Raker tooth

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Raker tooth

Postby SalmonCreek » August 22nd, 2014, 8:38 pm

I have a light weight bucking saw with one broken raker, that I want to repair by welding on a new section. I don't have any junk saws this thin, wondering if anyone might have a junker saw willing to break off about 3/4" of a raker. My saw is .075 thick at the raker tip, and about 9/16" wide at the break. But I could certainly go a little thinner than .075, and most any width I can make work.

Thanks for your consideration, as this is my favorite small bucking saw.
Mike
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Re: Raker tooth

Postby Jim_Thode » August 23rd, 2014, 8:39 pm

Mike,
If you have any thicker junk saws you could cut our a piece for a replacement raker from the thinner part of the tapered saw blade. Even thick saws will taper down to about 0.060"

Or, you could use a thicker raker and grind it down to match the thickness of your saw. In any event welding on the raker is going to mess up the harness and temper and it may have to be hardened and tempered to get back to near the harness of other teeth.

I probably have something I could cut up if you don't.

Jim
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Re: Raker tooth

Postby SalmonCreek » August 24th, 2014, 6:00 pm

Thanks Jim. I will probably try to grind down a thicker raker tooth. As the raker is towards the end, I don't think I will worry to much about the hardness after welding, just really trying to keep the arc of the saw.

Mike
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Re: Raker tooth

Postby Starling_Saw » August 27th, 2014, 1:02 pm

After welding your new tooth in place, clean to a bright shine and heat area to about 550° . It will have the approximate hardness and temper of the rest of saw steel. John
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Re: Raker tooth

Postby Diabolo » August 28th, 2014, 7:35 am

Jim, how would you proceed to re-harden a welded tooth ? The process has many variables (rate of heating, time to maintain the right temperature, rate of cooling) that all depends on the steel composition, and will affect the quality of the hardening and the hardness value...
I don't think that hardening a single tooth that is already welded on the saw is achievable without affecting the blade itself. Either you heat treat the whole saw, or you don't heat treat anything. IMHO, I wouldn't touch anything in that direction...
The welding process will necessarily affect the tooth hardness. But I can't see how. I think it's a good idea to let the weld cool down slowly to avoid any cracks between the weld itself and the steel, but tempering the tooth after welding without having quenched the steel first would mean that the saw steel is a self-hardening quality. Am I wrong ?

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Re: Raker tooth

Postby Jim_Thode » August 28th, 2014, 8:46 pm

Hardening and tempering/softening teeth on competition saws is a common practice. Over the life of a saw individual teeth over the length of the saw may be softened, hardened and tempered several times.

To harden heat the tooth to a cherry red and quench with a blast of compresses air. The tooth then may be very hard and brittle and needs to be tempered to a usable condition. On competition saw they are left so hard that a file will not cut it and a diamond hone must be used for light sharpening. For more radical sharpening the teeth must be softened again so that a file will cut it and after filed the whole process starts again.

Of course the type of steel will effect how it reacts. I have not tried it but have a saw that one end went through a fire and is dead soft. I should try to harden the soft teeth and see what happens. In welding a teeth on a vintage saw I have unintentionally hardened an adjacent tooth so hard that a file would not cut it.

Jim
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Re: Raker tooth

Postby Diabolo » August 30th, 2014, 12:44 am

Yes Jim, I've seen the post with the saw your are talking about. Of course, as you mention, the steel must have stayed a long time in the fire to get warped this way, but that's precisely what I fear. Heating a tooth to red will affect the plate at the base of the tooth, and will necessary deform it, even a little, as it will move tension. Does it mean that hammer work is required on competition saws each time teeth are rehardened ? Also theorically, you can't heat treat steel as many time as you want, because the steel grain tends to grow and you end with a brittle / non homogenous matter, that could be critical on a saw tooth. I really wish I had more info on the way racing saws are processed.

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