Finding the center of a piece of steel....

Crayola

Crayola

Joined
Sep 23, 1999
Messages
3,831
I'm learning how to make knives and man am I having FUN!!! I'll be taking a pic of my first knife soon and I'll post it. Now to my question- I have seen a little gizmo a knifemaker I know uses to score a line on the edge of a blank so you know where the centre of the steel is to get a good grind. Any tips on finding the centre of the steel? Do I need to make a gizmo? Can I buy a gizmo from someone if I need one? (I know gizmo is the correct term for when you don't know the name for a thing-a-ma-jig!)

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"Come What May..."
 
I think I know what gizmo you're talking about...gosh darn it I can't remember what it's called, but I used one this summer in the Mech Engr shop at school this summer. The gizmo I used looked like a lathe bit that acted as a scribe, attached to a dial caliper so you could measure and scribe at an exact height. Very cool tool, lots of uses. I'm sure someone knows what it's really called and where you can order one from.

~Mitch
 
I read here that you can also use a regular drill bit. Just dykem the edge of the blade and keep trying different sizes of drill bits. Scribe one side then turn the blade over and scribe the other. If that looks wrong, just try another size.

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A.T.
http://www.customknives.com
AKTI #476


 
Ok,

I'm going to try to describe a widgit one more time and see if my explanation is any clearer than the last one. To scribe the center of a knife blank edge, take a piece of scrap bolster material and drill 3 holes in it on a line, with just over 1/8 inch between the center of the middle hole and the inner edge of each outer hole. Epoxy a piece of rod stock into each of the outer holes with about 3/4 of an inch sticking out, parallel to each other and perpendicular to the surface. They should be just over 1/4 in apart. Epoxy a piece of carbide or broken drill bit with a point ground on it (centered)into the center hole (parallel to both of the others) with just the point sticking out a little.

Now, to scribe the centerline on any thickness of steel, put the widgit on the edge with one pin on each side and the scribe on the edge of the blank, twist the block slightly, so that the pins are tight against each side of the blade, and slide down to the tip.

I don't remember where I got this ideal, but it ain't originaly mine. It might have been in Bob E's catalog though.

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I love my country! I just don't trust my government!
 
K&G sells what they call an ACCU-CENTER SCRIBE for $17.95. It's hand held and not the easiest thing to use, but I finally got the hang of it. Works fine for me now that I stopped trying to scribe a 1/8" deep line in my steel, pushed it too hard. It has a small scribe point inserted into a round rod that moves through a 1/2" steel block for adjusting depth. The reason for using it isn't for finding the center, it's for laying out the edge thickness before you grind a blade. I used to grind them too thin alot before I got this little tool. K&G's number is 1-800-972-1192. The item number is CTS1. Take care! Michael

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"Always think of your fellow knife makers as partners in the search for the perfect blade, not as people trying to compete with you and your work!"
 
EASIEST WAY-now pay attention......take a file, an old worn out one is best...grind the end...the HARDENED end...into a point that is the height you want your scribe to be, put it on a flat surface and scribe away. you may have to grind a little back and forth to get the point at the center of the steel you are using...but actually its best to have two lines about .025" apart.. this is not rocket science...anything close is ok...

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http://www.mayoknives.com


 
Sounds better than the accu-center Tom!! saves ya $20 too.

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"Always think of your fellow knife makers as partners in the search for the perfect blade, not as people trying to compete with you and your work!"
 
I have exclusively used the "drill bit" method for a few years now. I have to agree with Tom Mayo, it is better to have two scribe lines and that is what I shoot for. A drill bit "close enough" to the width of the steel is good enough. This is simplist, cheapest, down and dirty way to get a center line with something we all have in our shop but whatever works for you is the right answer.

Knifemakers are something like fisherman. We can't have enough tools and fisherman can't have enough lures.

(I was kind of waiting for someone to come up with some mathematical equation!)

C Wilkins
 
Center = thickness of blade/2

Sorry CL, I had to say it
smile.gif
- Well you did want a mathmatical equation right?

Regards,
Glenn
 
that is way too simple....you take the thickness of the blade...multiply by 3.14167/ divide by the radius of the drill bit you are using to scribe the center line, take half of that....subtract .025 and you are on target....or to put it in laymans terms.....grind a file to the right heigth.

[This message has been edited by tom mayo (edited 17 December 1999).]
 
Thanks everybody!! Especially thanks to C L Wilkins- drill bit= very easy solution to my problem! I have 18" of 1095 that is going to be cut into blanks in three days and then, after I open up my belt sander that Santa is bringing me (I hope I hope I hope) I'll be grinding away!!!!
Yehah!!!



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"Come What May..."
 
I use a variant of the drill bit method. I'll try to explain it. Take a piece of very flat wood (I use the stuff used for making kitchen cabinets -laminated plywood). With a round file, file a slot on one edge (I mean, file a small round groove that begins at the edge of the wood (somewhere in the middle) and ends at the flat side of the wood. This groove will accomodate a sharp scribe (or drill bit).
I put the wood and the scribe in my vise to keep the scribe well positioned. One can adjust the height of the scribe point by moving the scribe in the groove. When the point is in place, push your knifeblade against the flat surface and against the scribe and draw a first line. Keep everything in position, turn the blade and scribe a second line. Between these 2 lines is the center.
This method is very simple: the scibe height is adaptable and you only need one scribe. 5one doesn't need to sharpen a lot of drill bits)

I hpoe you understand what I mean. Feel free to email...
 
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