Disc grinders

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Rookie7

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Feb 17, 2006
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I talked with a professional knifemaker in my area, and he advocates using a disc grinder for some of the rough grind. And he suggested that a good disc grinder should be reversible. I'd like some feedback on both the utility of disc grinders (I've been solely using a 2x72 belt grinder so far), and whether it needs to be reversible. Thanks in advance.

Phil Millam
 
Rookie7 said:
I talked with a professional knifemaker in my area, and he advocates using a disc grinder for some of the rough grind. And he suggested that a good disc grinder should be reversible. I'd like some feedback on both the utility of disc grinders (I've been solely using a 2x72 belt grinder so far), and whether it needs to be reversible. Thanks in advance.

Phil Millam
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Reversible is a desireable feature because you can move the blade to the other side of the disc to grind the oposite side of the blade and you can orient the blade the same way and the grinder won't throw sparks and debris in the air.

A large disc grinder is a plus if you flat grind because it allows you to make your bevels flatter. You can hog off material on the belt and true up on the disc.
 
9-inch variable-speed disc (steel) sander from Rob Frink of Beaumontmetalworks.com. Expensive, but worth every single penny.
 
Definitely reversable and definitely variable speed to maximize flexibility.
You seldom if ever need to run at full speed and will find 90 degree grinds on the ends of handle material, etc. are pretty handily done on a disc grinder with table....but a full speed grinder can easily cause heat and burnthe handle material....also very slow is ideal to finish fit the handles to integral double bolsters on slipjoints. I hope you never find that running a disc with a table, if you get your finger caught, can be disasterous.....
A.T. Barr flat grinds his blades on a disc and noone can argue with the fine quality of his grind lines....
 
I have a variable speed reversible 9" disc. I doubt it would be nearly useful without reverse
and variable speed. Also floor switch is absolutely necessary.
 
9 inch disc is handy for several reasons. You can get a great flat grind as mentioned previously. It saves space, the disc is more compact than a 2x72 belt. Variable speed is great but not absolutely necessary. I used a 1750rpm for years befor I got a VS unit. REverse however is highly recommended. I have heard of at least one maker that uses a non reversable unit but I find it a must. I only have disc grinders and do not have any plans to buy a belt ATT. The biggest advantaage I found is if you run out of paper you can run down to the hardware store and buy enough to get you through until you can re order. I learned on a disc so it is what I use. If you start on a belt then you will probably like it better. It all depends on what you can afford and how much room you have.

Good luck
Chuck
 
I've got the 9 inch VS reversible from Rob Frink of Beaumontmetalworks.com and absolutely love it. I use it for truing the flats, bevels and tapers on everything....tang, blade, guards and especially the ricasso. Not only did it make knife life a little faster and easier but also more precise.
 
Padrig said:
I have seen vertical units and horizontal ones. Any reasons for choosing one or the other?

Pad
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Yes, a vertical unit grabs the workpiece and throws it down into the ground. The horizontal unit grabs the piece and throws it about waist level into whatever, or whoever's in front of the workpiece, anywhere across the shop in it's path/trajectory.

I can see great uses for a horizontal belt grinder with workrest, but for the life of me could never see any advantage of a horizontal disk grinder over a vertical one.:confused:
 
I could see an advantage of a horiz grinder but with low speed. I have seen them used as a type of blanchard grinder if they are large enough and absolutely flat. Other than this I canoot see an advantage either. Some who use them say they can grind both bevels without having to reverse the disc. But as Mike pointed out if you lose control it could be devistating. though even the verticle discs, or any power tool, can be dangerous if you are not careful.

Chuck
 
I have horizontal and vertical and use both. I can also grind both bevels without reversing but it is much harder.

A person can get along with one grinder....it just makes life much easier to have a lot of grinders.
If you just want to try your hand at a disk grinder to see if you like it, go to Woodcraft and buy a 9" disk. They are about $15.00 as I recall.

Mount it on a fairly heavy motor and grind away. If you like it, make a DC version using a heavy duty DC motor. Make it reversible and Variable speed.

If you still like it.....buy one of Rob's.
 
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