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Thread: Flattening the sole of a cast steel hand plane?

  1. #1
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    Flattening the sole of a cast steel hand plane?

    On YT there are a lot of videos that show how to flatten the sole on hand planes. It seems fairly easy, but I wonder if there are anything that can go wrong if the tecnique is not right?
    Can one accidently be "rounding" the sole instead because of more gringding at the ends than in the middle of the sole ?

    Is a granite plate from a window usually flat enough for the job ?

    What grit size should I end up with ?

    Thanks..
    Best regards

    Lasse Hilbrandt

  2. #2
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    You can end up with a convex sole fairly easy, and even with care it will likely still end up a hair convex (few thousandths). This is not the end of the world, and is much better than other sole conditions save for dead flat. It can even be beneficial compared to a dead flat sole, in that it counters the normal tendency to plane the ends of a board more than the center. But only if it's a small convexity- if it's large than the plane will be difficult to keep in the cut and very sensitive to which hand is applying pressure.

    #3 through #5 planes lap fairly easily. I have a granite surface plate from woodcraft, 4x18", very affordable and very flat. This is perfect for the smaller planes. For larger planes you really would want a lap that is 3 or 4 feet long- a thick piece of glass on a flat backing surface is probably the way to go there. I am not sure what you mean by granite plate from a window, but it may be flat enough for the job. I'd want to check with a good straightedge before using. The straightedge is also a good idea for checking your progress as you lap.

    When lapping I like to hold the plane as though I am actually planing wood, with the same grip, and push forward only, with firm but not excessive pressure. No rapid back and forth strokes - I think that would be a good way to get more convexity than is desirable. Start with 80 grit PSA paper and keep it fresh and clean. Every stroke or two I use a magnet wrapped in cloth to clear the swarf- this helps keep things flat. And the sandpaper will need to be changed every few minutes- a fresh sheet of 80 grit seems to remove more metal in the first two minutes of use than in the next 10 combined. So it's worth it to change the paper often, annoying as that is.

    I would take it up to 220 grit at least, with a progression like 80-120-150-220. You will still be doing a little flattening work with the 120 and 150, and 220 is fine enough, especially as it gets worn, to give a smooth surface that will slide well.

  3. #3
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    At a Lie Nielsen event one time a man demonstrated flattening a plane sole by using 80 grit for a minute, then going up thru three more grits and back to 80.

    He said this cycling worked faster than trying to get the sole flat initially on just the 80 grit.
    I haven't had to flatten a metal plane sole since then so I can't comment on this from experience.

    He also had rolls of maybe 3" wide adhesive-backed sandpaper from which he took a length and stuck it on a flat surface. Looked better to me than the single sheets in a row I have used.

  4. #4
    Quote Originally Posted by Lasse Hilbrandt View Post
    On YT there are a lot of videos that show how to flatten the sole on hand planes. It seems fairly easy, but I wonder if there are anything that can go wrong if the tecnique is not right?
    Can one accidently be "rounding" the sole instead because of more gringding at the ends than in the middle of the sole ?

    Is a granite plate from a window usually flat enough for the job ?

    What grit size should I end up with ?

    Thanks..
    Lasse,

    there are lots of tings which can go wrong and cause your plane to end up less flat than it started... Your results are dependent on technique and equipment.

    I have not found plate glass adequate for lapping larger or heavy things. It may be fine for small stuff but I feel it's just too flexible for anything outside of very small planes..

    The biggest thing for me is frequently checking your progress against a real ground straight edge or a surface plate to see if you are making things better or worse.

  5. #5
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    You will probably wear yourself out before you really mess it up. Note that getting it basically flat enough means getting the mouth area flat, as well as an area near the toe and heel. The spaces in between are not nearly as important.

  6. #6
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    I had problems attaining a straight flat surface on glass with sand paper .
    I ended up using a flat 12" mill file to get my soles flat and square.
    Check frequently with a good straight edge.

  7. #7
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    Every stroke or two I use a magnet wrapped in cloth to clear the swarf- this helps keep things flat.
    This is important, if the swarf builds up, the cutting action will not be where it is needed. My magnet is wrapped in paper, about the same. There is also a steel screw on the side of my granite bench to hold the magnet and paper so it is always handy.

    My advice on plane soles is to only lap them if it is really needed, as many times it isn't needed.

    If a plane can take a shaving without problems, the sole likely doesn't need to be lapped.

    With a longer plane when edge jointing a convex sole will start a cut and then as pressure is applied to the back of the plane it will come out of the cut. A concave sole will not cut until the blade is well extended or pressure is applied, then it will dig in and won't be able to take a thin shaving. Those need to have some work done on them.

    The casting does have a little flex in use. This can be a source of problems when lapping.

    If the sole is concave and pressure is applied to the center of the sole, it can actually worsen the concavity.

    If the sole is convex and held at the ends going back and forth this problem can also be exacerbated.

