Ok be ware I will provide some shameless plugs here!
#1 get a Dewalt Cordless 4 1/2 inch angle Grinder $300
#2 out fit the above grinder with a Green wheel from Alpine Machine $175
#3 buy 2 extra battery's and have enough chargers to charge at least 3 battery's at a time! $175
it will take you 3 battery's to sharpen a Sandvic wheel if you are good, as many as 5 if you are learning or just let it go too long! at least 2 required to sharpen an 8 tooth Multi tip wheel.
when sharpening Imagine you are creating a shaver .... a round edge will be similar to beating a stump to death with a ball peen hammer ????? the closer to a 90 degree edge you can make the better off you will be.
I Sharpen my teeth EVERY night after 5-8 hrs of grinding time. this makes sure my chips are smaller than your little finger nail and mix nicely with surrounding dirt. A round DULL tooth will "STRING" out your stumps especially in Soft wood!
Grind off your face first thinning the carbide, then grind the sides and top attempting to create a point of 90 degrees or there about so as to act like a shaver.
this action will Quadruple the usable life of your teeth when the carbide gets thin enough to start fracturing then and only then replace your teeth.
I also take my Dewalt to grind with me so if necessary I can Tune up the teeth as the day progresses! my Machine is fully Remote control so I watch the cutting action full time if it is cutting better one way than the other or the chips start coming out way bigger than they should I spend the time to look at the cutting teeth. This action may take a few minutes but in the long run it saves both time and money!
I incorporated this Idea as a result of a conversation that I had with a Sawyer buddy of mine, and a post I got replied to on this site, where in stump grinders were spoken down to, and looked upon as some one who could not make it other wise in the tree Business. This as you well Know is Crap. but I thought I would go about educating those that would listen about what it will take to improve standing in the industry and make us all better.!
If you call Kieth at Alpine Machine he can hook you up as well as give you any advise you may ask for! if this was helpful please like the post!
good luck!