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.

[SuburbanFarmer]

I’m not confident in the plywood solution. That’s pretty weak stuff.

You need oaken beams, for true strength.

[Speaker to Animals]

Somebody call the police.

[Montegriffo]

I’m not confident in the plywood solution. That’s pretty weak stuff.

You need oaken beams, for true strength.

Plywood is far stronger than oak of the same thickness.
6 inch oak beams 4m long would be expensive too.

[Hastur]

So, basically home brew glulam. Interesting. What kind of glue do you use? What do you use for pressure?

[Hastur]

I hope you got marine-grade plywood. You don’t want it to be killed by some rain or dew.

[SuburbanFarmer]

So, basically home brew glulam. Interesting. What kind of glue do you use? What do you use for pressure?

This. You can’t just slap some together, and treat it like a beam.

[Hastur]

So, basically home brew glulam. Interesting. What kind of glue do you use? What do you use for pressure?

This. You can’t just slap some together, and treat it like a beam.

The principle is sound if a bit fascist. A lot of very good wood glue around as well. It sounds feasible to me. More lightweight than oak anyway.

[Speaker to Animals]

Has Okie taken strength of materials yet? This could be fun.

[Fife]