Dale Allen
Member
Over the past year I have tried various techniques, made jigs and I have bought a number of tools that are supposed to make this easy.
Marking corner to corner is in fact a very accurate way to do this on any stock that is not square, not rectangle or is in fact a perfect square.
But it seemed that no matter how hard I tried it was often just a bit off.
I find it difficult to get the straightedge exactly on the corners and hold it there while I draw a line. Then you have to try to adjust for the pencil lead offset. My fingers don't work as well as they used to.
After many responses that pointed out the method described here, it has been my only method for months. I see others struggling with this too so I have put together some pictures that may explain it better then just words.
Basically I use a small scrap piece of wood and a 2 dollar pocket rule.
The 2nd picture shows a blank that is not square and not all corners are at 90 degrees. This is where many of the tools don't work well.
The wood piece is .35" thick and .46 thick. I didn't make it that way it was just a scrap that happens to work for me. Other thicknesses will work depending on the size of the stock. What I am going to do here is scribe a line as close to the midpoint as I can from flat side to the opposite flat side. On this first one the .350" happens to be exactly half the width so two opposing scribe lines are the same line. The other opposing sides are not because the stock is thicker in that direction. After all 4 sides are scribed it shows a very small rectangle at the center of the stock, or in this case a sortof 'H' configuration. (Ignore that piece of purpleheart as it is jut there to hold down the ruler for the picture)
Another picture shows me scribing a piece of walnut.
I then use a 1/16" drill bit in a pin vise to start a hole at the center of the scribed rectangle. Admittedly, there is some room for error with this method but it is quick and easy and as close or closer than anything else I have tried. I have not tried it on a Celtic knot blank yet but I'm sure it will work as well to find the center.
Marking corner to corner is in fact a very accurate way to do this on any stock that is not square, not rectangle or is in fact a perfect square.
But it seemed that no matter how hard I tried it was often just a bit off.
I find it difficult to get the straightedge exactly on the corners and hold it there while I draw a line. Then you have to try to adjust for the pencil lead offset. My fingers don't work as well as they used to.
After many responses that pointed out the method described here, it has been my only method for months. I see others struggling with this too so I have put together some pictures that may explain it better then just words.
Basically I use a small scrap piece of wood and a 2 dollar pocket rule.
The 2nd picture shows a blank that is not square and not all corners are at 90 degrees. This is where many of the tools don't work well.
The wood piece is .35" thick and .46 thick. I didn't make it that way it was just a scrap that happens to work for me. Other thicknesses will work depending on the size of the stock. What I am going to do here is scribe a line as close to the midpoint as I can from flat side to the opposite flat side. On this first one the .350" happens to be exactly half the width so two opposing scribe lines are the same line. The other opposing sides are not because the stock is thicker in that direction. After all 4 sides are scribed it shows a very small rectangle at the center of the stock, or in this case a sortof 'H' configuration. (Ignore that piece of purpleheart as it is jut there to hold down the ruler for the picture)
Another picture shows me scribing a piece of walnut.
I then use a 1/16" drill bit in a pin vise to start a hole at the center of the scribed rectangle. Admittedly, there is some room for error with this method but it is quick and easy and as close or closer than anything else I have tried. I have not tried it on a Celtic knot blank yet but I'm sure it will work as well to find the center.
