Gye Greene's Thoughts

Gye Greene's Thoughts (w/ apologies to The Smithereens and their similarly-titled album!)

Wednesday, April 25, 2012

Marking knife

The property that we live on used to belong to my wife's grandparents.  And grandad was a bit of a hoarder:  if he found something that was potentially useful, he'd bring it home and put it in a shed, or in a pile somewhere in the backyard. 

This means that there are oddball stashes of things all over the place.  Like this pile of metal bits and pieces -- bracket, car parts, whatnots -- that I discovered when clearing the brush for the chicken coop in-progress.

I found this item somewhere in the yard, two or three years ago.  It seems to be a homemade half of a hinge -- or a hinge that has been bent.  I've placed it across my work glove to provide a sense of scale.

I'd always intended to make it into a marking knife, which is a knife used in woodworking to make a very precise reference line:   more precise than a pencil mark, as a knifed line is very thin.

But, I was waiting for a grinding wheel, to shape it.  Finally got one for Christmas -- and then it took me another four months to actually set it up!

The above photo reflects what it looks like after I used the wire wheel on my bench grinder to clean up the loose rust and crud.  So this is an ''almost-before'' photo.

My aim was to make it functionally (but not stylistically) into a marking knife like the one to the the left:  two bevels, with a flat back that is the ''reference surface'' that is pressed against the ruler, trysquare, or other reference item.

To do this, first I used a hacksaw to cut off the tip, at an angle, because I knew it would take a long time to remove that much metal through grinding.

Then I used the grinding wheel to shape it, and put on a knife bevel.

I didn't bother further sharpening it on a whetstone, as it just needs to be sharp enough to score the surface of wood.

Below is the mostly-finished item. I used it in the laying-out process on a side project I've somewhat started:  seems to work.

In the photo below, you can see just how curved it is.  But it still works as a marking knife.  Depending on whether I'm marking the left or right hand of the reference item, I hold it in a pencil-like grip, or else in a handlebar-style grip.

Here (below) you can see my efforts at flattening the back of the knife.  The back needs to be flat, all the way down to the tip, so that the tip will mark the surface of the wood perfectly in line with the ruler, trysquare, or whatever.

So:  functional, and unique.  Clearly a ''user-made'' shop item.

Seems to work.  :)


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