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(08-17-2017, 12:24 PM)JosephP Wrote: I think this may be the best place to get a good answer for my question ...
I have several Silky brand hand saws for pruning trees. Some say they are sharpable others are impulse hardened to hold theur edge longer and are not sharpenable. Replacement blades are not cheap. Can I use heat to soften an impulse harden blade and successfully sharpen it? I know it will not hold the edge as long. But it is at the end of its useful life as it is... so if it will work I might as well.
I doubt you would get acceptable results trying the anneal these blades without first knowing what kind of steel was used.
But as you said, if the blade is used up and intended to be tossed, then there is no harm in trying.
Some questions:
Your plan is to heat to loss of ferromagnitism, quench, then temper?
Do you know what kind of steel is used in the blades? This would tell you about the tempering temperature.
Are you shooting for a particular Rockwell number? This would tell you about tempering temperature and time and Currie temperature.
Can you replace the impulse hardened teeth blades with "conventional" blades from Silky? Then if you did invest in the right files (feather files perhaps?) you could maintain them.
Don't sweat the petty things and don't pet the sweaty things. -- G. Carlin
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(08-17-2017, 12:24 PM)JosephP Wrote: I have several Silky brand hand saws for pruning trees. Some say they are sharpable others are impulse hardened to hold theur edge longer and are not sharpenable.
Just to be clear, you have several, and some "say", ie, are marked in some way to be resharpenable? As far as the impulse hardened ones, I frankly would not waste my time unless, as noted, you know how to deal with the steps in making them soft enough to sharpen, then re-harden. If you have some in the first category, I'd contact Silky's customer service for a suggestion on what file (feather most likely, as noted) to use, then sharpen 'em up. File sources:
http://www.leevalley.com/us/wood/page.as...3072,43089
http://www.toolsfromjapan.com/store/inde...f751e828e9
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The saw is SK4 High Carbon steel...per specfications.
yes it would be with a feather file to sharpen it. I have sharpened the ones that I can. There are different styles and sizes. The one with a really narrow blade is great for getting in tight spots...it is hardened (says it cannot be sharpened...or more accurately Silky lists saws that CAN be and it didn't make the list). I don't know about the technical numbers of Rockwell hardness Etc I just want it to cut wood quickly like it used to. It is not bad now...i suspect somebody who has never used a Silky would be impressed. But it isn't what it was.
I guess that is my question...how hot get it? Propane torch glowing red then plunge into water???
Here is the specific saw i want to sharpen. Or just replace the blade if need be.
Thanks for any thoughts!
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The impulse hardened saws I've seen have had a distinct line of darkness at and along the teeth.
Maybe the best way to find out would be to try to sharpen one!
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Bake in oven, till blue. You can file the teeth then.
Or use a diamond file.
Cheers
Pedder
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(08-17-2017, 02:27 PM)Bill_Houghton Wrote: The impulse hardened saws I've seen have had a distinct line of darkness at and along the teeth.
Maybe the best way to find out would be to try to sharpen one!
Maybe a dumb question...would that hurt the file? They don't come cheap either and it is kind fragile with the very narrow edge. I have already chipped one.
The saw(s) in question have that dark line.
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(08-17-2017, 03:27 PM)Pedder Wrote: Bake in oven, till blue. You can file the teeth then.
Or use a diamond file.
Cheers
Pedder
What temp?
Let it cool slowly or put in water when it comes out?...right away or natural cooling then plunge? Should I put it on an old cookie sheet (and turn it) so the rack doesn't cause uneven heating???
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I was talking to the owner of Boggs Tool and File sharpening several years ago about file sharpening, and he mentioned that he could sharpen saws with impulse-hardened teeth with his sharpening process. I've never had them do anything for me except file sharpening, but I've been very happy with that.
You might give them a call and see if they can sharpen your saws.
Here is the link:
Boggs Tool
Rick W
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(08-17-2017, 06:24 PM)RickW Wrote: I was talking to the owner of Boggs Tool and File sharpening several years ago about file sharpening, and he mentioned that he could sharpen saws with impulse-hardened teeth with his sharpening process. I've never had them do anything for me except file sharpening, but I've been very happy with that.
You might give them a call and see if they can sharpen your saws.
Here is the link:Boggs Tool
Rick W
Now that is interesting.
Don't sweat the petty things and don't pet the sweaty things. -- G. Carlin
