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Thread: Unable to sharpen plane iron, sharpening equipment suggestions needed

  1. #1

    Unable to sharpen plane iron, sharpening equipment suggestions needed

    I'm working on restoring an old plane. The iron in it was in pretty bad shape, with the cutting edge far from perpendicular to the iron, so I elected to replace it with a Hock iron. My understanding is that the Hock irons should come in pretty good shape and just need a little bit of work to sharpen them initially.

    My current equipment:
    8" DMT DuoSharp bench stones (220, 325, 600, 1200 mesh)
    Norton waterstone (4000/8000 grit)
    Veritas honing guide

    I started by using the DMT bench stones to lap the Norton waterstone. I started with 220 mesh and finished with 600 mesh.

    Next I moved on to the blade, and began by attempting to lap the back side. Using the 220 and 325 mesh DMT stones, I worked for several hours on the 1" nearest the cutting edge. I didn't make a whole lot of progress, and the time investment was significantly more than I expected.

    Wondering if the Hock iron was not as flat as originally thought, I took it to a machine shop and had the back stone ground flat. It was only necessary for them to remove .001", so clearly it was pretty flat to begin with and my DMT stones weren't removing much material.

    After getting the iron back from the machine shop, I cleaned off my DMT stones with soap and a nylon brush hoping that would improve their performance and the blade would just need some quick work at this point. Not the case at all. Another 15 minutes of work and it became apparent the DMT stones are not removing material evenly. I don't think they're flat, and I don't think they're doing much.

    What equipment do I need to pick up that will allow me to successfully sharpen a new plane iron? I think the DMT stones are making it more difficult than it needs to be. I am thinking I might scrap the DMT stones, add a 250/1000 grit combination waterstone and a Norton flattening stone.

    Thanks
    Last edited by Josh Hutchinson; 11-16-2017 at 7:30 PM.

  2. #2
    Join Date
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    Josh, I had a similar experience with the exact same DMT stones you have. I bought the 220, 600, and 1200 from sharpeningsupplies.com, the 220 seemed to cut nicely at first but then it quickly because useless. I tried cleaning it per DMT website's suggested methods but to no use. sharpeningsupplies.com has a 90 day satisfaction guarantee so I took advantage of it and returned them.

    Instead I purchased an Atoma 400 grit diamond plate which are supposedly much flatter and more durable. I also got the Norton waterstone set from sharpeningsupplies which has a 220/1000 stone in addition to the same 4000/8000 you have (and the flattening stone which I haven't used yet). I'm mainly using the Atoma diamond plate to flatten the waterstones, but I've used it directly for rapid metal removal and have had no complaints so far. The coarser waterstones also cut very nicely. Seriously I understand your frustration, I spent more than an hour rubbing the back of a plane blade back and forth on that DMT stone and accomplishing nothing.

  3. #3
    Join Date
    Sep 2007
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    16,394
    Howdy Josh,

    You do not mention if you have an O1 or A2 blade.

    Hock irons need more work than a Veritas blade to flatten the back. Though getting a back perfectly flat can be a challenge to do by hand. My O1 Hock blade took similar amounts of time to get flat and shiny. Though if it mates well to the chip breaker it is likely flat enough for most work.

    jtk
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
    - Sir Winston Churchill (1874-1965)

  4. #4
    Quote Originally Posted by Steven Mikes View Post
    Josh, I had a similar experience with the exact same DMT stones you have. I bought the 220, 600, and 1200 from sharpeningsupplies.com, the 220 seemed to cut nicely at first but then it quickly because useless. I tried cleaning it per DMT website's suggested methods but to no use. sharpeningsupplies.com has a 90 day satisfaction guarantee so I took advantage of it and returned them.

    Instead I purchased an Atoma 400 grit diamond plate which are supposedly much flatter and more durable. I also got the Norton waterstone set from sharpeningsupplies which has a 220/1000 stone in addition to the same 4000/8000 you have (and the flattening stone which I haven't used yet). I'm mainly using the Atoma diamond plate to flatten the waterstones, but I've used it directly for rapid metal removal and have had no complaints so far. The coarser waterstones also cut very nicely. Seriously I understand your frustration, I spent more than an hour rubbing the back of a plane blade back and forth on that DMT stone and accomplishing nothing.
    Thanks Steven, it's reassuring to know it's not just me. Also appreciate the Atoma 400 suggestion; I may look into purchasing that instead of the Norton flattening stone.

