belt sander - which grits for sharpening?

[James Scheffler]

I recently was the lucky recipient of a free old belt sander, which takes 1"x42" belts. I plan to use it exclusively for sharpening, and I need to decide on an initial set of grits to buy.

Probably I will use the sander for rough shaping and/or grinding out nicks prior to switching to waterstones and/or sandpaper stuck to glass (depending on whatever the particular tool needs). Although, I'm also curious to hear about sharpening plane irons or chisels entirely with a belt sander. I also plan to sharpen kitchen knives, a drawknife, and some other miscellaneous tools.

I was hoping to avoid buying a gazillion different grits. I've understand you can skip some grits with a power sharpening system, but I'm not sure which ones. Should I consider buying a leather belt to use with green compound?

Thanks,
Jim S.

[Brian Kent]

I may be wrong, but I think a high quality 80 grit would be right. High quality for the seam that doesn't have a bump and high quality for having even grit. With a light touch the belt sander forms the blade angle (flat or hollow) and then you hone on a couple of stones.

[Dale Sautter]

Congrats, you're going to enjoy it! Sounds like you have your strategy right... use the belt(s) for rough shaping/grinding, then on to honing. If you want a belt that lasts a pretty long time, stay cooler but costs a bit more... look into getting a Norton Blaze belt, here's one source:

http://www.trugrit.com/belts-manufacturer-norton.htm

scroll down to:
001x42:142-060-980 1x42-60 R980 Blaze Ceramic $5.35

You can polish/smooth with your belt grinder too, check into a Trizact belt for that:

http://www.supergrit.com/products/products_belts-misc.asp#trizact

One thing to keep in mind though... belt speed. If it's possible for you to slow down the speed a bit as you go finer in grit size, it'll help you keep from burning whatever it is that you're sharpening. A longer belt will also help keep things cooler/last longer... but you have a 1x42, so make the best of it with a light touch and hopefully a good tool rest or even maybe something like the Veritas tool rest or the Tormek bench mount kit.

[Mike Davis NC]

Dale saved me a bunch of typing. I've been buying belts from trugrit.com for a few years and they are the best.

Another helpful hint I discovered. Go to the tile store and get a small ceramic tile to put between the belt and the vertical support. It gives you a nice smooth surface that doesn't over heat as much and raises the belt a little to get a flatter face.

[tico vogt]

Mike, what size tile do you use?

[Dale Sautter]

Another pretty good option: Ceramic Glass Liner for flat platen (http://www.usaknifemaker.com/ceramic-glass-liner-for-flat-platen-2x9x-0192-p-1181.html), usage instructions on that page. You should be able to find Pyroceram (fireplace insert glass) at your local glass shop or fireplace shop and have it cut to size. Side warning though... static electricity generation, but it's easy to hook up a grounding wire/strap/whatever to a direct ground to avoid that nuisence.

[Mike Davis NC]

Mike, what size tile do you use?

On my 1 x 30 I use a 2 x 2 and on the 2 x 72 I use a 4 x 4. Just double sided carpet tape to hold it in place. I tried smaller ones but the belt kept running off.

[Bruce Haugen]

80 grit is probably fine for shaping a bevel, but it doesn't come anywhere near to the grit you need for honing. Knife makers use grits up to 600 and higher for final polishing of a bevel, but then we're talking about presentation quality.

If you're just talking about setting the bevel, 80 will be fine, or even a little coarser. Use one of the blue belts. Occasionally Klingspor has a free shipping sale.

One word of caution, for the love of all things holy DO NOT grind steel and aluminum on the same grinder for any reason under the sun. That creates a combination called thermite, and it will burn so fast and hot you simply won't believe it. I still remember our USMC troop leaders in infantry training demonstrating thermite grenades to burn the hull of a tank. You will find it useful to place a little flat container of water at the bottom of the grinder to catch and extinguish the sparks as they come off the belt. And be sure to clear out your wood grinding dust first, DAMHIKT.