    Not removing the swarf every few strokes can leave the sole with a shape more like a hollow or round plane. Here is an old post of mine working on a #4 that had such a problem:

    https://sawmillcreek.org/showthread....70#post1339970

    With a flat sole that plane took this shaving:

    Fine Shaving 0.0002x?.jpg

    If you have a need for better, then it might be best to seek out a good machine shop to do the work for you.

    jtk
    Last edited by Jim Koepke; 04-10-2018 at 2:59 AM. Reason: wording
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
    - Sir Winston Churchill (1874-1965)

  8. #8
    been puttering with this lately. Started using stick on 3M auto body paper that is 2 3/4" wide. I have that from 150 to 500 grit. Sometimes put WD on even though its dry paper. Works well but I dont have coarse enough. I stick it on a shaper table. Other day tried a used stroke sander belt. Better as it was 100 grit, better as its burgandy and a much stronger sandpaper, its six inches wide and as long as you want (full belt 309") being long you can just clamp it at each side of the table and pull it tight.

    Put lines accross with a sharpie, ive yet to find one that was flat, still all of them worked fine more or less as they were. Im wondering more about final finish and if finer and finer continues to make them glide better, that is maybe past 500 and more makes a slipperier base.

    Been planing some wood to get to know it again mostly a machine guy, not warming up to the wood planes people have given me. They sound nice but find the center of gravity high and this tapping to adjust I dont know, already enough on going challanges in life. Metal plane you can advance a blade incredibly tiny amount make a shaving whatever you want, side to side adjustment not quite as fine but still way easier for me than the wood ones.

    Paul Sellers has a you tube or two on plane bases and he seems to angle off all outside edges about 3/8" in or so. Not sure I want to do that but have bevelled off all outside edges

  9. #9
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    If you lap do not remove the blade, frog, etc. Just retract the blade.
    Don

  10. #10
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    If it is a valued plane, I would take it to a machine shop. I've had one flattened. It did not cost that much.

  11. #11
    Join Date
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    "Warped Sole" is a rare thing....99% of what I see doing rehabs is from wear. It has been so well used over the decades, the sole has been worn to the "warped" some seem to think. Toe, in front of the mouth and in back of it...and the heel, all need to be coplannar As long as rest of the sole isn't sitting "proud" of these three areas....sole is fine to use. IF you are spending all day long flattening a sole...walk away, just walk away. Rethink what was going on. Chances are, you have made an "ok" sole much worse than when you started. called OCD-Sole Flatness Syndrome.....Machineshops need the business, anyway...

    Ok, try this very simple test, to check the sole of a plane:
    Have the plane all set up for work, and retract the iron ( don't want it sticking out)
    Place said plane on a flat surface..like your workbench

    Place a fingertip on each end of the plane.
    Fingertip in the center on both ends....does the plane rock? No?
    Fingertips at a diagonal from each other...does the plane rock? No? switch corners, try again...still no rocking?
    Use the plane, sole is fine.

    There now, that wasn't so hard, was it?
    IF things do rock:
    Black Sharpie pen, make a bunch of lines across the sole. Sand until the lines are gone. Plane is still set up with the iron retracted. Do NOT push the plane like you are planning wood. Index finger and thumb hold around the front knob and the rear tote...only use enough pressure to move the plane, do NOT bear down. 10 or so swipes, check the lines. Might be surprised at how well you are doing. Clean the belt as needed, continue until the lines are gone. Done.

    Unless it IS a shooting plane, sides do NOT need to be exactly square to the sole. You are planning with the sole, not the sides.
    The reason for the lighter grip, instead of "Full Power Planning"? You will cause a twist in the plane. And you have just sanded that twist into the sole. A lighter touch is easier to control, less stress on you, and, you can feel a lot better on how the sole is doing ( remember the Fingertip trick?)

    Try this sometime.....you might like it..
    Last edited by steven c newman; 04-09-2018 at 4:39 PM.

  12. #12
    had at least one previously owned plane used so much it was bellied all down the center. Guide coat one sandpaper showed that, it sat flat and it wasnt.

  13. #13
    OK, I'm kind of intrigued and baffled by all this sole flattening.

    I'm intrigued, because the level of accuracy people are striving for seems to be far greater than anything needed in normal woodworking. I could see maybe having one or two smoothers capable of shaving a couple thou in thickness as a final pass, but a jack plane or jointer? no way, those planes are for taking off material quick. You don't need to have a sole flat to 0.003 to do that. The whole measuring your shaving with a micrometer thing seems like it started around the time of the internet. . . . .

    I'm baffled, because when I read threads and see videos and articles on sole flattening, people are typically using things to both measure and flatten (plain steel or aluminum rules, granite tile from Home Depot, glass on a workbench, table saw wings) that are not nearly as accurate as the accuracy that they are striving for. Not to mention not close to being rigid enough to maintain that flatness with someone pushing a plane across them. To accurately measure a plane sole to a couple thousands, you need an actual surface plate or machinists straight edge, and machinists tools. When you look at lists of woodworkers tools of yore, you don't see surface plates, feeler gauges, 1-2-3 blocks, micrometers, or lapping compound. Why is it that they are suddenly needed now?

    So I am truly curious, how flat do folks think their planes need to be (and why)?


    And now I am ducking before people start hurling their LA jack planes, high frog smoothers, bronze bodied planes, and thick irons at me

  14. #14
    I dont know about tolerances just that each one ive checked is different and the one 6 I made flat tons of years ago was nicer to use. This is the five I last checked.


    2.JPG

  15. #15
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    Looks like that has seen a few miles of edge grain...someone used it as a jointer, for a LONG time...

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