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Setting an initial edge.

Started by jmforge, September 12, 2013, 05:39:13 AM

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jmforge

I am a custom knifemaker.  Normally I set my edges on the KMG belt grinder.......and sometimes have to go back and hand sand the scratches where I missed. ;D I am going to be producing what we knife knuts call a "mid tech" line which is another word for small production run with some hand work still involved. What this means is that I will have to set the intial edge on anywhere from 40-200 knives per run. I will be using some rather abrasion resistant steels like Crucible CPM 3V and 4v, CPM S35VN, CPM 154, Carpenter CTS-XHP and maybe Bohler-Udddeholm Elmax, M390 or Vanadis 4E all at a minimum hardness of 60Rc on most.  Will the T7 work for this application and if so, do I need to buy the black silicon carbide stone?

grepper

I'm curious... What type  of belts do you use on the KMG for  initial edge setting?  Carbide?  Zirconia etc.?  What grits?

For that type and volume of work, I'd think you would have to continuously spend a whole lot of time with coarse side of the stone grader to keep the grinding wheel aggressive enough to remove that much steel. 

I also suspect that you set the initial edge on the KMG freehand?


jmforge

Quote from: grepper on September 12, 2013, 01:41:43 PM
I'm curious... What type  of belts do you use on the KMG for  initial edge setting?  Carbide?  Zirconia etc.?  What grits?

For that type and volume of work, I'd think you would have to continuously spend a whole lot of time with coarse side of the stone grader to keep the grinding wheel aggressive enough to remove that much steel. 

I also suspect that you set the initial edge on the KMG freehand?
Actually, you can use almost any belt, even AO. Typically, you start with say 220-320 and then clean up with 400 or 600 grit.  Oddly enough, the one type of belt that does not seem to work so well in this application is the Trizact 'Gator". I set the edge freehand.  That would be a problem with the new project as the blades may already have a Cerakote type coating so even if I had the time, I couldn't go back and hadn sand away any near misses.

grepper

The T7 is going to take more time compared to your KMG, but it will have the advantage of holding the knife in a jig which will pretty much eliminate scratching up the finish on the side of the blade.

The grinding wheel  does not maintain grit abrasive consistency, and tends to get less abrasive pretty quickly, so you have to redress the wheel with the stone grader often to keep it cutting well.  This is not an so much of an issue for a small number of knives, but could prove to be a lot of work for 200 knives.

The T7 will work well and give you a consistent edge with less screw ups, but it can't match the production speed of your KMG.  It's also going to take some practice, especially for getting a perfect curve and tip and avoiding a concave edge profile.

I don't have the black silicon wheel so I'm not qualified to comment on its HSS removal capabilities, but other folks here have it so I'm sure they can give some advice about that.

Here's a knife rest that I made that works on my Kalamazoo with the belt rotating away from the knife edge:
http://forum.tormek.com/index.php?topic=1679.msg8488#msg8488

Oddly, I'm not a big fan of the Gators or as I hear the 3M dudes call them "bricks".  Guess a lot of folks swear by them though.


grepper

Don't want to change the subject, but a quick question:

Can you run a 1" belt on on your KMG?

jmforge

#5
Quote from: grepper on September 12, 2013, 04:20:13 PM
Don't want to change the subject, but a quick question:

Can you run a 1" belt on on your KMG?
Yes, i can and I also have the KMG rotary platen atttachment. That still doesn't totally solve the problem of bad hand-eye cordination and heating up the edge.  ;) My other option is the smaller Catrasharp machine, but even at the GREATLY reduced prices you see today, that is still like $1300 shipped plus more if I want a second set of finer grit wheels.  For that $1300, I can get a T7, the knife jig, a black wheel and a Japanese waterstone wheel as best as I can tell.

grepper

I don't make knives, though I wish I did,  :) but I sharpen a lot of them.

I use both the T7 and Kalamazoo 1SM.

The T7 is very accurate as far as edge angle goes and produces no heat at all.  As well as knives, It works well on scissors and woodworking tools and other stuff too.  It products a hollow grind, and there is no dust to deal with.  You might also want to check out this: http://forum.tormek.com/index.php?topic=1592.0  Very handy with the T7.

You can put together the jig that I showed in the previous post http://forum.tormek.com/index.php?topic=1679.msg8488#msg8488 or something like it for under $50.  It works great on the 1SM, gives you complete edge angle adjustment and fine control whilst sharpening.  Seems a jig like that would work perfectly with the KSM set for vertical sharpening with the rotary platen.  It completely solves the freehand hand-eye issues.  The 1SM is nice and slow for a belt grinder and runs at belt speed 1750 rpm, Heat does not seem to be an issue at all for sharpening, but unlike the T7, it can get the blade warm if you try hard enough.  It is a belt after all.  The 1SM is about $250.

As well as the expensive Catra machines, there is also the F. Dick RS-75 and RS-150.  I have also thought about trying a Chef's Choice electric sharpener at about $200, with some models for much less, for quick and brainless sharpening.  It's another dual diamond wheel sharpener.   I think one of the Chef's choice models has adjustable angle ability. 


grepper

Mr. jmforge,

Um..., Got to say..., I'm impressed. The knives you make are beautiful!

Forging and hammering out your own 450 layer damascus, eh?.  :)

I especially like the 400 layer random damascus blade and fittings, with the fossil walrus ivory handle and Tree Stump Leather sheath.  Such simple and clean lines.  A real work of art.

I also really like the 450 layer ladder pattern damascus blade and fittings, with old growth Honduran rosewood burl. I love it's overall look and blade shape.  What a pretty knife!

Impressive. Beautiful. Really great work!


jmforge

Thanks.  I have done a blade like that of 180 layers and it looked really good, very bold, but you really have to get up over 300 layers to get the "3D shimmer" on ladder pattern steel.
Quote from: grepper on September 12, 2013, 11:09:53 PM
Mr. jmforge,

Um..., Got to say..., I'm impressed. The knives you make are beautiful!

Forging and hammering out your own 450 layer damascus, eh?.  :)

I especially like the 400 layer random damascus blade and fittings, with the fossil walrus ivory handle and Tree Stump Leather sheath.  Such simple and clean lines.  A real work of art.

I also really like the 450 layer ladder pattern damascus blade and fittings, with old growth Honduran rosewood burl. I love it's overall look and blade shape.  What a pretty knife!

Impressive. Beautiful. Really great work!