Here's something I've been meaning to post for awhile, and this thread seems like a good place to put it.
It's been sitting on my computer for some time now, but when my brother recently wanted to learn to sharpen on the HF 1x30", I finished compiling it all (mostly). It wasn't meant to be so much of a "how-to" on belt grinder sharpening (there are plenty of good, thorough write-ups on that already; I recommend the one by Jerry Hossom, titled "Sharpening My Way", posted on some other forum, but you'll have to Google that on your own), but I wound up adding a section at the end describing how to do this anyway. I hope it helps!
For belts, I like to go to
TruGrit. IMO, they have more stuff under one roof than anywhere else I've found, and their customer service is great.
Here is the link for all of their 1x30" belts.
For starters, I'd recommend at least 2 of the "Surgi-Sharp" leather stropping belts (Item #LTHR130-LEATHER, $16.50 each). Once you use a particular polishing compound (or diamond paste) on one of the leather belts, that's all you should EVER use on that particular belt!
For really rough work (spine re-profiling, etc.), I recommend a ceramic belt because they don't heat the steel up nearly as much during cutting. I like the Norton Blaze in a low grit (Item #BNRT130-0060-980, $3.40 each; Trugrit only has down to 60 grit, but I wish they had 20 or 30). Get a couple. That's all you'll really need unless you plan to start making knives.
Most of my edge sharpening work is done with the 3M Trizact "Gator" belts. If I haven't sharpened a knife before, I typically start with the 240 grit (Item #BL3M130-0240-A65CF, $3.65 each) to establish the edge profile (convex or flat), and once it looks/feels good I move on to a finer 600 grit belt (Item #BL3M130-0600-A30CF, $3.65 each). I'd recommend getting 2 or 3 of each of these, which should be enough to get you by for several years of casual sharpening at home for your family and friends.
For my final pass, I use a Norton Norax belt in 1,200 grit (Item #BNRT130-1200-X16U254, $3.10 each). These belts are softer than the Trizact Gator belts, and they seem to wear out a lot faster, so I'd recommend getting 2 of these for each set of the Trizact Gators.
There is now a ceramic version of the Norax belts that I want to try (Item #BRNT130-1200-X16U936, $4.00 each). Being ceramic instead of Aluminum Oxide, and having a heavier-weight backing, it should last longer and work better than the regular Norax belts, but I don't know for sure yet having not used it before (though that will change very soon).
A person could also get the 3,000 grit Norax belts too (Item #BNRT130-3000-X5U254, $3.20 each), if they wanted to get a really, really mirror-polished edge. Personally, I think the 1,200 grit is plenty before going to the leather strop, but that's just my opinion.
Now, for the newer 3M diamond micro-finishing film belts. These are especially useful for some of the more modern "super steels" with high carbide content (especially Vanadium carbides) like S110V, etc. And boy, these belts are expensive!
I think a good grit progression (similar to above) would be the 45 micron, 30 micron, 20 micron, and then the 9 micron. Unfortunately, that's about $60 in belts!!! It's up to the individual, but I'm not personally spending that much! I opted for the 30 micron and the 9 micron (Item #BL3M130-0030-675, $14.00 each; and Item #BL3M130-0009-675, $17.05 each), and just start off with the Trizact 240.
Finally, a person should get some polishing compound for the leather belts. I use the green Chrome compound (Item #KNBCGREEN, $9.75 per block), which I think is sufficient. You get a HUGE block for that $10! More than you'll probably ever need. I've considered getting some finer compound, but I don't think it's really needed. Diamond micron paste could also be used here, but again, being diamond it can get really expensive.
There are also Scotch-Brite belts available. These are good for doing a satin finish, or nicely blended convex zero-edges. However, they won't work on the HF 1x30 without modifying the sander a bit because they're a little small and they're so thick. I wouldn't recommend bothering with them until you've gotten a bit of practice in on the sander, but they're worth mentioning. The HF 1x30 requires a bit of modification and removal of the safety guards in order to use them.
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Here is a pretty decent .pdf version of a grit to micron conversion chart that might come in handy. Save it and print it.
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Without being so wordy, here is my typical 4 stages to sharpen a knife I've never sharpened before:
- 1.) 3M Trizact Gator 240 grit
- 2.) 3M Trizact Gator 600 grit
- 3.) Norton Norax Aluminum Oxide 1,200 grit
- 4.) Green Chrome compound on leather belt
If I have sharpened a knife on the belt sander before, rarely do I have to ever go back to the 240 grit Trizact. Usually it only needs the 1,200 Norax at worst, and a lot of the time I only need to strop with green compound on the leather to bring back a hair-poppin' edge.
