Trebuchet CATAPULT Project/Worklog Updated 12/12/06 Please COMMENT

Hehe this thread inspired me to build my own model trebuchet with pens and electrical tape, using 2 C-cell batteries are counter-weights. It works really well, is so much fun lol.

_C

 

Guide, Double_C? I want a mini trebuchet!

 

Guide?? Build it yourself, its not difficult lol. I'll post pics in a minute.

_C

 

when do we get pics of the big one?

 

http://www.ripcord.ws/plans/plans.html Those are good plans for a small tennis ball launcher. You can downscale it if you want a desktop version.

The big one will be started after May 8th stay posted for updates. This will be a worklog so if you want use this as a guide I will try to make it as detailed as possible.

 

The project is not dead. Ap's are over so work will start shortly. Currently plans are being reviewed and calculations made. Unfortunatly my local hardware store does not have o rings strong enough or big enough wood. "Maxed out the hardware store" So to home depot which won't give me discounts . Oh well once work starts I will keep you guys posted. I will be posting some pics tom of work area and some materials I have already.

 

Updated I have some pics of the weight and some tools.


This is the weight pile. There is 800 pounds worth of weights there. More on the weight level above the stage about another 100 pounds there.


This is what normaly these weights used for which is as counterweights for hanging things like lights and scrims on movable poles above the stage.


My tools just a handdrill a dremel and a couple accessories. I have a chop saw a jig saw a belt sander and a couple more drills which I will be getting latter in the week.

I will be ordering wood tom or next monday after the weekend. So yeah project is progressing.

 

A small update got almost all the hardware.

Um you should be able to tell what it all it there but the harder to tell stuff is the 100 1/2 bolts and 100 1/2 washers and those rods are 1/2 6ft threaded rods 4 of them. The gold thing is a regular door bolt which is going to be my trigger release after a couple of modifications .

Things are starting to pick up and there is going to be a documentary made on this project by the film class. So yeah stay tuned.

 

Hey sorry long time no update. Currently still salvaging wood from the stage and other materials. But thought you might like to see this pic of my teacher dremeling some bent nails off. Yeah I know gross overpower but hey sparks are cool . Plus she wanted to use some power tools so I was like why not. (She didn't know what a wrench was) So yeah not exactly an expert with tools.

Once real work starts I be posting lots of pics.

 

Nice to see this getting off the ground. Good luck getting the door latch to work correctly to use as a firing mechanism. If it doesn't work out I'd look for a marine release mechanism (I forget the exact name) which works pretty well.

 

WOOD GOT TODAY. GOT TO LOVE IT WHEN HOME DEPOT GUYS GO WTF YOU GUYS DOING WITH ALL THIS WOOD.


My friend standing by our cart full of wood. Got to love how this isn't all of it this is just suplementing the stuff we got already


Inside of car loaded up with 15 8ft 6 by 2's


Top of car loaded with the 2 16ft 8 by 2's. After we took the ropes off. Don't have a good pic of it with all the tie downs but it was a lot looked like a spider web lol.


After we unloaded it all into the auditorium. Got most of wood in shot but I was against wall so there is even more. So the long pieces go off a about a foot more then the pic. Just for size comparison. He is working on the project and decided to take a nap from moving all that wood.

Yeah this is getting off the ground so yeah we will have this done by probally the second week of june if there are no hitches.

 

Excellent, can't wait to see how it goes. I'll be following this with great interest!

_C

 

BUILDING STARTED ON COUNTER-WEIGHT BOX


All the wood we need for the box cut into size already. Sorry had no pics of the cutting process but we used a handheld circular saw and a chop saw to cut all the pieces. In total 8 20inch 7 by 2's 8 14inch 7 by 2's and 4 4by4's that are 21 inches long. The rest is scrap wood which will be used as spacers or anything else I might need them for.


Started and you can see the floor is made up of two 7 by 2's that are 20 inches long. The 4th 4by4 isn't on yet and those are 21 inches high.


3 screws are being used on the bottom of the 4 by 4 to attach the 7 by 2 the 4 by 4. It is a little over the lip so it will fit with other pieces we are putting on and will allow the weight to fit nicely.


The side getting planked up to make the sides of the box. Some of our tools are there the others are on the floor. One drill to make pilot holes and another to screw it in. The screw driver is there cause one was giving us a lot of trouble. The botttom one has about 10 screws in so it will help hold it together while the other pieces are only held by 4 screws since they will have virtually no weight on them.


I only planked up one side today didn't have time for the other sides. And you can see how the weights are going to be stacked.


An aerial view and you can see where I left spaces so that there will be room to put your hand in to load and unload the weights


This is the bottom where you can see 2 14 inch 7 by 2's that are going across the bottom to give better strength.


Havn't finished yet but there will be a lot of these puppies all along the inside. Hurray for L brackets .

Well that is all that was done today will have more pics up later.

 

Big day today got a lot done. We will possibly be done with the base by the end of this week.


Put a spacer in so that when I put the 14 inch pieces on it won't run off.


Here is an aerial view of the spacer the 14 inch 7 by 1 will go all the way down so yeah just put the spacer in so it has more to sit on and I can put more nails in.


Here you can see we switched from screws to nails with the planking up of the box as the screws had some troubal going in and the nails will do fine. The nails we are using are 3 inches long so yeah.


As I said massive reinforcement from the brackets. There are also 6 on the outside but didn't get a good shot of that.


My friend Gabe who is working on the project putting some of the bottom brackets in.


Here is the box finished with some weights piled in. It will be completly filled on launch day .


BRACKET CRAZYNESS


The finished box sitting there havn't drilled the holes for the cable yet but it will be done latter after the support frame is finished.


Started cutting the side beam supports will be 8 of these. That is a 45 degree angle cut.


Here you can see the whole thing


Finished the base outline need to put the cross beams in but that is the way everything looked at the end of the day when we needed to pack up.

Yep this is going along I am hoping to be finished by the end of this week.

 

Nice work, good to see plenty of pics too!

 

Looks like you're making good progress there. My biggest concern there is that those small brackets wont hold up to all that weight. Don't forget that during the launch that bucket is going to be swinging all over the place under extreme stress. It would be disaster if the arse fell out of it during the launch. My suggestion would be more reinforcement AND do a test of the suspended bucket with the total weight you will be using on the day to see if it can handle it while being moved around.

 

metal stuff around it?
if anyone knows what im on about... metal strip stuff should help it a fair bit?

 

I will be making a load test before we are on launch day. Though there is significant reinforcing from the wood. I believe that the wood was good enough to hold by itself the brackets are just a safety buffer in case something does go wrong. If I remember correctly there are about 24 screws in the bottom already connected the bottom straight to the the 4 by 4's which will be holding the brunt of the force. Then 14 L brackets inside and out for reinforcing. But a test will occur.

 

I agree with Constructacon... the weight box does look a bit week. I would have recommended using some wood glue or epoxy to join the wood together as well.

Don't forget that screws have very little lateral strength. BUT hopefully the L brackets will be sufficient. You can never have too much reinforcement!

 

Angle iron is what your are talking about. That's what I was thinking about. You need to spread the supported load out as much as possible. It would be even better if you could make a square out of that iron so it would slip over the bottom lip of the box like a cup (get the shop boys/teachers to weld it up for you). That will prevent the bottom boards from ballooning out.

Just my thoughts on the subject.