Here is the basic lock up for all the joints on Phoenix’s field frames.

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The angle on the under wedge is 2 degrees.  With the first wedge we hammered home, there was some frictional galling between the wedge and loop.  The torn metal was easily filed smooth.  A smear of grease prevented it from happening again.  Technically, bronze would be a better metal for the wedges as it would never gall against the steel.  However, part of our game is to pursue designs that represent simplicity and ease of manufacture for ancient metal workers stationed out in the boonies;  forging steel being simpler than casting bronze. And no!  hardwood wedges ain’t in the cards.  Too many rattles I don’t need to bother with.  Cellulose has it’s place, just not at the heart of our souped-up torsion racer.

So, iron wedges and a flick of grease would be my tip to the aspiring village blacksmith turned ballista-maker.  The balance  between easy and superior is not always contentious.

2 Responses to “No rattles”


  1. Charles W. Fink says:

    Maybe that steel to steel friction will help to keep the tensioning wedges from backing out. It seems like it could be tricky for the fine tuning to stay where you put it when the Phoenix is fired. It always seemed odd to me how one locomotive could pull so many loaded cars on smooth rails. Nice touch to put a tap out surface on the wedge.


  2. Nick says:

    The vertical keys go through slots that have been cut in the wedges. The wedges are thus trapped by the keys and held tight in their hammered home condition. All very snug and mechanically immovable. That’s not to discount the notion that friction can be our friend, no matter what the locomotives say.

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