Full flat grind, how?

T

TigerBlades

Joined
Sep 21, 2021
Messages
52
So, I was wondering how to pull off a clean flat grind. I've done scandis and convex, nothing else. I'm getting into more slicey knives, but don't really know how to pull off a ffg. I have a bench grinder (makes ugly scratches), Ken Onion worksharp (doesn't remove much material) and files (would take forever). Yes, I could forge them, but do I want hammer marks over the entirety of the blade? Would that be ugly?
Anyways, please help.
 
Last edited:
Time spent with files can do the job. You can file away all the forging marks if you want to forge the bevels in first. If you want it done fast you'll need a belt grinder of some kind. A 1x30 would be better than a bench grinder but not spectacular without practice.
 
Have you tried files or do you just assume that they take forever? I made some knives with files when I started and it did not take very long at all. You can probably do a 4" blade in an hour or two. If it takes much longer than that the file is probably dull. If you have not seen it already, watch the youtube video by Aaron Gough about his file jig. I build something similar from scrap I had on hand and it worked pretty well.

 
N.W. Gean said:
Time spent with files can do the job. You can file away all the forging marks if you want to forge the bevels in first. If you want it done fast you'll need a belt grinder of some kind. A 1x30 would be better than a bench grinder but not spectacular without practice.
Click to expand...
Ok, thanks. What was your first belt grinder (no one I've asked can agree which is best for a belt grinder noob)
 
Hubert S. said:
Have you tried files or do you just assume that they take forever? I made some knives with files when I started and it did not take very long at all. You can probably do a 4" blade in an hour or two. If it takes much longer than that the file is probably dull. If you have not seen it already, watch the youtube video by Aaron Gough about his file jig. I build something similar from scrap I had on hand and it worked pretty well.

Click to expand...
I've used them on my first 3 knives. Took about a week each. Maybe my files are dull, maybe I'm an idiot, but it took FOREVER. New files?
 
N.W. Gean said:
A 1x30 which I quickly lost patience with and built a 2x72. That's when I learned that a 2x72 doesn't make you a better knife maker :)
Click to expand...
It doesn't, just makes things easier. Like the people who forge in a fire with no electricity, and make beautiful knives, they show it is possible.
 
Hubert S. said:
Have you tried files or do you just assume that they take forever? I made some knives with files when I started and it did not take very long at all. You can probably do a 4" blade in an hour or two. If it takes much longer than that the file is probably dull. If you have not seen it already, watch the youtube video by Aaron Gough about his file jig. I build something similar from scrap I had on hand and it worked pretty well.

Click to expand...
And I do plan on making one, and buying a new file. Another guy recommended the same. What specific file is best? I use a bastard file.
 
my first knives were all made using files. Do you know about draw filing?
 
I don't forge bur maumasi has a great series on a forged to final shape on YT.

You could also do bulk removal with an angle grinder and then come in with a file to flaten everything. Some kind of plunge guide/stop would help you to not overshoot the plunges. Even mild steel is better then nothing.

There is even a simple grinding jig with an angle grinder on YT.
 
There is no one "best" belt sander out there. You have to look at your budget and what you want to do and look at your options. I had a 1x30 and it sucked. Low powered, short belt life, bouncy platen, narrow belt etc. Some use a 6x48 for full flat grinds; they often have a 1HP motor and a wider belt which helps keep your bevel flat. The problem is due to the belt width, it is easier to bog down with pressure due to the larger contact area. 4x36 are usually under powered all around. 2x42 or 2x48 are another option, but may often suffer from the same 1x30 issues. Rule of thumb is 1 HP of motor per inch of belt width.

Some go with a Grizzly Knifemakers 2x72, which is a very fast moving grinder and one speed. Do up a nicer platen and it will work well for hollow, flat and slack belt grinding and you can wrap sanding belts around the left side arm to use as a small wheel assembly for smaller diameter grinding. The fast speeds means it will be easy to over heat steel after heat treating with finer belts, but it is doable (just more hand sanding or doing a belt satin finish on stuff). The platen and tracking adjustments are the weak points of the Grizzly other than the single fast speed.

Others go with a inexpensive grinder like an OBM and run step pulleys to get different speeds. Most go with a 2x72 with a VFD and 3 phase motor to get a variable speed setup, which is much more versatile. Still others use a filing jig like above. If you are on a budget, you are probably better off going with a filing setup (mistakes will be made slower and easier to correct) and see if you want to invest more in equipment.
 
If you want to speed up your process quickly and don't mind taking time to "modify" some things then you could do this. Acquire a 1x30 belt sander and reinforce the crappy platen that it comes with and add a ceramic glass platen to it. Then I would head on over to Combat Abrasives and buy some CERAMIC belts that they sell for a 1x30. I would get 36,80, and 120 grit for a good start and just work with that until you realize that you are ready for something better.

I am not saying that the 1x30 is going to work amazing with this set up, but it will definitely be better if you were just using AO belts without a stable flat grinding surface. For the hobbyist maker like yourself that is doing a couple of blades per month (I assume) you should be able to run with this for a little while. Make sure that you are also using SHARP belts. You are going to have a hell of a time (trust me I have learned) if you try to cheap out on yourself and use the same dull belt for several blades.

Also whether you are going the 1x30 route or you continue to file in your bevels, I highly recommend that you do this if you are doing plunge lines on your blades. It will set you up for your grind and it made things a lot easier for me when I first started when I was using files to do my bevels. Its kinda like a handicap for putting in your bevels. ;)

 
You can do ffg with a bench grinder and files. Use the grinder to grind a series of grooves along the blade. They should be deeper at the edge and shallower towards the back of the blade. Then use the file to flatten the ridges to a ffg. You will need to get pretty good at draw filing. Good luck!

Kevin
 
Draw filing is a bit different than the regular filing motion you are probably familiar with (up and to the right). Basically instead of standing at the edge of the knife where the blade is at your right to left (or left to right), you stand at the tip. You hold the file with both hands and you pull the file toward you. If you pull toward you, you want the tang of the file in your left hand, and the tip of the file in the right hand. If you push the file, hold the tang in the right hand and tip in the left hand. I think you could probably find a video that gives a visual reference for you. It is very aggressive and will help the grind to be fairly flat. If you really want to hog the steel off when using draw filing, don't use the full face of the file, but rather lift that frond edge just a tad so that the pressure is concentrated towards the back edge of the file. A 14" Pferd chipbreaker is a mean beast and will remove steel big time!
 
Just be careful when draw filing, especially when your edge thins out. since you are pulling and pressing down with a fair amount or pressure it is very easy to slice your fingers open:eek:. No seriously, be careful when doing this. Better yet put a piece of scrap 2x4 underneath the blade and make sure that the knife is situated so that it sits ON the 2x4 so that not edges nor the tip is exposed so you don't accidentally stab yourself. Also do this when you are handsanding the blade. I cut my fingers pretty bad once not doing this method and I ALWAYS make sure I have something to keep the edge away from my fingers.

I don't understand why people just clamp blades to the table and just sand/file away with a thin edge next to their fingers. Literally it costs you nothing to potentially save you from a pretty bad accident.
 
You must log in or register to reply here.
Back
Top