Thread: Knife sharpening with machine-driven belts

I'm a fan as well. I use a copy of a KMG belt grinder. I mostly use it as a slack belt grinder as I prefer convex edges on knives but I use the flat for most other tools. To be honest, even after years of sharpening I'm not all that great at putting skandi grind on knives using the flat platen. Maybe I never put the effort into it as yet. Top results with the convex edge though.

I did watch a YouTube video of a guy making belts for these little grinders out of W&D sandpaper. Bunnings sell the W&D on rolls if you wanted to give it a shot. Just check if they are perforated every meter though. I think he backed the belts in fiberglass carpet tape... I think...

I'm not keen on W&D. Doesn't last that long.

Taking a closer look at the Lee Valley offerings, the grinding belts sound very much like 3M microfinishing abrasives.

They're exxy but they last.

I'll be ordering some soon. If anyone wants to join in and share postage let me know.

I agree with W&D not lasting long. It's a good place to get your feet wet though. For sharpening 90% of the use on my grinder is the 36grit zirc belts. The rest is just a few swipes then to a finer belt.

Yeah I had a range of belts made up for mine (1" x 30") in Zirc and Trizact. When it came to finding someone to do some more I drew a blank.

Just out of interest I sharpened the Japanese petty knife to #6000 on a ceramic whetstone and used it for a bit. Then ran it on the slack section of a 9 micron belt. No diff on the fingernail test.

Just had a play with the leather honing belt from Lee Valley that I got in some time ago with Veritas green crayon.

Wow.

2 out of 3 thoroughbred Japanese knives showed significant improvement*. The 3rd showed little - but I have geometry probs with that one.

One of them had a fine line of corrosion (the Watanabe gyuto) up from the edge that this rig took out easy peasy. Had got some Jiff in for that.

Knives were presented edge down on the platen in this case. Edge up on the slack section in cases mentioned above.

(Skanki grind was new to me Ben Dono as a label. Types of knife grind was interesting to read up on.)

...

* cp last sharpening on a #6000 stone

(Some edits made for clarity).

That's good to know you did not find much of a difference! I have always found convex edges to perform much better in choppers. If it's a small knife used for slicing like a chef or pocket knife, I grind to a thin edge convex then I put a slightly bigger secondary bevel on them with flat stones.

What is 'sharp' bugged me for years. Everything I sharpened was to a power stropped finish. Now I'm a bit more comfortable stopping at a level that's appropriate for the tool.

A lot of bushcraft knife sites really go for the skandi edges. I get it but have never tried one out. It looked like a whole lot of steel to be working on each time you want to touch up the knife. I might pick one up soon and give it a go.

I really love power stropping! I really enjoy sharpening and can hand strop, but I can powerstrop in 30seconds what I can achieve in 20mins by hand. I save the hand strops for the work bench now for a quick lick while I work.

The green if great. The light blue is finer and the white( tandy leather brand) is the finest for carbon steels. Your starting to split hairs with them though. The green is pretty darn good. And it's the one I leave set up for just about everything.
The leather belt strops get better with age. If your getting good results with them just use the compound. You can add greasing agents to some belts where belt stretch is not an issue like neats foot oil, paraffin or bees wax. That softens the belt and unfortunately lengthens it at the same time. It depends on your setup. The grease in the crayons will end up getting there in the end, it just takes a bit longer.

I use laminated cork floor tiles made into 300x50 buffing wheels. I build a variable speed buffing grinder from an old bandsaw. Love the cork wheels for power stropping. They take a while to break in but they end up as smooth as MDF but with a little give.

Honing compound on leather is new to me.

These 3 knives are for slicing only. Hard and brittle but with care keep their edges for months.

Chopping knives get different treatment.

Thanks for the tips. Yes, the belt is drier than I'd expected but it works.

The steels in this case were IIRC 60+ HRC.

Rig pic attached.Mech honing.jpg

Well I had try #2 with a fine edge on the honing belt and boompf, in the blink of an eyelid or less it sliced right through it. Clearly the edge presented in leading mode was too obtuse

Next time I'll try trailing presentation.

There's an order in for a bunch more belts from LV. Thanks FenceFurniture.

