A little of an update on my test track. I have been experimenting with the point rodding to see if I can make it functional (madness I know!). I have also been looking into how I might procure some nearer prototypical Midland rodding
cradles. To this end I tracked down some pretty good photos and have been in conversation with Alan Buttler at Modelu about an addition to his range.
NRM 1 copy 4.jpg
Midland compensator.jpg
Alan developed this 3d model ...
MR Point Rodding Chair v1.jpeg
If printed to 4mm scale the
cradles are very small and unworkable for anything but cosmetic installation. However if printed to 6mm with slight adjustment they can be designed to accommodate a .7mm capillary tube with internal diam suitable for a .5mm nickel silver wire. Looking at the 4mm
cradles insitu, to my eye they looked too small ... almost as if the size didn't really scale as the eye read them as being just too flimsy to carry out their task. The 6mm ones curiously looked much more convincing to me ... (might just be me
)
So the plan was .... bond the stools to appropriate bases; bond a small section of capillary tube into the top of the
cradle such that the rodding 'wire could run freely within .... the theory being that the
cradles/tube sections would restrain the wire preventing lateral distortion without unduly effecting the action. First experiments are encouraging -
Point rodding in place with rodding max forward
point rodding - 3.jpg
Point rodding in place with rodding max backwards
point rodding - 4.jpg
Detail of capillary tube bonded to
cradlepoint rodding - 5.jpg
I have included a omega loop to ensure that there is always tension/pressure within the system (will be covered by some strategically placed boards). Everything seems to move quite freely and positively with little drag and the wire has no distortion. It also all feels surprisingly strong and robust ... so time to transfer to the test track and give it some use. Next up a homemade pivot lever actuator/frame
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