheaper than forming from sheet, but that's just wild to me. But I guess $30 for a chunk of brass and a couple hours of machine time is nothing for a $7000 camera with low (?) production.

how do you even mill stuff that thin?!!!?!?!?! (what do I know anyways - I just build crappy race cars...)
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Old 03-06-2017   #13
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Quote:
Originally Posted by B-9 View Post
I wonder why they decided to go back to brass?

Wouldn't the Zinc have a tendency to crack before bending/denting? Especially since it is cast?
I think that was part of the reason. I'd rather have a dent than a crack. And I read that there was some trouble with slight distortions of the shape.
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Old 03-06-2017   #14
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CNC... nice

I'm curious if the M8 top is also milled?
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Old 03-07-2017   #15
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Brass is better suited to engraving than zinc alloy, and in the case of the digital M cameras, perhaps they felt the need for some additional mass. Brass is softer and easier to dent though.
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Old 03-08-2017   #16
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If Leica were producing large numbers of cameras then stamping dies would be less expensive per part and a good choice. For low production, dies would be very expensive up front with few pieces to cover the cost. CNC (computer numerical control) offers easy set up, adjustment and reasonable run times with the added benefit of the ease of sending the program and drawings to a vendor to farm out the part.

There is also the old argument that brass covers, under impact, will deform and absorb much of the shock thereby protecting the machinery inside. Is that true? I don't know but I suspect it is. Joe
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Old 03-08-2017   #17
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Quote:
Originally Posted by michaelwj View Post
For the bottom plates, some early M6 ones were zinc, but it cracked at the point where they go over to bolt so they were later changed back to brass to be more forgiving.

Why did the top plates change back? Zn is a better material, and wasn't the cause of the 'bubbles', that was a layer under the chrome not the zinc. If it was the Zn, then all M6s would corrode like this but they don't, just some early ones do. As for Zn compared to brass; sure, Zn will crack rather than bend or dent, but on a top plate, the impact required to crack it would be pretty big, whereas the brass can dent with a relatively minor impact.

My best guess is they changed back to brass when Leica finally realised that the only way they were going to stay in business was to offer a 'premium' product that recognised its history, rather than a practical and more affordable product.
I remember them driving a car over a R camera and the top stayed in tact. Leica Photography, date ???
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Old 03-08-2017   #18
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I'm fairly certain my M6 classic does not have a brass top, but I wish it did. It would curb my desire for a MP or M-A.
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Old 03-08-2017   #19
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Quote:
Originally Posted by gnuyork View Post
I'm fairly certain my M6 classic does not have a brass top, but I wish it did. It would curb my desire for a MP or M-A.
The Zn top on then M6 is a great gateway drug to the brass top MP!

But unless it's black paint, you'll never get it back to the brass anyway.
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Old 03-08-2017   #20
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Quote:
Originally Posted by michaelwj View Post
The Zn top on then M6 is a great gateway drug to the brass top MP!
[i]
But unless it's black paint, you'll never get it back to the brass anyway.
I know...meant to say brass top black paint...
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