How do I scribe a center line?

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wadeblade

Joined
Mar 3, 2006
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Sorry to bother you with a noob question, but I'm having no luck searching this forum for this. How do I scribe a center line on my blade blanks before grinding?
 
You can get a tool for this from the major supply houses, such as Jantz, Sheffield, or Texas Knifemakers.
 
If you have a small machine vice, a scribe and a flat surface you are set to go. lay the barstock and the vice on the flat surface. place the vice on its side and clamp the back end of the scribe in the vice so the pointed end is about midway on the edge of your blade blank. Holding the vice and scribe with you strongest hand, use the other hand to slide the blade blank along the point of the scribe. Flip the blank over and repeat the porcess from the other side. This will leave two scribed lines wit the center of the blade between them. This will usually get you close enough to the center for grinding purposes.

Jim Arbuckle
 
Thanks to you too, Jim. I see you're about three hours away from me. Nice to know there are others makers close by. How long have you been a knifemaker?
 
something i did before i bought a centerscrib was to use a dial caliper and measure the width of the piece then divide by two and use the caliper to scribe the center lines..........hope that helps........Erik
 
I made this one last winter out of scrap aluminum, allthread and a piece of 0-1. The 0-1 rod was turned to a point and then hardened(even has a hammon:jerkit: ). By screwing it up or down you change the hieght of the scribe. The hieght change is slow enough to get it dead on. I darken the edge of the steel with a Sharpie so the scribed line is more visible.

Centerfinder001.jpg
 
Buy the $16 6" digital caliper from HF - it is a workhorse that is a must
to have.

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=47257

Measure thickness of the blade, divide in half, substract
1/2 of the intended finished thickness, set it on caliper and scribe
on the bland, using both edges as guides, after bluing the surface
with Dykem.


Example: blade is .125 (1/8). YOu want the pre-HT thickness at the
edge to be 40 thous. So 1/2 of .125 is .62.
.62 - (40/2) = .42. Set caliper to that and scribe 2 lines,
using both edges of the blade as guide.

Having 2 lines is better than having just one centerline IMO.
Of course, you can scribe the centerline as easily, with digital
caliper if you want to.


The jaws are made out of incredibly hard space edge material and
will last you a lifetime.
 
I use a bit of wood with a screw trough it in 45-degree angle.
By turning the screw left or right the point of the screw goes up or down.

You can also use a dril-bit of the same thickness as your steel. The point of the bit will be in the middle. Lay it flat on a flat surface and you can scribble a line by passing your steel along it.

Lowtech & foolproof ;)
 
Take an old file and sharpen the handle end to a point. lay the bar stock and the file on a flat surface and using the file scrib a line down the bar stock. Flip the stock over and repeat and you will have a center line. This will work on forged blades as well.
 
wadeblade said:
Thanks to you too, Jim. I see you're about three hours away from me. Nice to know there are others makers close by. How long have you been a knifemaker?
Click to expand...


I've been working at it steadily since 1996. Three hours away doesn't narrow it down much, North or West?

Jim A.
 
I agree with all of the above posts, keep it simple! I just can't turn down a shop project and a reason to play with the power tools.
 
I read a great post right here in Shop Talk last summer saying the following:

Lay your scribe flat on the bench.
Take a magazine or paperback and put your knife blank on it.
Flip down the pages (taking your knife off first, obviously) till it sits in such a position that the center is level with the scribe's point.
Move one or the other, holding them both flat on their respective surfaces.

Now THAT'S low-tech.
 
I make my blades from ground flat stock. I took a scrap bit of steel and ground a bit of a chisel point on it, hardened it, then tuned the grind to a sharp edge. I have something like this for each thickness of stock that I use frequently. I just G-clamp the little bit of scrap to a flat surface and draw the blank past it, flip it over and do the other side. I get a pair of parallel lines about 0.030" (0.75mm approx) apart.

If I am working steel I don't have a scribe for, I just shim under it until I get it in the right place. Paper works for shimming, and lets me keep the blade on a hard flat surface.

I know this wouldn't work so well for forging, but it works for me and is dead cheap and accurate.
 
A cheap way to get you by in an emergencyis to use drill bits. 1/8 inch stock take a 3/16 drill bit and drag it down the edge flip and drag again. 3/16 stock use 1/4 inch drill bit drag flip steel and drag again. Will give you two parrellel lines down edge - works better with dykem blue or red or if you have to a magic marker make sure your grind lines are across the edge not down it
 
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