Powered thinning on knives and hardened blanks

[weeeeeeum]

I'm very familiar with coarse and super coarse stones but when it comes to some of the knives I work on and blanks I want to work on they don't nearly cut it. I also have a horizontal wet wheel grinder which will be very helpful but still won't be enough for blanks and still slow for particularly troublesome knives. At this point I know it's pretty much only going to be belt sanders but would also like to consider any other options.

As for the belt sander, what kind and what specs? What length/width of belt, what configuration (I would like a sanding face parallel to the bench), what grit etc.

I would also like to hear the experience of others who have worked on hardened blanks/turbo thick knives as well as any tips I should know.

Much appreciation in advance.

[taz575]

Variable Speed 2x72 belt sander is what most knifemakers use, usually with a 2-3 HP motor. You can also use a pulley system to get different speeds, or go with a single speed machine (like the Grizzly Knifemaker), but you are more limited for belts because if you get too fine of a belt with too fast of a motor, you can mess up your steel by burning it. Variable speed 2x72 are around $1500, but there are some kits you can do if you can have it welded locally and then get a cheap VFD and mount the VFD box into another box to protect it from dust and be around $1000-$1200. 2HP, 240V, 3 phase motors are around $275 or so and you need the 3 phase to use a VFD, but you may be able to find one used for less. They make VFD's that step up 110V to 240 V to use a VFD and there is a Chinese version for around $130 instead of paying $400+ for a KBAC sealed VFD. You could do pulley setups, but it will introduce more vibration when you go to a different pulley to change speeds, but you can use a regular 110V motor with those, too. You would need a pulley for the motor and one for the grinding, axle, pillow bearings, etc and have it mounted perfectly, so it's often more of a PITA to deal with pulleys. Most belt sanders are set up to have the face of the motor the mounting point, so it's basically screw the motor to the machine, mount the drive wheel and you are all set.

Grizzly came out with a 2x42 recently that uses a 110V DC motor and is controllable speed wise. A few tweaks are needed to really use it for knife making and some of the motors have blown up with less than an hour of use, so it's not reliable at this time. I am not sure if you can adapt a different motor to it, like using a 240V and a different VFD? AmeriBrade had a variable speed disc grinder and a 2 x 48, but they are almost as expensive as the 2x72.

[Jeff B]

Unless you have a building wired for commercial use you are not going to have access to 3 phase electricity.

[taz575]

The VFD converts 110V or 240V single phase to 3 phase for you. Sorry, should have mentioned that!