The renovations in our apartment have finally come to a phase where I have been able to resume work on my cheiroballistra.
A few days back I finished attaching the triggering mechanism part to the composite slider which I created a few months ago. The composite construction can be seen in this image:
The back-end of the slider is of elm for hardness and splitting resistance, whereas the frontend is of pine to keep the weight down. The two pieces are joined together with a half lap splice joint, glue and two vertical wooden dowels. This type of joint should work well, as the slider has to endure mostly compressive forces. The slider is slightly wider than previously, which gives it additional strength. The angle of the dovetail has been adjus…
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The cheiroballistra project has stalled for quite a while as we've been renovating our apartment thoroughly since July. Fortunately after Christmas I could spend two days at the forge.
The results of the ballista-related work are these:
On the left there is an old ring for the cone and below it is an old 3mm thick pi-bracket. On the right side, from top, two spare 5mm pi-brackets, a new washer, three thick rings for the cones and eight thick pi-brackets with partially formed tenons. They attempt to fix a few mildly annoying issues with the cheiroballistra:
- The 3mm thick pi-brackets were a bit flimsy, even though they had survived earlier fairly high power tests.
- One of the old washers could not be easily rotated. This was probably caused by s…
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It has been quite a while since I actually published pictures of new cheiroballistra parts, so here it goes. First the new little ladder forged from 6mm spring steel coupled with a better and stronger little arch forged from concrete reinforcement steel. Note how the tenons of the rungs simply project above the beams, instead of being riveted or otherwise attached to the beams. This allow one to bend the little ladder beams outwards when inserting their tenons into the pi-brackets in the field frame bars.
As can be seen from the picture below, the little arch's retaining pins are significantly stronger (5mm) than the previous ones (3mm):
Because the little ladder tenons are larger than previously, the wedge system needs to be adapted slightl…
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In the recent weeks I've been working on several new parts for the cheiroballistra.
The new case, which is made of pine, now has the crescent-shaped from the old cheiroballistra. I originally intended to make the new crescent-shaped piece from the crooked piece of spruce I had lying around, but that would have slowed down the project for basically cosmetic reasons. The female dovetails are basically ready, but they have not been glued to the case because the slider is missing.
The new slider is of composite construction, with the front part composed of two vertical layers of pine, and the short rear part made from a single piece of elm. The lamination step was not really necessary, but it reduces the change of the slider bending and getting …Read more >
Routledge is having an open access week. This is of particular interest because there are some ballista articles in there. In particular the Performance of Greek–Roman Artillery by Rossi et al 2015 is extremely interesting. After the open access week is gone, that article probably goes back behind a paywall.
Because this is a blog, and in blogs one is allowed to rant, I will take this oppurtunity to rant about these paywall-erecting publishers. Take the article "The Reorganization of the Defences of Romano-British Towns in the Fourth Century" for example. It contains the word "ballista" in it, because it shows up in the site search. However, there is probably no way to know if the article is actually relevant to ballista research in any way…Read more >