Harbor Freight has a nifty little mini chop saw that works.
I screwed mine down to a 4 foot long 8 inch wide wood base. I screwed down a piece of 1 X 1 aluminum angle that is 36 inches long so it line the arrow up with the chop saw. I used a mini C clamp and a small block of cocobolo I had for holding the arrow in place. I dremeled out a hole for the nock to slip into the block at just above the aluminum angle and then gently tapped in a finish nail in the middle of the hole to hold the nock. I also mounted a metal measuring stick to the auminum angle so I can see the length I am cutting at a glance.
I got the idea from Brock at Bull Mountain Archery. He loaned me his home made cutter as a model. Once I had the componenets I put the system together in 20 minutes in my garage.
Buy some 3 inch cutting wheels and take the shield off the chop saw, throw away the blade it comes with it is junk.
The system works great, I cut 2 dozen shafts to length and cut 2 dozen external footings for them in about 35 minutes right after I got done building it.