The Humble Velocipede is a precision machine and it's important that there be as little friction as possible between all the joints, so before assembling a it's a good idea to check the hole sizes of your parts. 

The holes in the 3d printed parts should already all be to spec, but it never hurts to double check. 

Hole dimensions

Breastplate hipshaft holes: 5/64"
Ligament pin holes: 1/16"
Ligament crankshaft hole: 3/32"
Breastplate crankshaft hole: 7/64"
Endplate crankshaft hole: 2/3"

If you don't have calipers or a set of drill bits handy, an easy way to standardize all your hole sizes is to use this precision screwdriver set. 

The 1.8mm (dark gray) and 2.4mm (green) size screwdrivers are perfect for checking your hole tolerances.

Use the green screwdriver to check the larger of the two holes in the ligaments.

This is the hole through which the crankshaft will pass, and widening it to exactly 2.4mm (0.094") will give it just enough clearance to make it around the bends.

Use the gray screwdriver to ream out the smaller ligament holes.

These are the holes through which the 1/16" spring pins will pass. Checking them with this screwdriver will ensure they have enough clearance to rotate freely.

Don't forget to check the small hole in the PCL.

Use the hipshaft to check that it can pass easily through the larger apertures on the thigh and PCL. 

You should feel a small amount of friction when passing the hipshaft through the breastplate. This is ok. These parts will form the frame of the machine, which should be as rigid as possible.

Lastly, check that the top bar can move freely through the keyhole in the top of the breastplates. It should pass loosely when flat, but once rotated 90 degrees it should lock firmly into place. 

If the assembled frame feels rigid and the hipshafts can spin freely through all the thighs, you should be all ready to assemble your Humble Velocipede!

Go on to the next page for full assembly instructions!