We've recently been looking at medieval weaponry, and siege warfare, and as a result of that we ended up making a trebuchet and an onager, both of which were used a lot for laying siege to castles and such like many years ago, weapons like these were the most advanced war machines around, on a recent trip to one of museums we were looking at armour, swords and other hand held weapons.
I decided it would be good for the kids to have a crossbow each (non lethal crossbow) this would show them how hand held weapons have changed over the years, and give them an idea of what soldiers would have had in the way of weaponry and what it might be like to use such a weapon.
Here's what we ended up with -
Not historically correct, but fun to play with.
As you can see they are very much toys, but they do show what it might have been like to load,aim and fire a weapon like a crossbow, I've included a video of my daughter using her crossbow in the garden, and I've also worked out how much it cost to make both crossbows, the cost for both of them comes in at a cheap £4.27 (that's for both crossbows) not bad, it will work out cheaper if you already have some spare bits of wood lying about.
Here's everything you'll need to make your own crossbow -
Doesn't much look like it'll make a crossbow, but it does.
Ingredients list (for 1 bow) -
2 bits of batten, one at about 40cm and one at about 35cm in length.
1 length of 9mm dowel & 1 length of 6mm dowel.
2 old corks
1 meter of elastic
1 screw (about an inch or inch and a half will do)
1 scrap piece of wood for a trigger.
A wooden skewer.
A wooden tooth pick.
The basic design is a cross shape, I've used batten for both bows, which can be bought in a pack of 8 x 1.8 meter lengths for £8.42 (from B&Q) I've been using this batten for a while to make things like this, it's cheap and quite versatile, I only used 1 length to make both bows, so if you get a pack you'll have some left over, or you could just buy a single length, which comes in at about £1.56 or there about.
Okay, first thing I did was to get the trigger set up, to do this you'll need to make a slot in the longer piece of batten, first measure in around 8cm from one end of the longer piece of batten and make a line, then measure about 6cm from the first line and make another line, now find the centre of the piece of wood and mark a line between the 2 marks you've already made.
Like this -
Ready for drilling.
If you've ever made a mortise and tenon joint you'll find this easy, but it's not that hard any way, the next thing to do is drill some holes along the centre line, this makes it easier to slot for the trigger.
Holes drilled -
Just needs tidying up.
I used my needle rasps (small rasp files) to tidy everything up, and once that was done I used a bit of sand paper to smooth it all.
Trigger slot done -
Not perfect, but it'll do.
Next you want to mark down the sides of the longer piece of batten, you need to cut a notch out of the wood, this is where the elastic will sit when the bow is loaded.
Lines marked down the side, and notch marked out -
I used a coping saw to cut it out.
Notch cut out -
Some adjustment might be needed.
The next thing I did was to make a groove all the way down the longer piece of batten, this acts as a guide for the bolt, and makes it easier for the kids to use, to make the groove I marked a line down the centre and using a small sanding drum in my multi tool I sanded the groove out.
Groove line marked -
I wasn't too precise.
Here's the sanding drum -
These come in handy for all sorts of jobs.
Groove done -
How easy was that ?
If you don't have a multi tool you can always use files and sand paper, it'll just take longer.
Back to the trigger, I cut out a rough shape from my scrap bit of wood (an old bit of tongue and groove) using my coping saw, then I gave it a sand to smooth it off a bit.
Basic trigger shape -
I drew the shape free hand.
Cut out -
It's about 8cm in length.
Next I tried it for fit, you want the trigger to be all the way forward, but just below the notch you made, the idea here is that when you pull the trigger it moves up and pushes the elastic out of the notch.
Trigger pin marked -
Once drilled the 6mm dowel will work as a pivot.
Hole drilled, you can see the trigger is below the notch when fully forward -
Just drill all the way through, this way the holes will line up.
Trigger pin sorted, just needs tweaking -
Trigger done, just needs tidying up.
The next thing I did was to make a notch in the end of the batten opposite to the trigger, this is where the shorter piece of batten will sit, to mark out the notch I just set one piece of batten on top of the other and marked it out with a pencil.
Marking the notch -
I had already marked the notch out.
Once you've cut the notch out of one piece, slide the other into it and mark out another notch, make sure that there's an equal amount of wood on either side of the notch, once you've cut out both notches you can slide the 2 parts together to check the fit, but don't fix it together yet.
Checking the fit -
Looks good to me.
Once I was happy with the fit I marked out where I was going to drill a pilot hole for the screw that will hold the crossbow together.
Fixing hole marked -
Just needs drilling.
Pilot hole and counter sink done -
I used a bit of glue as well as the screw.
Next it was a case of making things look a little nicer, which basically meant rounding ends of, and giving the trigger a nice shape, I also had to drill out the holes to hold the bolts when the bows isn't in use, and the holes that hold the pegs that control how tight the elastic is.
Trigger shape done -
I just cut out a half circle.
To round the ends off I drew round a plastic pot, and I used a protractor to mark out the curve for the cross piece.
Rounding ends off -
Anything round will do.
