Introduction: Make a Quick Knife From a Clutch Finger

Picture of Make a Quick Knife From a Clutch Finger

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.


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

Picture of 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?

Picture of 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

Picture of I Mean It!  Broken Grinding Disc Vs. Eye


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

Picture of 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

Picture of 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

Picture of 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

Picture of 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!

Picture of 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

Picture of 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

Picture of 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

Picture of Sharpen

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

Step 12: Sheath

Picture of 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.


PowellMade (author)2015-01-20

Whoooaaaaa all I could think was "fffffff that must have hurt" When I saw that picture. I saw a guy chop his finger clean off once. Sad because he never got it back on either a good reminder to everyone. Thanks for this write up. Do you know what kind of steel those fingers are made from?

black hole (author)2013-02-05

I bet you could make a lot of push knives using this method.

idlymr74 (author)2012-04-21

after completing a two week OSHA course i learned that harmonics is one of the answers, if you tap your grinding wheel with a screwdriver and listen for a clear ringing sound you can tell if the wheel has cracks or defects. Guards were invented for a reason though and retro fitting one or getting rid of tool is best bet.

mat1978 (author)2011-07-14

Best warning ever , and you have to click to see it , and please tell me you have replaced the grinder for e better one .
btw I'm glad you're ok :D

iac (author)2011-07-14

200,000 teachers to an enemy country where the 500,000 pupils ( OH, GOOD PUN ) are armed with ak-47s ??

tipaklong (author)2011-07-14

i cannot unsee what has been seen...

the one snow man (author)2011-01-28

Why didn't you just use a torch? It would have been so much easier, faster, and much more safe.

Pumpkin$ (author)2010-11-04

Because war didn't make us everything we are today...


Shadow13! (author)2010-10-28

My neighbor and I made something similar once only instead of making the blade we welded the blade from a broken pocket knife on. The pic of the eye is extremely gross but if that won't convince someone to take proper safety precautions nothing will.

Rainh2o (author)2010-09-21

My grinder also expoded a cheap grinding wheel once, hit me in about the same place too!...mine did have the guard on, the piece went around the guard...

Dodge (author)2010-09-19

Nice knife...

*puts guard back on grinder*

Russell2ii (author)2009-03-27

Congratulations on throwing politics into an otherwise good instructable.... Semper Fi...

Baronrc (author)Russell2ii2010-08-09

I agree, this is instructables, NO POLITICS PLEASE FOLKS. You all know we'll never agree.

jakebuck (author)2009-03-18

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

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

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

Damage, Inc. (author)jakebuck2009-03-20

Wrong? How is that "wrong"? All my life I'd been told smoking was bad, but the point didn't hit home until I went to the exhibit at the museum of natural science that showed what a smoker's lung looked like next to a normal lung. A picture is worth a thousand words. The picture is an adequate warning to people, and it pertains to the instructable. It shows what can happen to someone if they don't follow safety procedures. Yes, it is a shocking picture. It's SUPPOSED to be.

jakebuck (author)Damage, Inc.2009-03-21

Its wrong for multiple reasons. There was an inadequate warning. This site is generally family-friendly. If the pic was on anyone else's instructable, it would have been removed. Enough said.

rocketkid (author)jakebuck2010-06-12

there was a perfectly adequate warning. you just didnt read it.... =/

Damage, Inc. (author)jakebuck2009-03-21

The warning was adequate. It is mentioned once in the first step, again in the second step, and also in the third step. To see the Full picture, you have to click on it. That's 4 warnings. GENERALLY family friendly. That doesn't mean ALWAYS. Also, this is an instructable about making a knife from parts from a car. I doubt that anyone very young will be viewing this. If it were on anyone else's instructable, it would've been removed? I doubt that. I think you're just assuming this. Have there been past examples of things like this being removed?

jakebuck (author)Damage, Inc.2009-03-21

It was mentioned once in the first step, he has since changed it. Stop assuming that I am wrong, can you find any other instructable with gore like that? I've been watching this site for years, haven't seen any.

