Sunday, 27 July 2014

Mini onager...

I have been meaning to write a post about the mini onager / catapults I made for some time,I actually made the first one last year as an experiment to see if I could make a small scale siege weapon,that would be a little easier to make than the others we've made.

There are some links to the other siege type weapons we've made at the bottom of this post and there's a short video of me making one of these (I was messing about with time lapse videos) and firing it in the garden as well.

Here are the finished onagers (one for each of the kids) -

Simple and cheap to make.

These are powered by a piece of slingshot elastic,but you could use large rubber bands,bungee cord or something like shock cord or indeed anything that's stretchy.

Construction is easy,it's basically a rectangle shaped frame with a few bits added for support and because these don't use the torsion bundle system like the larger onager we built,the throwing arm uses a pivot and a couple of bits of wood either side that act as guides,other wise the throwing arm would flap about all over the place,and even though these are small they can still give you a bit of a nip if you get your fingers in the wrong place.

Here's a picture with some of the parts marked - 

Click on the picture for a larger view.

These can be built in a similar way to the larger onager,but because of the pivot point I'd recommend making the frame first so that you can work out where you want the pivot point,and then drill it out before you make the other parts.

Quick diagram of the basic frame (sizes just for reference) -

There's no reason these can't be made much larger.

Once you've worked out how big the frame work will be and marked where you want the pivot to go you can take the 2 longest sides and drill straight through them both,this should mean the holes for the pivot will line up,I used a bit of 8mm dowel for the throwing arm to pivot on,but anything straight and round will do.

Below is a picture showing how the throwing arm pivots on the dowel - 

Simple but effective.

The guides either side of the throwing arm serve to keep it straight and they also help make sure it fires smoothly and doesn't twist,these aren't really needed but they do help keep everything in line when firing and they do seem to help with the accuracy of the onager.

To work out where to put the stop bar and other parts what I did with this and the larger onager is to work out the point at which the throwing arm is upright and at around 90 degrees to the frame work,from there you can mark the frame and work out where to put the stop bar etc,you'll also need to work out how long you want your throwing arm,I made mine about 20cm (8 inches) and from that I worked out the height at which to put the stop bar,which in my case is at about halfway up the throwing arm.

To stop the elastic from getting caught up and to keep it in line when it's loaded I've used some small eye hooks,this also gave me a point I can tie the elastic to,I also used an eye hook on the throwing arm to stop the elastic slipping down the arm when it's loaded.

Loaded - 

Ready for action.

Closer picture - 

There are other ways I could have done this,but this works.

The trigger is the same as the one I made for the larger onager,it basically uses 3 eye hooks and a pin and a length of string,again this one of a few ways a trigger could be made, but this works and it's simple to use.

What you use as a holder at the end of the throwing arm for your ammunition is what ever works I guess,you could use a sling type holder,like I've done with the larger onager,or a cup like I have used with the smaller onagers,I just used what I had lying about in my shed from various wood turning experiments,half the fun of making things like this is to experiment and see what works and what doesn't

The trigger (you can also see the eye hook that stops the elastic from slipping down the throwing arm) - 

Doesn't really need to be more complicated than this.

Video of it being assembled and fired - 

And that's about it really,these aren't super powerful,although it will depend on what you use as a power source,be it bungee cord or slingshot elastic,you can use variety of things as ammunition,I used a small ball of baking foil in the video,but almost anything will do,and I've since discovered that with a tweak to the elastic these are pretty good water balloon launchers.

Links to other siege type weapons we've made - 

How to make an onager (opens in new window)

How to make a trebuchet (opens in new window)

Hand held ballista (opens in new window)

Thanks for reading.

Saturday, 12 July 2014

Simple wooden picture frames...

As you may (or may not) know Game of Thrones has finished for another year,and while I'm waiting for the next series I decided to make a frame for my map of Westeros,which I got in the box set of books that my wife bought me for christmas (yes I've read the books as well) it's not hard to do,and I'm pleased with the end result.

Here's it is,in it's new place in the front room -

Winter is coming.

It was easy to make,although I did use a router,but there are other ways of doing this,the wood cost no more than about £2 the most expensive part of this was the clip frame I bought,which cost £3.50 I don't know how much a piece of glass would have cost,but the clip frame was cheap enough, I added some squares of wood to each corner with a Dire wolf burned into them for a bit of added interest.

I didn't take pictures while I was making this,but to give you a rough idea of how it's done I made a frame for a smaller clip frame,and there's no reason why you can't make picture frames for small photo's in the same way,and it's not just frames for pictures either.

Here's a clip frame - 

Nothing special,just a clip frame.

To make the wooden frame all I've done is to get some tile batten and using a router I've made a channel down the middle of the wood about 5mm in depth and wide enough to fit the glass and the board backing of the clip frame into.