Nice curve.
Making the bow curve -
Ready to cut out.
To make the bow curve I measured in from each end of the cross piece, then using a protractor I marked out a curve, then I cut it out roughly and smoothed it out using my lathe sander.
I also marked and drilled the holes for the adjuster pegs and the bolt holders, I marked the adjuster peg holes out by measuring down from the line I used to mark out the curve, and then I measured across about 1.5cm.
Adjuster peg holes marked -
Easy peasy.
Once it was all cut out and sanded the next thing to do was to put it together, and then sort out the peg that holds the trigger in place and the 2 adjuster pegs, this is just a case of cutting a bit of dowel (I used the 6mm dowel) to the right length and then drilling a small hole all the way through it on both sides, then using a bit of skewer pushed into the holes on either side to stop the peg coming out.
Trigger peg sorted -
This method works well, and looks good.
There's something about using pegs in this way that kind of makes things look older, and generally more aesthetically pleasing.
To make the adjuster pegs it's basically the same method I used for the trigger, but instead of using bits of skewer I used bits of toothpick and only in one end of each peg because the elastic needs to go through the other end of each peg.
Pegs made -
Pegs done.
Holes drilled.
Next I threaded the elastic through the pegs -
Loop in one peg.
Knot in the other peg.
I also made a small groove for each adjuster peg to sit in, this will stop them twisting and the elastic unwinding, the basic idea is that by twisting the pegs the elastic twists and gets tighter, this means you can adjust the amount of power in the bow string, the elastic I got for 40p from our local market (20p per metre)
Adjusting the elastic -
Simple but effective.
Lastly the bolts, these are just lengths of 9mm dowel (about 24cm in length) with a cork stuck on the end, we have plenty of corks about the house because of our wine making exploits, to make the bolts just drill a hole in the end of the cork, make it slightly smaller than the dowel, then put some glue in the hole you drilled in the cork and then stick the dowel in, and that's it, you could also add fletchings (flights) to the bolts for greater range.
The bolts -
Doesn't get much easier really.
Here's the video of my daughter firing her crossbow -
Another Halloween themed toy, this one however incorporates a bit of physics, it's basically a Halloween take on the old woodpecker toy, the one that slides down a pole when you move it.
Here's a picture of the ones I made -
Look familiar ?
These toys have been around for many years, and more traditionally they were wood peckers, but seeing as it's coming up to Halloween I thought I'd see if ghosts would work seeing as the principle is the same.
All you need to make these are some bits of wood and a spring, one from a pen would do, but you can buy packs of springs from hardware and diy shops, and it's always handy to have a variety of springs lying about.
Ingredients -
Few bits of wood and a spring.
Basically you need a piece of wood for the base, a small piece of wood for the ghost, or you could make some other shape (a pac man shape for example) a piece of thin dowel for the pole (I use 6mm dowel) and another piece of dowel to make the collar (I used 15mm dowel)
Dowel in a variety of lengths can be picked up for around 99p for a short length from most diy shops, and lastly a spring, like the ones you get in pens, but again springs can be bought in packs.
Okay, in the piece of wood you use as a base you want to find the centre, if you have a square / rectangle piece of wood draw lines from each corner diagonally and this will give you the centre of the wood, then measure up from this point about 2 or 3cm and drill a hole just big enough for the dowel, so if you use 6mm dowel use a 6mm drill bit, you may need to sand the end of the dowel a little to get it in the hole, and use a spot of wood glue (pva) to make sure it doesn't come out.
Finding the centre -
Ignore the other marks, it was scrap bit of wood.
You can just make out where I made the mark for the dowel, just above the centre mark.
Hole drilled and wood sanded to get rid of the pencil marks -
Next the dowel and a drop of glue.
Okay so once you've drilled the hole go ahead and stick the dowel into it, the length of the dowel can be what ever you want, I made mine 22cm in length, this allows for the bit that is stuck into the base.
So you should have something that looks like this -
That was easy, what's next ?
Now the next part is making the collar, this will be the part that the spring attaches to, I used a bit of dowel and I drilled a small hole in the side first for the spring to fit in, then I drilled a 6mm hole in it for where it will sit on the pole.
It's best to use something to hold the wood still while drilling, and if you can get hold of one use a post drill, or a vice of some sort to hold the wood while you drill it, one it's safer and two your holes will be more accurate.
Holes drilled, one at a right angle to the other -
Reading for fine tuning.
Before you glue the spring into the hole you made for it you'll want to check to see how the collar fits on the upright piece of dowel, I used a 6mm drill bit which meant I had to sand the inside of the collar a little to get it onto the dowel, stop sanding once the collar will go onto the dowel easily and will slide all the way down if you let it go, if it's too loose it will just fall straight down when you try to use it with the spring and ghost attached, if it's too tight it won't move at all.
This is the collar, you can see where the holes need to go -
Bit blurry but you get the idea.
Next the ghost, this was the easiest part, I took a roughly cut small block of wood and using a couple of triangular needle files I made grooves in one end of it.
