Replacing lost adjustment screws on a Cartel EX target sight

The screws on my Cartel EX target sight (and everything else on my bow, for that matter) are always coming loose. I managed to lose the brass windage adjustment thumbscrew today. I’m not sure on the exact specification of it, but the thumbscrew from a VGA, DVI or other D style connector is the same thread. A handy replacement!

While I was at it, I checked the elevation adjustment, and it is a M5x0.9 thread, which is the same as the two 3mm allen head bolts holding the vertical rail/scale to the extension bar. Can’t imagine this one would be easy to lose though as your sights would drop if it came loose.

The Rat Arrow

Both Rat in that it is made from scrounged urban materials, and Rat in that it can be used on small game (including rats, if you were so inclined). There’s a lot of traditional archery enthusiasts, but I wanted to try making a “modern traditional” arrow. The sort you’d find in use in the slums of a big third world urban slum, or a post-apocalyptic wasteland.

Overall I’m fairly happy with the arrow. Flight is reasonable, and it is very tough. The difficult part would be making a set with matching spine, but as a one off this is reasonable. Here’s how I make it.

(All measurements are in metric, cause imperial are the sorts of units that bitches use.)

The shaft is made from a small culm of South Kalimantan Bamboo, a small clumping bamboo variety. Pretty much any type of bamboo with appropriately sized culms could be used though. Bamboo garden stakes are a good source if you don’t have access to any plants.

The shaft was cut to approximately one metre. Straightening was achieved by heating with a butane blowtorch, straightening, then setting by wiping down with a wet rag. The shaft was then cut to approximately 840mm (33 inches for the bitches). The shaft was sanded down, in particular the nodes to reduce the bulging.

A self nock was then cut by sawing a slit with a tenon saw, then enlarging with a thin file. Electrical tape was wrapped just ahead of the nock to reinforce it and stop it from splitting.

It is important to note that the nock is at the narrow end of the shaft. This is something I’ve noticed isn’t talked about too much, but it is important to nock at the narrow end, not the thicker end as you might expect. My initial reasoning was that since it is being driven from the nock end, the strongest/stiffest portion of the arrow should be there. However, for correct flight, the arrow’s centre of gravity needs to be forward of it’s aerodynamic centre (given the simple shape of an arrow, it’s aerodynamic centre is, unlike a plane, pretty much the same as its actual centre). One of my initial attempts had the nock at the thick end. This lead to very unstable flight, with a lot of yawing during the flight. Centre of gravity was pretty close to the aerodymanic centre. Adding weight via wraps of solder at the tip helped this, although at the expense of a heavier arrow.

The head of the arrow is an M5x20mm hex head bolt, weighing around 6 grams (again, for the bitches, around 100 grains). The hollow was enlarged by hand with twist drills, then it was epoxied in. Electrical tape is again used to reinforce the bamboo around the head.

(the screw in points I have all have a shoulder that is approximately 5mm diameter – these can be expoxied into the hollow. Inserts for 1716 alu arrows should be around 6.33mm, so could be used for larger diameter bamboo arrows)

Fletching was made from chicken feathers (thanks to Ethel and the other ladies). Polyester thread was used to bind the feathers front and rear, and superglue along the fletching and to hold the threads in place.

Finished, here are the specs:

  • Total Length: 845mm
  • Weight: 55g
  • Centre of balance: 355mm from tip, which is 8% forward of centre (in terms of the entire arrow’s length)
I’m happy with how it shoots. Plenty of punch. Here’s what it did to some 7 ply 11mm plywood board, at around 7m from a 32lb recurve.

I’m planning on making a spine testing/fletching jig, so for subsequent arrows I’ll be able to roughly match for spine, and also apply feathers/vanes more consistently. I am also going to make some steel dies which I can force the culms through, hopefully reducing the need for sanding nodes down to get roundish shafts.

Some general bamboo arrow making tutorials which I found helpful are here and here.