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View Full Version : making sure the bit is perpendicular to the table



paul_z
05-30-2010, 06:41 PM
I noticed some ridges on the side of cuts that had multiple passes per cut.

In the past I have used a digital level with 0.1 degree resolution to square up the Z axis but the results were barely acceptable.

This time I made sure my router body was parallel to the Z axis. Then I made an extremely simple jig out of a piece of 1/8" music wire. I bent it twice so that I could see how close the end of the wire was to the table. The longer the horizontal section of the jig is, the more accurate the results will be.

I mounted the wire in my 1/8" colette and rotated it by hand, I was able to see immediately that the z axis needed to be rotated slightly in both the x and y directions. It only took a few minutes and I was done. The ridges in the multiple pass cuts are gone and my small parts are much more accurate.

Now for the obvious question ... how accurately does the wire need to be bent? Amazingly, it doesn't matter!!! Any point (such as the far end of the wire) revolved around the cutter axis is in a plane perpendicular to that axis.

It's the best (and cheapest) jig I ever made.

Paul Z

curtiss
05-31-2010, 01:36 PM
I made a z tool with a piece of stiff wire attached to an old 1/4 drill bit... not real attractive but...

I did use the high dollar Gorilla tape.

knight_toolworks
05-31-2010, 02:37 PM
with some bb plywood I made about a 10" gauge holder. one end has a 1/2" hole for a 1/2" drill rod the other holds a dial gauge. it makes it easier to really see how much it is off.