Instructables

How to Re-Tip A Knife Using Dremel

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So I've had an old and lonely chef's knife hanging out in my knife kit for a while now.  I retired it and bought a new one shortly after a coworker used it to pry open a stuck robot-coupe and cracked off the tip off.  People are no longer allowed to use my knives to say the least...hard lesson learned indeed!  Well, I was looking at this knife the other day and thinking about how perfectly usable it is, except for the fact that it has no tip...an essential item for speed and/or precision knife cuts. Soooo I thought...why not?  No job Dremel can't handle!  And so it was...pulled out of retirement and fully repaired, my trusty work companion and arm extension is back in action!  In this instructable I'll show you how to save a few bucks by repairing your own knives.
 
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Step 1: Gather Materials

Picture of Gather Materials
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To put a new tip on your knife you'll need the following:
  1. Broken knife
  2. Marking device such as a pen or marker
  3. Dremel
  4. Dremel Attachments (metal cutting blade, grinding bit, sanding bit, wire polishing brush, synthetic polishing brush, and felt polishing tip with polishing compound applied)
  5. A clamp for supporting the knife
  6. A sharpening stone or other sharpening device
  7. A honing steal
tkalko10 months ago
As some have properly noticed, the excessive heat can easily lead to damaging the blade. The damage from loss of blade heat treatment is not something to worry about in a 10$ kitchen knife, but for any quality knife dremel should be avoided if possible. For smaller tip repairs just prolonged sharpening with a coarse sharpening stone (or a quality sanding paper on a mouse pad) will do - but it will take slightly more time than the dremel butchering (depending on the blade steel and sharpening tools beinv used)
jarikcbol tkalko10 months ago
I was about to point this out myself, heat from abrasive cut off tools can really be bad for good knives. I've done several knives simply by marking it out, and slowly grinding it down on a cheep coarse sharpening stone while listening to an audio book or listening to a show on TV (pay more attention to the knife than the TV tough, stay safe!) Takes longer, but you don't risk messing with the temper of the metal as much.
gwiener110 months ago
I have the same knife set from my years at the CIA. :) thanks
JFabor (author)  gwiener110 months ago
I share your Alma matter. Class of april 2009. :) this was my school issued knife.
gcanders10 months ago
Great! I have to do this with a Shun knife I invested over $300.00 in. Thought the missing tip is very small, in my case, the tip that is left is slightly bent. Any idea how to unbend it without breaking it further? I was counting on the heat from the grinding to aid me in unbending it, but maybe I should keep it cool during the grinding and find another method to straighten it. The tip that is missing is 1/32" but it is noticeable when the knife is shown with my other knives. They are hanging on a magnetic knife holder on the wall. One day, I grabbed it, but dropped it on the counter and bamm, the tip broke and bent the knife at the end.
JFabor (author)  gcanders10 months ago
I also own a couple shuns...its probably not wise to retip a shun utilizing this method. i know shuns come with a lifetime warranty. U should be able to send it in to the company, and they will either repair it or send u a new one. Visit the official shun link for more details.
knottyarts10 months ago
The heat generated by cutting will possibly ruin the temper of the tip. It depends on the knife, how you cut it, if you use an oil or some other cutting fluid, and dozens of other factors. The two big things I would add here are 1) use some sort of oil or cutting fluid when reshaping the tip. Less friction equals less heat. And 2) work in 1-2sec on 4-8sec off bursts. You will accumulate heat much faster than you lose it. If the steel becomes colored in any way (blue, brown, etc.) you burned it.

Personally I just rebuild the edge to create a new tip, but most people don't have the patients for the hours of hand work that requires.
vumbaka10 months ago
I think the heath produced by the friction of the power tool could damage the temper of the blade, couldn't it?
tkjtkj vumbaka10 months ago
Re: vumbaka ... re: heat causing loss of temper

My guess is that as a dremel is use intermittently ( ie, ? 2 secs cutting,, few secs off the work ..etc) that risk is very low .. Further, i really doubt most knives are tempered at all .. otherwise, they'd be a bit** to sharpen ..
The volume of knife metal, too will suck heat quickly ..

But you're good to raise such important considerations no doubt applicable to many heat-producing tool use ... but not in this case ..
tkjtkj10 months ago
Yes .. good job ... Dremel's are handy!

BUT:
Do add to your 'Required Items' list: Safety Glasses or full face shield!!!
Phil B1 year ago
Congratulations! It gives you a good feeling to restore something like this knife to a useful condition. Sometimes I appreciate the restored item even more because I feel like I have made it mine in a way it was not before.

I did something like this on a smaller stainless steel general purpose knife owned by my mother-in-law. Someone had used its tip to pry and the tip broke. I ground a little on both the cutting edge and the back of the knife for aesthetics. All I had available was a standard electric grinder. I ground slowly and kept it cool with water. Although it was not a quality knife, the knife was more useful with the point restored.
JFabor (author)  Phil B1 year ago
Phil B, Thanks! I agree with you, after restoring this knife I experienced a whole new sense of connection to it. I appreciated it before, as it was the knife I learned how to cut with, and I've prepared many delicious foods using it, but now the experience is a little more intimate. Such a fulfilling task!

Good job with your mother-in-laws knife! I've seen so many knifes over the years be disrespected and used for all the wrong tasks, then as a result of misuse they end up as pieces of junk people cast aside to be forgotten forever. Kudos to you for recognizing the potential of an otherwise forgotten item!