  5. #5
    Quote Originally Posted by Jim Koepke View Post
    Howdy Josh,

    You do not mention if you have an O1 or A2 blade.

    Hock irons need more work than a Veritas blade to flatten the back. Though getting a back perfectly flat can be a challenge to do by hand. My O1 Hock blade took similar amounts of time to get flat and shiny. Though if it mates well to the chip breaker it is likely flat enough for most work.

    jtk
    I don't honestly remember I bought the plane and Hock iron several years ago and am just getting around to finishing the project. I suspect I went for the O1 steel. I will say that I spent at least eight hours attempting to sharpen the original blade with the same DMT stones a few years back and was getting nowhere with that either.

    I'm almost positive the DMT stones aren't flat because I used them to lap my waterstone. After getting the iron back from the surface grinder at the machine shop, my DMT stones were taking off material in the middle while my waterstone was taking off material on the edges. This suggests the diamond stones have high spots in the center. A straight edge indicates the same.

  6. #6
    I've ordered the Atoma 400 diamond plate and a Shapton 1000 grit ceramic stone to compliment my Norton 4000/8000 stone. Will report back next week with results.

  7. #7
    Join Date
    Dec 2015
    Location
    Dublin, CA
    Posts
    3,319
    Quote Originally Posted by Josh Hutchinson View Post
    I'm working on restoring an old plane. The iron in it was in pretty bad shape, with the cutting edge far from perpendicular to the iron, so I elected to replace it with a Hock iron. My understanding is that the Hock irons should come in pretty good shape and just need a little bit of work to sharpen them initially.

    My current equipment:
    8" DMT DuoSharp bench stones (220, 325, 600, 1200 mesh)
    Norton waterstone (4000/8000 grit)
    Veritas honing guide

    I started by using the DMT bench stones to lap the Norton waterstone. I started with 220 mesh and finished with 600 mesh.

    Next I moved on to the blade, and began by attempting to lap the back side. Using the 220 and 325 mesh DMT stones, I worked for several hours on the 1" nearest the cutting edge. I didn't make a whole lot of progress, and the time investment was significantly more than I expected.

    Wondering if the Hock iron was not as flat as originally thought, I took it to a machine shop and had the back stone ground flat. It was only necessary for them to remove .001", so clearly it was pretty flat to begin with and my DMT stones weren't removing much material.

    After getting the iron back from the machine shop, I cleaned off my DMT stones with soap and a nylon brush hoping that would improve their performance and the blade would just need some quick work at this point. Not the case at all. Another 15 minutes of work and it became apparent the DMT stones are not removing material evenly. I don't think they're flat, and I don't think they're doing much.

    What equipment do I need to pick up that will allow me to successfully sharpen a new plane iron? I think the DMT stones are making it more difficult than it needs to be. I am thinking I might scrap the DMT stones, add a 250/1000 grit combination waterstone and a Norton flattening stone.

    Thanks
    Given your likely volume I'd suggest getting some rolls of coarse-grit Aluminum-Oxide PSA sandpaper and a sheet of untempered 3/8" glass. It'll be dead flat and is probably the fastest of the low-investment options.

    Coarse waterstones tend to dish quickly. One way to think of it is that coarse stones lose more thickness each time the stone "sheds" a layer of used-up abrasive. Coarse waterstones therefore don't have as much of an economic advantage over sandpaper as finer ones do. I'm not a huge fan of coarse oilstones, either, as they tend to be slow and/or soft compared to sandpaper.

    If you can tolerate the up-front and hassle one very fast and accurate way to go for flattening is diamond paste on mild steel or cast iron laps (accurate because the laps don't dish very much). It's also a bit cheaper over the long run than sandpaper. That's what I do, but I don't think it will be worth it unless you plan to be maintaining a lot of blades.

    At this point I only use diamond plates to flatten stones. Like you and others who've posted I've had bad experiences using them directly on metal, as the abrasive "slows down" too quickly. If I'm going to use diamonds I'll use either compounds or lapping films, both of which allow me to replace the diamonds with fresh ones more frequently than with plates.

