Make a Quick Knife From a Clutch Finger

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Introduction: Make a Quick Knife From a Clutch Finger

About: Tim Anderson is the author of the "Heirloom Technology" column in Make Magazine. He is co-founder of www.zcorp.com, manufacturers of "3D Printer" output devices. His detailed drawings of traditional Pacific...

A dozen spring steel fingers encircle the pressure plate of an automotive clutch.
Here's how to make a nice knife from one of those spring steel fingers in a few minutes.
It's got a nice long handle so I can use it as a Crooked Knife.

GORE WARNING: STEP 3 IS THE WORST PHOTO IN THE WORLD. VERY SCARY AND DISGUSTING.

What you'll need:
A junk pressure plate from a clutch.
A chunk of stainless steel tubing an inch or less in diameter.
A vise
An angle grinder and some abrasive cutoff wheels.
A belt sander
Safety goggles

Step 1: Cut Apart the Pressure Plate

I'm using an abrasive cutoff wheel to cut off the rivet heads that hold the assembly together. Every pressure plate is made differently. Be careful. There may be some spring-loaded parts that can jump at you or bind your tool.

The abrasive wheel is dangerous enough by itself. It may fling metal shards into your eye. It may break and fling fragments at you. How do I know that?...

Step 2: Dangerous?

So there I was, happily grinding away and "BANG!" PAIN IN MY BELLY.
I didn't want to look. Scared to death I gimped into the next room yelling "check me!". I thought I'd be bleeding and maybe disemboweled.
Here's what it looks like.
The grinding wheel had broken and threw a piece that hit me in the gut.
Another piece hit the wall, making a sound like a gun.
If I'd been hit in the face or the eye, I hate to think what would have happened.
The piece that hit me did this damage through two vests, a shirt, the top of my pants, and belt.
I guess that's why they want you to leave the guards on the tool and wear a grinding mask.

This particular grinder is a very dangerous one.
There's no guard, and it's so old it never had one. There's no speed regulation, so it can spin at excessively high rpms when there's no load.

I'm so glad it didn't hit me in the eye because I've seen THE WORST PICTURE IN THE WORLD,
which is the next step.. Skip it unless you want to see a horrible photo and read some ranting that won't help you learn to make knives.

Step 3: I Mean It! Broken Grinding Disc Vs. Eye

WARNING!!: HORRIBLE DISGUSTING PHOTO

So while I waited for the pain to die down enough to continue working, I did a search to see if the tool was as dangerous as I thought it was. According to the New South Wales Institute of Trauma and Injury Management it is. And they took this photo to prove it. He lost the eye.

This photo reminds me how much I'll regret building ANYTHING EVER if I have a serious accident or if any of you have one.

This is the sort of injury fragmentation munitions are designed to produce. Remember that the next time we decide to invade some random country. Or if someone offers you a job doing that. They'll probably tell you the job is "defending your country". I have a better plan. Let's send 200,000 teachers to some country that's messed up. I bet their casualty rate will be extremely low. I doubt they'll destroy towns or kill each other in "friendly fire" accidents.

Okay, that's it for ranting today, let's get back to making that cool knife.

Step 4: Cut Off Some Fingers

Cut them off the pressure plate that is.
If the metal changes color, pour some water on it to cool it or quench it with a wet sponge.
If you overheat the steel it will soften the temper.

I've got to get rid of that grinder. There's no bracket to attach a guard. If you ever have to use a tool like this, keep the parts of your body you care about out of the plane of the spinning disk.

Step 5: Stainless Pipe Handle

Cut a chunk of stainless tubing and squish it in a vice as shown.
It doesn't have to be stainless, suit yourself. I like a long handle less than an inch in diameter.

Step 6: Grind the Tang

The tang is the part of the blade that fits into the handle. It needs to be a little bit oversized. I left shoulders to seat against the edge of the tubing.
I used a belt sander to grind mine down.

Step 7: Keep It Cool

I poured water on the belt so it wouldn't heat the blade as much. It still heated it, so I kept dipping it in water to keep it from overheating.

Step 8: Assemble!

You can see the finished shape of the tang, including square shoulders with the blade.
I used the vice to squish the tube as much as I was comfortable with. I left the tang a little oversized.
I pounded it into the tube with a hammer.

I took it out of the vise and tapped it on the table. It makes a really nice ringing sound.
Very solid and tight.

Step 9: Deburr the Handle

The handle had a burr where I'd cut the pipe to length with a hacksaw. I used a flat file to deburr the outside. I used a rat-tail file to deburr the inside of the pipe.

Step 10: Blade Shaping

Back to the belt sander. First I shaped the outline of the blade, then I ground the bevels on the blade and rough sharpened it. I kept the blade wet and kept dipping the blade in water. I didn't overheat and discolor the blade at all.

Step 11: Sharpen

I sharpened the blade on a diamond stone. Want more details about knife sharpening?

Step 12: Sheath

I cut a chunk of bamboo to use for a sheath. You could also wrap the blade with paper and tape to make a hasty sheath, or use a chunk of plastic tubing squished in a vise.

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    127 Discussions

    0
    jakebuck
    jakebuck

    11 years ago on Introduction

    flagged as inappropriate, the eye pick was the wrong choice.

