How do you mark the centerline for stock removal?

peripatew

peripatew

Joined
Jul 31, 2007
Messages
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What some good methods for this? I've tried using calipers, but I had trouble with this. Any homebrew methods that you all have found successful?

L
 
i do mine by eye and feel now but when i used to mark mine with calipers, i would always leave a 1/32" wide strip for my centerline when i would grind a convex edge. you dont want to grind to an edge or you will end up with problems when doing the heat treat.
 
i use a sharpened chunk of chain saw file where the sparpende point is not centered but all the way to one side kinda like a chisle but pointy. i then clamp it to a block of steel plate and roll the chain saw file intell the point is at the height i need then clamp down.
 
If you're using a fixed thickness, you can lay your profiled blank on a flat surface and draw in against a drill bit that's around the same thickness. Flip the blank over and do it again just in case the drill bit point isn't centered.

Good luck, Craig
 
I use a drill bit and flat surface. If the steel is say 1/8" thick I use a 1/8" drill bit. I lay the drill bit and blade flat on my granite block and the point of a 1/8" drill bit is in the exact middle of a 1/8" piece of stock. Sometimes if the steel is a lil bigger than specified I flip it over on it's other side and run the drill bit down the edge again and they are off center but give a perfect line to grind to. Just make sure the bit is laying on it's side flat and the same for the blade.
 
I took a broken metal scribe (just a sharpened rod of tool steel), drilled a hole the same diameter as the scribe in a piece of aluminum block and pinned the scribe in the block with a punch. I clamp the block in a vise with the point at the right height. Lay the blade blank flat across the vise and pull it around so the point scratches a good line.

I hope that made some sense. It works great, because it will do any thickness of metal with a quick adjustment of the block in the vise.
 
For my first knife, I used the sticky-out-ee piece on the end of my vernier calipers to gauge the centre, then did the other side. For my second knife that I am working on I taped down a sharpee so that it was angled to the centre. Maybe I will try the drill bit thing.
 
the golden standard for many is using HF's 6" digital caliper.
The jaws are made from excellent hardened steel and last
forever when scribing centerlines. Just in case, you use one
"jaw" as guide and scribe with the other.

it helps when you grind the edge a bit to get grind marks going
in vertical directions. Blue it with Dykem machinist blue, let it dry
and then after a bit of math, scribe the lines :) . I'd clean the edge
with acetone whatever before applying dykem so it sticks better

Say you are to grind a .125" flat bar down to 30 thou thick edge.
(125-30)/2 =~ 48 thou. So set the caliper to 48 thou and scribe
against both edges.
 
I use a Dial Height Indicator here in my shop. I been using one since I started making knives. It work really well on all of my knives. Single or double lines right down the center of the edge. :thumbup:
 
I have been using an adjustable blade scriber that I obtained from Koval knives 20 years ago. I think it was only about 20 dollars, and the tool will last forever.
 
Teknition said:
Make one of these up.

http://andersonknives.ca/Blade%20Scriber.html

It is easily adjustable so you can get a single or a double line down the center of your steel, which ever your preference is.

Brad Anderson
Click to expand...

That looks almost exactly like the setup I was trying to describe. Instead of round stock, it's square and I just clamp it in a vise. Works great, and it's small enough to just throw into one of the catch all junk bins on the bench.
 
I use scraps of old utility knife blades clamped to my drill press table. Leave the top one slightly long, lay the blank flat on the press table, and slide it along as needed to put a nice deep mark in. Flip over and repeat. Voila, 2 parallel scribed lines near the midpoint. It doesn't necessarily leave a nice fixed gap but you get a pretty good ideal of where the center is.
 
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