Hi i just built a spine finder similiar to the one in Tom Kirkmans book only mine sits in a metal housing. My bearings are six in. apart .When i bend the tip am i supposed to rotate the blank at the same time?? or do ijust kind of throw in the finder then bend the tip? And call that the spine? And also does the butt end have to be in al the way to the stop at the end of the second bearing ? thank you Marcel

You'll want to put the butt end on the back bearing but no further or you won't get a good reading for the entire length of the blank. When you flex the tip down it should spin by itself and show you the spine.

With the blank flexed you can rotate it and you should feel when you get it to that place where it just seems to want to stay put. Any time you try to move it off that spot it will seem to want to return and come to rest. That is the spine. If you are flexing downward, the top of the blank is the spine. If you are bending it upwards, then the bottom of the blank will be your spine. As they say, it is the outside of the curve that is the spine.

After placing the rod blank in the spine finder place a piece of masking tape around the blank about a foot out of the spine finder. Flex the blank and mark the tape with a pen. Just make a line along the blank's axis. Now move the blank and re-check a couple of times. Make any necessary adjustments until you are satisfied. Some blanks have two spines and it takes a little experimenting to verify the correct one. When this problem arrises the verticle spine finder will expose the true spine.

Good luck,

Bruce Young
Landing Gear

Don't forget to replace the bearing grease with oil. Get a good solvent to clean bearings thoroughly, then lightly oil. This allows much less friction and free-er (SP) movement of the bearings. And since we are not rotating these bearings at 1xxx + RPMs, no harm done to the bearings.