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Workbench Creations

Workbench Creations is the place for conversation and discussion about do-it-yourself (DIY) projects. This DIY blog will feature projects completed by its owner as well as projects completed by other do-it-yourselfers. Workbench Creations is the place where DIYers can discuss ideas, learn about what others have done, and share their expertise.

Flight Bow Shooting Machine

Posted January 24, 2018 9:06 AM by Del the cat
Pathfinder Tags: archery shooting machine

I've been messing around with flight bows and their arrows for some time and it's virtually impossible to get consistent test results.
There are so many variables and worst of all is the loose (the act of releasing the bow string).
It's been on my to do list for some time to make a shooting machine so I had a go.
The mk1 was based on Clarence N Hickman's machine, this proved some of the geometry and exposed some of the problems.
His machine was designed for light weight bows as he was developing the modern recurve target bow.
After the mk1 was the mk1.5 modified for heavier bows shooting at 45 degrees (see pic below)

I want my machine for flight bows and warbows of much heavier weight (up to 150 pound draw weight!). One problem is pulling that weight in a stable controlled fashion and getting the machine to loose the arrow at the preset draw length.
Note, it's no good cocking the bow like you would in a crossbow, as wooden bows (especially highly stressed flight bows) shouldn't be held at full draw whilst you mess about loading in an arrow.
Here's the mk2:-
It has a sliding latch, so the bow can be cocked and loaded at about 12" draw. The latch is then pulled back by a rope running through a pulley. The latch runs on a steel track and while the rope is being pulled, the whole contraption is held firmly down by placing your foot in the stirrup.

The bow is lightly clamped (wrapped with rubber strapping) at an angle (about 30 degrees to horizontal) this allows the limbs of a big warbow to clear the ground whilst keeping the machine compact, it also ensures the arrow rests in the correct position.

The whole thing dismantles into two parts:-

I got a new camera for Christmas that takes reasonable slo-mo and I filmed the arrow leaving the mk1.5 machine:-
Note the arrow isn't really going sideways at the top of its flight, the camera is slightly left of the machine and the arrow is starting to arc over at the top. You can clearly see the flexing of the arrow as it has to get around the grip of the bow.
This machine will hopefully allow me to match arrow to bow better and select the arrow configuration that flies best.
Self evidently, once the arrow has left the bow, it's all about the arrow, here are some of the variables that need to be considered when making a flight arrow.
Length (shorter is more aerodynamic)
Wood (bamboo is sometimes used, or in modern categories carbon fibre)
Shape (usually barrelled, e.g thicker in the middle)
Point of balance (usually about 10% forward of geometric centre)
Point shape and material
Fletching size and shape
Shape, strength and size of the nock
Of course some of these variables are interrelated, it's very much an empirical science, which is right up my street

24 comments; last comment on 01/28/2018
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Garden Shed

Posted October 21, 2017 11:02 AM by phoenix911
Pathfinder Tags: Garden Shed

Good day fellow members.

I had posed a question last February about soil and foundations;

Floating Slab or Footings Below Frost Line

I appreciate your responses, concerns and suggestions from that thread.

Just to bring you up to date on my recent project, which was a garden shed.

I had just completed the project, I did do quite a bit of documentation and I like to share it here with you. The documentation was quite extensive, it is on another site. I'll copy the link here.

It was interesting and quite enjoyable project. And even more enjoyable now that's it's complete.

where it started with a sketch.

and ended with

14 comments; last comment on 11/21/2017
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Del's Quiz Question!

Posted January 11, 2017 1:18 PM by Del the cat

You obviously couldn't make an arrow out of 2 layers of printer paper, it would buckle as it tried to flex round the bow.
What would happen if you made a paper crossbow bolt to shoot from a 50 pound draw weight 6" draw bow pistol? Give it a 50 grain point and a short wooden stub at the back end for string contact. Will it buckle or collapse?
The bolt is made as a tube, 2 layers of paper thick rolled into a tube 5/16" diameter same as a regular arrow.
If you want to see the result click the link:-

15 comments; last comment on 01/12/2017
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MkII Archer Automaton

Posted December 28, 2016 8:03 AM by Del the cat

Over the last few weeks I've rebult the Archer automaton with several improvements. Although there are only two basic movements driven by cams the interaction of the parts is surprisingly complex. It took an awful lot of fiddling and trial and error to get it working reliably.
Easy enough to get it working once, but I had to take a lot of slop out of the system to make it reliable.

Here's the video:-

One of the key elements was turning a tiny cone of antler on my little lathe, this is fitted onto the string and allows the archer's finger to slip over it in one direction and to snag onto it as it draws back.

The control rods that run up the back were originally of ply, then copper sheet and eventually steel.
I decided to power it from a hand turned crack and wooden gears which were made from this site's free gear drawing program (the old version of the program worked better for me).

19 comments; last comment on 01/07/2017
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Archer Automaton

Posted December 07, 2016 4:29 AM by Del the cat

For ages I've been tinkering with the idea of making an archer automaton. There are some superb Japanese ones, but while they are incredible pieces of craftsmanship, the actual drawing action of the bow is all wrong.

I've just made a very simple prototype to prove my ideas... it's already being improved.
This very brief video shows it working.


24 comments; last comment on 02/01/2017
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