Like so -
Needles files are cheap and handy for wood working.
Then the next thing to do is drill a hole in one side of the ghost shape, again use the same sized drill bit as you used for the hole in the collar where the spring will go, I used a 5mm drill bit as my spring was roughly 5mm.
Ghost finished, just needs a paint job -
Kind of pac-man esque.
You can see the hole where the spring will go, the next step is to fix the spring to the collar and the ghost shape, I'd recommend a glue gun, or some kind of quick drying glue, and when you do glue it make sure to keep everything as in line as possible.
Assembly complete -
Ready for some decoration.
As I'm going for a Halloween theme I painted them white, and gave one googly eyes, and the other I just coloured in with a black marker pen, I've used the same water based white enamel paint on these as I used on the jumping jacks.
All done, I could have painted the base and pole, but decided not to -
Very spooky, well maybe not.
I've included a short video of them in action at the end of this post, but first a little bit on how these work, see it's all to do with friction and gravity and the momentum of the spring.
The spring and the weight (in this case a ghost) cause the collar to sit at an angle on the pole, this causes friction and stops it from falling, which is why you don't want to make the hole in the collar too big, if you did it would just drop, due to very low friction.
So how does it move down the pole ? well when you set it off, by making the ghost go up and down on the spring this causes the collar to move as well, and there's a point where the collar is in line with the pole, then gravity makes it fall a short way.
So the collar rocks back and fourth in such a way that it will align with the pole and gravity makes it fall, the weight (ghost) causes the spring to rock one way and then the other, and in turn this causes the collar to rock one way and then the other and the inertia of the weight (ghost) keeps the spring moving.
In theory if you could some how keep the pole on a loop this would run forever once you started it off, it's because it has a base that it stops, if you made the pole say 100 metres high this would in theory run until it hit the bottom.
Here's a very rough gif animation of what's going on -
The red stars show where friction occurs.
You can see in the animation where the collar lines up with the pole, and gravity then makes it fall a short way, you can always search online for 'Kinetic woodpecker toy' which will yield much better descriptions of how this works than mine.
And if you feel like making something similar to this (it works on the same principles) then have a look here - Oscillating Woodpecker (opens in new window)
Well despite the sunshine it's autumn (well more or less) so we can expect more cold weather and no doubt more rain, so here's an easy project for a rainy day.
These aren't by any means a new idea, but they are easy, cost very little (if you have stuff lying about like me) and they are also good as a teaching aid.
Here they are -
The won't win any design awards, but they are fun.
All these are made from scrap bits of wood, and they are all powered by rubber bands, they are basic I'll admit, but they can be messed about with, and it's more about what you can do with your imagination, and it shows how you can store energy.
All you need are some bits of wood, some rubber bands and a few tools.
The Tank -
See anything familiar about it ?
Okay, calling it a tank might be stretching things a bit, but I used to make these as a kid, from a rubber band a pencil a match stick and an old cotton reel, much to my nans, and my aunts annoyance if memory serves.
I've just used slightly different materials, but the principal is the same, the rubber band drives the wheel, and the stick (in this case a bit of dowel) holds it steady (ish)
The rubber band is held in place by a bit of skewer that sits in a groove, this stops the whole thing from just unwinding on the spot, I did have to add a little bit of rubber to the wheel though, this was because it slipped a fair bit on our floors as we don't have carpet.
Next the bike -
It's a bike honest.
Again I'm reaching a little, but it has two wheels, front and back, that makes it a bike in my book, as with the tank this is driven by one wheel with a rubber band through it, each wheel is actually made in two parts (all will become clear later)
With the back wheel I added a small nail sandwiched between the two parts of the wheel to stop the rubber band just twisting about with out moving the bike, I've made a small diagram of what I'm on about.
The bike drive wheel -
Hopefully that goes some way to explaining how it works.
For the front wheel I just used a small piece of dowel as an axle that goes through the wooden frame of the bike, or you could just glue it onto the frame, the rubber band also goes through the frame of the bike, and as long as you make sure you can secure it, the bike should move easily, you can just use a couple of small hooks in a similar way to the paddle boat, which is up next.
If you want an easy way to make wheels for this type of thing then I'd suggest buying a set of hole saws, they can be picked up for very little money for a set like the one in the picture below, great for making wheels, and cutting holes oddly enough.
Hole saws -
I have about 4 sets of these for some reason.
And last, but not least we have the paddle boat -
Likes to paddle.
I'm pretty sure you've seen this done before, if not where have you been ? these used to be the staple of most kids toy boxes years ago, they are great fun, and they also explain how those old paddle steamers used to work, obviously we've replaced the steam with rubber bands, but the principal is the same, that being big paddle drives boat.
Here's a diagram showing how to make a simple paddle -
Quick and simple, but quite effective.
And there you have it, a lesson in wood working, and potential energy (or is it kinetic ? I forget) and it's also fun.
Just in case you are wondering if any of these work, I have video evidence, all be it slightly shaky and a bit too short, but you'll get the idea, have fun.
