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I Forge Iron

Knife Making Log Class 103: Grind and File

Steve Sells

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Steve Sells
I have a Bader B-3 that has a 1.5 Hp motor, and uses 2 x 72 inch belts. This is the most common size for knife makers, and has a very wide selection of belts available to us. I start with Blaze in 40 grit, they are not cheap to buy, but dollar vs work they are very cost effective.
this is the blade after a few passes on the 40 grit. I like to start with the sides, that is the flats of the blade, from the back to get them parallel and removes all hammer marks that I can feel after I get the flats trued up, I clean the outer profile, then the cutting edge bevel
at this point I have sharp edges, and clean lines, if you are not used to using your eye, a nice layout fluid is great for marking off where you want to go, I choose to use Permanent Marker, as it doesn't wash off when I cool the blade in water just mark where that bevel you are working on needs to go and grind up to that point. ON larger blades take it in smaller sections of 3 to 4 inches wide, and after getting the entire blade length done, blend them in Also a way to keep the flats FLAT rather than having waves, I change the angle a bit and grind from end to end

this also explains why my tang area is so long, its for a hand hold, keeping fingers away from the belt, as a ceramic belt at 5500 will take off a fingers flesh to the bone before ya notice it. Don't ask how I know this for safety I have a metal bucket below the grinder to catch the flash and metal dust as it gets hot I can take off 3/16 from a blade in one pass with this machine not that I really even need to remove that much. after I get the 40 I move to a Norzon 120 grit and repeat this process. Remember to remove ALL grind lines form the 40 before I finish with the 120 and move to the 220 grit then to 400. I would like to point out the blade is NOT hard at this point, so over heating in most cases will not harm the blade, but it hurts my fingers. so a 5 gal bucket of clean water is nice to keep it cool Also this make a mess of the area with metal dust all over, a small trick I do to keep finer grit belts clean, is here

I made a belt storage area in the walls of my shop I labeled the grit sizes in this photo to make it esier to see how they are kept clean, and organized so I can find them fast for quick changes while grinding

this pic shows how the doors close to keep out diry and grit. after I continue from 40, to 120, trio 220 to 400 this is the result, and I am ready for heat treating

after hardening I get the 220 back out to remove the crud that forms on the blade from the burning oil and some scale then 400 and 800. most blades stop here,. Some I go a far as 16 micron like Damascus because the acids work better with a high polish some kitchen blades also I go finer, as smaller scratch marks leave less area for rust to start. Anyone have questions or have comments ????

when grinding, edge up or edge down?

Steve Sells
depends on what bevel I work, simple answer is the side I am working is up so I can look directly down on it to assure angle at the grinder. I set angles by EYE but my day job as a contractor I am use to angles my eye, and at work constantly re check with gauges and lasers to confirm so I can adjust my eye perception that way as well Use a guage if you wish nothing wrong with using tools to help you notice I do not have the knife rest attached to the grinder, I used it when I first began,and my teacher took it off demanding I train my eye it has paid off well for me in long run let me remind you that changing angles in direction of the belts to blade, helps to see if grind lines are removed from the prior grits work. I turn it over to Rich Hale now

Rich Hale
One of the last pics i showed last week showed some ugly old hammer marks i put where the bevels would be.... I did most of the heavy forging in low light and they showed up the next day, So with better light I took more time to hammer from the other side of the blade,,making sure I kept bevel angles correct,,anvil on side with dent gave a nice smooth surface, hammer control on top side kept it from happening again. I tested the steel and found it did not accidentally air harden so i did not need to anneal, used the two files shown for smoothing sides flats and bevels. one is A farriers file the other a double cut rather fine file


To hold this blade for the file work I used ry wall screws into a board, Cheap as i know, then i can file with it in one place, I did the ricasso area first and ran it onto the tang and down the blade,,, It is really important to check the blade often and see that the sides are parallel and you are not tapering it sping to edge in these areas I eyeball for parallel sides.


As Steve said earlier i file at different angles to see high spots,,and on this blade I fle with the file lengthwise and in line with the blade to see peaks and valleys,,, One more real important item is the place where the ends of the ricasso meet the tang,,if you leave a sharp corner that may create a place for a crack to develop in heat treat or in use,, I use a round needle file and make an arc there,


this pic shows the blade with some little scale spots that show rough file work, they have to come out,

If I just file those spots out I will have a big dip in that area of the blade,,I have to work the whole length of the blade to remove them


Steve Sells
After I get the blade looking like I want I harden by heating the blade to AC3, which is 1600F for this blade then quenching in oil. I wear a glove on the hand holding the blade as it will flair up. I full harden the blade tang and all. I leave it in oil till the blade reaches about the same temp as the oil, which is about 130F the wipe is clean and place it on home kitchen oven 2 hours at the temp I wish for desired hardness. 360 in this case. after I take it to my shop again, and using the Acc/Oxy torch I now heat the tang to a very dull red wile the blade is submerged in water to prevent messing with its temper what this is doing, is a high temp tempering of the tang making it sift as possible while also keeping it in the martinsite structure if I were to not harden the tang when I did the inital hardening, there may be a dramatic line of demarcation of the austinite and martinsite structures and their could be stress risers at that line. Now the tang has been made very soft I will trim and shape the tang to proper profiles, this includes cutting back on the large radius I did at first at the blade/tang area as well as thinning the tang into its own distal taper , so it is not a bulky chunk, but more graceful tapers I will also drill pin holes for the handle material pins. I only finish the sides of a tang with 40 grit as I want it rough to better hold the glues I use epoxy even when I pin to keep stable and keep out liquids.

Francis Trez Cole
When you reach the stage of dull red on the tang do you let it cool or do you quench it?

Steve Sells
I quench the full blade in water so the heat doesnt creep into the cutting parts f the blade. This is referred to a type of differential temper, leaving one section harder than another, It is also used on larger blades for the spine softer than the cutting edge that is left harder.



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very understandable, and nice job...............I buy my grinding belts in big quantity, because buying them wholesale is way less expensive than buying them in small amounts. One more trick: if I use a coarse grit belt on the initial grinding, the next finer belts I use, I grind the sections perpendicularly to the previous coarser grit that way I remove every trace of the finer grit before I graduate to the next finer graded grit, which I grind perpendicularly to the previous grit, and so forth and so forth, until I get a mirror finish with the last and finest grit I use, removing all signs of the previous coarser grit I had previously used

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  • 5 years later...
28 minutes ago, bobasaurus said:

The photo links are not working, could you re-upload them somewhere? 

Almost all the photos in IFI got deleted in a forum host software "upgrade" a few years back. Some members have indicated that they still have access to their own photos and have been able to re-post them in old threads, but I don't know if @Steve Sells has been able to do that with this thread (or any other, for that matter).


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