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Repair

Don’t like words? Check out the video.

If you use a scythe, you’ll damage it.

Unfortunately, that’s a fact. You can do a great deal to prevent damaging your blade:

  • Ensure your action is slicing, not hacking – with a nice arc you’re more likely to strike obstacles with the point of the blade, and even those that do come into contact with the edge will do so at more of a slight angle rather than as a full frontal attack.
  • Don’t use excessive force – keep the blade sharp and let it do the work for you.
  • Keep the mowing terrain clear. Depending on your situation, this can be very difficult. Kids leave stuff behind, thoughtless motorists throw rubbish over fences, and even we scythers may occasionally forget to pick something up…

But, it’ll happen. You’ll find a rock you didn’t know was there, or you’ll misjudge a fence line and hit the wire, or the stem you thought was still green has started to die off and is much tougher than it looked.

Damage to the blade’s edge can include dents, chips, tears, and burrs, or, in a nasty case, a combination of all four. In the scheme of things, these are all good – that is, they’re easily repaired if attended to quickly. At the other extreme you can induce a stress fracture on a blade – typically around the area where the tang’s neck turns into the blade and starts thinning out. These are not good and the long term prognosis is a complete replacement. A stress fracture is also an indication that you should assess your mowing action – it suggests that the blade has been taking a lot of abuse and this is basically the blade ‘giving up’.

In an ideal world where we are all making our own snaths from local timber, a snath breakage could also be considered a good thing – a light snath can be a bit like a safety fuse for your blade; if you’re abusing your blade, the snath breaks rather than the blade. With our Canadian snaths however, this is highly unlikely – they’re tough (white ash is used to make sports equipment like baseball bats) and quite thick at 32mm. Thinking of swinging one with the force required to snap one of these makes us feel physically ill; if it ever happens, you can rest assured that you’re doing something wrong.

So, all going well, you’re only likely to have to repair a blade edge. (Do also read about one case of stomach-churning damage of which we were informed).

Repairing a dent

Just tap it… put it on a solid base (the jig, an anvil, or any other bit of hard steel) and tap it with a hammer. If the dent is severe, tap it from the back of the dent (the concave side) – you’ll be less likely to damage the edge further.

Repairing a burr

If you’ve run your blade along a bit of fencing wire or similar, depending on how thin the blade is, you’ll likely visibly burr the edge and you can even fold an edge over on itself. This is best taken off with a light file, then honed, and if the repair takes more than a millimetre or so from the edge, peening that part will also bring it into closer uniformity with the rest of the edge. You should also first check for any cracks as these are the real risk to a blade’s longevity.

Repairing a crack or a chip

Recommending what to do with a crack or chip is a bit of a dilemma for us. You can take a “wait and see” approach, and if all goes well, and you avoid peening that part of the blade, there may be no problem and with repeated honing you’ll eventually take off enough steel such that the crack ceases to exist. However, the wait and see approach is really only likely to work if you have a nice mowing action and you’re unlikely to do whatever caused the crack in the first place, again.  So, on balance, we recommend that a crack should be addressed as soon as it’s noticed, or it will run deeper and deeper into the blade. A couple of cracks in close proximity may also lead to a chip. Similarly, if you don’t repair a chip straight away, you’re running the risk of inducing a crack (or deepening the crack that gave rise to the chip) because the chip creates a ‘shoulder’ in the blade’s edge which becomes a point of impact at which a lot of force can be applied.

A blade with an inadequate repair, which led to a very deep crack.

A blade with an inadequate repair, which led to a very deep crack.

The basic idea of an edge repair is to restore the edge to a similar (but not identical) state to the edge on either side of the damage.

  1. Identify how far into the blade the repair has to be made. If the blade is only chipped, you need only file out to the depth of the chip (in doing so you’ll go a little deeper, which is a good thing, in case there is the beginning of a tear that you can’t see). If the blade is torn, you’ll need to look closely at where the tear ends, and then allow a few mm beyond that for the tear that you can’t see.
  2. Use a file to file out the blade to the required depth. Depending on the shape and size of the damage, a chainsaw file or half round file is a good choice. Take out extra steel on either side of the repair so that there’s not too much of a shoulder – that is, you’re aiming for the repair to have a more gentle curve, rather than a sudden drop deep into the blade.
  3. Peen around the edge of the filed steel, starting a few mm back from the new edge, drawing the steel down. Don’t be over-zealous; if you thin the steel too much you’ll end up with the repair being a soft spot which is likely to require attention again in future – so leave the repaired edge a little bit deeper than the surrounding edge.
  4. Hone the repaired edge to get it fit for mowing.

 

Peter Vido’s diagrams are a useful resource, and we’ve got a video here.