Spyderco Forums

Hey everyone, I saw an actual Rotary Grinder kit for a cheap price, the entire kit and here is my question: The ad said it can do 120VAC-powered 8,000-30,000 rpm mini grinder. Would this system by itself, perhaps with a few other inexpensive tools, allow me to modify my knives if I wanted to, like alter the grind angles and such, or not good idea?

Hand-held rotary tools (such as Dremel) are very useful in many aspects--knife making or modding being one of them. I have three Dremels at this time (two corded and one battery-powered). I use mine pretty much exclusively on knife making and they work well. I'd definitely purchase a model that offers a wide range of variable speeds. Also, you might want to purchase an inexpensive 1x30" belt grinder to mod things like blade grinds, etc. (Trying to do this on a rotary tool would be very time-consuming also very frustrating). :)

Dremel type tools have their place. But be sure that you understand their capabilities and limitations, as well as have good mastery of the tool and bit used before you use it on a knife you care about!

Thank you for the replies. Yeah I wanted to safely modify some grinds and also touch up edges.

SpyderEdgeForever wrote:Thank you for the replies. Yeah I wanted to safely modify some grinds and also touch up edges.

No problem at all.
Again, you will be much better off using a belt grinder vs. trying to use a Dremel tool if you intend to reprofile blades or edges. (There's really no good way to steadily and consistently maintain the proper angles if trying to free-hand sharpen with a Dremel. It would be very risky at best). You can easily pick up a cheap 1x30" at Harbour Freight, etc., and the proper belts at Usaknifemaker.com or Tru-Grit.com.

Which Spydercos are you looking to mod?

A Dremil type tool should do a great job of ruining the temper and hardening of the steel.
It is useful as a cutting tool, drill, etc., but I would keep it far from the blade. It would work fine for some aspects of modding a knife, but not for grinding the blade. I have used a 1x30" belt sander for that ...with care. You don't want to overheat the steel edge.

One of the ones I want to mod is an Endura 4 plain edge. I sharpened it and sortof messed up the edge a bit. I would like to see if I can reprofile it a bit, and perhaps give it a Scandi grind to see how it would work out.

Just be careful.

Practice on something cheap.

SpyderEdgeForever wrote:One of the ones I want to mod is an Endura 4 plain edge. I sharpened it and sortof messed up the edge a bit. I would like to see if I can reprofile it a bit, and perhaps give it a Scandi grind to see how it would work out.

A Scandinavian grind is something you can't go to from a FFG blade, zero grind could be done, but I'm not sure that would hold up to any kind of use except for slicing hair, paper, soft vegetables or boneless meat...

A dremel is emphatically *not* the right tool for resetting an edge, a coarse diamond bench stone is best if you have no experience with belt sanders, as it's impossible to overheat the edge and much harder to over or mis-grind the blade when you are working by hand. If you have a good feel for stock removal with a belt, then a belt sander with the right belts will get the job done quicker, but the rapid stock removal ups the ante when you make a mistake, and you can destroy the heat treatment of the blade by leaving the it on the belt for just a few seconds too long!

**sorry to restate what you already said Arty, somehow I skipped over your post while reading down the page**

Short answer- Not a good Idea

Long answer: Good idea for adding a choils or anso pattern or something (presuming you mean a dremel as a rotary tool is pretty broad) But if you want to change your blade grind, you're going to want to invest in a belt grinder, and if you're wanting to sharpen the edge, get some better stones or a guided sharpener sucha s the wicked edge, edge pro, KME etc

I'm with the post above for most purposes. The speed is too high and the working surface is too small for doing anything other than "filework" on the spine or perhaps setting a sharpening choil.

Just finished using my 1"x30" belt sander and my rotary tool to "wave" one of my spydies, next up acid stonewash, then custom scales when they arrive...

That was something else I wanted to be able to do: Take a Sheepsfoot blade like an Atlantic Salt, and correctly add a point to it, while keeping the overall sheepsfoot rest of the blade, similar to the modification done on the Jumpmaster as seen in other threads on here, and, on the modified Atlantic Salt that was on another thread.

Belt sander will be much more neat and consistant, I attempted to shape the choil some so I could sharpen the entire blade with the wicked edge, was not pretty.

SpyderEdgeForever wrote:That was something else I wanted to be able to do: Take a Sheepsfoot blade like an Atlantic Salt, and correctly add a point to it, while keeping the overall sheepsfoot rest of the blade, similar to the modification done on the Jumpmaster as seen in other threads on here, and, on the modified Atlantic Salt that was on another thread.

With care you can do that with a bench grinder using a white stone. Keep the wheel clean and sharp, use a light touch. Just don't go right to the very point with any sort of power tool, the last bit can be done stones or a diamond file.

If you're using a bench grinder for that sort of purpose, you want a low rpm grinder made for working with edged tools.

I use my dremel for just about anything you can imagine? It's the one tool I've used so much I had to buy a second because the first was so worn out.

You better practice with it though because you'll ruin a blade in a blink of an eye if you're not careful. I can't stress enough how easily you can screw up with the dremel so PRACTICE :D

I've fixed snapped tips on a Gerber my buddy wanted pointy again and on an old Endura 3 ATS--55 SE my uncle gave me and they turned out great. I found the rotary bench grinder to be much easier to do tip work with than the hand held Dremel though and a 1"x30" belt grinder would probably be even better but I still have to pick one of those up.

I guess FRN Byrd's would be good to practice on.
I love Dremel for carving bone/micarta/G10 but I wouldn't use it much on (hardened-) steel.

Joris Mo wrote:I guess FRN Byrd's would be good to practice on.
I love Dremel for carving bone/micarta/G10 but I wouldn't use it much on (hardened-) steel.

Agreed, that's why I say bench grinder and belt sander.

JNewell wrote:If you're using a bench grinder for that sort of purpose, you want a low rpm grinder made for working with edged tools.

Ideally yes, however I just have a normal 3000rpm grinder. It's OK with care, but I never go right to the edge. To be honest I think a low speed grinder would also be quite capable of overheating the edge if not used carefully in any case, unless you're talking about a really slow water cooled grinder.