C2 or C5 (maybe C6) grade? *The higher the number the "harder" -not exactly the right word- the carbide and the harder the carbide the longer it stays sharp and the harder the material it cuts easily but the easier it chips.
I think I've bought them there, but I've bought bits from multiple suppliers over the years and can't swear to it.
They all seem to be about the same if they're Chinese made ones, not bad for the price but usually not sharpened very well and need sharpening to cut properly. Not the best, but for the price usually what I end up using for most of my needs. I've often wondered if they (the Chinese) are all that particular when it comes to the grade of carbide used, or use the same standards for grading it.
Use the right grade for the metal you are cutting and they work OK (after sharpening). They're cheap enough you can feel free to experiment with different grinding angles and such without being concerned about the cost if you ruin one.
hey, thanks for the info. I'm not a total numb nuts, but I just started working with metal and my mini metal lathe is still somewhat of a mystery.
I don't understand sharpening carbide, but if you would be so kind as to lightly explain the whats and wherefores I would appreciate it. My Email is
okiebugg200@cox.net if you would send me some info. A super thanks for explaining what you did about the different grades of carbide....
You e-mail link fails so let me just give you this link
http://www.team358.org/files/mechanical/Sharpening_Lathe_Tools.pdf for a basic reference on lathe bit sharpening.
It isn't carbide specific but will give the basic knowledge of what you are trying to accomplish when you sharpen the bits.
One thing is imperitive - you need a special grinding wheel for carbide. You need green silicaon carbide wheels, the normal aluminum oxide ones you use for everything else just won't work with carbide (and the silicon carbide wheels will wear out surprisingly fast if you use them for steel).
A simple bench grinder will work fine with the right wheel(s) on it (I keep one green wheel and one regular wheel on one of mine and it's just a cheap 6" bench grinder). The bits you bought should already be the shape you want, all you need to do to sharpen them is put a good edge on them with the grinder (I usually like to cut a bit of relief angle on the front and leading edge since I find that works better for my style and my lathe).
You can reshape any of the bits to any shape you want, but the C style (square piece of carbide) lends itself to anything from grinding a radius to an off center 60 degree for threading up to a shoulder (or grinding for whitworth or acme thread styles).
The most important thing is to keep them sharp (as in really sharp). I have a machinist friend (a real machinist, not a hack and whack hobbyist like I am) that keeps a diamond sharpening stone with him and routinely gives a quick touch up stroke to the edge every time he puts a bit in or stops the lathe between cuts.
