Trebuchet news

[Montegriffo]

So, Trebuchet Guevara which we built 2 years ago has been dragged back into the field for repairs.
The frame only needs one rotten beam replacing which is ok considering its been out in the weather for 2 winters.
The throwing arm broke off about a yard from the pivot point leaving plenty of good timber to graft the new arm onto it. This will save us from having to redo all the holes and fittings for the swinging counterweight and the pivot.
I've bought 2 sheets of 3/4" ply which I am going to cut into 6" strips and screw and glue together to make a laminated beam about 4m long.
Last time the arm was too long for the height of the frame which meant it touched the ground before the counterweight was at full height. If I reduce it a little in length I am hoping that I won't lose more power than I gain by cocking it to full height.

There's one week left of the convention.
Watch this space.

How did the plywood go ?
I would be very cautious using plywood in this application. If you thought wood timbers were adversely affected by environmental conditions like water, sun and freeze, you won't be happy with what it does to plywood.

Boats and aircraft have been made very successfully made from plywood, it works. However, having a complete seal on all plywood is critical to maintain at all times.

I ended up having to work all through the Bungay Balls Up last year so I never had the time. The frame was starting to rot out as well as the broken arm. It has been out in the weather for 3 years now.
Will probably have to start again next time.
I think the plywood arm would have worked and been very strong but I would have had to take it off and put it in a dry barn when not in use.
I think my next one will be in oak with an ash arm but smaller due to the cost. At least with a smaller one I will be able to take it to other juggling conventions/parties etc.
Trebuchet Guevara was made from recycled timbers and cost nothing to build but an oak one will be pretty expensive. I keep looking up at the 25' oak roof beams of my house here in France and thinking what a nice trebuchet they would make.

BBU 2019 is only about 3 weeks away but I've got 6 days of film work right in the middle of it which only leaves 5 days so I doubt I'll have time for it this year either.

[C-Mag]

I have no idea what the preferred trebuchet timbers were during the renaissance war period, I think mostly they used what was available locally. I do know that American White Pine were the premium timber to be use for sailing ship masts. Great strength to weight ratio, and great flexibility. This also made American White Pine the premium lumber for wooden aircraft, from the Wright Flyer to Brit Misquitos. I would think white pine would be outstanding. Alas, extremely expensive in the dimensions you would need.

[Montegriffo]

I have no idea what the preferred trebuchet timbers were during the renaissance war period, I think mostly they used what was available locally. I do know that American White Pine were the premium timber to be use for sailing ship masts. Great strength to weight ratio, and great flexibility. This also made American White Pine the premium lumber for wooden aircraft, from the Wright Flyer to Brit Misquitos. I would think white pine would be outstanding. Alas, extremely expensive in the dimensions you would need.

They used an oak frame with an ash arm. The frame needs to be strong and rigid while the arm needs to be straight and flexible.
Pine could be used for a smaller counterweight and projectile but for something the size of Warwolf it wouldn't be strong enough.

[Hastur]

[C-Mag]

This is how you do it Monte

[SuburbanFarmer]

This is how you do it Monte

Clearly not a trebuchet. But beautiful work, nonetheless.

[TheReal_ND]

Squirrel launcher