Damage, Inc. (author)jakebuck2009-03-23

he changed it between 1:02 AM, when you posted, and 2:14 AM, when I posted? If that's the case, well, I guess you're right. Just because there hasn't been gore like this before doesn't mean it can't exist. And I asked, have there been past examples of things like this being removed? If not, then you have nothing to base your argument there upon. If there are, then again, I suppose that you are correct.

cry_wolf (author)jakebuck2009-03-21

Family friendly? We have instructables on how to put on condoms, make bombs, have sex, and kiss. Please stop being such an ignorant child, and get some facts before you jump to conclusions.

Lithium Rain (author)jakebuck2009-03-19

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

jakebuck (author)Lithium Rain2009-03-21

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

cyborgpigeon (author)jakebuck2009-03-21

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!

jakebuck (author)cyborgpigeon2009-03-21

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.

zzoe (author)jakebuck2009-03-21

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.

jakebuck (author)zzoe2009-03-22

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.

jtobako (author)jakebuck2009-03-23

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

Lithium Rain (author)jtobako2009-04-16

Excellent point.

drummonkey92 (author)jakebuck2009-04-16

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.

zzoe (author)jakebuck2009-03-25

...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.

Lithium Rain (author)jakebuck2009-03-21

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.

jakebuck (author)Lithium Rain2009-03-21

Show me.

Lithium Rain (author)jakebuck2009-03-21


Let's see, How to skin and clean a dead snake and Mouse Taxidermy are pretty graphic by some people 's standards. How to skin a Deer, Catfish, and Badger are fairly gory.

Need I go on? ;)

cry_wolf (author)Lithium Rain2009-03-24

Bahaha, well done Lithium =D

Lithium Rain (author)cry_wolf2009-04-16


and it's lithium for the win


Scurge (author)jakebuck2009-03-19

I personally can take gore pics, but eye stuff really makes me cringe. Though this does compel me to go put the guard back on my grinders. If that disk did that through all that padding, it would rip through a pair of safety glasses like a hot knife......
That totally caught me off guard, LOL I was just scanning through new subscription i'ble's real quick before leaving for school and BAM eyeball hanging out. Never saw the "warning" at the top of the page at all. Not gonna flag it, but a link to the pic (or at least make it a thumbnail) or a little more visible warning, instead of a huge pic in the middle of the page should strongly be considered.

masterochicken (author)Scurge2010-06-11

Actually you'd be surprised. Proper safety glasses are extremely durable. I once saw a pair a pair of safety goggles get run over by a train and I expected them to be crushed. Much to my surprise they just sort of molded around the track.

cry_wolf (author)jakebuck2009-03-21

really? he gave you a warning, and yet you still look at it. If he warned you it would be offensive, why in the world would you look at it if you did not want to? your ignorance is staggering. And also, its anatomy, get over it. Oh my a little blood, if you cant take that i suggest you get off the internet, or take an anatomy class, let alone a minor biology one.

jakebuck (author)cry_wolf2009-03-21

The only warning when I looked at it was in the first step, which I like many people do not read, as its usually not that informative.

Damage, Inc. (author)jakebuck2009-03-24

Do you usually read the manual to something when you first purchase it? If you don't, then you have no right to sue or complain when you don't follow safety procedures outlined in it and get injured.

cry_wolf (author)Damage, Inc.2009-03-24

You dont read the first step!? Thats what explains the instructable for goodness sake. i really hope you dont follow instructables like making thermite without reading the first step. and Damage Inc, well said.

masterochicken (author)cry_wolf2010-06-11

Weather or not he gave a proper gave proper warning is pointless. He gave a much more important warning. This can happen to you! If you can't handle seeing this warning then don't use power tools. I know from first hand experience that things like this happen all the time, even with less dangerous tools. If you can't handle it then don't pick up a power tool.

bustedit (author)jakebuck2009-03-20

i just flagged you for mis-spelling "pic"

jakebuck (author)bustedit2009-03-21

Nice try, but I was referring to the choice to put the "pic" up, not the actual picture.

Lithium Rain (author)jakebuck2009-03-21

Nice try, but you used the wrong word and got called out.

About This Instructable




Bio: Tim Anderson is the author of the "Heirloom Technology" column in Make Magazine. He is co-founder of, manufacturers of "3D Printer" output ... More »
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