My G3YUH AMPLIDAN Mk2 Project
This is the Start of my Amplidan Mk2 project, I was quite pleased with the result of my first attempt at a copy / facsimile of this famous key, the action was very similar to the original, and although it didn't look exactly like an original Amplidan it left no doubt  as to the origins of its design, I learnt a lot making it, and got a good insight into the original Amplidan design and what makes it such a remarkable key, the real problem for me was the construction of the adjustable pin pivot bearings, which were quite difficult to make with my limited tooling and skills, any lack of accuracy here can seriously affect the performance of the action, so in this key I have moved away from the original design and fitted 7mm ball race bearings,  I'm sure this will improve the action, but at the same time I have hidden the bearings inside the holders to preserve the original appearance. On the right is the bearing holder cut from a solid block of brass, 2mm wider than the original to accommodate the ball races, I have even fitted dummy side adjusters :) the only give away are the two small bearing tighteners at the back.  Perfectionists may argue this is a wrong move but I'm hoping for a key with a performance BETTER than the original but looking almost identical.
Another change from my Mk1 Amp is the stepped base, which I'm making from two pieces of 6mm Acetal this is an attempt to follow the original design more closely, next job is to cut the handle
The Handle is now cut filed and polished up a bit, it is far more accurate in its swept down angle than the Mk1, the axle is made and fitted into the handle and the whole assembly pushed into the bearings and checked out, even if I do say so myself it has come together very well, a precision fit an almost frictionless pivot with no side movement at all, I'm very pleased with it so far, I had to make a couple of small compromises like increasing the slot size on the bearing tighteners, and sweating the axle in permanently for ease of assembly, also made a few other Amp type bits, the waisted tension adjuster and the spring loaded gap adjuster slide and cap, I might make the gap adjuster assembly next so I can get a much better idea of how it will look when completed, to spur me on :()
On the left is the Mk2 Amp next to the original, the only major difference at the moment is the modification to include ball race bearings in the bearing holder, of course some imagination is required as the black plinth needs to be rounded off and the long metal base is yet to be fitted and all the front contact and terminal assembly, I'm hoping for at least a 1 or maybe 2mm similarity to the original when its completed, with not so many "compromises" as the Mk1, that was just a warm up :()
Only a small amount done today as the UK is having a cold snap and its a bit chilly in my little workshop, but the flat spring is now mounted and the insulators and contact strip fitted, the key is now starting to build in complexity, both the contact adjuster and tension knobs are just balanced on the key at the moment, the tension kob has to sit in a 14mm milled recess, I tried using a 12mm ]drill on the Mk1 and it wasn't that good a fit as it was dome shaped being a drill, so I have ordered a 14mm end mill to do the job correctly this time, (may even go back and sort out the Mk1 later :)
As soon as that's done I can fit a coil spring and test it out for the first time
 
On the left you can see the Mk2 with the contact stop fitted and the tension adjuster sitting its milled recess, the adjustment is a bit gritty yet, the original Amp has a very fine non metal washer that I don't have, so room for experiment there, on the right you can see the Mk2 action rigged up for it's first tests which are quite promising, not quite as good as the original yet but still a way to go :()
The spring loaded top contact is now fitted and brass side terminals cut ready to fit, also cut the heavy base plate to size, this is 3/8 brass and was about the heaviest cutting job I've undertaken, in the original Amp this is steel but I have no means of cutting steel plate so used brass instead, which was difficult enough, also far more expensive as well, this is about the most expensive key I've made in terms of materials, Left you can see the Mk2 compared to the original and on the right the two end on, below is the almost finished key.
The above key is now mechanically almost complete, all that remains is a suitable piece of brass to be fitted under the knob, a cable clamp of some sort on the front, the guide screw for the tension adjuster, and of course the final touch of Nickel plating, it is without doubt a fine action key, with an almost identical action performance to the original, which I had hoped for, and the ball race bearings seem to add an even more precision feel to it as I'd hoped they would.
Below the G3YUH Amp Mk 2 more or less finished, the front adjuster is a little on the high side owing to the washer that is under it which is a temporary fit until I find a better one, there are a few other little odds and ends that I will come back to, the action performance is as close to the original as I think I can get with the simple tooling I have available, there is only so much you can do by hand, I enjoyed this project better than the last as I didn't make so many compromises except for the ball race bearings , It was great fun, I might make another with a slightly modified bearing block and bearings as an experiment.

 

An insight into the Amplidan 50713