I need to get a stone for sharpening TIG electrodes, what material - and what coarseness? I know the tungsten cant have deep scratches from grinding, so real coarse is out. But need to sharpen somewhat quick, so super fine is out.
I recommend just a regular grinding wheel (60-80 grit.) for most sharpening. Point the electrode against the direction of the wheel and sping the electrode with your fingers. Do it slow enough so as not to create a spiral in the stirations left from the stone. Some people put the electrode in a cordless drill. Your taper should be 3-4 times the diameter of the tungsten.
Some people advocate the use of belt sanders. This works but there is some discussion on wether the bonding material that hold the grit to the belt is contaminating the tungsten.
For the best finish use a diamond wheel. This is expensive initally but it is cheaper in the long run especially in production situations. Also many of these diamond systems have dust recovery to keep it out of your lungs. California has recently enacted some legislation about thoriated tungsten.
Its amazing how many of the tig machines that customers send in for repair have improperly sharpen electrodes. It really effects arc stability.
YOu can chuck up the electrode in a cordless drill and use the drill to spin the electrode. Gives a nice even, centered point.
They also make dremel type tools specifially made for sharpening electrodes. Work really slick.
Getting back to the initial question, a standard bench grinder and wheels is all one "needs." Get a course one and a finer grit one. Rough the point using course grit side, then jump over to the finer grit for "polishing" up. As mentioned above, grind in the direction of the point.--Grant
Whatever grinder or belt sander you choose, you will want to reserve it exclusively for your electrodes to keep the contamination down.
I think "contamination" is a relative term.
If I was welding jet engine turbine blades, or parts for the space shuttle, I would be shooting for one level of quality.
If I was making a coffee table from 1" square tube, it would be a different story.
Yes, in the theoretical world, contamination of tig tungstens could be a problem. But for most real world applications, its not.
We run two tig welders pretty much all day every day. We mostly weld stainless, but with a fair amount of mild steel as well, some aluminum, and occasional copper and bronze alloys.
All the tungstens get sharpened on the belt/disc sander, both of which are running Alumina Zirconia, 50 grit CS411 from Klingspor.
We chuck up the tungsten in a makita cordless drill that sits next to the sander, and if the weldor is fussy, or the job precise, we use the belt sander, aligning the tungsten downward so the length of the tungsten is parallel to the direction of rotation.
If the weldor is quick and dirty, like me, since I am the boss, I just use the disc sander, and approximate a parallel grind.
I find it works just about as well, and since I have been tig welding for 25 years or so, I can fake it pretty good.
I used to use a grinding wheel on the bench grinder- and it was slower, not any better, and left big grooves in the grinding wheel- meaning periodic refacing of the wheel, fast consumption of the grinding wheel, and it was useless for anything else, as it wasnt flat. Cost more, too.
I find the disc/belt to be much faster, just as good a tip, and cheaper. The discs run me something like 3 or 4 bucks each, the belts a bit more, but they last weeks and weeks of use in a 3 man shop before changing.
We grind everything on this grinder- we touch up stainless parts all the time, sometimes even sand wood or plastic with it. Never had a problem with a bad weld due to tungsten contamination.
Of course, my welds arent getting x-rayed, but my guess is that for most average shop use, contamination, either of a grinding wheel or sandpaper, is just not a big worry.
If your just a hobbiest, i wouldn't worry about any of the contamination stuff, because im sure your goint to dip the filler rod into the tungsten from time to time anyway, you'll get some real pretty colored flames, but im sure your not going to bother stopping and regrinding, every time it happens. Just use what you have.