:thumbup:
Of special note, before we go any further, take care NOT to ever let the blade even get warm while sharpening! I like to keep it
COLD! Check the edge after every pass and be sure it isn't warm to the touch. This is extremely important, as you could harm the heat treatment of the steel if you're not careful!!! I keep a bucket of some cold water and a towel nearby to keep the blade cool while sharpening (I cut the top off of a plastic 1-gallon milk carton and fill that with cold water). I don't have too much trouble with this when my garage is 30 degrees and below in the Winter, but when it's 90 degrees and more in the Summer it becomes quite important.
To begin, I like to eyeball the edge angle before turning the grinder on. This gives me an idea of what the factory edge was set to, and I can decide if I want to thin it out or go thicker. A protractor or edge guide can help here, but after some time, you'll get a pretty good feel for the angle just by looking at it and the gap between the knife spine and the belt (of course this also is a function of blade height too). Something to remember with a convex edge is that the edge itself is at a bit steeper of an angle than the blade is as laid against the belt due to the "wrap-around" inherent in a convex edge. If your belts are flexing the proper amount, it shouldn't be any more than about 5º-7º more (inclusive) than a flat grind would be.
When sharpening, move the edge at a constant rate across the belt as you go, and
don't go too slow! Unfortunately, the little 3,400 RPM HF 1x30 moves that 1" belt pretty darned fast, at about 40,000 - 42,000 inches per minute (~700 inches per second, which is ~60 feet per second or ~40 miles per hour
), so it can heat up the edge pretty quickly if you aren't careful.
Do NOT ever stop in one spot!!! A good rate to move the knife edge is at about 1" per second, or maybe just a touch faster. Just keep it moving steadily. Also, don't push too hard against the belt. Let the belt do the work for you; light, consistent pressure is key here, and will help to prevent removing steel at too rapid of a rate and heating the edge too much.
When you get near the tip of a knife, lift the handle and rotate the knife along the radius of the belly, carefully keeping the same edge angle. It is important to keep the edge of the blade perpendicular to the belt as much as possible where the cutting action on the belt is taking place, at all points along the edge as you move, otherwise you will not maintain the same edge angle. Unfortunately, it is pretty easy to screw this up near the tip of a knife, especially with larger knives with big bellies, and either fatten or flatten out the edge here. This just takes practice to master. Also, do NOT drag the tip of the knife all the way across the belt. This will result in rounded tips, which you do not want! Instead, when the tip reaches the halfway point (at most) while moving across the belt, pull the knife toward you and straight away from the belt. This will yield nice pointy, sharp tips.
Finally, it is much better to make two smaller passes than one heavy pass. Usually you only need multiple passes with the first, coarsest belt, and even then it's usually only the very first time you sharpen a particular knife.
I know that's a HUGE post, but I hope that the information is useful to folks. It's been a work in progress for well over a year now, and I think it's a decent write-up. Take care! :thumbup:
PS - Here's a condensed list of what I'd recommend, at minimum, to get started, for ease of printing/writing a list:
- 2 x #BNRT130-0060-980, $3.40 each (Blaze 60)
- 3 x #BL3M130-0240-A65CF, $3.65 each (Trizact 240)
- 3 x #BL3M130-0600-A30CF, $3.65 each (Trizact 600)
- 6 x #BNRT130-1200-X16U254, $3.10 each (Norax 1,200)
- 2 x #LTHR130-LEATHER, $16.50 each (Leather)
- 1 x #KNBCGREEN, $9.75 per block (Compound)
SUBTOTAL: $90.05
Optional:
- ? x #BNRT130-3000-X5U254, $3.20 each (Norax 3,000)
- ? x #BRNT130-1200-X16U936, $4.00 each (Norax 1,200 CERAMIC)
(If you get some of the above ceramic belts, might cut down the number of regular Norax 1,200 belts)
- ? x #BL3M130-0045-675, $14.25 each (45 Micron diamond)
- ? x #BL3M130-0030-675, $14.00 each (30 Micron diamond)
- ? x #BL3M130-0020-675, $12.95 each (20 Micron diamond)
- ? x #BL3M130-0009-675, $17.05 each (9 Micron diamond)
:thumbup:
Oh well. 
