dikman

Razor Sharp system

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I have all sorts of gear for sharpening blades - oilstones, Arkansas stones, wet-wheel grinder, belt grinder etc, but while at the annual Adelaide Knife Show a chap was demonstrating the Razor Sharp system. I was quite impressed so bought it. Basically it's two paper wheels with one being coated on the outside with 180 grit and the other (slotted) wheel given a coating of fine rouge.Using them he brought an ordinary kitchen knife to a hair-shaving edge in very little time. I bought the set for a 6" grinder, but because both of my 8" grinders are in use I had to buy a 6" grinder too! I decided to buy the cheapest I could find as I didn't need something with a lot of power for this job - the Ozito is only 150w but has a 3-year warranty so it seemed like the most practical option for $35. It came with two grinding wheels but I reckon it would have been underpowered  for anything other than sharpening drill bits! I stripped the wheels and guards off and raised the base to clear the 8" Razor Sharp wheels. It takes a few seconds to come up to speed but is plenty powerful enough for this job as sharpening knives doesn't load down the motor.

A quick try and it works well, although like everything there will be a bit of a learning curve. Should be good for my leatherworking tools (and woodworking stuff too).

Sharpener a.jpg

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I’ve got some of these paper wheels on a grinder and they work good. 

Give you some advice I learned the hard way. Turn your grinder around so wheels rotate away from you. If the knife catches it will throw it away from you. 

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Thanks for the reminder JKH, the chap selling them mentioned this but I forgot. I removed the base and rotated it 180* so the switch is still at the front. Now I just have to rig up a guide system to get consistent angles.

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So I made a jig to (theoretically) get consistent sharpening angles. My first idea was to just fit a bar across the wheels but I soon realised that wouldn't work because of the knife handle, dragging the knife across the inside of the wheels would raise the blade and change the angles. So, version 2 with blocks the width of the wheels, version 3 with added spacers under the blocks for more clearance. Looked good, but unfortunately there is a slight problem with such a design, because the wheel is rotating away from me it tends to grab the blade and try and drag it forward along with the wheel. This results in an uneven bevel. Pressing down harder on the blade didn't work as that also put more pressure on the wheel and yes, it's quite easy to burn a blade doing this!!

The only way this can work would require a fairly elaborate means of clamping the blade to the guide, such that it can slide but not lift, or perhaps some sort of arm coming from the rear of the guide, over the top and finishing just above the front of the guide by the wheel to stop the blade lifting. This may be the easiest to do but would need to be adjustable for different thickness blades. Could be getting a bit complicated.

 

 

Sharpener jig 1a.jpg

Sharpener jig 2a.jpg

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Version 4! The guide wheels are some plastic things that I had and I used the lathe to cut a V groove in them. Not the prettiest of things, but as long as it works (which it appears to do) it doesn't matter. The wheels took a bit of fiddling to get them adjusted right but now the blade doesn't lift as I pull it across. If the wheels prove too soft I'll make some new ones from nylon.

 

Sharpener jig 3a.jpg

Sharpener jig 4a.jpg

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