Sandpaper Sharpening

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Hi everybody, I have been experimenting with using sandpaper to sharpen chisels. I've been starting on the grinding wheel to establish an angle, then using a Veritas Mk II angle guide with varying grits of sandpaper. I have been able to get a very sharp edge using this method, but I seem to blow through the sandpaper _very_ fast. It seems like I only get a few minutes of use before the grit is worn off.
I'm using the "wet/dry" sandpaper available at auto parts stores - no water or oil. I've read about silicon carbide sandpaper, and I think that's what I'm using, but the packaging doesn't specify.
Has anyone been getting better longevity out of sandpaper, and if so, what brand/technique are you using?
I have tried a waterstone, but the thing didn't stay flat for very long. What is an inexpensive way to flatten a waterstone?
TIA,
Mike
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Mike wrote:

DO use water or oil ... it allows the swarf to be carried away rather than filling in the spaces between the abrasive chunks and leveling the playing field.
Bill
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I tend to have the same results with wet/dry sandpaper, even with water. Works well, but eats through sandpaper quickly. I guess the theory is that you're supposed to have several grits of sandpaper, so you don't need to spend more than a minute on each grit. I'm still playing around, but overall, I'd say I'm happier with a waterstone. I have a 1000/6000 combo, and I find the 6000 stays flat pretty well and rarely needs maintenance. With the 1000, I try to use the whole surface evenly (lapping the long back chisel face across the whole stone, doing plane blades at least the width of the stone, doing figure 8's or ovals with chisel bevels), but when it does develop some dish, I use more wet-dry sandpaper (220 or so?) to flatten it, and flushed with plenty of water, it goes quickly enough. I've heard coarse diamond sharpening plates work well. They also sell special stones for flattening waterstones, but I haven't used one. FYI, Rockler has a good deal on a waterstone set right now ($35 for a 1000/4000 combo, a 6000, and a nagura stone) Hope this helps, Andy
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Two things will make a HUGE difference:
1. Use 3M papers available from www.antiquetools.com 2. Don't run the wheel of the jig on the sandpaper. Only run it on the glass.
For more details, read Brent Beach's site: http://www3.telus.net/BrentBeach /
Mark
Mike wrote:

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Mark Wells wrote:

I forgot 1 more:
3. Use baby oil as a lubricant.
Mark
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Mark Wells wrote:

I would think that the difference in thickness between grits of sandpaper would mess up the angle, causing you to have to do a lot more work. Unfortunately, the finer grit papers are thinner that the coarse paper, meaning that each time you go to a thinner paper you will start griding away at the 'heel' of the blade. I realize that there will only be a very slight difference, but I'm getting the feeling that you want to make just a minimal number of passes on each grit.
I'll try the 3M papers though.
Thanks,
Mike
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Mike wrote:

OOPS!! I realized just after posting that that I was thinking backwards. The thinner paper would mean that the front edge of the blade would hit first - thereby making the process go even faster, not slower.
Um, so that's a good idea then...
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Mike wrote:

If you read Brent Beach's site, he has done a ton of study of sharpening, looking at edges under a microscope. He has found that increasing the angle 1 degree at each paper change produces the best edge. I have verified that. Check out his site. He has a ton of info! He also wrote a recent article in Fine Woodworking on sharpening.
Mark
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Mike wrote:

If you don't want to wait, this stuff is often found at auto body suppliers. Look under "Auto Paint" in your Yellow Pages.
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Mike wrote:

remember to up the angle a little bit each grit. it'll make the whole process go a lot faster and make the paper last a lot longer. it looks like the Veritas Mk II has a mechanism built in for that- use it.

good sandpaper isn't cheap, eh?

that's the right stuff.

try using a very light touch with the steel to the paper, use more in between grits if it's taking more than about 20 strokes per grit and keep the paper flooded with water.

on a concrete paver.

