Brittle Plough plane blades

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  • #692375
    Kasper
    Participant

    Hi,

    I bought Marples 044 plough plane about year ago. Didn’t need at that time so I only used it the first time this week. The problem I’m having is that the blades don’t hold an edge at all and keeps breaking off after 5 shavings even on pine. There is some ”case hardening” marks on the side of the blades. Is it possible that someone ruined them by letting them heat up too much during sharpening process? Do you think there is anything that I can do to make them work again or should I be looking for new blades. I’m not sure are the blades original or not.

    I can send pictures of the blades tomorrow if that’s any help.

    #692379
    Darren
    Participant

    I’ve had mixed results with brittle chisels and irons.

    Sometimes you can put them on a very coarse stone and hog off a decent chunk of metal to get down to good metal.

    Sometimes the heat damage goes a long way, and I have given up on some chisels like that.

    One thing that might help is to go for a larger angle grind. What angle are you sharpening them to?

    Cheers

    Darren.

    #692625
    Kasper
    Participant

    Thanks! I sharpened them to 30 degrees and already took 1 cm off from one blade and regrinded the bevel but the result was the same.

    Looks like I need to find new blades unfortunately.

    #692628
    Larry Geib
    Participant

    Try a little steeper, say, 35 degrees and take another mm or so.

    Record and Marples 044 irons were made with Tungsten steel, which is a lot like high speed steels such as A2.
    They are often happier with steeper angles. 30° is kind of the lower end for these steels.

    I don’t think you would have much luck trying to retemper the irons, though. Hardening and tempering Tungsten steel is a bit more complicated and at higher temperatures than an easy to work steel like O1.

    The good news, I guess, is a full set of irons from Ray Isles or Classic Handtools is only about £40.

    #692633
    Nikolaj Thøgersen
    Participant

    Do you have some pictures? I would like to see the case hardening marks and the broken edge.
    Case hardening is a process where the outside is hardened, but the inside is soft. This is typically done on files, which must be very hard, but not break if dropped on the floor.
    It could be that they are not properly tempered. This is done after hardening to regain some toughness in the steel.
    You could attempt this on one of the blades, before you discard them. If your oven is fairly accurate, try the following:
    Heat the blade in the oven for 2 hours at 200°c
    Let the oven cool down to room temperature before removing it. Do this twice.
    Try the blade. If it’s still too hard, raise the temperature 25°, and repeat the process.

    #693059
    Kasper
    Participant

    I sharpened the blade to 38 degrees and now it works brilliantly! I tested on pine and beech. Thank you very much Larry!

    #693100
    Larry Geib
    Participant

    Congrats! Glad it helped.

    Just be careful you leave some clearance angle when you resharpen the iron. If you round the tip convex you might not have any clearance angle from the 45° bedding angle of the plane. 38° is pushing the limits in that direction. You might consider backing off a little And instead introducing a back bevel of a degree or two on the “flat” side .

    David Charlesworth has developed a method using a guide like an Eclipse guide to introduce a back bevel here:

    He’s showing the method with a bench plane iron, but the principle is the same.

    Plough irons are pretty small and dificult for me to hold, so I generally use a guide for sharpening them.

    You’ll understand when you are old and have arthritis. 😉

    #693491
    Kasper
    Participant

    Here are pictures of the ”case hardening” marks. I havent’t tried sharpening these two blades yet, so i have no idea do they work or not.

    Thanks for the insight Larry! I didn’t even think about that. I’m young I still struggle to hold small plane irons😂 what would be your recommendation for guide to small irons. I have the cheap version of eclipse and I have tried to modify it but I still don’t like it for small irons.

    #693504
    Darren
    Participant

    I’ve seen people sharpen small irons and spokeshave blades with the Lie Nielsen sharpening jig, but that is WAY expensive…

    #693508
    Larry Geib
    Participant

    That’s not case hardening. Somebody ruined the temper by overheating the tip while grinding and probably burned off surface carbon, making it softer. Your multiple attempts at sharpening probably ground enough steel to get past the ruined tip which had carbon in the steel burned off. . It likely had little to do with the sharpening angle, but if you had success, keep doing it. The steeper angle gets you past the burned part sooner.