Whoops! I have nicked them a few times being careless. Was it a neat cut? Im guessing but it might have been a nicely pre skived join. Have a go at splicing it back together with a canvas backing so you don't shrink the length. It will give you a bit of practice with it and if it does not work out you would have learnt a good appreciation of them!

Sounds like very good advice BD.

It was a nice clean cut. The evidence was binned some time ago so I can't do a post mortem.

A replacement will come with FF's bulk LV order.

This is not a biggie for me. Just part of the exploration of possibilities. It won't be part of my std procedure. My JP knives are for slicing so micro-serrations are desirable.

That leads me into the territory of natural stones at higher grits and I'd rather not go there. Damned expensive.

Hahaha, your too kind! I don't know if I would put it in the "good" advice bin...but it was a long shot at a suggestion.

I have thought at times if I should try stropping in reverse...if I was being extremely gentle, maybe it would work? Thanks for posting it up though.... I think you saved me from doing the same thing. I'm sticking with stropping in the tried and true direction.

Have you done any reading on the dangers of power buffing and stropping? The standard bench grinder speed buffers are very usable, but can fling a sharp tool pretty quickly.
For the first few months I used a bench grinder with buffing mops attached, I flung every odd shapped thing well across the room or down at my foot......I got a bit better now..
I now buff at much slower speeds and I'm very mindful of what I am doing.
If your stropping a knife in reverse, I could see that it would be easy to loose control of the sharp tool if it grabbed a belt and not cut all the way through... Just a thought. I took a chunk out of one of my stropping wheels last month when I had the buffer running in reverse. Yeah.... It was one of those mindful moments I was just talking about.... It flicked the knife in my direction. I'm glad it was only a little flick.

I'm thinking I should post every little accident I have on this forum! It might help some fellow Aussies a save a bit of bark.

post #1. I consistently cut up my fingers when I sharpen up the chainsaws! Oily chains and sharp bits = me always dropping a bit of claret on the floor. That are nasty bloody cuts as well! The last one was a winner. I was scrubbing all the pitch off the chains with a wire brush. I skipped off the chain and dragged 2 fingers on the right across the chain. Because I was committed ( I'm thorough like that) I followed through with the tops of the next 2 fingers on my left!

BD, I enjoy reading your posts. Thanks.

My gig is woodturning so bench grinders are, er, grist to the mill. That said, I haven't played around with a hard felt wheel on one nor a mop (but have been tempted to try).

This territory is new to me. Normally with the good Jap knives ceramic whetstones are more than enough for my uses. Turning tools are mostly used in hacking mode and otherwise can be touched up manually with a diamond hone.

Chain saws I agree can be a beech. Have used a clamp-on guide (like to keep the claret in the glass too) and more recently an Oregon-knock-off electric grinder after the local mower place detempered a perfectly good chain, sod em. I should've looked at the thing before handing over the money; but they'd been good 'til then.

All up, I'm hooked on sharpening and have shed many a red blood cell in service of this obsession

Haha cheers mate!
I think I have posted this a few times before but I have learnt a lot from people sharing how not to do things!

My local Stihl shop sharpens chains for $10 on the spot if your there first thing in the morning so I have been putting off buying a knockoff grinder like you have. I take them in when I have chipped them too badly or 'lost my way' with hand filing.
It's a shame they burnt the cutters. Good chains are not cheap! How did the burnt chain perform?

I just made a mental note to clean the chains before I take them in and check them when I get them back.

What are your thoughts on the cheap chain grinder? I was thinking about getting one and beefing it up a bit to make it a bit more accurate. Are they worth the effort?

My guy was charging $12.50 and with two chains I was doing simple swap-overs.

The blued cutters were crap but thankfully it was towards the end of the chain life. I sourced a new Oregon bar and chain online from the US (inc. shipping) for not much more than a new chain would've cost locally.

Re the electric grinder, I'm not sure it's worth the money or the bother. The chain has to come off the bar whereas with a good clamp-on guide it doesn't. The bar just goes on the engineers vice and with a bit of practice manual sharpening is pretty quick. And you can do it in the field if needed.