Archery Straightness Tester and Cresting Jig

As a longbow archer who uses wooden arrows - I like to check my arrows are straight and when I'm making up a set of arrows I crest the ends of the arrow with paints or markers to make them look good.

For cresting you need a jig which rotates the arrow so you can paint stripes onto the arrow shaft in your colours.

My instructable comes in two parts - the first part is the straightness testing jig, then you can add on the drive to rotate the arrow for cresting.

Step 1: The Straightness Tester - Supplies

For the straightness tester you will need:

1 A4 3mm acrylic sheet (or wood)
4 skateboard bearings
4 bolts
Acrylic (or wood) glue
Spanners
The pattern - I have included this in 3 formats

Step 2: The Straightness Tester - Cut and Assemble

Cut out the parts - I used a laser cutter to cut the acrylic - but if you use wood you can do this by hand.

Slot the tabs for the end pieces into place and glue.
Glue in the 4 corner pieces.

Now bolt the 4 skate bearings into place - tighten using spanners. Make sure the bearings rotate freely.

That's it - easy!

You can now use this tester to check the straightness of your arrows - I particularly use this for wooden arrows. By hand rotating and watching the ends of the arrow you can find where any bend is and then take the arrow off the jig to straighten - there are plenty of videos to show you how.

Step 3: The Arrow Rotator Drive

For this you will need:

An old tin (the height of the tin should be the height of your straightness tester)
300RPM 6V High Torque Cylinder Magnetic Mini DC Gear Box Motor
Battery Holder Case Box Wired ON/OFF Switch w Cover
Tape
Small piece of (7mmOD x 5mmID) silicone tubing
Soldering iron
4 AA batteries

Solder the connection wires from the battery holder onto the motor.
Slot the batteries into place in the battery holder, flip the switch and make sure the motor is working (if not - check your soldering)

Tape the motor to the top of your old tin. I always intended to come up with a more elegant solution to mounting the motor - but this works!

The motor has a metal shaft - so you need some way to be able to slot in an arrow.
I solved this by adding a sleeve of silicone tubing over the metal shaft of the motor. The tubing is longer than the shaft, so the nock of the arrow can be fitted inside the end of the tubing. You may need to build up the motor shaft so that the tubing fits, either do this with tape or a tighter fitting piece of tubing.

Step 4: Ready for Cresting

Slot an arrow nock into the silicone tubing on the cresting drive.
Set the shaft of the arrow on the straightness tester bearings

Turn on the motor and the arrow will rotate on the bearings allowing you the use a paintbrush and paint or cresting markers to add your arrow cresting.

I mark up a design on graph paper and then mark with a pencil the ends of each coloured section (the pencil marks will be painted over so won't show)

.... and here's a set of arrows I made earlier - fully crested and ready to fletch.