    Case hardening is the controlled introduction of carbon INTO a thin surface layer of the steel. The modern method is by heating the steel in a high carbon gas environment. The “case” is the thin high carbon layer formed over the softer core.

    The ancients knew about case hardening, usually accomplishing it by heating iron in charcoal dust or any high carbon concoction including dead animals and meat, or even urine.
    They didn’t understand the chemistry, which made conversion to steel a the stuff of magic dwarves and such. Ill confess I think of Wayland or Hephestius every time I see a Smith do it at a forge

    #693513
    Larry Geib
    Participant

    I’ve seen people sharpen small irons and spokeshave blades with the Lie Nielsen sharpening jig, but that is WAY expensive…

    A $10 eclipse style guide will do as well on narrow planes of a plough plane. The Lie Neilsen is nice for wider plane irons, but offers no real advantage on narrow ones.

    They will probably have to be modified, but it’s not hard. Lie Neilsen’s Deneb Puchalski even offers a video on filing the lands on the guide so irons fit better. The goal for plough irons is usually to enlarge the “V” that holds the small irons without filing the part the iron registers on, keeping one side flat and the other round to ensure 3 point contact.

    Before you spend money on the premium jig, make sure it fits the irons and chisels you own. I recommend taking your tools to a lie Neilsen tool event if one is offered near you ( after the pandemic). There is no great loss if you ruin the cheap guide, but it’s different story if you screw up a $130 stainless steel one.

    #693516
    Larry Geib
    Participant

    Bob Van Dyke also offers a tutorial on modifying the eclipse guide

    He seems a bit more aggressive on filing the flats. The goal is to make sure the irons lie flat

    There are other cheap eclipse style guides that seem to have better shaped lands, but I have no experience with them so i won’t recommend any.

    • This reply was modified 1 year, 7 months ago by Larry Geib.
    #693543
    Sven-Olof Jansson
    Participant

    Please allow me to point out that Lie-Nielsen offers a separate pair of jaws for narrow blades.

    https://www.lie-nielsen.com/products/bevel-edge-chisel-honing-guide-jaw-pair?path=honing-guide&node=4239.

    Whether that will help with the many types of plough plane blades, I don’t know.

    Sven-Olof Jansson
    London, UK; Boston, MA

    #693545
    Larry Geib
    Participant

    That’s true. It also bumps the original $125 purchase to $160 plus shipping. And you still don’t know if the jaws will work with whatever chisels you own. Those jaws are only guaranteed to work with LN chisels. They will probably work with Stanley old and new 750’s, LN copied, for example, but probably not other lines of Stanley chisels. Until you try your irons, you will have no idea if they fit.
    They make another set of jaws for short irons like on a spokeshave.

    If you are really into boutique tooling you can add another $250 in jaws. That’s getting close to the cost of a baby Tormek.

    And none of that expense guarantees your irons will fit. Lie Neilsen designs their guide and jaws expressly for the irons they produce without any guarantee they will function properly with irons made by any other manufactures. You might still have to grind jaws that alone cost twice an eclipse guide.

    I found that out when I took my irons to a hand tool event. I wanted especially to be able to sharpen the iron on the skew iron for my stanley #289 moving filletster but the LN skew jaws were the wrong angle and the wrong length. (. I figured that might justify (sorta) the $150+ for an iron that is hard to get right.. I went another route.)

    If you go the LN route, I again strongly urge you make sure it will work with your tools. Go to a hand tool event and physically put YOUR irons in their guide. It’s not an impulse purchase to make.

    At the minimum, ask them about their return policy and know you might be paying shipping twice and end up with nothing.

    • This reply was modified 1 year, 7 months ago by Larry Geib.
    #693625
    Colin Scowen
    Participant

    I also use a modified version of the cheap and cheerful version of the eclipse that I got in B&Q a few years ago. I find you need to be gentle with it, to avoid rocking, but it works well enough.

    Colin, Czech Rep.

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