Turning Tool And Facing Tool Questions

[Joe Pitz]

Thanks mikey, I appreciate all of the good info.

Joe

 

[Joe Pitz]

[QUOTE="I normally just use a cheap (from Harbor Freight) AR-8 brazed carbide tool and grind a little more clearance on the nose so the angle is less the 90 degrees. I own a set of cheap insert holders, but I've only used them about 2 times. I would rather just grind to shape I want for the job.

Jim, could you show me an image or drawing of how you grind a little more clearance on the nose. I set up my tile saw today and made an attempt to clean up some carbide brazed tips. The tile saw did a pretty good job. So later this evening I stopped at HF and picked up a diamond hone set. I want to try your less than 90 degree modified AR-8 tool.

Thanks

Joe

 

[JimDawson]

Here is a picture of an out of the box AR8 brazed carbide. This is the base tool used in the following examples. The cheap HF tool bits will not cut right out of the box, clearance needs to be ground before use. All of the grinding was done on a standard gray aluminum oxide wheel on a bench grinder.



This is one example, in this case the carbide has been ground to about 85 degrees and a bit more clearance ground on the supporting steel.



Another example of a highly modified bit with a chip breaker ground in with a diamond wheel in a Dremel. This creates the little curly chips rather that the stringy mess without the chip breaker as above.



Another view of the same bit

And I have no idea what the 3 black dots are, on the side. I couldn't see them with the naked eye.




and another view



I should note here that this tool was cutting just fine and had been for about an hour of cutting 4150, Here is a picture of one of the parts that was cut with this tool. As crappy as the tool looks, you can see the finish was just fine. This started out life as a 1.25 dia chunk of 4150.



Here is the same tool on another job, that is a 3 inch dia chunk of 4150



Here is an AR8 ground into a threading tool

 

[kingmt01]

Nice wrote up Jim.

I read on here about threes guys grinding there cheap carbide tools so I have it a try. First I tried grinding the soft metal with a white stone which seems to slowly remove the carbide also but that isn't part of the plan. I then finished the shape on the diamond hone returning to the white wheel every time I got back into the soft metal. I then made a arbor to turn my diamond wheel & tried another tool on it. Both ways of making citing tools produced very nice cutting tools but shaping them on the hone was the fastest.

I didn't remove anything on the top like Jim shows so I may have to try that next time. I have found that not only does my ground carbide tools cut better then the out of the box ones but they last longer also.

One suggestion is once your close to the shape you want is to have the tool nice & cool so you can finish the tool in one holding at the stone because if you take small grinds you won't get the tool held just right when you start the grind again. On a hone it is easy to pick up the shape again.

 

[Joe Pitz]

Thanks Jim, that is amazing the flexibility that you get by grinding the carbide.

Joe

 

[Strtspdlx]

I'm a complete newbie when it comes to tool grinding. I have an atlas 10" and all I've ever used was hss. That being said I went with trial and error for grinding bits and seeing how they cut. I bought a ten pack of cobalt hss and wasted half of one to figure it out after watching tubalcains video. The most important thing I got from it is you want to present the cutting edge to the work. I
Make up my angles I've never once measured one and to this day I haven't had an issue. If I don't get the finish I want I stone the edge to round it and magically I get a good finish. All other variables aside learning to grind hss tooling is mainly trial and error I wouldn't worry about pretty right now. Make it work and once you figure out what works then you can pretty it up. All my grinding is free hand also.


Regards-Carlo

 

[Joe Pitz]

Thanks Carlo, you make it sound so easy. Your advise makes a lot of sense. I will keep on practicing.

Joe

 

[Strtspdlx]

Thanks Carlo, you make it sound so easy. Your advise makes a lot of sense. I will keep on practicing.

Joe

Just don't be afraid to mess something up. The only way I learn is the hard way. And the only way to get good at something is by doing it (experience)


Regards-Carlo

 

[Tozguy]

Joe, I definitely think that you will get comfortable with grinding tools because the eventual payback in enjoyment is tremendous.
It is not always easy to interrupt a job to sharpen the tool but once you have a taste of using a really sharp tool it will become second nature. A good magnifying glass will help you see what the work sees.

The following product might be worth a look for ease of sharpening. I have no relation with the company other than being a happy customer. It was the ole 'cry once' principal but have had much pleasure using this tool ever since. http://bay-com.com/product-list.php?DIAMOND_TOOLHOLDER-pg1-cid35.html

Good luck, Mike

 

[Joe Pitz]

Thanks Tozguy, the price is quite steep in the diamond tool holder, but I watched some of the videos, and with cobalt the performance is amazing.

Joe