# I learned a new trick today



## JimDawson (Jun 14, 2014)

I am turning some 4150 and needed to grind a chip breaker into the cheap HF POS brazed carbide bit.  I was heading for the carbide grinder and noticed I had a few Dremel 545 diamond wheels in the top of my tool box that I had bought for another project.  I thought, hmmmm:thinking:.  I grabbed the Dremel, chucked it up, and tried it, it cut carbide like butter.  I was able to grind a nice chip breaker in the tool and do a bit of other shaping on the bit also.  This is one of those things I never thought of before.

Just thought I would pass it along.


About $18 at Home Depot or buy online for less.



	

		
			
		

		
	
 From Dremel's description:  ''_The 545 Diamond Wheel is completely coated with fine diamond particles for working with hard materials. Designed to be long lasting and not lose its shape or break, it provides smooth, fine cuts. Great for cutting, sawing and carving of hard materials, such as marble, concrete, brick, porcelain, ceramics, hard epoxy and soft and hard wood_''


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## AlanR (Jun 14, 2014)

JimDawson said:


> About $18 at Home Depot or buy online for less.


Been using those for years.

Get them for cheap at http://www.widgetsupply.com/category/dremel-diamond-coated-disk.html

Lots of other shapes too, click up a category.


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## echesak (Jun 16, 2014)

JimDawson said:


> I am turning some 4150 and needed to grind a chip breaker into the cheap HF POS brazed carbide bit.




Excellent idea.  I've used 4" tile grinding/cutting blades on the outside of my grinder wheel.  But it's only good for flats and such.

How about a photo for us chip breaker neophites?

Eric


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## george wilson (Jun 16, 2014)

Use light pressure with diamonds. DO NOT USE THEM ON HSS. Carbide is fine. The diamonds will migrate carbon into HSS,and get worn out.

I do have a 200 RPM diamond tool grinder-NOTE:200 RPM. It is fine at that very low speed for HSS. High speed will soon ruin them on steel though. Disobey this at your own expense!!


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## cazclocker (Jun 16, 2014)

george wilson said:


> Use light pressure with diamonds. DO NOT USE THEM ON HSS. Carbide is fine. The diamonds will migrate carbon into HSS,and get worn out.
> 
> I do have a 200 RPM diamond tool grinder-NOTE:200 RPM. It is fine at that very low speed for HSS. High speed will soon ruin them on steel though. Disobey this at your own expense!!



Thanks for the heads up. Another tidbit for my miniature mind!


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## Andre (Jun 16, 2014)

Tile saw blades are also diamond, and they will cut carbide.


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## barrydc1 (Jun 16, 2014)

I love to see a pic or your work on the brazed tool as well.  I've tried some chipbreaker grooves, but not sure how well it worked.  I'd love to see what yours looks like.  Thanks for the tip.


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## JimDawson (Jun 16, 2014)

Here are the best pictures I could get.  This is a standard AR-6-RH brazed carbide 1/2 inch tool from HF. 
	

		
			
		

		
	




 I also had to grind some off of the back to get clearance for the center, I did this on the bench grinder.

The tool is a bit beat up from about an hour of machining, but it was still cutting just fine.

I hope this gives you the general idea.  It took a couple of grinds to get the chip breaker to work the way I wanted it to, but it now curls the chip back into the work ahead of the cut, thus breaking the chip off.





A top view.  I don't know that the 3 black spots are in the side of the tool, I can't see them with the naked eye.  Must be a lens flair or something.




The front view.  That double dip was not intentional, it should be a smooth flow, but my hand slipped.  The ridge in the back is from the back rake I ground in, seen better in the next picture.





The cutting edge as seen from the work's perspective.





Here is in picture in action.  Note the little curly chips on the tool bit, this is what is coming off of the tool.





Same material and conditions using a tool without a chip breaker, note the rats nest is starting.





The little widget I made with the tool, I can't tell you what it's for or I'd have to shoot ya. :lmao: This started out life as a piece of 1 1/4 stock, so I had a lot of material to remove.

The pins are 1/8 inch dowel pins.


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## echesak (Jun 16, 2014)

I need to experiment with this some.  I've never ground any chip breakers in my tools, opting instead to pick up tossed "rats nests" pieces all over the shop.  Would be a lot easier to clean-up the equipment, as well.  I've been reading an old book called "Theory of metal cutting", which discusses chip breakers, but the majority of the theory is on the engineering aspects of how a tool cuts metal.  Sounds dull (no pun intended), but it's actually pretty interesting.

Thanks for sharing, 

Eric


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## barrydc1 (Jun 17, 2014)

I'm impressed with your pictures.  And glad you posted them.  That is not at all what I had envisioned.  I'm going to have to try some experimenting as well.  Just need to get a couple of these other projects out of the way.  Thanks so much for putting up the great set of pictures!

Barry


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## JimDawson (Jun 17, 2014)

Eric, Barry, you are quite welcome.  As you can see a chip breaker can be pretty crude and still work as desired.  In fact the entire tool grind is pretty crude.  This illustrates that there is not really a right or wrong way (as long as safety is kept in mind) to do something when it comes to machining, it's really a matter of what works for the application.  In a high production environment, you would want to use properly engineered tools to optimize production, but as a home/hobby machinist you have a lot more latitude.

Normally I would have ground that chip breaker in on the edge of the carbide grinder wheel, but in this case I had the Dremel diamond wheel sitting in my tool box so I tried it, why?, because I had never tried it before and it looked like a reasonable solution to a small task.

In general, grinding tool bits is not magic, just provide enough clearance in all planes around the cutting edge so that the cutting edge is the only part of the tool touching the work in the desired direction of travel.


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## joesmith (Jun 17, 2014)

Thanks for sharing.  I need some of the Dremel disks!.  I have had good luck with the brazed cutters after regrinding the angles.  I look forward to trying a chipbreaker.
Joe


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## countryguy (Jun 17, 2014)

you guy's blow my mind!  I'll post a comment in about 5 years when I've earned a few stripes and even know what a chip breaker is!  Jim,  You always have good stuff to post! Regular Reader here!   

thanks! CG


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