    0
    Tool Using Animal
    Tool Using Animal

    Reply 11 years ago on Introduction

    Somehow I doubt flagging Tim's stuff is going to do much, you might wanna check the "about" page ;-)

    0
    jakebuck
    jakebuck

    Reply 11 years ago on Introduction

    And one vote doesn't make much of a difference; the point is to let those in power know when they do wrong.

    0
    Lithium Rain
    Lithium Rain

    Reply 11 years ago on Introduction

    I don't think Tim did wrong. Perhaps you didn't like it, but legally or morally, he hasn't done anything "wrong".

    0
    jakebuck
    jakebuck

    Reply 11 years ago on Introduction

    If that was on any other person's instructable, it would've been taken down already, and that is wrong.

    0
    cyborgpigeon
    cyborgpigeon

    Reply 11 years ago on Introduction

    jake wow you are persistent in you pointless views / rants. having seen first hand the scars a 10" 2.5 hp hand grinder can leave i implore you to please for the love of Pete be silent. you know not of what you rail against, which makes your point moot. those who use these tools cannot be warned enough! Imagine people being laid open from the corner of your mouth to almost to an ear! the poor unfortunate soul that had this happen to him was in his late fifties. I met him while working one summer. my boss at the time warned me not to wield a large grinder vertically because of the risk it may kick and tear up my face. the man then asked if i knew how the old guy had got that scar? Of course i knew not. he then told me that one day the victim was using a grinder at or above face height. without wearing a face shield or a guard on the tool. the grinder caught / kicked and lacerated the victims mouth / face to were the jaw meets the skull. the victim suffered massive blood loss and was ambulanc'ed to the hospital in critical condition. if not for the hospital being within five miles the man may have died on the job site. I too have had a close call with one of those large right angle grinders. in high school one kicked off of the lip of a large pipe. the disk shattered, the whole thing spun end over end toword me. flew 4-5 feet up in the air then landed disk first on my head! if not for the welding helmet i was wearing I would have gotten way more messed up. I was in shock and bleeding a lot. I asked a friend how bad it was thinking i was gashed to the bone. he told me it was just a scratch about 2.5" and that there was still hair in it. when i looked at the grinder i discovered that 1/3 to 1/2 the blade had shattered an what remained was a nasty criss cross of fiber glass with hair stuck in it! mind you what i was working on was about 2.5-3 feet high an a was standing. so for that thing to end over end and land on my head it had to have literally launched 4-5 feet up! please folks wear safety glasses , face shields, hard hats, etc. use the proper safety gear for the job at hand. power tools be they air or electric are no joke! that pic may be gross but so are the potentially leathal injury one may suffer due to improper use of or faulty power tools. grate ible!

    0
    jakebuck
    jakebuck

    Reply 11 years ago on Introduction

    I'm not arguing against workshop safety, but a gross picture is not the way to educate people, and there was not enough warning about the content of the instructable. A link to the image on a separate page would be much more appropriate. That was all I was saying, but people are ridiculous and take any excuse to blow things out of proportion.

    0
    LilTex
    LilTex

    Reply 3 months ago

    I for one think this to be a very effective warning. That picture showed the horrible extent to which you can be hurt, Mate this is just a fact of life. Just because it ain’t pretty doesn’t mean it isn’t true.

    1
    zzoe
    zzoe

    Reply 11 years ago on Introduction

    As i said above - "If even one more person takes a safety precaution, and later is saved from harm, then all the complaining about 'appropriateness' becomes wildly irrelevant. What's more appropriate is not letting people get hurt, maimed or killed. I think that should take precedence over protecting our minds from a little visual discomfort." And i will add that those of us who have not yet (myself sadly included) posted an inst'able should, perhaps be more modest in our criticisms.

    0
    jakebuck
    jakebuck

    Reply 11 years ago on Introduction

    Send me your address then, I'd love to sit outside your house with pictures of car crash victims when you go driving. Or maybe a nice stillbirth or premie picture when you're having sex? The correct thing to do would be to educate people on the proper safety precautions and gear, with maybe an image of said gear or a diagram of the proper usage of the equipment. Shock value is just entertainment. "And i will add that those of us who have not yet (myself sadly included) posted an inst'able should, perhaps be more modest in our criticisms." - ractice what you preach, your post was an unsolicited and unnecessary, not to mention rife with hypocrisy.

    0
    jtobako
    jtobako

    Reply 11 years ago on Introduction

    Hypocrisy? The only difference is that you use words instead of pictures-is there really a difference?

    0
    drummonkey92
    drummonkey92

    Reply 11 years ago on Introduction

    shock value isnt 'just entertainment' and i doubt many people were entertained by that picture of the eye. shock value shocks you, and seeing something like that will make you think more about the dangers than seeing a diagram of a gaurd on an agngle grinder will.

    0
    zzoe
    zzoe

    Reply 11 years ago on Introduction

    ...and yet i remain uninjured and unoffended. We must agree to disagree, or we shall both end up ranting. I must add that i fail to see the hypocrisy mentioned above. If i am guilty i apologize.

    0
    Lithium Rain
    Lithium Rain

    Reply 11 years ago on Introduction

    That is not so. There are problems on instructables, but nepotism is not one of them. Or perhaps you haven't seen many instructables? Some of the pictures can be quite graphic.