Disc Grinder Descision

T

thegeek574

Joined
Sep 3, 2010
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2,460
Everyone,
I have decided it is time to go with a disc grinder, and so, while doing my research, I came across a couple different places where people disagreed on issues I would like to get a consensus on. Now, here are a couple parameters.
I will be using this for everything from flattening bevels to truing up flats, and so it needs to be generally all purpose. I have access to what is essentially a machine shop, and so modification isn't really a problem. Now, here is where I am having trouble deciding.

Should I go with steel or aluminum? I hear that steel is stronger and won't mar as easily, but I am prepared to take full precautions on a aluminum disc if it has other advantages.
Also, should I go for flat or 1 degree bevel? I think both would work, with beveled having an advantage for flat grinds and flat having an advantage for mating surfaces. Which do you prefer for all around? I'm prepared to accept imperfection.

As always, price is huge. Mainly, lower is better. I have a total budget of about 100 for the project (free motor- thanks Brian!), though slightly higher is totally acceptable.

Thanks all,
Steven
 
You probably want the aluminum 9" beaumont unless you know where you can get a steel disc for $80. If you find the steel one, let me know.
 
You can get the steel disc for about $115 shipped from K & G (knife and gun finishing supplies). I was told by those more experienced than myself that the aluminum is easier to get dinged up on the edge and after a while you may find it difficult to keep your plunges crisp. Made sense to me.
 
I have a couple of the Rod Nielsen disc systems. It is an aluminum hub with magnets that you can change discs with. I use flats and 1 deg bevelled discs for larger blades. I also have a few discs of each so that I don't have to tear off a sheet of sandpaper that isn't worn out when I want to go to different grit. I can just change discs with proper grit already on it. It costs more initially but I believe it has paid for itself in savings of sandpaper. It is also very fast to change plates on this system which saves time. I am very happy I spent the money up front.
I would wait and save for this if you are intent on buying a disc grinder setup.
Jim
 
Steven,

I have used both steel and aluminum discs. I prefer the steel disc for a few reasons. One as mentioned it is much tougher. Two the kinetic energy developed by the disc actually helps keep things going smoothly. Steel is magnetic and you can make a sheet magnet pad system to change out for some finishing processes and even sharpening.
I have only used a flat disc. I do not have any problems even with larger knives. I have ground a blade over 24 inches long on the flat disc. Yes you do get a bit of throwback from the upward side of the disc but I have managed to live with it for over 20 years now. I have never used a 1deg beveled disc since I have developed my ability to grind on the flat disc easily. Also even with a one degree bevel you are actually grinding on a cone. There will be a very slight concave grind to anything you put on the face of the disc. Even though it is slight, it is there and not truly flat. It can be cleaned up easily on a lapping plate or a sheet of sandpaper glued to a surface plate or similar flat object. If you have a machine shop available to you you could turn your own disc. It just takes time and a chunk of steel. You will need a large enough lathe though. A 12-13" swing would be adequate. We can even swing by the scrap yard while you are here and see what they have in the way of drops.

Looking forward to your visit Friday. We can discuss the disc issue a bit more then also. You can also try both of mine while you are here.
 
In a perfect world steel at 1°.

In the real world - whatever fits your budget at 1°.

If you make mainly folders, flat is fine. Longer blades need the 1°.

Almost as important as the disc is the paper. Use good grade paper and you get better results.

If at all possible, you want the motor reversible. Variable speed is a plus, but reversible is almost a necessity.
 
I have used an 8" aluminum disc and now have a Nielsen 9" disc with both flat and 1-deg taper steel discs. I definitely recommend steel over aluminum... (my old aluminum disc is fairly dinged up). I also prefer the flat discs for nearly every situation. I have no problems grinding longer blades on the flat discs and really like a flat-flat. As Chuck mentioned, a 1-deg beveled disc is still a cone. Most folks would say it is so insignificant an angle as to be practically unnoticeable... which is probably true; however, for the way I use my disc grinder, there seems to be little benefit from the taper. It's flat steel discs for me. ;)
Erin
 
A C Richards said:
Steven,

I have used both steel and aluminum discs. I prefer the steel disc for a few reasons. One as mentioned it is much tougher. Two the kinetic energy developed by the disc actually helps keep things going smoothly. Steel is magnetic and you can make a sheet magnet pad system to change out for some finishing processes and even sharpening.
I have only used a flat disc. I do not have any problems even with larger knives. I have ground a blade over 24 inches long on the flat disc. Yes you do get a bit of throwback from the upward side of the disc but I have managed to live with it for over 20 years now. I have never used a 1deg beveled disc since I have developed my ability to grind on the flat disc easily. Also even with a one degree bevel you are actually grinding on a cone. There will be a very slight concave grind to anything you put on the face of the disc. Even though it is slight, it is there and not truly flat. It can be cleaned up easily on a lapping plate or a sheet of sandpaper glued to a surface plate or similar flat object. If you have a machine shop available to you you could turn your own disc. It just takes time and a chunk of steel. You will need a large enough lathe though. A 12-13" swing would be adequate. We can even swing by the scrap yard while you are here and see what they have in the way of drops.

Looking forward to your visit Friday. We can discuss the disc issue a bit more then also. You can also try both of mine while you are here.
Click to expand...


You nailed it Chuck:thumbup:

Where guys have trouble with the longer blades on the flat disc is applying pressure on the upward spinning side. I hold the tang/ ricasso area in one hand and adjust the other so that I'm only applying pressure on the downward spinning side of the disc. When your hand that's holding the blade moves close to or past center is where you run into trouble. I'm constantly moving the blade hand and adjusting.
 
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