Like so - 

A bit tricky to do,but a few clamps help.

There are a couple of ways you can go from here,you can have mitred corners (angled) or you can just butt the bits of wood up against each other.

If you go for mitred corners then what I did was mark the back of the clip frame,to help get the wooden parts of the frame in the right place,otherwise the mitres will have gaps in them.

Like so - 

It helps to have a guide.
You can see that I've marked out each corner at 45 degrees,and I've also marked down 5mm (ish) along each side and from these marks I got the measurements for the bits of wood I needed to cut.

To cut the bits of wood I used a mitre saw,these are great for small jobs like this,they can cut a variety of angles and are easy to use,and cheap to buy.

My mitre saw - 

It's served me well,could do with a new blade.

Here's one piece cut,you can see it almost lines up with my marks -

Close enough.

To fix the pieces together you can use screws,or glue and clamps,either way works,but if you use screws you'll be able to change the picture,if however you go for glue then that's it you won't be able to get things apart without damaging things,as I'm not bothered about changing the picture I went for glue on the map frame.

Screwing together - 

It's easy to fill the holes,a bit of dowel will do.

Gluing together with clamps -

Don't worry I haven't glued this one together without a picture.

Using clamps like these can be a bit tricky when it comes to getting things lined up,you can buy a special frame clamp that will make life easier or you can make one,there are various how to's online.

Here's the back of the clip frame complete with the wooden framing - 

You get the idea?

If you don't have a router there is a little cheat, find some tongue and groove,you should be able to use the groove side to fit the clip frame into,you'll obviously need to cut the wood to size,but it does work.

Here's the glass from a clip frame in a piece of match board - 

Perfect fit.

In fact this is how I made the front of my wife's wedding anniversary present - 

Joins could have been neater.

If you don't fancy trying mitred corners you can just butt the bits of wood up against each other,in some cases this maybe more appealing,but I guess it depends on your tastes.

Easy way of doing things - 

More of a rustic feel,I may do this on the next one I make.

It's not just picture frames you can use this for,I made a cupboard for our keys in a similar way,only instead of glass I used a piece of thin plywood that I cut a heart shape into,and I also made a box for my son to keep some of his fossils in,kind of like a display case,I used the glass from another clip frame for this as well,I think they turned out well and they are cheap and easy to make.

The key cupboard - 

I like it,so does my wife,everyone’s a winner

The fossil display case - 

Keeps the fossils safe and shows them off.

Thanks for reading.

Friday, 11 July 2014

Allotment update (first harvest of 2014)

After the hard work keeping the weeds at bay comes the good bit,harvesting the stuff you've grown,it's then you discover that the aches and pains from the digging,weeding and everything else have all been worth it.

We dug our first lot of spuds up in June (this post is a bit late) and despite the plants looking a bit sorry for themselves we actually got a good haul of new spuds,12kg in fact,which is 3kg more than last year.

Spuds -

Not bad,should last a while.

I've already filled the hole where the spuds were with this years sweetcorn,and it won't be long before some of the other stuff can be dug up,like the carrots and possibly some of the onions.

Sweetcorn planted - 

More plants than last year.

Fingers crossed we'll get a crop of corn,these plants are all grown from seeds we saved from last years crop,kind of experimental maybe,but it'll interesting to see what happens.

We've also picked the broad beans and although we didn't get quite as much as last year this is because we've picked the beans a bit earlier while they are still smallish,even so we've still got over 2kg of broad beans,which have now been blanched and put in the freezer (by my lovely wife) for the winter,they are very good in stews.

Shelled broad beans ready for blanching -

Very tasty,and good for you.

I enlisted the help of some bean picking elves to help with harvesting -

Get yourself some picking elves,they come in handy.

The pea harvest was a bit of a non starter really, we got enough for a meal,but we would have had much more if it wasn't for the rodents,yes we've had a bit of a rodent problem on the site this year,we're not the only ones having issues with the furry buggers,and it has to be said some people aren't helping by giving the rats and mice places to hide,but enough about that.

Some of the squash plants are starting to show signs of fruits,hopefully the rodents won't get too them,we'll have to make sure they don't.

Baby squashes,they'll soon get big (if they don't get eaten) - 

I'm hoping for some large pumpkins this year.

And here's everything we got on the kitchen table,there's some rhubarb and a couple of beetroot's,but we've got more on the way,and even though we've got slightly less of some things we had extra spuds,and I guess that in years gone by this is something farmers and gardeners of old would have had to adapt to.

The harvest so far - 

Can't beat home grown veggies.

There's plenty more going on at the plot,and the council have seen fit to change the rules again so there's that to get to grips with as well,it's all good fun.

Thanks for reading.