Center scribe blade edge...

One thing I noticed is that a sharpie works better than dykem. The blue dykem discolors when it gets hot. The Sharpie stays pretty much unfazed. I just use calipers to scribe the lines.
 
A height gauge and a granite surface plate is the best way to do it.

There's no way a drill bit is going to give you a line that is as deep and easy to see as a carbide tipped gauge.

All the gizmos and calipers don't account for blade warp. They will follow along the edge of a boomerang and put a line in the center of it. A height gauge and surface plate won't hide anything. ;) :)
 
NickWheeler said:
A height gauge and a granite surface plate is the best way to do it.

There's no way a drill bit is going to give you a line that is as deep and easy to see as a carbide tipped gauge.

All the gizmos and calipers don't account for blade warp. They will follow along the edge of a boomerang and put a line in the center of it. A height gauge and surface plate won't hide anything. ;) :)
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Agreed. It would be best to have the blade absolutely flat ground before starting to mark the edge. In this case, scribing the edge with a constant height on a surface plate is the way to go.

Yet, if the blade is "basically" straight to begin with, then the caliper scribing method is not all that bad. The challenge is making sure that the blade is relatively flat and straight within the most practical number of thousandths of an inch before scribing with HARDENED calipers.

When the only tools available are a 2 x 72 grinder with a flat platen, calipers, or micrometer, then one can take time and get very close to "flat", but never perfectly flat before scribing their edge.

Mike L.
 
Am I going to get my pee-pee slapped for admitting that I don't scribe centerlines on any of my blades? I have never had an issue with uneven grinds. Perhaps I'm just lucky. You'd probably throw up in your mouth a little if you saw me grind a blade, Ha!
 
Grind with a Bubble Jig and you don't need to mark center lines. Matched plunge lines with matching bevels.
 
flatblackcapo said:
I used the drill bit method until I picked up this little guy. I think I got it from USA knife maker, I'm not 100% though. Works pretty good on stock up to 1/4"
14371915338_8e08c3d14d_b.jpg
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I really hate to ask what is perhaps a really dumb question, but how is that used to scribe a line in middle of blade edge? Looks like the pins are too far apart, and how do you adjust for different thickness blades? I'm just not seeing it (blind I guess).

Ken H>
 
Simple - I wondered if that's how you did it, but didn't think that would be precise enough. Now I see your dwg, I can see it'd work great. I do think that just might work better than anything else. I'll make one of those in a few days. VERY simple to make.

Mr biker - THANK YOU for the quick response. What do you ride? I'm an old reformed hog rider who's now on a GW.

Ken
 
Ken H> said:
Simple - I wondered if that's how you did it, but didn't think that would be precise enough. Now I see your dwg, I can see it'd work great. I do think that just might work better than anything else. I'll make one of those in a few days. VERY simple to make.

Mr biker - THANK YOU for the quick response. What do you ride? I'm an old reformed hog rider who's now on a GW.

Ken
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I've had many, but the latest is a 02 Fat Boy.

I made a scribe like the one shown and found that one post will fall off the blade before you have scribed the entire length of the blade. You lose the distance from the center scribe to one of the guide posts. I've started using a height gauge on a granite block as Mr. Wheeler has suggested. This works the best of all the methods I've tried.
 
I learned to scribe 2 lines on my blade edges from watching an old Johnny Stout video on hollow grinding. I measure the blade thickness after flattening the steel and then subtract .025 or blade thickness at the edge before heat treat and divide the remainder by 2. I used to set my pair of calipers for that measurement and scribe the edge both top and bottom. The 2 lines would be .025 thick and centered on the blade. The problem is that using my inexpensive calipers for this task wears out the tips of the calipers rather quickly so I bought a height gauge with hardened scribe and a piece of marble to set the gauge on and mark my blades. I also mark the grind lines and centerlines for tactical knives and also use the same method for making a proper swedge or false edge. I can't be the only one using this method of scribing lines. Larry Lehman
 
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Rick Marchand said:
Am I going to get my pee-pee slapped for admitting that I don't scribe centerlines on any of my blades? I have never had an issue with uneven grinds. Perhaps I'm just lucky. You'd probably throw up in your mouth a little if you saw me grind a blade, Ha!
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I rarely scribe centerlines either, unless there is a special reason.

My normal procedure is - after profiling the blade, I grind a quick edge with 45° angles. This gives me a "center" that can't go away. I grind the bevels using it as the reference.
 
Same here, Stacy. Using the 45deg bevel as a guide, grind until they almost disappear. After I grind the 45's I dull the sharp edge with a stone. There is something about having a sharp edge facing into the belt, that I don't like.
 
NC Biker said:
I've had many, but the latest is a 02 Fat Boy.

I made a scribe like the one shown and found that one post will fall off the blade before you have scribed the entire length of the blade. You lose the distance from the center scribe to one of the guide posts. I've started using a height gauge on a granite block as Mr. Wheeler has suggested. This works the best of all the methods I've tried.
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Hmmm, I can see where that would be a problem. I got to thinking that perhaps it might be hard to hold the blade steady for scribe while doing a big belly type knife also. Maybe I'll just pass on making one and continue with my calipers or height gauge. Thanks for the input.

Ken H>
 
I use this center gauge that I made. Vey precise and quick to use. It has a carbide insert and marks hardened steel easily as well. I have 3 of them pre setup for the most common blade thicknesses that I use. It is the quickest way I have found. Jeff



 
I have at least six different scribing tools, Most are carbide and very precise, and some were expensive. Unfortunately the blades most knifemakers profile are rarely precise, dead flat, or evenly thick ( consider a hand forged blank). A straight 45 degree edge down the center will allow grinding without any risk of the bevels being uneven.

I understand the precision needed for a folder maker working with PG O-1, but a surface plate, height gauge, and carbide scribe tip is a lot to spend (and takes a bit of time to set up and put away), when all most folks need is 60 seconds at the grinder.
 
Nice, best idea I have seen.

J. A. Baker Knives said:
I use this center gauge that I made. Vey precise and quick to use. It has a carbide insert and marks hardened steel easily as well. I have 3 of them pre setup for the most common blade thicknesses that I use. It is the quickest way I have found. Jeff



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Stacy E. Apelt - Bladesmith said:
I understand the precision needed for a folder maker working with PG O-1, but a surface plate, height gauge, and carbide scribe tip is a lot to spend (and takes a bit of time to set up and put away), when all most folks need is 60 seconds at the grinder.
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Well if someone thinks a folding knife is the only knife that can be made better with precision, then you can just throw out any advice I have to share. :rolleyes: :)
 
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a granite plate and height gauge is the way to go. These can be had for a total of $60. These will come in handy for all,kind sir things. How would you check the height of the finished edge with ease? You will find many other uses for this along the way like checking for level of anything including a warped blade? How warped is something? You get the point ;) :)
 
Stacy E. Apelt - Bladesmith said:
I have at least six different scribing tools, Most are carbide and very precise, and some were expensive. Unfortunately the blades most knifemakers profile are rarely precise, dead flat, or evenly thick ( consider a hand forged blank). A straight 45 degree edge down the center will allow grinding without any risk of the bevels being uneven.

I understand the precision needed for a folder maker working with PG O-1, but a surface plate, height gauge, and carbide scribe tip is a lot to spend (and takes a bit of time to set up and put away), when all most folks need is 60 seconds at the grinder.
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Scribing a line with a granite plate and a height gauge takes like 12 seconds. I would never want to move a granite plate around the shop, that's why it sits put in most shops.
 
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