Save for the grind and finish work, the upgrades on the field frames are completed.  The Hi-test weld that has been added to the outside of the curve on the stanchions,  has caused this part of the field frame to exceed the dimensions of the original as depicted in the Baatz drawing.  So far this is the only variation from the Baatz drawing we have allowed.  If our field frames had been made from something tougher than mild steel, this increased girth would not have been necessary.  In this fuzzy area it seems appropriate to use our guiding principle of trending towards maximum performance.   The safer assumption appears to be that the original Orsova ballista probably had all of its critical parts made from tempered carbon steel.   Anything less  runs the risk of underestimating Roman metallurgy as it would have been applied to one of their high end products.  Not a safe bet at all I should think.

I had expected to use a new piece of 4140 rectangular bar to upgrade the kamarion.  As it turns out,  it seemed better to save that piece of material for another part of this project.  In its stead, work has started on straightening out an old Chevy coil spring.

The plan is to continue forging this 3/4″ diameter piece of spring steel into a backing, and then  Tig weld it onto the current mild steel kamarion.  The final version should be close to the cross sectional dimensions represented in the drawing by Aitor Iriarte  (See posting titled  “The paper”).  The kamarion we have been using to date, was based on the Baatz drawing, which is notably less tall in cross section than the Iriarte version.

It occurs to me that the astute reader may wonder why I have torn Firefly apart after recently announcing, ” The bundles have settled. Consistency at last”.   The reasons are twofold.   First, now that we have pretty well established that this machine has impressive levels of power, the next task will be to revisit the whole question of shooting precision and accuracy.  The only way to get to that,  is to improve the reliability of the machine through more upgrades.    The second reason is that in the previous round of testing, the main objective had been to establish that the nylon bundles would reach some kind of equilibrium and not lose velocity with continued shooting.  After we saw a  dozen shots with 7,000 grain bolts maintain speeds of 300 feet per second,  with barely 2% variation, there  really was no logical reason not to tear her apart and move on to the next phase.  …… Which, is where we are now.

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