Struggling with Paul's sharpening method – any tips or things to look out for?

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  • #315624
    Dave C
    Participant

    I’ve been trying to move to using Paul’s sharpening method (freehand, with the 3 diamond plates and strop).

    I’ve tried it 10 times in total (6 times with chisel, and 4 times with planes), and twice got amazing and very sharp results, the other 8 times I’ve ended up with blades so dull they couldn’t even cut paper.

    Is there anything I should look out for to try and figure out what I’m doing wrong? I’m worried that I’m just repeating the same mistakes each time without really figuring out what’s going wrong.

    My blades end up with a very polished (and slightly curved) bevel, but if that’s not cutting, could that mean that I’m not sharpening right to the edge? Should I try raising the angle I use when sharpening? Or could I be lifting the blade too high and accidentally dulling the tip that I’m trying to sharpen?

    Also, should I be applying heavy downward pressure when sharpening, very light pressure, or something in between? Are there any telltale markings on my blades I should look out for to try and diagnose what I’m doing wrong?

    • This topic was modified 4 years, 11 months ago by Dave C.
    #315626
    David B
    Participant

    Do you have a device with which you can check the angle of your blade? Is it possible that you have not removed the burr when you have not had good results? A lot of downward force is not necessary but you need to use enough force that the diamonds (or sharpening substrate) abrade your iron and remove some steel.

    You might try coloring your edge with a sharpie so that you can see where you are effectively sharpening the blade when you do it–maybe you have, at times, sharpened the heel of the blade instead of the cutting edge?

    Did you flatten the back of your cutting iron?

    Just a few thoughts to get the ball rolling…

    #315627
    aanghelescu
    Participant

    Here are some thoughts based on my own mistakes (hopefully they’ll be helpful):
    – make sure you don’t roll the blade while polishing it on the strop. The up/down movement that creates the cambered bevel on the stones will round the cutting edge on the strop, because the blade “sinks” a little into the leather. So make sure the blade is held at a constant angle while you’re pulling it over the strop.
    – check the edge when you move from one stone to another – is light reflecting off it? If so, you haven’t created a good cutting edge
    – is your angle too steep?
    – to echo @dbockel2 – if the back of the cutting iron is not flat and polished, you won’t reach as good an edge. This applies all the more to old plane irons, which may be pitted.

    As a bit of encouragement: it takes some practice – If memory serves, I went through 25-30 attempts (ruining a few pieces of scrap wood in the process), before I got to the point where I was content with the result. Then, I was pleasantly surprised that more practice helped further still. So, keep trying 🙂

    #315629
    Dave C
    Participant

    Thanks for the advice (and encouragement – I guess this is a skill that probably takes a while to master).

    I’ve got a protractor somewhere, I guess I could make an angled block of wood to help match the angle initially (so far I’ve just been trying to feel for when the bevel is flat against the abrasive).

    One thing I’ve noticed is that very often I’m not getting any burr on the back – would that hint that maybe I’m not sharpening right to the tip?

    Using a sharpie sounds like a good idea too – can hopefully see which areas are actually getting abraded then.

    #315630
    Harvey Kimsey
    Participant

    Were your successful efforts at the start? If so, you probably rounded over the edge on a subsequent sharpening and with further sharpening you were unable to get rid of that rounded over edge. I use diamond stones like Paul, but I aim for a straight bevel. I hone on the coarsest stone until I feel a slight burr on the back all the way across the blade.

    For a cheap angle guide, you can figure out the run:rise ratio using the trig functions on a calculator. Hope this helps!

    #315635
    Dave C
    Participant

    That’s a good point – my earlier efforts were indeed better. So I guess I need to try and get rid of that round over (I guess I just keep trying to sharpen as normal and it’ll go away?).

    #315637
    Ed
    Participant

    Correct. No burr means you are not to the edge. Paul goes through all three stones before breaking off the burr. While you learn, it may be helpful to break the burr after each and every stone. That way, you know that you’ve gotten to the edge on each stone. As you gain experience, you will discover that you can hear and feel when you reach the edge. There is a scratchier, more hissy sound that happens as you reach the edge and it feels like there is more friction. These are really vague descriptions: Best I can do. When you need to hog off material on a coarse stone, have at it (with due care), but when you are raising the burr, you need to slow down, feel, and listen.

    Most likely, you are just not reaching the edge any more. Another (worse) possibility is that you’ve gotten so steep an angle that you don’t have clearance any more. In that case, even if you get to the edge and raise a burr, it won’t cut for a plane iron, although a chisel will still cut.

