Stoning honing or grinding carbide lathe cutters

[Twmaster]

I hope this is not too silly of a question...

I have some of the brazed carbide tooling that fits my lathe. I've recently tried to use these on some aluminum and steel with mixed results.

Mostly not good results. My little Chinese lathe came with a carbide cutter like the others I have in one of the tool holders for the included QCTP. It cuts fantastically on whatever you ask it to cut.

The only real difference I can -see- is the edges look better than the other stuff I have.

I'm assuming the gentleman who previously had the lathe (a retired tool and die man) had hand ground or honed that bit.

I'd like to clean up these bits I've got. Now before any of you folks pop off and tell me to just use HSS and grind my own, I do that. ;D It just seems a waste to have this tooling sitting about.

So, please do share on how to touch these up and make them cut well.

Thank you.

 

[Jasonb]

A small diamond stick/file will do for touching them up, for more major work then a green grit wheel in your bench grinder is whats needed, a noprmal one will glaze over.

J

 

[DaveH]

If you grind your HSS tools, just grind (lightly) the brazed ones in a simular manner.(Green wheel)
All I do is grind 'em use and abuse 'em.

I think one is suppose to hone them, but I never do because when ever I've tried I make them worse.
It is very easy to "roll" the edges - well I find it easy!

I grind it lightly and then see if it cuts - if it does perfect, - if not back to the grinding wheel.

Dave

 

[Captain Jerry]

I stone my HSS tools on an India stone or an Arkansas stone. You have to learn to lock your wrist and move from the shoulder to keep the angle. I keep the stone close to the lathe and take a few swipes every time I mount the tool.

For carbide, I have a small diamond disc in my Dremel tool in a fixed bench mount that I use to reshape and hone the brazed tools. I have found that even the cheap imports can be made to work well by cleaning up the relief face of these tools and adding a small radius to the tip. Once I discovered this method, I have pulled a lot of brazed carbide tools out of the junk drawer and put them to use again.

To test the edge on a HSS or carbide tool, I take a scrape across my thumbnail, sort of like sharpening a pencil. A sharp edge will scrape up a little dust with a smooth drag. If it just slides with no dust scraped up or if it bites and bounces it needs more work.

Jerry

 

[Deanofid]

Mike, I did a post on this a while back.
http://www.homemodelenginemachinist.com/index.php?topic=9576.0
This works well for me. Pay attention to Bogs post about 4-5 down in the thread. His
tip is a good WRT the direction you should grind.

 

[Twmaster]

Dean, thank you. I had completely forgotten about your VERY informative post.

I'll be hitting a couple of my cutters tonight.

 

[slotdrill]

Hello mate - many years ago I got involved with tool and cutter grinding while working for GM. If you want to get good edges on carbide there is only one way - diamond laps or wheels, period (or "full stop" as we brits say)!

Green wheels can with effort produce a compromise but its messy and the edges produced are second rate. You also run a very real risk of cracking the carbide from excesive heat which will be generated from the grinding process.

I never did find a way of getting a GOOD edge back on a blunt carbide tool without proper diamond tooling but bear in mind that my experiences in this area date back to the 'eighties and that these days you might be able to find hand tools to do the job.

I always reckon that life is to short to worry about achieving the impossible. My advice would be to chuck out the blunt stuff and source new kit from a car boot sale (Ibelieve you call 'em yard sales) or auctions (not fleabay though - so expensive)!

I'll keep watching this thread though as if anyone comes up with a revolutionary carbide sharpening medium that is more efficient than diamond I'd love to hear about it - and before anybody suggests Kryptonite - don't - I've tried it!!!!!!

 

[doc1955]

I would say diamond wheels are the best way to sharpen carbide tool bits. That is why one of my first purchases after getting a lathe set up in my home shop was a diamond wheel. I believe I spent around 60 bucks for it and I wouldn't be with out it. The only use I have found for a green wheel is to get me close and then finish the edge with the diamond wheel. The thing with a diamond wheel is that you don't grind anything but carbide on it.

 

[Twmaster]

When you folks talk of a 'diamond lap' is this what you mean?

 

[doc1955]

Yes that is good for light touch up and small radius. For more aggressive like a chipped carbide the best way is a diamond wheel. The price on these wheels have come down a long way you can find them from suppliers as low as $35.

 

[Twmaster]

I spent some time cleaning up some of the imported cutters I have. I managed to make 2 of them look really good. I wrecked another one. And wouldn't ya know it... Stupid me ruined my one really good carbide cutter by running it into the work piece and fracturing it beyond repair. DUH!

 

[jct842]

What kind of speeds do you need to turn a diamond wheel? I noticed on richontools.com they have some small ones like a 50mm with a 10mm hole. ($12.95) looks like they vary a lot in price and size too. I realize small must turn faster than large. I might just give grinding one a try since I do have quite a few carbides that do not cut smooth. john

 

[doc1955]

Here is the wheel I purchased
CDCO Tools

http://www.cdcotools.com/item.php?itemid=209
And I am running it at 1725 RPM (a motor I just happen to have handy) and it seems to do a good job for me.
I wouldn't be without it not if I'm going to use carbide.
If you use carbide tipped tool bits do yourself a favor and get a set up with a diamond wheel and sharpening carbide tipped tools will become a simple task. Also the thing with a diamond wheel don't push hard when sharpening.