Carbide Woes

[Ray C]

Thanks Rich, that's good advice.

Also wish to mention that interrupted cuts put a quick end to carbide. Also, the 1st passes on a piece of rusty/scaly stock chips the surface too. I've gotten into the habit of sandblasting first and also using cheap HarborFreight brazed carbides to remove scale. They're good for several descalings and can be touched-up with a wheel. -And for 50 cents a piece, it's no great loss if one chips deeply.

Ray

One more thing, you guys probably know this, but will add for the beginners. Be sure not to stop the spindle when the carbide is engaged in the metal as it will crack or chip the carbide. Make your pass and move it back or screw the tool back. Even dragging the tool over a stopped part will damage the cutting edge. I would also suggest you look at a Glendo Grinder for sharpening the tools, slow speed and no heat. I have one I have used for 20+ years and only replaced the 600 grit wheel 3 times, but I also use it in my scraping classes. For an occasional user a wheel would last for years.

 

[swatson144]

Thanks Rich, that's good advice.

Also wish to mention that interrupted cuts put a quick end to carbide.
Ray

For interrupted cuts I step down to c2 or c3 even on steel, The softer carbide (more cement) handles the pounding better. compared to breaking on impact I'll take the faster wear any day. It's pretty much all I use on fly cutters anymore.

Steve

 

[Levi]

You mentioned having changed the tool height when you changed to HS steel, and then back when going to carbide. I would suggest that when you were initially using the carbide tool you may have accidentally had it in just the right location, and when you changed back you didn't get it in the same place. Carbide can sometimes cut better with a negative rake, which is what you would have if it were set it below the centerline. I recommend (after you're sure the tool is sharp) that you try setting the tool at various heights other than right on center to see if there is a sweet spot. Also I always use a small diamond stone/hone on a carbide tool as a final step in the sharpening process, or sometimes just to touch up a tool.

 

[refinery Mike]

I agree on the idea of hand honing carbide bits. I have two identical 3" x 4" diamond hones One fine one course. They cut carbide like butter. Actually they cut carbide faster than they sharpen steel. The only thing is that you should remove just enough brazing below the carbide if it is a cemented tip. The brass fouls the hones.

 

[Allan]

I guess ignorance is bliss.
Steve, I'm not sure what type of carbide I bought. It is a brazed bit on a 1/2" sq tool bit. Mike, I had plenty O' interrupted cuts before the edge went south. I was turning down a hardened MT sleeve and the slot for the drift taper made a consideable "cha-chunk" every time the tool went over it. Maybe it was the softer grade?

I,too, was amazed that the diamond hone would work so quickly on a dreaded carbide tool. This took a few minutes- not hours to put right. I had to grind away a bit of the under lying steel to get some clearance angle back. Worked great until I was done.

Levi, I fiddled with tool height, thinking the same thing. But once I honed it it didn't seem too fussy abaout the exact height. Thank you all for your input. I have never used carbide B4 and don't anticipate using it much but it is nice to know it can be used without fear.

Al