Hi,
From the various instructional videos I've seen about sharpening recurve blades, the central theme seems to be that the grinding wheel must have have a radius on the edges, over which the recurve section is carefully ground.
This is fine with wheels like the SG-250, but how about if you want/need to use a diamond wheel like the DC-250? As I understand it, the diamond wheels consist of a rigid cylindrical form on which diamonds are deposited - the edges cannot simply be ground over to make a radius. The edges are always going to be 90°
Any thoughts then on using the Tormek diamond wheels to grind recurve blades?
TIA,
Nico
PS: I am attempting to re-establish the edge on a cutting blade for a brush cutter. Kind of looks like this:
I suppose that with (jedi-)master-level skills it could be doable. But it's probably a very bad idea.
Diamond wheels do not like pressure so if you use only the shoulder you'll have to be extra extra light, as all the force of the blade will be focused there. Avoiding damage will be very difficult, though if you have just a couple blades it might no be such an issue.
Conversely, you'll be applying all the grinding effect on just the part that touches the shoulder of the wheel. So you'll have a lot of action just there. Grinding evenly to maintain the shape will be a real challenge.
And as will all stones you can't use the usual means (jig/bar) that allow for controlled angle grinding, which will not help.
Now about your brush cutter, I can't help but wonder : Are you 100% positive it is a recurve blade ? It looks to me like a straight blade but ground only in the tip area. You shouldn't have too much trouble grinding those on the Tormek, even freehand.
I have a very similar if not exactly the same brush cutter blade. I'm almost certain that it is only the flat triangular section that you need to sharpen. As the previous poster said, should be no trouble on a Tormek.
https://youtu.be/uj8P6O-qIYs
Here is a Tormek Video for gardening tools. Minute 53:53 shows a brush cutter blade sharpening.
Thanks for all the replies.
The blade is an Echo part. I have a brand new spare blade, and indeed, the curved parts that join the triangular tips are ground to a bevel. It's an extremely coarse bevel, to be sure, at least 30 dps, but it is a bevel nevertheless. From that stock image that bevel is not so visible, but it exists on my blade. The flat triangular parts don't pose any difficulties to sharpen like normal blades.
Thanks for confirming what I suspected with the diamond wheel. I will attempt it freehand with the SG-250, which I have created some generous radii on the edges.
Quote from: HaioPaio on Yesterday at 07:14:44 PMhttps://youtu.be/uj8P6O-qIYs
Here is a Tormek Video for gardening tools. Minute 53:53 shows a brush cutter blade sharpening.
Thanks... Very useful! I have blades like that one, which do have straight edges. The Echo blade however comprises a recurved section in between the triangular tips.
I would use a single cut half round file. It is not as if it needs to be precision sharpened!
A file will indeed work well, as will the rounded out SG. The worst that can happen is that you'll round it out some more. And you don't need any of the precision that comes with the Tormek for this : most of this part of the blade has such a low velocity relative to the brush being cut that it won't matter anyway.
And it would be a shame to risk your diamond wheel for this.