[How-To] Grinding/sharpening tungsten: does abrasive direction matter?

[keeena]

Feel pretty stupid asking this, but: does the abrasive wheel direction matter when grinding tungsten electrodes? Typically when grinding anything (particularly similar sharp or pointy bits like knife blades, drills, etc..), the abrasive makes contact with the leading edge of the part. I've always assumed so it leaves less of a burr; probably a whole bunch of other reasons that I'm ignorant of.

Anyway: I'm cobbling together a diamond wheel grinder and jig setup for my electrodes. It would be easier to use the existing grinder's dust collection if I grind away from the electrode tip. Any good reasons why I shouldn't do it this way?

 

[vtcnc]

Not a stupid question at all. There is a very good reason for proper graining direction on a tungsten tip. The arc flows better from cone to tip by aligning the grain direction with the tungsten axially, rather than radially. A radial pattern will destabilze the arc as it flows. Tip angle matters as well, but you seem to be on top of that by coming up with a fixture for grinding.

Here is a YT explanation of what I'm talking about....

 

[1Bender]

Yes it does…I use a belt sander to sharpen mine…that belt is dedicated just to sharpening my tungsten rods…I put it on before I sharpen them and take it off as soon as I’m done…so I don’t contaminate my tungsten which is pretty easy to do…always sharpen them in the direction in which you want your arc to flow…when I first got my tig I sanded them rotationally and had all kinda issues…a guy told me to try to sharpen them from butt to tip and it helped me a lot…hope this information helps you

 

[keeena]

Ah, my bad - let me clarify: I am aware that you want the grinding direction to be along the length of the tip (longitudinally?), no spirals, and as fine as you can get. I'm 100% doing that. That's one of my gripes with those small, dremel-type grinders...the wheels are so small that you inevitably get spirals. I'm using 6" diamond discs; 180 for initial grind and 400 grit for finish.

What I'm asking if there's good reason/s for having the abrasive to start at the tip of the electrode vs. at the heel.

 

[jwmelvin]

I imagine people say grind into the edge to reduce a burr, and I do that on my belt grinder. But I sort of doubt much of a burr forms on such a hard material?

 

[vtcnc]

I imagine people say grind into the edge to reduce a burr, and I do that on my belt grinder. But I sort of doubt much of a burr forms on such a hard material?

Right… and at the cutting edge level. Which is a piece of alumina. Would be difficult to imagine a burr forming on a tip at that size but then again I’ve never looked at a tip up that close to take notice.

 

[GeneT45]

My guess is that any burr gets cooked off immediately, so doesn't really matter. I'm not an accomplished tig welder, but I see no difference. I went from using a dedicated wheel to using one of the small tungsten grinders, and it does leave a sort of spiral, but I don't see much practical difference there either. YMMV.

 

[keeena]

My guess is that any burr gets cooked off immediately, so doesn't really matter.

Agreed. Also, I always blunt the tip - how much I blunt it depends on what I'm welding (in addition to grind angle).

 

[benmychree]

Agreed as to direction, I always ground on the side of the wheel with scratches axial with the tungsten; diamond wheels are entirely unnecessary for grinding tungsten, aluminum oxide works fine, in a fairly fine grit.

 

[pontiac428]

From the good ol' textbook: