Hi from New Zealand -Virgin crossbow maker needs advice!

Hi All,
I'm just starting out on my first crossbow build which will be a western European design of modest draw weight. If anyone has photos of extant examples I'd love to see them. I have yet to source a prod (probably going to be a leaf spring) so I have not got any dimensions for the stock worked out.
So far I have turned a rolling nut blank (35mm dia) from an antler stem and I am wondering about the ideal position and profile for the spurs and the sear pin.
I was planning to just use some 8mm mild steel rod for the sear pin(flattened where it contacts the tickler) held in with epoxy.
I have some nice English oak from which I want to make a one piece stock.
Currently the plan is to drill the nut socket through and hold the nut in place with side plates rather than create a mortise block for the nut. So, I am currently looking for info on the geometry of the tickler, leaf spring and the associated socket/channel that needs to be excavated.
Loads to learn ...should be fun!
Cheers,
Ed

Braythwate,

Welcome! May I suggest you peruse the whole forum.... there is a lot of info here and help a plenty ! Don't be shy with ideas and questions .....this is a great bunch of folks ........enjoy and good luck on your build !

Chaz

Braythwayte,

There are any number of possibilities for arranging the parts of the lock. The important thing is to make sure that the action of lifting the tickler does not produce any rotation of the nut. If the action of releasing the nut tends to roll the nut "back", the release will be stiff. If it tends to let the nut roll "forward", it will be insecure, and may go off by its self.

The working face of the tickler sear should lie on the circle that is centered on the tickler pivot. The corresponding face of the nut should be tangent to a line drawn from the pivot to the point of contact.

As long as these constraints are satisfied, the pivot of the tickler and the face of the notch in the nut may be in a range of different locations. It is a good exorcise to work out some possibilities on paper with a compass and a straight edge. A couple of notebook pages devoted to this will give you a "feel" for it. If you draw full scale, or larger it will be easier to see what is happening.

I hope you don't mind being given a homework assignment. It really is better to come to an understanding of the geometry than to just have a rule of thumb.

Mac

Show us pictures please!
There is a lot of knowledge here from some great professional builders!
Technical data and help enough to make the calculations neccecary!
U will have some reading to do.
Lots of topics on any subject u can wish for!!
Feel free to ask anything and everything!
Always exciting to see a new build come along!
Good luck!

It only hurts the first time....and then you're addicted!

Thanks for the replies guys,
I'm not sure which is going to be the biggest challenge here; making a crossbow or working out how to use a forum. I'm much happier in a workshop than in front of a computer.
Anyhow, progress so far:
I'm making a prototype from pine with a steel nut before cutting into my English oak and antler. Sadly my knowledge of crossbows is embarrassingly limited so I am going for the suck-and-see approach. I've started by making a prod. The local auto spring people offered to sell me 3mm, 5mm or 6mm steel, so I bought some 3mm and 5mm (not knowing what sort of draw weights to expect) and cut out some prod shapes based on the info that I gleaned from this forum, and had them hardened and tempered.
I clamped them to a beam in the workshop and pulled down on them whilst standing on a pair of bathroom scales to see what draw weight they were.
I wasn't surprised to find the 3mm was pathetic (22lb). The 5mm had a draw weight of around 65lb with a 10"draw which seemed okay for a first go.
Based on the draw of the prod I roughed out a chunk of pine for the stock.
Next I plan to make a prototype nut from steel (I'll use antler for the actual bow) and make the tickler. I'm working on the nut being 35mm diameter with 10mm of it sticking out of the stock.
PS. I have tried to add 3 photos to this post. If you can't see them I would appreciate some advice as to how to include images.
Cheers,
Braythwayte

Steel will make a very heavy roller nut (slower shooting), but as a test it'll be OK.

Best way I've found to add pictures is to
1. store them in Photobucket or some other space.
2. Copy the IMG or Image URL,
3. Click on the Image icon (not Host an Image, but the next one to the right) at the top of the message block and paste in the URL. Then click OK

[img][/img]

Okay, I think my photo problem was related to Flickr and so I have moved the photos to another gallery. Hopefully you can see these.

Looks good now. Is that Australian Pine(Casuarina), Norfolk Island Pine (Araucaria) or some other species?

Hi Kenh, the species of pine used for protobow was 'Scrapus workshopii'
I made a steel nut for the prototype and a tickler, and fitted them to the stock. I was chuffed to find that they seemed to work together perfectly with no adjustments ...beginners luck.
I also made a crude stirrup from 5mm bar. Only when I came to bind it to the stock did I realise that I had made the end that fits against the stock too wide. This meant that I couldn't use Lightly's binding method of putting a loop through the binding hole and over the end of the prod. I had to feed the whole thread through the binding hole and then through the stirrup. Still, it didn't take too long. Lesson learned!

I used el cheapo hemp string for the binding and the black thread is waxed polyester shoemakers thread (because that is what I had to hand at the time)
I put side plates on to support the tickler pin. I also mounted the nut on a steel pin.
Anyone know what was generally used in period to keep the nut in its socket in early western European crossbows?
Once it started to come together I began to develop an itchy trigger finger so I wound a string directly onto the prod to see if it was actually functional.



It works!
Now for the real thing...
I'll document the build on a new thread "Braythwayte's first build"
I like to keep things authentic(ish) so I'd really appreciate any links to where I can find images of early western European crossbows for reference.
Cheers.

That' s a mighty fine chunk of Scrapus workshopii. Turned out really nice!

Depending on which period, the roller nut could have been held in with A) Nothing but the fact that the hole is more than a 50% circle; B) Cord run through a center hole in the nut and through a hole in the tiller below the nut; or C) A pin of some description.

Great proof of concept!! Now go find a nice piece of Red or Black Beech to make the final tiller!

Holy mackeral, your "beginner" bow is pretty darn good!
As for images of bows, there are a bazillion posts here where folks have posted some great photos, or links to photos. If you have any specific kinds you are interested in, we can point your that way as well...
And, I agree.. it IS far easier to learn to make a crossbow, than navigate  a forum... Poor Ivo tears his hair out when I try to post photos, sometimes....

Can't wait to see more, tho!

Best;
Lightly.