  8. #8
    What Patrick said - but AlZn 80 grit roll on 1/2" float glass for the first whack, then on to AlO and Imperial Wet/Dry for the finer grits. Don't have issues with getting a flat water stone off of the DuoSharp XC/C, but I suspect there are folks that assume flat, rather than get a straight edge on them before use. Easy enough to ask the vendor to send you a flat DuoSharp...then check it on a straightedge when received. Diamond plates get used here to quickly strip off a dull edge and flatten stones...cast iron and other metal flattening chores get abrasives and diamond paste for final polishing.

  9. #9
    Join Date
    Apr 2013
    Location
    Stone Mountain, GA
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    229
    I've never liked diamond stones for back flattening. I've never really liked any coarse stones under 1000 grit, either. For a new or used iron that needed a lot of work, I'd use 80 grit PSA on a granite surface plate. You could use glass, too. A fresh sheet of 80 grit is significantly faster than any stone I have used, and on a large surface plate or glass sheet you can really go to town. Then switch to 150, then 220 grit paper. You can start with 150 or 220 grit as well, if there isn't too much pitting, etc. to remove. From there you should be able to jump to a good 1000 grit waterstone, then proceed with your 4k/8k Norton's.

    My recommendations: I would not use the diamond stones for sharpening except for bevel work on rare occasions. Check their flatness with a straightedge...hopefully at least one of them is good...then use the coarsest good one to flatten your waterstones. Get a surface plate or glass sheet and some rolls of PSA abrasive in 80, 150, and 220 grit. Also, add a good 1000 grit waterstone (I think the Shapton Pro 1000 is excellent). This is a good stone to transition from sandpaper, and for beginning your sharpening routine if you have much wear to remove.

    The 1000 grit waterstone is surprisingly fast at back flattening, much faster than my worn-in X-coarse DMT. With most new blades you wouldn't need to use anything coarser to flatten the back. I'm pretty sure that was the case with my Hock O1 iron, which did not arrive as perfectly dead flat as a Veritas iron but did not warrant using coarse sandpaper.
    Last edited by Robert Hazelwood; 11-17-2017 at 12:39 PM.

  10. #10
    Join Date
    Feb 2017
    Location
    Minnesota
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    What's the best source for glass acceptable for this application?

  11. #11
    Quote Originally Posted by Robert Hazelwood View Post
    The 1000 grit waterstone is surprisingly fast at back flattening, much faster than my worn-in X-coarse DMT. With most new blades you wouldn't need to use anything coarser to flatten the back. I'm pretty sure that was the case with my Hock O1 iron, which did not arrive as perfectly dead flat as a Veritas iron but did not warrant using coarse sandpaper.
    Excellent, I'm hoping the 1000 stone I ordered, once lapped with the Atoma 400 plate, will get the job done. The iron did come pretty flat; I don't think a whole lot of material needs to be removed.

  12. #12
    Join Date
    Dec 2015
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    Quote Originally Posted by Nathan Johnson View Post
    What's the best source for glass acceptable for this application?
    I buy offcuts from my local glass shop. Basically everything they sell is float glass and manufactured flat, so the main thing to watch out for is that it not be tempered as that can add a few mils of warp. I typically use 3/8" glass for the extra stiffness and durability.
    Last edited by Patrick Chase; 11-17-2017 at 8:15 PM.

  13. #13
    Join Date
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    Minnesota
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    Quote Originally Posted by Patrick Chase View Post
    I buy offcuts from my local glass shop. Basically everything they sell if float glass and manufactured flat, so the main thing to watching out for is that it not be tempered as that can add a few mils of warp. I typically use 3/8" glass for the extra stiffness and durability.
    Thank you.

  14. #14
    One thing to note...as long as the edge is perpendicular to the sides, you don’t need to flatten but just the very edge of the back. Remember that a cutting edge is just two surfaces meeting...the need to flatten the back is a waste of time. Look up Rob Cosmans sharpening technique and you”lol see what I mean.

  15. #15
    Join Date
    Jan 2005
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    2,997
    Many people on these forums end up buying some sort of grinder, 8" or even 6" will do. Certainly the stones that come on most of these machines require some care on the users part to prevent over heating. I ended up with diamond wheels on mine, such wheels are much less prone to heating up and they can cut faster and longer too. The issue being that such wheels are not cheap.

    Many have found that "hollow grinding" blades can reduce sharpening times and provide a more stable surface to rest on a stone.
    http://www.inthewoodshop.com/Woodwor...ningSetUp.html
    Last edited by Mike Holbrook; 11-19-2017 at 10:43 AM.

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