End of Stanley plane blade has gone blue from grinder
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Tagged: burned metal, plane blade
- This topic has 7 replies, 3 voices, and was last updated 6 years, 2 months ago by Larry Geib.
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Hi Folks,
I just inherited an old Stanley No 4 which seems to be in good condition apart from some rust in the usual places eg blade above the lever-cap.
However, when I removed the blade to sharpen it, I found the cutting edge was blue to about 3-4mm back from the edge in a couple of places which had been hidden by the chip breaker. This looks like it had overheated when the previous owner put it to the grindstone to aggressively.
I’m not sure if this means the blade is ruined or recoverable. the blade seems to be fairly normal length so I don’t think it’s been sharpened too often. I don’t particularly want to grind back all that metal if I don’t need to, but I also don’t want a blade that won’t take or hold an even edge.
Can I ignore this and let it disappear over time as I sharpen or do I need to grind it back until the bluing is removed now? Can you also tell me how much of the blade I should expect to be hardened and is it at the end of its useful life once you sharpen all the way past the end of the hardened section or is the blade considered worn out at some point before then?
If the blade was not decarburized during its first (or any possible subsequent) hardening(s), you could re-harden and re-temper the entire blade (info on that widely available on the internet), but if that’s not something you’re interested in doing, then you’ll want to remove the blued portion as it has lost its temper. Any straw-colored metal on the border of the blue portion is still OK.
I am not familiar with Stanley’s procedures, but I think it likely the entire blade was hardened and tempered, not just the tip, so you can likely use it until it will no longer sit in your frog.
26 February 2018 at 5:15 am #484854In my experience, there are two types of blades. Older ones are laminated tool steel edge on a mild steel body and only the tool steel is tempered.
Solid high carbon blades are only tempered to about the slot. The rest of the blade is still pretty soft. You can Check with a file.
The only thing to worry about is that you don’t create a hard transition if you retemper those irons.
26 February 2018 at 5:31 am #484862I looked for a picture and found this
https://paulsellers.com/2015/05/laminated-stanley-plane-irons-n-more/
26 February 2018 at 11:16 am #484968Sometimes the lamination doesn’t become apparent unless the iron is etched or something. I first noticed it on one of mine after an overnight vinegar bath I put it in to derust it. After polishing, I couldnt see it again.
But irons after the sweetheart era generally weren’t laminated
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