[george wilson]

I have a dedicated vacuum for my belt grinder,and never sand wood on it. Have other belt sanders for that. Good tip about the thermite. I doubt anything could quickly put it out!!! They used to weld railroad tracks together in situ with a box the put over the joint,then filled with thermite. After the stuff stopped burning,they took off the box and hammered the joint smooth.

[Bruce Haugen]

What kind of belt grinder do you have, George? Mine is a home-built affair, 1 X 42, that is good for wood, but just barely adequate for metal (however, it does a spectacular job of sharpening lawn mower blades). I lust after something like a Bader or Burr King, but the old problem of champagne taste and beer budget comes into play. Even good contact wheels can cost a small fortune.

[Mike Davis NC]

The 3-M Trizact/Gator belts are available up to 2000 grit. I use 600 on my belt grinder. Like George, I keep separate sanders for wood or metal.

[James Scheffler]

This is a lot of good information to think about. Another question - do you run your sanders with the belt travel going up or down, or does it depend on what you're doing? (Or if horizontal, going toward or away from you?) My sander has a reversible motor, but I would need to rewire it to change direction. Not something I'll want to do very often.

[steven c newman]

I've got a 3x21" "Dragster" beltsander. It has an adjustable "D" handle on top. I clamp that D into the vise, and lock the trigger in the "On" setting. I run it so that the belt will run away from me. I use a "honing guide" from Veritas, to guide the blades along on the belt. I keep at least one finger ON the steel, sometimes both if the blade is wide enough. Why a finger on the steel? Heat. If the blade gets to hot for my finger, I just lift the whole thing off the belt. Temperture control at it's finest. Once I have the edge where I want, i goover to the stones, without taking the honing guide off. Works.

[Mike Holbrook]

I did my research for belts for my belt sander quite a while ago but as I recall there are belts designed for wood (Aluminum Oxide), wood & metal (Zirconia Belts) & others that are better at metal (Ceramic Belts) and other specialties too... There is a very large selection at the stores that cater to the knife making crowd. Supergrit, Tru Grit Inc. (has very helpful descriptions of each belt by Manufacturer), ECON Abrasives... I have several different sizes of several different types of belts.

[Dale Sautter]

do you run your sanders with the belt travel going up or down?

Down with the iron/chisel edge facing up... keeps the tip cooler. Good point/practice from Steven Newman... if it's too hot to touch, you don't want to keep at. Better to dip/cool the metal before proceeding.

[jamie shard]

Just a quick note, since I didn't see anyone else saying it... I find that belts are great for knife sharpening and touching up chisels, but for plane blades it is very difficult to create a flat bevel (or gently cambered bevel) with a narrow belt. Although I bought the leather honing belt from Lee Valley... I almost prefer some of the very fine grit belts for most touch-ups.

[Mike Holbrook]

The leather belts I have are not even in terms of their width. There are multiple places on each belt that are between say 1/8 to 3/16" different than the rest of the belt, very easy to see even at a quick glance. I wonder if others who have bought leather belts have had the same experience or if I just got some bad ones?

I also wonder if anyone knows whether or not the buffing compounds can be reformed? I have a green and a white/pink compound. A good size rat got into my shop through the garage above and apparently thought the green compound looked appetizing. It ate big chunks out of the block over most of it's surface. I know it ate it because it also left lots of quite firm little green pellets in the cabinet where the compound is. Now my green buffing compound looks like an off color baby swiss. Understand, I'm not planing to reuse the compound the rat ate, although it's current shape might suggest that it is malleable in a warm/hot condition. I was just wondering if applying heat to the compound would enable me to mold what remains into an easier to apply shape?

[Dale Sautter]

but for plane blades it is very difficult to create a flat bevel (or gently cambered bevel) with a narrow belt.

Jamie, pardon the poor SketchUp pic but I've had pretty good results with something made in the shop:

http://i53.tinypic.com/okyceg.jpg

Angle your tool rest to the angle you want then rotate the top board back and forth till you're there.