Wednesday, June 25, 2008

Trebuchet: Part 10

I stayed up later than I probably should have working on the trebuchet. But I got a lot done on it. Prepare for a long post.

Here are the smaller dowel pieces I cut from the very long ones. These will be used as tread dowels to combine the two sides of the winch wheels.

Here I have a few in place. I'm just using glue for now. That's why the rubberbands are there. I'll take those off after a day or so after the glue has fully dried. Eventually, I may use some twine to lash the dowels to the wheels. It would help a lot structurally, but it would mostly just look really cool. But the glue should do fine for now.

All the dowels are on the first winch wheel. You may notice the edges of the dowels are a little rough. That's because they came from a much, much longer rod. After measuring the length I needed, I scored it a bit and snapped it off. On the dowels used other places I sanded the ends after doing that. But there's just too many to do that here. Besides, maybe it makes it look more authentic? If I need to, I can always sand down the ends quickly with a dremel. Depends on how it looks once it's all together.

Both winch wheels assembled and sitting in their approximate final place.

A few of the axle holes needed to be reamed out a bit. These axles will be involved with the pulley system, so they need to spin freely. Note to self: when using a manual round file to make an existing hole a bit bigger, be careful where placing the bracing hand. When the file suddenly released on the other side, it grazed the top of my knuckle a bit. Just a scrape, but I figured I better band-aid it up. I'm guessing it wouldn't be good to get sawdust in a wound.

Good news on the A-frame width! While reaming the holes through the A-frames and holding the sub-frame, I accidentally loosened the glued connection there. And with a little more wiggle and prying, I was able to separate it. Then I sanded down the tops of those outrigger supports that were pushing in too hard. This time when I glued it all in, I used a level. Success!

Additions to the subframe to hold the winch wheels. That longer horizontal dowel is the axle where the winch wheels will attach. It will move with the wheels, but spin easily within the A-frames.

Both winch wheels attached. There are axle struts on the frame to solidify the stability of the wheels.

The trolley block. The twine from the winch axle will eventually lead to here. This will go on the trolley line on the arm.

I forgot to put a trolley line on the arm! So I redid the lashing near the arm axle and left a loop on it. I then just tied a line between that loop and the bit of loop I left when lashing on the release pin at the end of the arm. In this picture you can see that line hanging there. And the arm/counterweight box sits on the axle between the A-frames just fine now. I think this is going to work!

Lots of the pieces together, and it looks like a trebuchet! Just a bit more for completion. The main thing left is the trigger. Once the arm has been winched down, it will be held down by some more twine going across the top of it. Then the winch line can be released. That way, when it's fired, there won't be the drag of the winch unwinding. After the trigger, I think all that will be left is the sling and the trough. Seems like I'm missing something, though. The winch wheel axle is held in place with spacers which are glued onto the axle. But the rear and front dowels have nothing like that. As it is now, they can slide out of the holes. I could put some kind of stop on the dowel inside the frame. Just need to figure out what to use.

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