Do it yourself spine finder
By Kevin Cahill

I went to my local Ace Hardware
store to see if I could build an inexpensive spine finder to work with. What
I ended up with is a unit that works quite well, requires no special tools,
and costs under $15 if you had to buy everything. Here's what I did.


1 1" PVC sched. 40 "tee" (.79)
2 "radial bearings" o.d.=1 3/8", i.d.=3/4" (3.10 ea)
1 "radial bearing" o.d.=1 1/8", i.d.=3/8" (3.10)
1 #12 hose clamp, (the metal band you tighten with a screwdriver) (.49)
12" light chain link (10#-15#)(.35)
1 screw eye
1 "s" hook

(the radial bearings were in the hardware section with all those pull out
trays with every type of nut, washer, and screw ever made that those stores
always have)


The 2 (3/4" i.d.) bearings go in both ends of the PVC "tee". They are just a
"hair" to big to fit so you have to sand down the openings in the PVC "tee"
just a bit (I did it with a dremel tool with a round sanding band in about
30 seconds). Don't sand too much - you want a tight friction fit. With a
good friction fit they'll stay but I epoxyed them in for good measure.
That's it for the spine finder. Set it up in your vise at a 20-30 degree

The other bearing is put around the tip of the shaft and used to apply
downward pressure to the shaft while finding the spine. To do this wrap the
hose clamp around the 3/8"i.d. bearing and tighten it. I used 3/8" because
it's a snug fit on a .370 iron shaft, you can use other sizes if you want.
Then attach the chain to the hose clamp (I used some wire).

Put a test shaft into the finder, put the 3/8" bearing on the end of the
shaft and attach the screw eye to your workbench where the chain dangles
down. Pull down on the chain to apply some pressure to the shaft and attach
it to the screw eye with the "s" hook. Now you can rotate the shaft near the
finder and find the spine. Oh, you need to put an O ring or a backwards
ferrule on the tip end of the shaft to keep the bearing from coming off when
you apply pressure.

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