Cleaner lines ?

H

huntersedge

Joined
Dec 8, 2005
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7
Don't know if this has been covered in the past, but I haven't been able to find anything on the topic.
My question is pertaining to the transition area from the blade edge to the ricasso area of any blade. I don't know the technical name for this region of the blade, if there is one. I am using a KMG and have created a convex ground, a hollow ground, and a flat ground blade using the metal removal method. My concern is the stress riser created where the grind line transitions from cutting edge to full thickness of the blade. I have looked at many a production knife and always wondered how the washed out detail was created without changing what looks to be the same grinde direction / pattern on the blade. Any help here would be greatly appreciated. I will try and post pics of my last two knives I gave away as Xmas presents. :)
 
That area is called the choil, or ricasso, where the full sized part leaves the bevels and runs to the guard or handle.

The word for the part where the bevel starts is called the plunge, or plunge cut.

Lets start at the beginning. When you have your profile done and your centerlines scribed in, figure out where you want the bevels to begin and mark that area on the back of the blade with a sharpie, etc.
Next get some masking tape or whatever you prefer and make a couple of turns around the area right up against the mark.
The tape will be towards the handle area, not covering areas to be ground. The tape is there as a visual reference mark when you have the edge up while grinding and it will be there when the sharpie mark washes off the spine in the dip tank, so keep it straight.

Start your bevel grinds 1/8-1/4" shy(towards the point) of the marks and go at it.

When you have your rough grinding done and switch to your lighter grit "J" weight belts, track the belt off the side of the contact wheel about 1/8-1/4" and using a piece of flat scrap steel held at a 45 degree angle to the face of the wheel(the edge of the wheel) push it into the edge of the wheel against the tracked off part of the belt, forcing it to bend around the corner.

Be careful not to gouge your contact wheel doing this. It just takes seconds to accomplish what you want. You don't have to really use brute strength, the belt will bend easily. The actual amount you track off will vary with the thickness of your blade and experiance will tell you how much, in time.

Let it make a few revolutions and then repeat the same thing on the other side by tracking the belt off there.

Now, when you go to clean up the rough ground bevels, track the belt off the wheel on the side the choil will be on, and as you come to the place of the plunge cut run it into the edge of the belt where it bends around the edge of the wheel.
It should take on a curve as it hits the plunge.
You will have to play with the amount tracked off the wheel, to get the desired contour but it's not hard.
Be very careful here as when the plunge hits the rolled edge of your belt it tends to want to lift that part out from the wheel if you push too hard and it will give you the dreaded 2" groove on the other side of the wheel where that part of the belt digs in.
You have to keep it straight.
You will see the 90degree cut start to take on a contour as it hits the curved edge of the belt, and the reason you started short of the mark when you did your plunge cuts, is so you now have room to bring your plunges back to the line gradually and not run past. It's just some built in room for error.

Repeat on the other side.

Don't get discouraged, it takes practice more than anything.
I hope that's what you wanted to know, or I've wasted a lot of time here(slow typist).;)
 
here is a pic....pretty rough in stage, but you can picture what was so perfectly described above....
3.jpg


After the plunges are fairly close like this, I usually clean them up using a 1/8" rod with sandpaper wrapped, just to make sure they are perfect.
 
Okay Mike that makes alot of sense. You didn't waste your time. I like the masking tape idea also. I have been just going by eye and patients sneeking up to where I wanted the plunge line to end up. I will have to try this out on the next few knives. Really got the itch right now to make as much as possible, but only being a part time guy with other responsibilities is really eatting up all my free time. I also need the weather to break so I can get back outside to work with the G-10 outisde the basement, huge mess on the last two handles. Had a real bad idea and ended up cleaning up for three days after words.

Again, thanks for the advise.

Pete
 
Heh...g-10 makes my skin go crazy. I avoid it at all costs. I am a big fan of wood in general. Ironwood burns my nose if I am not wearing a mask, and African Blackwood makes my whole skin feel on fire....i think i am allergic....Gotta love dust.....cant wait to get my house this year and install a big dust collection system directly below my grinder. My current setup is to blow it out the window onto my neighbor's car....
 
TikTock said:
Heh...g-10 makes my skin go crazy. I avoid it at all costs. I am a big fan of wood in general. Ironwood burns my nose if I am not wearing a mask, and African Blackwood makes my whole skin feel on fire....i think i am allergic....Gotta love dust.....cant wait to get my house this year and install a big dust collection system directly below my grinder. My current setup is to blow it out the window onto my neighbor's car....
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Ironwood can give you a fungal infection of the lungs that in extreme cases can prove fatal. It's full of nasty stuff and has more natural pesticides in it that most over the counter bug sprays. Not to mention that the government now recognizes most wood dust as carcinogenic, and a definite health hazard.

G10 is really nasty stuff to breathe and very harmful to the health.

I would recommend you ALWAYS wear an organic vapor dual canister type respirator when working with anything pertaining to knives. Seems most of what we use is toxic.
I use a 6000 series mask by 3-M and organic vapor/formaldehyde dual rated cartridges to cover micarta and other phenolic resin materials which give off formaldehyde gas as well as phenol. Regular organic vapor cartridges alone, are not that effective against formaldehyde, but are better than nothing and of course will be fine for most things.

You can get them at the hardware store of home depot for about $30.00 max., including cartridges. I'd recommend getting the cotton dust prefilters and adapters to go over the cartridges.
Store the whole thing in a zip lock bag after cleaning and the cartridges will last a lot longer.
 
alexmin said:
What would be the least harmful handle material?

Alex
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bread. french bread.

Seriously?

There are none that I know of that are particularly safe, but a framelock of Titanitum would have to be the safest in my opinion, or a Tai Goo wrapped handle maybe.
 
I am right behind Mike, on this subject. Dust or fumes of any kind are not good for your lungs. A high qualiy mask with prefilters plus an exhaust system that draws fresh air into the shops working area is a must. Just remember you
cannot smell carbon monoxide, for one, and it will kill you, as dead as a man can get. If you are just beginning, think fresh air first. Get that new grinder after you protect your health, eyesight and body parts. Fred
 
Once you go past a para-cord wrapped handle on a survival knife,you start running into health hazardous materials.I never (well,almost never) turn the grinder on without the hood on.I am really thinking of building an outside air umbilical system.I want something light and clean.The drug laboratory helmets and umbilicals are really nice.I think I can get a helmet on the Internet fairly cheap (compared to their original cost) and built the outside air filtration and delivery system.Another plus for this is the ability to add a second or third umbilical to it so others could be in the shop with me.
 
jhiggins said:
There are none that I know of that are particularly safe, but a framelock of Titanitum would have to be the safest in my opinion, or a Tai Goo wrapped handle maybe.
Click to expand...

Jeff,

Don't forget about the Vanadium when grinding Ti. That stuff is pretty nasty as well.

Bill
 
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