Where to buy a STEEL, knife-edge disc??

Bob Ohlemann

Bob Ohlemann

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Dec 5, 2013
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I know Nathan made a run of nice discs well before I got into knifemaking and he seemed pretty adamant that he wasn't going to do it again. I've considered the Neilson system but I don't really need it. Is there anyone else out there making a high quality steel 9" disc with a knife edge?

Bob
 
Hey Bob....Why don't you shoot an email to Rob over at Beaumont (KMG) he lists 9" aluminum discs...perhaps he can knock out a Steel Disc for ya?! In recent memory I can't think of anyone other than Nathan that was offering any disc's.
 
Contact Nathan. He might do a one off for you. If he says no, maybe look for a machinist local to you who would be willing to make one.
 
I can't understand why Beaumont hasn't already jumped on this. The aluminum discs are fine (I have two) but for folders, a nice knife-edged disc plain rocks. If I have to get one custom made, I'll probably just make it myself.

Bob
 
RangerBobTX said:
I can't understand why Beaumont hasn't already jumped on this. The aluminum discs are fine (I have two) but for folders, a nice knife-edged disc plain rocks. If I have to get one custom made, I'll probably just make it myself.

Bob
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I'm just guessing that the Price of a HUNK of Stainless or for that matter Carbon Steel that is going to be turned on a lathe to make a bunch of ittybitty swarf and Balanced Disc is probably cost prohibitive in comparison the the price of that same size Hunk of Aluminum....probably some weight factor in there also?! I agree a Knife-edged disc would Rock!!!
 
To set up and make a single precision machined steel disk, heat treated and balanced and zero runout, is somewhat involved to do properly. I could charge $1,000 on a single and still lose money on it. For me it was only feasible to do in a lot because all the setup.

This might not be a great project for a do-it-yourself. A 7 pound knife edge steel disk spinning over 1000 RPM on the end of a skinny motor shaft a few inches from your balls isn't the best place to learn about machining. I'll wager Beaumont does solid aluminum because it's much more forgiving.
 
Nathan the Machinist said:
To set up and make a single precision machined steel disk, heat treated and balanced and zero runout, is somewhat involved to do properly. I could charge $1,000 on a single and still lose money on it. For me it was only feasible to do in a lot because all the setup.

This might not be a great project for a do-it-yourself. A 7 pound knife edge steel disk spinning over 1000 RPM on the end of a skinny motor shaft a few inches from your balls isn't the best place to learn about machining. I'll wager Beaumont does solid aluminum because it's much more forgiving.
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Which is why I would do it myself rather than farm it out to a machine shop. Hell, for the amount of time I'd take to make one, I might as well just buy a Neilson setup. I can make more money making knives than I can save making my own disc.

Bob
 
Well, Bob, Rod Neilsen's set up is an excellent system with the magnet discs but to have it work well for you, you need to use a variable speed system. On most of the work I do, no blades yet anyway, I'm only running at about 25% of output. For me it's the real answer for a lot of the sizing down I do for folders.
Frank
 
Frank Niro said:
Well, Bob, Rod Neilsen's set up is an excellent system with the magnet discs but to have it work well for you, you need to use a variable speed system. On most of the work I do, no blades yet anyway, I'm only running at about 25% of output. For me it's the real answer for a lot of the sizing down I do for folders.
Frank
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Frank, it was the Neilson discs that got me turned on to wanting a knife-edged disc. I found out how valuable it was when I took Johnny Stout's Fine Folder class. I've got variable speed on my discs so that's not a concern. I don't have a beveled disc so maybe I'll get a base, a flat knife-edge disc and a beveled disc. I don't find myself needing to swap papers much because I have two. I keep 60 grit on the horizontal and 400 on the vertical and pretty much just replace when worn out. It is quite likely that I have not experienced all the wonders of a disc grinder yet as I have never ground bevels on one as well. If I ever venture down that road, I might need a couple more discs.

Bob
 
Hey Bob I hope you don't mind me derailing your thread for a moment. Could someone enlighten me on what the difference between a beveled and knife edge disc is? When I first read this I thought you meant a 1* beveled disc but I gather that they are not quite the same.

-Clint
 
Augus7us said:
Hey Bob I hope you don't mind me derailing your thread for a moment. Could someone enlighten me on what the difference between a beveled and knife edge disc is? When I first read this I thought you meant a 1* beveled disc but I gather that they are not quite the same.

-Clint
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A knife-edged disc is beveled on the back side to create a very thin outer edge. That thin edge is ideal for maneuvering into tight spots when profiling the tang area of folder blades and other detail work.

Bob
 
Yes, take the backsquare of a slipjoint tang...it is ground less than 90°, and when you need to skim just a bit of metal there for dialing the flush positions a knife-edged disk is the way to go.
I had done my redneck setup by back beveling a cheap wood lathe flat chuck ;) it's not big and not so fast, so it's fine for folders
A 9 inch disk at full speed is another beast and needs to be very precision made
 
You could take a thick aluminum disk from Neilson and bevel the edge, no? Doesn't seem like a difficult mod for a knife guy...
 
RangerBobTX said:
A knife-edged disc is beveled on the back side to create a very thin outer edge. That thin edge is ideal for maneuvering into tight spots when profiling the tang area of folder blades and other detail work.

Bob
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what is the dimension of the thin edge?
Can you make a quick dimensioned sketch of the cross section?
I'd like to show it to our lathe man.
 
I like to try to do follow-ups on my threads so, here's what I ended up with. I ordered a Rod Nielson magnetic hub, a 1° faceplate, and a modified (knife edged) flat plate. The setup runs with no noticeable runout or vibration on my grinder up to 1800rpm. It is a significant improvement over the Beaumont disc I had on the grinder which, though useable, had a good amount of runout and vibration. Total price shipped to my door in Texas was $438.

Bob

Untitled by Bob, on Flickr
 
Yeah I agree. I find mine indispensable for slipjoint making. I've got 3 discs, all flat one knife edged, which I had gotten them all that way although no big deal to fix them.


I had two aluminum discs and hated them.


I wont say I change discs very often on my setup, but I've got 3 discs and could get by with 2, but I do like keeping one course grit (which lasts a lot longer, and then use another for 400ish paper, which you'll be replacing constantly. If you dont already use it, 3m 77 spray adhesive works great. I tried feathering adhesive and found it to be a mess, and a pain in the ass to clean up. Now I keep a piece of cardboard about 3 times as big as a sheet of sandpaper laying near the disc and a can of the 77 spray, lay the paper on the cardboard, quickly spray with 77 from about 10 inches away just coating the paper. Let sit for 10-20 seconds, and then attach to the disc. Has plenty of hold, but will easily peel off when you're done.

Faster than monkeying with the feathering goop and trying to get it evenly spread before it starts getting tacky, once it's been on a disc for a few months it's nearly impossible to remove. 77 spray cleans up with high proof iso-pro or similar and a scotchbrite pad with the disc running slowly and some pressure.
 
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