    Try going back to your coarsest stone and working until you raise a burr. Take it off, then move to your other two stones in the same way and see what that does for you. If you can test without *any* stropping, that would be good. If you get it to cut, then strop and polish. If it stops cutting after stropping, it means you are lifting the blade during stropping and killing the edge. There shouldn’t be any scooping like movement when stropping.

    #315638
    Ed
    Participant

    There shouldn’t be any scooping like movement when stropping.

    I guess it would be reverse scooping? Not sure what to call it. It shouldn’t be like flicking a hockey stick or sweeping a broom. Just go straight across the strop.

    #315639
    Harvey Kimsey
    Participant

    If the round over is severe enough, you’ll have to remove significant amounts of steel to get back to your ideal bevel edge. When this has happened to me I usually head to the grinder, then back to the diamond stones.

    #315663
    Dave C
    Participant

    Using a sharpie definitely helped me see what the issue was, thanks for the suggestion. I’ve attached an image now, looks like the blade (it’s from a 2nd hand plane from ebay) needs a lot more metal removing to reach the very edge (which still has some sharpie marks on it after sharpening a bit).

    That leads to another question – without a bench grinder (my workshop is a corner of my living room, so no room for one!), is there a suggested way of removing large amounts of metal quickly? It’s taking a very long time even on the coarsest diamond stone I have (250 grit I think). I was also wondering how I’d do that if the blade ever got a nick in it.

    Should I look for a coarser 120 or 80 grit stone? Or move to sandpaper for that? Or is it basically impossible to do without power tools?

    #315667
    Ed
    Participant

    Diamond stones are actually slow for this kind of work. Get some 120 grit sandpaper and use it instead. You may need to change frequently, but it will cut quickly. If you have a jig, like the Eclipse honing jig, that also speeds up the process.

    You can use the back of your diamond plate as your lapping surface. If you are working on the bevel, you can try working on loose paper, but never use loose paper on the back of the blade. Glue it down with spray adhesive, like 3M. Spray a thin, thin, barely there coat on the back of the paper, give it a moment to tack, and then press it onto the surface. “Barely there” is just one brief squirt, less than a second, if you manage to aim right. You can clean excess with lacquer thinner (double glove, good ventilation). Personally, I wouldn’t even do the bevel without glue. I’ve turned too many edges using loose paper. But, this should make fairly short work of it, even without a jig. Of course, depending upon your personality, “short work,” is measured in seconds, minutes, cups of tea, or hours. Oh, get some 180 and 200 paper, too in order to get your 120 grit scratch marks out before returning to the stones. You won’t need much. The scratches in your photo seem to be in random directions. Are you doing circles? You may be better just moving back and forth for this.

    #315670
    Byron
    Participant

    Hi

    I use a file sometimes to correct the shape of a new-second-hand blade if I cant get it on a course stone, as I dont like using a grinder at all. Its quiter, more gentle and less destructive. I would discourage you from getting a grinder. It can be helpful to set up a guide that helps you to file consistently at the right angle. Once the bevel is established at the reight angle, and the edge is roughly perpendicular to the blade length you should rarely have to re-adjust if you sharpen consistently. Does anyone else agree? I’m no expert as I only sharpen to ‘sharp-enough’ not scary-shaving sharp.

    ReUser

    #315686
    btyreman
    Participant

    I’d recommend trying 3m microfinishing film for it if you still have problems, it is far superior to normal sandpaper, and obviously ideal for lapping, it also cuts a lot faster and remains abrasive for a very long time, you can keep using it again and again, just use it for the initial lapping using a piece of plate glass and then move onto higher grits from 100 up to 15 microns, then you will have a perfectly flat back that will remain flat.

    I have recently got some and can’t believe how good it is, wet/dry paper is very expensive in comparison because it doesn’t last longer than a minute before you have to change it and it often doesn’t stick down well or stay flat. Once you’ve finished with the microfinishing film grits, then going to diamond stones will take about 1/10th of the time because the back will be so flat and consistent.

    #315727
    Dave C
    Participant

    @btyreman Thanks for the pointer – I didn’t even know that microfinishing film existed, looks a lot less hassle than sticking down sandpaper.

    One other question, how do the micron sizes of the film match up with grit sizes? Lower micron sizes would mean smaller particles which means higher grit?

    • This reply was modified 4 years, 11 months ago by Dave C.
    #315728
    Dave C
    Participant

    @ed I was mostly moving back and forth, but just moved to trying circles/figures of 8 etc. at the end to see if that was one of the problems (it didn’t improve things anyway).

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