Very sweet!  Maybe I'll get around to showing you guys my trebuchet.

Chris

Chris,

Hey that would be really cool to see video of your trebuchet.  If you have that option, post a video in the video section.  I love the slings on trebuchets.  I think a lot of the Roman catapults had slings attached too.  That's cool.  

Barak,

My workshop is bare essentials.  I got a workbench from my Grandfather.  The whole surface is almost black from cigar ashes and whatever else he did with it.  It's my favorite tool.  Drill press, jigsaw, and files.  Other than that, not much.  Well actually I also inherited a tablesaw from the 60's.  But I never have use for it for most of the stuff I make.  

The Scorpion could easily be made in most any size.  If you're thinking about making a bigger one, I wouldn't go over about 3' tall.  Over that and you're going to start getting into bow weights of maybe several hundred pounds.  Atleast I'm guessing so.

If you didn't catch it, the whole arrow trough slides forward and backwards within the body.  You probably got that.  I think there is a good website up about these things now, but I don't know the address.  They even have blueprints for several designs from what I've seen.

You know, that thought about ropes is interesting. Nylon has some stretch to it forsure.  The wooden frame is very heavy in relation to the forces placed upon it from the string's tension.  You have to experiment with different quantities and tensions of rope.  Start off small and tight.  Too much rope ends up being almost impossible to twist and you can't get the tension to be consistent over the full travel of the arm.  The originals back in Rome used to use sinew.  It had problems in wet weather, but otherwise, was very powerful stuff from what I've read.  The upright vertical arm catapults worked by the same powersource.  Trebuchets were a midevil thing and were gigantic and not maneuverable because of all the weight.  The Roman's called their vertical arm catapults "onagers"  I think I spelled that right.  It means "wild ass."  Because they jumped up off the ground when they fired.  That's a lot more dynamic than what you see in the opening scenes of Gladiator!  

I've had that string tensed at full tightness for about 3 or more years now and I use the thing occasionally.  It never looses power or shows any signs of degeneration in the coils.  I'm impressed with the nylon.  That was one of the things I was worried about when I first made it.  That I wouldn't be able to get a good powersource.  The nylon works great!  

One cool thing about Scorpions, is that depending upon how far you set the trough back, you can vary your power between safe indoor fun, and lean mean outdoors target shooting.  It's great to see the darts fly through the air.  It's beautiful.  I put a slight bend on the fletchings and they spiral in flight.

I'm guessing my bow weight is around 20 to 30 pounds but it could be more.  The darts are pretty light and so they fly fast.  You'll notice the brass pipes at the bases of the bow arms.  I put those on there because my first two sets of arms literally crushed and broke under the power of the string coils.  It bit right through them.

I was just thinking.  I don't know much about rock climbing but that dynamic rope you're talking about is probably too dynamic for catapult use.  The static might be better.  Probably the best is plain old nylon rope from the harware store.  Or paracord or something like that.  I've seen some guy use sisal rope on that website.  I think that's what it's called anyway.  You know, the vegetable fiber stuff.   

                                  Ben    

That scorpion design is very impressive!  Do you also have a precision aiming system for it?  How did the ancient Greeks and Romans aim it?

You might be able to sell scoped pickup truck bed-mounted versions of this for quiet, long range pest control on ranches and farms !

I aim with the release screw, off the end of the arrow ramp.  It's like the reverse of a pistol, with the post at the back. 

The release is pretty simple, very similar to the originals, except slightly more simple.  I just pivot the steel release from the middle, and put a lever underneath the back end with a post coming out of the slide to hold one end in place.  When I wish to fire, I pull the cord on the lever and it slides out from under the release, allowing the front end of the release to elevate and let go of the string.  The arrow is blocked by a little steel post from touching the release in the slot, otherwise it might get lifted too.

This design was used on Scorpions, because it is very durable, without having a heavy "trigger pull."  And there is no chance of a misfire, since the string is held above the arrow groove and behind a piece of steel that goes into the groove.

                            Ben

Johhny,

Yeah, they were just cold rolled steel from the hardware store.  It can be formed cold, or with a little heat to help relieve any stress from the bends.  The rest is just filing and sandpaper. 

A few weeks ago, my wrists were feeling better for a time.  Then they got much worse.  During that time, I, probably unwisely, did an upgrade on my Scorpion.  I added a much improved windlass that uses a pulley to reduce draw weight.  A ratchet, and bronze fittings. 

I also upgraded my bow arms to hickory, with bronze sleeves for added support.  This increased their weight, but allowed me to significantly upgrade the bow weight. 

So I made new torsion skeins that are twice the size of the originals.  I also fitted some bronze washers to carry the skein and upgraded the size of some of the steel bars. 

I made new bolts, and was able to purchase some steel target points to fit on the ends. 

The results are awesome!  I tested it a few days ago and got a maximum range of 155 yards.  At 30 yards in my backyard today, I was sending the arrows through an 133 page JC Penny Catalog.  The arrows went right through it and into the target behind.

I'll put up some new pictures here.  I already put one up in the first post, but I took some this afternoon, to put up. 

                                                Ben

Very impressive.

Chris

LOL,

Well it's pretty small, so..., but the other day, I set back the winch to just 15 clicks (about 1/3) draw back.  And tried to shoot up at about 55 degrees for a nice graceful slow shot across my backyard.  The thing shot over 35 yards into my neighbor's backyard.  I swallowed hard, and was able to use a magnet on a really long pole, to retrieve the arrow the next day.  I should have known, but I thought it would have less power than that on 1/3 draw back.  My back yard has a big field behind it and is about 40 yards across, so it makes up for the fact that I do live at the edge of suburbia.

                                      Ben