September 18th, 2015 Progress Update ...
Chassis layout and testing...
With the motor & gear train pretty well finished, it was time to attack the fuzziest part of the Mk II project -- the chassis --due to both my fuzzy memory of the specific details of the 4 chassis designs (after all, it has been 45 years since I built the originals!), and the poor fidelity of the surviving Car Model article photos.
The main rails, as on the originals is .044” OD music wire – chosen as it fits perfectly inside the .058’ OD hypo needles, forming the hinges for the drop arm & side pans. Several experiments were tried to join the critical main rails to the cross rail – without damaging or freezing up the drop arm hinge needle (always a problem with the originals).
First experiment was to form a “U” shape cross rail with the hinge needle in the center. Managed to make it work, but the results were too wide which made the side pans too narrow.
Then I tried a micro brazed “T” joint. By reducing the length of the needle a little, this proved both very strong and the needle was free to work as designed.
Next, laid out final sized side rails, brazed in the minimum length (to just clear the motor width) cross rail. I made up the motor supports at both ends – now it was shaping up as I wanted.
Mounted up the motor/gear train.
I machined up wheel/tire dummies and made a rough layout of the side pans – now more in line with the original Mk IIs.
The chassis was mounted up on a chassis building jig (an increasingly valuable gift from Ron Bernstein).
Time to test fit the body master.
It’s beginning to look more like a Mk II now.
This is what you use to micro braze these joints.
The partitioned box that the completed subassemblies has been shown before, but you may find it amusing that the size of this box:
Is substantially smaller than the Support box – containing most of the jigs & fixtures and other components:
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