Machining a custom top plate

I designed the original M-Mate that Luigi sells, it's a replacement baseplate for the M8/M9 that has battery and SD card access. CNC from aluminum. We were reasonably confident that the fit was correct, but even just a smidge of a hair of a millimeter can make the difference between a perfect fit and a loose fit. We took the camera to the machine shop and they built three or four units, making minor adjustments, which we fit onto the M8 until it was perfect. Machine time and machinists are expensive, so you need to be very very close before doing this.

This project certainly is doable in aluminum, but to make it financially viable you'd need to be able to sell the productions, and to do that, you'd have to offer some additional functionality. Not sure what that might be. 🙂

There are some desktop CNC machines coming out, for prototyping and low volume. I'm not sure what kind of tolerances these machines are capable of, however. And there aren't any 5 axis that I know of!

Protolabs in MN can send you an aluminum part in three days if you don't want to mess with all that, and they do an absolutely amazing job. But you're talking at least $1,000 for the bottom plate, and probably a lot more than that for the top, just for the prototypes. If you're on a budget you'd need to make sure your measurements are absolutely spot-on. For the designs that I currently do, it's pretty common to have to send three sets of CAD to Protolabs before it's perfect.

Before doing that, get a 3D print made. That will reveal many of the measurement errors, but not all.
 
The "Ur Rapidwinder was machined out of a solid block of brass (5 lbs). It took 5 days to do on a Bridgepost milling machine. It works and it still does - a bit of an overkill as the lever action is fully ball raced. I had the tolerances and measurements supplied by Leica Midland. The compound curves around the ends of a M-top plate are extremely complex to integrate, some are only 4-6mm long before they flow into the next curve.
With a top plate you also need to access the "interior" to make frames for holding viewfinder windows - which is no easy task!
The original top and base plate for the M was formed with complex dies. the brass was heated and went through at least 4 different dies until it was done.
Current top-plates are CNC machined out of brass - allows Leica to change to different shapes ( Vintage type film rewind or M4 style slated rewind) by just changing the program!.
To punch form Titanium would be staggeringly expensive - apart from the cost of the dies (6 figures) and titaniums unwillingness to take the form in a die. It is fairly brittle and cracks easily.
Machining it is a bitch!!! You keep loosing cutters as titanium is very bad at dissipating heat - feeds it back into your cutting tool, which goes from red hot - to white hot and then starts spitting molten drops of carbide on you!
It would be possible to do it with a smaller Sheerline style of milling machine - but very slow as your cutting depth would be in the 10th of a millimetre. It is not really force that makes the cut, it is speed and depth of cut.
I think it would be more interesting to make the top and base from carbon fibre instead. Using a 3D printer to make the "moulds" and "wrapping the carbon fibre mats around those and then cure it.
 
If the objective is mainly aesthetic, perhaps stripping the chrome off and re-plating is more feasible. Given the amount of 'black painting' being done, I always wondered why no one is plating their Leicas in unusual metals. There are lots of diy kits available at
caswellplating.
 
Thanks for the input Tom, thats the kind of answer I was searching for, I knew it was hard but I just dont have experience with titanium nor complex curves and the inside holding bits around the windows on the top plate.

I spose im better off grabbin a TI plated brass M6
 
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