While grading my road yesterday with my Bota L4400 I hit a stump bending my 7ft Woods back blade. I was able to bend it back but the cutting edge broke in two and there is a crease in the moldboard. I was bummed thinking I would have to replace the whole asssembly but I realized that I may be able to just replace the cutting edge. The moldboard bent back easily and the blade is now straight, so it seems as though most of the strength is from the steel cutting blade. Is that true? Can I get by with just replacing it or am I at risk for breaking the blade again?
Broken Back Blade
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MJPetersen
Veteran Member
You can probably just get by with getting a new edge. The moldboard is just mild steel and you might straighten it a bit better by getting it HOT and hammer the wrinkles out. Finish with getting it HOT again and letting it cool slowly. Since hammering will produce work hardening and the reheating will allow it to normalize. If you do not do this it will be weaker in the the place that you bent it and it will bend there again more easily than the first time.
If it were mine--I would probably weld the edge back together too--Before you all jump on me, hear me out. I know that it is hardened and that welding will somewhat ruin that, but I would still do it. here is what I would do: bevel the broken pieces so that I can get complete penetration in the weld, clamp it to a strong back to keep it straight, heat the weld place from 400 to 600 degrees, and weld hot alternating sides until it was full dimension. I would then smooth it up on the back for mounting on the blade, heat it again and then let it cool. I believe that it will last for a very long time if you do that. Of course that is only what I would do, you are free to do as you please.
Mike
If it were mine--I would probably weld the edge back together too--Before you all jump on me, hear me out. I know that it is hardened and that welding will somewhat ruin that, but I would still do it. here is what I would do: bevel the broken pieces so that I can get complete penetration in the weld, clamp it to a strong back to keep it straight, heat the weld place from 400 to 600 degrees, and weld hot alternating sides until it was full dimension. I would then smooth it up on the back for mounting on the blade, heat it again and then let it cool. I believe that it will last for a very long time if you do that. Of course that is only what I would do, you are free to do as you please.
Mike
3RRL
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I love the way Mike approaches problems like that. It's very much like I do, that is repairing when I can. It's a blade after all and not a transmission or something intricate that has to be perfecto ... lol. So a repair like he suggests is a pretty good idea. Of course you could go new, but what the hey?
It's also a good time to see where you could add some reinforcement to the mold board to strengthen it. That too would add weight, not only strength. Added weight is a friend for future blade work.
Good luck...
It's also a good time to see where you could add some reinforcement to the mold board to strengthen it. That too would add weight, not only strength. Added weight is a friend for future blade work.
Good luck...
MJPetersen
Veteran Member
Thanks Rob,
I have to admit that I sometimes have some pretty far out ideas--brazed a chunk back into the block of a kohler that pitched a rod through the camshaft side in a 16 hp mower. Blocks are expensive you know. Last I knew it was still running!
I forgot to mention, although I thought it--my fingers did not work as fast as I was thinking--that I probably would add a "stiff back" to it too. that is a piece of angle or even a piece of flat stock placed perpendicular to the blade. I have looked at those blades, but they did not seem strong enough to me so when I made mine I tried to made it stronger! A stiff back will add a lot of strength and would be relatively easy and not expensive. Put it just at the top of the cutting edge mount.
Oh--Paint is optional!!
Mike
I have to admit that I sometimes have some pretty far out ideas--brazed a chunk back into the block of a kohler that pitched a rod through the camshaft side in a 16 hp mower. Blocks are expensive you know. Last I knew it was still running!
I forgot to mention, although I thought it--my fingers did not work as fast as I was thinking--that I probably would add a "stiff back" to it too. that is a piece of angle or even a piece of flat stock placed perpendicular to the blade. I have looked at those blades, but they did not seem strong enough to me so when I made mine I tried to made it stronger! A stiff back will add a lot of strength and would be relatively easy and not expensive. Put it just at the top of the cutting edge mount.
Oh--Paint is optional!!
Mike