Belt Sander Monster Clingy Burr

[bgentry]

I recently gave away a box of thrift store knives. I sharpened the last 3 I gave away. They were predictably dull, dull, dull and needed a lot of work. So I used the WSKO with a 200 micron Norax belt to do most of the work on them. Even at full speed it was a bit slow, but I got it done.

After 200u, 100u, and 22u, the blade should have been pretty toothy but really sharp. But it wasn't. I did a few deburring steps, but wasn't really getting anywhere. I find it almost impossible to effectively deburr on a belt sander.

So I pulled out the sharpmaker, set it to 15 dps, and did a few strokes. Then I watched in real time as HUGE burr chunks crumbled off the edge. It was kinda fascinating watching it slog off the edge as I pulled the blade down the sharpmaker rods. After a careful bit of sharpmaker, a little bit of cork, and some more sharpmaker, I had a very respectable burr free edge.

I repeated this on all 3 blades and got that same large amount of crumbly steel off each knife. I guess I just learned why almost every belt sander knife sharpening process finishes with a buffing wheel. You just can't get the burr off with the belt sander. ...and a burr like the one I'm describing is kinda firmly stuck on, and running it through a cork really does very little. It cleans it up a bit and leaves behind a bunch of shiny metal in the cork. But it doesn't remove it.

This teaches me that I really need to have a finishing stone, or the sharpmaker as part of my WSKO "kit". I've noticed this previously, but it didn't really stick. In my WSKO video there's a part where I stop the camera and come back and talk about a "big floppy burr", which is what I'm describing here.

The more I use the WSKO, the more I want a 1x42 "real" belt sander.

Brian.

 

[HeavyHanded]

I'm very spoiled, when I want to deburr on my belt grinder I reverse it and slow it way down, make a pass or two at the original grind angle with the belt leading. This doesn't leave it with the best edge, so I finish it some other way - usually on a hard strop or on a finishing waterstone.

Resetting cheap stainless to a lower angle can whip up some real big foil burrs.
I've even seen this using a wet wheel grinder, so isn't just the belt causing it.

 

[Wowbagger]

The more I use the WSKO, the more I want a 1x42 "real" belt sander.

I have cabinets full of hand held belt sanders and grinders . . . a Poraband and two floor standing band saws etc., etc.,
and I still say

Belt sanders are for . . . say . . . making a stock car, industrial production work . . . etc.

Sharpening stones are for sharpening pocket knives and fixed blades.

Just because it makes a lot of dust and noise doesn't mean it is the right tool for the job.
And especially after learning hand tool woodworking I came to realize how overly obsessed we are with PAHHWRRRR tools.

I am so tired of listening to neighbors use hammer drills to put in a couple of little screws I could spit.

Now if one is going to MAKE KNIVES that is all different. That takes moving a serious amount of metal.
But to sharpen a couple of little kitchen knives.
Nah dude, nah.

 

[eKretz]

Resetting cheap stainless to a lower angle can whip up some real big foil burrs.
I've even seen this using a wet wheel grinder, so isn't just the belt causing it.

In my experience many stainless steels - and especially so those of somewhat lower hardness - are very prone to burring - considerably more so than most plain carbon steels.

 

[bgentry]

Thanks HH for the commentary. I have MAJOR belt sander envy of Ken Schwartz setup. Reversible, 3HP motor (I think. I know it's enormously over powered), VFD, twin foot pedals for variable speed operation in either direction, on the fly. Now I'm envious of yours too. Still using a treadmill motor on yours?

Brian.

 

[bgentry]

Belt sanders are for . . . say . . . making a stock car, industrial production work . . . etc.

Sharpening stones are for sharpening pocket knives and fixed blades.

For blades where you care about cosmetics, I agree with you mostly. For basic blades that need a lot of work, I like a belt sander. You would spend your whole life sharpening some of the blades I'm talking about, which are worth about $2 each. The belt sander allows you to do good work in a short time. Many that I sharpen have almost no edge at all. I cut in brand new bevels on a lot of these blades. Because they've been used and abused for so many years that there's no edge bevel left. Or so small as to be negligible. Like 1/32" wide. Some have deep chips which require me to flatten the edge (I go about 75 degrees on each side, which effectively flattens it, but is safer on a running belt than 90 degrees). I sometimes take off 1/4" or more of blade height when doing this in order to get all the chips out.

