First off, we'll need to prepare the bearings that go into the joints of the finger. They are friction fitted, and it's a very tight fit.
You will need:
- Bike chain tool (like this
- An M3 bolt (6-16mm in length).
- Vernier calliper (Amazon
- 3 Standard ball bearings.
- 2 12mm steel dowels.
- 1 14mm steel dowel.
1. Take one of the standard (non-grovved) ball bearings and put a short M3 bolt through it, this acts as a guide to get the bearing positioned in the bike chain tool, and will be removed later.
2. Place the bearing in the bike chain tool and tighten the handle all the way (don't make it tight, just enough to have the bolt inside the bearing.
3. Tighten the bike chain tool from the other end (the bolt), this time you want to make it fairly tight to hold the bearing in place.
4. Unscrew the handle of the bike chain tool all the way and remove the M3 bolt.
5. Using a pair of pliers, get a 12mm steel dowel pin and insert it tapered end first into the bearing. With a little bit of pressure, you should be able to get it to hold in place. Make sure it's aligned as well as possible.
6. Tighten the handle of the bike chain tool so that it pushes the dowel into the bearing, the objective is to get it half way. READ STEP 7 NOW.
7. Measure the dowel to make sure it is exactly half way through. Although it should be 4mm on either side, I've found that due to the tolerances of the bearings and the dowels, 3.85mm works best. You could measure your dowel and bearing first to calculate this for your particular components. If you accidentally overshoot you can unscrew everything, remove the bearing and flip it around.
8. Unscrew everything and jiggle the bike chain tool around until the bearing falls out with the dowel snuggly in place.
9. Repeat steps 1-9 once with another 12mm dowel, and then again with a 14mm dowel.
End of part 1.