# Learning Opportunity #4: What is the thickness of a human hair?

 Blog entry by Don posted 06-28-2007 03:38 AM 2892 reads 0 times favorited 13 comments
 « Part 3: Forget the Easy Option Part 4 of Learning Opportunity series no next part

Yesterday, I took my new TS Aligner Jr. and DowelMax over to a friends home. (I purchased both of these tools during my recent visit to Canada.)

I was meeting with him and another Mate for a BBQ lunch and a chat about our mutual interest in woodworking. All three of us served on the executive committee of our woodworking club, so we have formed a close bond. I showed them the results of having calibrated my table saw with the TS Aligner by taking a sample of a perfectly fitted DowelMax joint. I was feeling pretty smug about the results, even though it had taken me a few hours to align my table saw perfectly.

So, naturally, my friend asked me to help him align his TS, to which I agreed. I set up the Aligner in his miter slot and began to measure his current set up.

The blade was a way out.

When I zeroed the gauge on the front of the blade, then moved the Aligner to the rear of the blade rotating the blade so that the same spot I’d measured at the front was then at the rear, the variance was a whopping .016. Wow! How could he do any fine joinery on this saw?

So, we then started to loosen the bolts that held the tabletop to the cabinet. (On this saw, one moves the cast iron tabletop to align the miter slot to the blade.)

Wait a minute!”, my friend protested. Just how much out is my saw?

That’s when the penny dropped. The gauge on my TS Aligner measures in point zero, zero ones of a millimeter. To visualize this, a human hair is .0254mm in diameter. We had measured a variance much smaller than the diameter of a human hair.

So then we all took a reality check. We were, after all, only talking woodworking, not micro-surgery. The human eye cannot even detect a variance of .016mm.

So sheepishly, I tightened up the two bolts I’d loosened muttering something about being glad I hadn’t moved the top out of alignment and chalked the experience up to another lesson well learned.

-- CanuckDon "I just love small wooden boxes!" http://www.dpb-photos.com/

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