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Mike,
Check out this write-up on the "Scary Sharp" technique using sandpaper.
http://www.shavings.net/SCARY.HTM

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I use Ezy Lap diamond hones with the Veritas honing guide. I follow up with a leather strop charged with honing compound to finish the job.
A fine belt on the belt sander and the Veritas guide will shape the chisel in a hurry.
I also have a low speed bench grinder I use on occasion.
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Mike wrote:

That's normal, even happens with diamond. Abrasives, to be hard, must also be brittle. Using them wears them down, breaks off the points, reduces the size of the grains, so that 600 paper very soon feels like 1200.
If it's cutting too slow, switch to the next coarser grit. Don't throw out the "worn" paper. Use it to hone the final microbevel prior to stropping. It's better for polishing the edge than fresh paper, since there are almost no oversized grains to scratch the otherwise mirror polish.
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Father Haskell wrote: <snip>

How important is the 'microbevel'? I've tried to do this using the Veritas guide, but what ends up happening is that the microbevel isn't parallel with the edge of the blade. From what I understand about the guide, the microbevel selector thingy offsets one side of the roller just a bit. Is that slight skew on the microbevel OK? Is the Microbevel supposed to make the edge sharper, last longer, or just make it quicker to re-hone after being used a bit?
FWIW, the last chisel that I sharpened I went up to 2000 grit sandpaper, with no microbevel. I was able to shave with it - but not really easily. I have a felt wheel and honing compound ordered from Lee Valley and I'm hoping that this will put the finishing touch on the edge.
Thanks,
Mike
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Oye! Mike - are you looking for a straight razor, a mirror, or a chisel? I've never gone past 1200 grit and I could easily shave hair off my arm at that point. Probably could have shaved hair at 800, and certainly at 1000. Sliced through wood effortlessly, and that's what I was really after. You can pursue this stuff to a point of (well past) diminishing returns.
Yeah, yeah, I know - it is cool to count your nose hairs in the bevel, isn't it?
--

-Mike-
snipped-for-privacy@alltel.net
  Click to see the full signature.
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Mike Marlow wrote:

Well, I suppose that I'm looking for a chisel with a mirror finish on the bevel and a razor sharp edge!! ;-)
The reason for the felt wheel and honing compound is that a buddy of mine is really into knives, and he showed me how he uses a wheel with rouge - and the results are spectacular. I'm hoping that once I put an edge on my chisels that I'll be able to touch 'em up on the wheel every now and then to keep a razor sharp edge.
It's funny - until just recently I didn't really worry about sharpening chisels, just pounded 'em through the wood. Now that I've seen how well they work when really sharp, I want to sharpen them every time I pick 'em up!
I'm sure that after a while I'll start to bow down to the diminishing returns, but for now I'm having fun seeing just how sharp an edge I can get.
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Mike wrote:

Red rouge? Try green chrome compound, brings up a mirror shine in 1/4 of the time.
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Mike wrote:

It's a time saver. You really only need to hone the blade immediately behind the edge.

It rarely is. It's easy enough to fix on the grinder.

Saves you time, and to a lesser degree helps the edge hold longer. Fastest way to set the microbevel is to slip an index card or two under the jig roller, hiking the angle up a tenth of a degree or so.

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The original reason for the "micro bevel" was simply to save time. Initial sharpening with no microbevel. Sharpening thereafter at a steeper angle just so the full bevel did not have to be taken down. When micro bevel gets to large, regrind and start again. Forget the buffing wheel and compound. Sharpen as usual and use a leather strop, by hand with no sharpening glop. All it takes is about three strokes on the leather.

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If you do a microbevel you won't chew up sandpaper as fast. Also I find I wear the paper out by putting pressure on the push stroke, so I put the pressure on the pull stroke and ease up on the push.
At any rate over time you are going to spend more on sandpaper than you would with waterstones; the paper isn't going to give all that much life. And be very careful not to contaminate your finer grits with coarse swarf.
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