I received a rather dull paring knife a few days ago. I had previously reset it on the belt sander. After about 8 months, it was missing most of its edge again, but I decided to hand sharpen only. After two sessions, both of which started with the DMT XXC, I had a very nice consistent edge that I could be proud of. Total time was ~35 minutes. I might have been able to do the whole thing in 20 to 25 had I been more patient in a single session. This same blade could have been done in 10 minutes with the WSKO. I suspect it could have been single digit minutes with a 1x42 sander.

For me it's about the job being done. Many times, the powered sharpener is the right tool. Other times it's not.

Brian.

 

[Obsessed with Edges]

I've never liked apexing 'soft' stainless with anything very coarse, or with much pressure or velocity exerted while doing so. It just invites big burrs into the process. If I ever use anything as coarse or coarser than ~ 220 or so, I usually stop short of the apex when it's close to being there, and switch to ~ 320 or finer to finish apexing, and with a much lighter touch. Keeping the stone/hone well-lubricated also helps a lot with soft stainless, as it's otherwise prone to quickly clogging up the abrasive, making burring issues even worse.

As unnecessary as it may intuitively seem for such steels, I've really liked using a diamond hone for apexing soft stainless, as it (1) cuts the steel very cleanly, and (2) does so at a featherlight touch, both of which will keep burring at an absolute minimum on these steels. My favorite finish for my Victorinox paring knives usually comes off a 600-mesh (Fine) DMT hone. Virtually no burrs at all, and I usually don't even strop them when I'm done.

 

[HeavyHanded]

Thanks HH for the commentary. I have MAJOR belt sander envy of Ken Schwartz setup. Reversible, 3HP motor (I think. I know it's enormously over powered), VFD, twin foot pedals for variable speed operation in either direction, on the fly. Now I'm envious of yours too. Still using a treadmill motor on yours?

Brian.

I wound up with a variable speed DC motor I scavenged out of some finishing equipment where I work, pretty sure its 7 amp. Top speed is about 1000 RPM but for sharpening I normally don't go much above 4-600, only go full out when doing a regrind. I have to adjust a dial for speed but for me it a great set-up.

I love my 1x30 for sharpening as the belts are so darn cheap and I have a lot of control when working on smaller items. Have been dabbling in hair shears lately and it does a great job w/out removing extra stock.

The thing I like best, and should look at selling this rig, is I can go from my belt grinder to my stones using the same clamp and jig arrangement ( I won't use belt grinder or wheel without a guide). My standard commercial edge is 120 grit Blaze or 125 micron diamond and then microbevel 2°/side with finishing waterstone or DMT EEF.

 

[HeavyHanded]

. This same blade could have been done in 10 minutes with the WSKO. I suspect it could have been single digit minutes with a 1x42 sander.

For me it's about the job being done. Many times, the powered sharpener is the right tool. Other times it's not.

Brian.

Commercial work I quote at 5 minutes a blade unless its something fancy. I'd be the John Henry of sharpening trying to make $ doing that manually, and we all know how that story ends...

 

[FortyTwoBlades]

Very fine belts usually at least weaken any burr present, and I find that a few belts away from finishing that if I run the edge through a block of wood it'll usually peel the burr off nicely at that stage and then the remaining belts take of whatever remains in the form of a now rolled-over wire, and then stropping on a piece of bare wood works anything raised in the final stages back and forth until it breaks off. Then hand stropping on compound does the last of the job.

 

[l1ranger]

I've never liked apexing 'soft' stainless with anything very coarse, or with much pressure or velocity exerted while doing so. It just invites big burrs into the process.

this right here.
I get knives of all sorts from friends and family - mostly unknown stainless kitchen knives that have been dull for years. I'll sometimes hit them on the belt real quick, just to get something close to an edge on them. then finish off by hand or with lansky guide.

it may take a bit longer, but anytime spent with a knife in hand is quality time

 

[dsalazar]

There is one knife shop in town. He uses a belt sander to sharpen knives and finishes on a buffing wheel. He is good at it. Everyone takes there knives, kitchen knives and what not there. Being thats the only place in town that sharpens. I take mine there to lower the angle. As he does a good job you can see how it doesnt stay as sharp or get as sharp as it can.

 

[CasePeanut]

B bgentry let us know what you end up learning. I’ve gained so much from your other posts and videos on sharpening with the WSKO.

I’ve spent some time reading through the BESS forum on burrs. They take it really seriously. It seems like one easy thing to try from their exhaustive experiments is to change the angle of the stropping to remove the burr and wire edge. So if you sharpen at 15* then stropping at 17* will help remove the remaining burr.