Forever-Sharp Hobby Knife
Sharpening Hobby Knife Blades by HilldaFlyer
On a few episodes, Josh Bixler has mentioned the reason he uses utility knife blades is because they are the most economical (cheap, cheap, cheap). I too, have used snap-off blades, utility blades, one-sided razor blades and #11 exacto blades, etc. My preference is to use the #11 exacto blades, but like all blades they get dull because of use. My solution - sharpen them… I bet with a little practice you could even sharpen utility knife blades too. But with a forever-sharp exacto blade in a handle, there is no reason to be using a handle-less blade.
With a little searching on the internet, I found in the rocketry forum with detailed descriptions of how to sharpen hobby knife blades. After trying it, I’m a believer and have been using the same two #11 exacto blades for 6 months. That’s incredible…. Here is how...
Credits:
http://www.rocketryforum.com/showthread.php?37330-Sharpening-X-acto-blades
http://www.rocketryforum.com/showthread.php?20558-Best-Hobby-Knife-Evar!&highlight=leather+strop
Materials:
Hobby knife
Old Leather Belt (I got one at a used clothing store for $3). It is good to get one with a rough side, but if not, you can scratch up any leather with 60 grit sand paper.
White jewelers rouge (available on ebay for $3). Note: some people wrote about using chrome polishing compound. I have not tried this, but the principle is the same and should work.
Sharpening the blade:
Work a layer of jewelers rouge into the rough side of the leather.
Lay the strop on a flat surface, like the edge of your hobby bench or mount it to a piece of wood.
Lay the blade flat on the strop and then tilt about 20 degrees.
Drag the hobby blade across the length of the strop in a direction away from the cutting edge (left to right below) keeping the blade at the same angle. Repeat 5 to 10 times.
Repeat on the other side of the blade (right to left, not shown).
Your hobby knife is sharp again.
When the strop becomes shiny and black, it is time to give it a facelift. Just warm it up a bit with a hair dryer (oven, sun on a sunny day, don’t use open flame unless your name is David Windestål). After it is warm, scrape off the excess jewelers rouge with a one-sided razor or similar scraping tool (don’t use your hobby knife). Then I apply a new layer of rouge while the leather is still warm.
Tips:
I think the hardest technique to learn is how to maintain a constant angle between the blade and the strop throughout the entire stroke. If the angle is not maintained, the sharpened edge will be slightly rounded (i.e. dull). My advice is to go slow and develop a technique. You don’t have to push very hard across the strop, just enough pressure to ensure good contact.
Hey, the hobby knife handle above looks like wood, well - it is wood. After having so much success sharpening the blade in my aluminum exacto knife handle and not having to replace the blade every day, I built an exacto blade handle out of a dowel, just to see if I could, and it works great! I cut a notch in the end of the dowel with a scroll saw, fastened the blade in the dowel with a small screw (filed off the protruding point of the screw) and wrapped the notched end with fiberglass. It is very light. Follow link 2 above for directions on how to build your own hobby knife handle out of a bolt. Both forums are good reads if you want to sharpen your blades… I highly recommend it.
Summary
Sharpening your hobby knife.
Use it up, wear it out, make it do or do without
Update October 2014 - For reference see Chris’ comment below - ChrisJ June 6, 2014
Thanks Chris. After reading your comment, I got to thinking that I may have a Arkansas stone. I grew up in Montana and used to go hunting. One of the items I packed was a knife, of course, and a sharpening stone. It was small but it got the job done. I rummaged through my old gear and loan behold, guess what I found… my sharpening stone and it was Smith’s Hard Arkansas.
I tried it out with mineral oil and I have to say that I am even more impressed with the edge the stone created. It is amazing, but after setting in on an angle, you can actually “feel” the grinding sensation turn into a gliding when the blade is flat with the stone. It takes about 5 to 10 strokes on each side and the blade is really sharp.
I would definitely recommend getting a good stone. Thanks again Chris!
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I just cut out my kraken and three spitfires with the same blade yesterday
Mike
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I own an Edge Pro Apex sharpener. I drew the line at #11 blades though.
I can get 100 #11s for around $5. It's not worth my time to resharpen them.
I know that sounds horrible, but I just can't see myself honing a 5 cent blade for even 5 minutes.
Cutting DTF doesn't strike me as requiring anything near laser sharpness.
Sharpening isn't free - I'll throw in an old belt, but the cost of the jewelers rouge or chrome polish will keep me in new #11s for years.
Best regards,
PCH
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Xacto brand 100 x #11 $12
No-name 100 x #11 scalpel blades with handle - $6.50
I haven't bought any for a while so it may take some searching to get down to $.05
Best regards,
PCH
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The best stone for forming and polishing the cutting angle is an Arkansas stone from America, better than all the man-made composites, its a (usually) white very hard stone, expensive, but you only need to buy it once, it will last all your life, mine has been in constant use for over 50 years.
You use with lots of oil, any oil will do cooking oil, linseed oil, mineral oils, but mineral oils are less smelly and less 'gooey' after a few years, engine oil, sewing machine oil all work fine, whale oil is the oil of choice, but you can't get it anymore (except in Japan).
Find the angle the edge has been ground at and polish all the grinding grooves out of it with the stone and lots of oil, the oil makes a cutting fluid when mixed with particles off the Arkansas stone, you always sharpen a blade or any action that is grinding the blade by pushing with the edge first.
Now your blade will easily cut a hair and slice through paper.
The final stage is stropping, stropping does not remove anything from the blade it uses friction to melt the blade molecules right at the cutting edge and drags the molecules over the edge forming a very hard 'wire' which breaks off and leaves an edge which is just one molecule thick, glassifying them and interlocking the molecules and should be done firmly with pressure in the opposite direction, away from the edge, and at a slightly steeper angle on a leather strop. In the past this was dressed with 'crocus powder' mixed with whale oil, the nearest you can get these days is jewelers rouge and Vaseline.
Stropping takes just a few seconds and the edge will last for weeks, the action of air molecules actually sharpens the edge, cut throat razors were often sold in sets of seven, you used a razor once a week then rested it for the other six days when it would re-sharpen itself! About once a year you'd take them to the barbers and He would strop them for you.
Is it worth all this palava? You bet, the edge is just one molecule thick, you can't get sharper, the blade now cuts on contact (you have been warned), very little pressure required and it cuts in the direction of the pressure, with the grain or across the grain makes no difference, the blade is actually safer to use as it's predictable, now you can cut a hair lengthways with precision, I don't why you'd want to, but you can :-). Stropping also hardens the edge so it lasts a lot longer and polishes it so it cuts a lot cleaner.
Cheers Chris
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