# Chip breakers



## Hukshawn (Feb 13, 2017)

Show me your best... 

This is getting annoying. 



Here's my tool


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## woodchucker (Feb 13, 2017)

I don't see a chip breaker on that.
This is an old style carbide that I don't use it's chipped. But it has a chip breaker ground in.


These two also have chip breakers ground in. They are there to cause the chip to roll up and break. Your tool looks like it has relief but not really a chip breaker.


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## Hukshawn (Feb 13, 2017)

There's no chip breaker on mine. I'm looking for suggestions on how to grind one in that still leaves for tool cutting well. I had to hog down a lot of aluminum and the birds nests were plentiful...


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## mikey (Feb 13, 2017)

Increase your feed rate. Quite often, taking too light a cut at too slow a speed will produce stringers. Aluminum does this anyway but feeding faster helps.


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## Jimsehr (Feb 13, 2017)

Chip breakers help manage the mess when turning . I use them most of the time . But you have to be carefull when cutting threads . You can change the profile of the thread form if you are not carefull.
Jimsehr


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## intjonmiller (Feb 14, 2017)

mikey said:


> Increase your feed rate. Quite often, taking too light a cut at too slow a speed will produce stringers. Aluminum does this anyway but feeding faster helps.


I played with that this past weekend. I was tracking down some chatter, and I knew that a more aggressive cut can stop chatter in many situations. I had some play in the cross slide because the screw wasn't held tight enough to the handwheel and saddle. That resolved the worst of it, and allowed me to go for much deeper cuts than before. Still nothing more than about 0.040", but that's a vast improvement over what I had been doing. Anyway, I tried varying the depth of cut, spindle speed, and feed rate, and it was fascinating to watch the different chips produced from a broad radius bit (one that is so large it barely goes into the tool post with some mallet tapping, so it wasn't likely to blame for the chatter). 

At 0.010" and the nearest sfpm rate my machine can do relative to the usual charts I was getting long spiral pasta noodle chips from my 940 bronze. Cool looking and manageable, but taking up a LOT of space relative to the tiny chips it made by increasing the depth of cut beyond 0.025". My next project should be out of aluminum, so I'm wanting to try the same thing with that same bit.


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## Hukshawn (Feb 14, 2017)

mikey said:


> Increase your feed rate. Quite often, taking too light a cut at too slow a speed will produce stringers. Aluminum does this anyway but feeding faster helps.



I couldn't feed any faster, I was taking .040"-.050" cuts and I was starting to stall. I honed the cutter a few times to keep it sharp.
It was actually the shallower cuts/slower cuts that kept the string bunched up into a mass, but it was going too slow for the amount of material I had to remove. 
I was getting annoyed with being whipped in the face...


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## 4GSR (Feb 14, 2017)

I have a turning tool I use on my 9" South Bend lathe I ground up years ago and still use today.

Take a piece of HSS any size suggest 3/8 or larger, grind a chip breaker on top of the tool bit using a Dremel or air grinder.  Use a 1/8" diameter rock to create the chip breaker.  Grind it about .030" deep, it'll take you awhile but you'll get there.  Make this chip breaker about 1/2" long.  The chip breaker will have the shape near that on a negative rake turning insert.  Once that's done, grind side relief on tool bit and the front clearance with about 10-15 degrees cut like a CNMG CCMT insert would have.  Next, just kiss the corner of the cutter, no more than .015", to remove the sharp edge.  Last hone the edges and you're ready to start hogging iron.  I can take up to about .100" dept to the side cut with about .003-.005" feed on my 9" SBL with this bit cutting  4140HT.  Finish is horrible, but that's fixed by running a finishing tool for the last few cuts to size.  When done this will look similar to that in Woodchuckers post above.  This is strictly a roughing tool.

Oh, I forgot to mention, when you grind the chip breaker, leave about .010-.015" flat between the chip breaker and the side of the cutter.

Ken


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## Hukshawn (Feb 14, 2017)

Could you take a picture?


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## pineyfolks (Feb 14, 2017)

Here are a few. I use a dremel tool with a diamond cutter. It makes it quick and easy.


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## Wreck™Wreck (Feb 14, 2017)

Think about what would cause the chip to break, if it is thick enough it will not be able to string without breaking, increase the DOC or feed rate or both. A slow feed and shallow DOC are excellent ways to create an annoying continuous chip.
If the chip comes off very hot it will be soft and not want to break, use coolant or slow down, slowing the spindle will often affect the finish however.
Grind the tool so that it forces the chip to tightly curl, this will often cause it to break.

Above all experiment until you learn how the chips behave.


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## mikey (Feb 14, 2017)

With some materials like aluminum and stainless, long stringers are a fact of life. While chip breakers _may_ help, you will still get stringers with these materials. Chip breakers are not magic. In order for them to work, you need to take a heavy cut so if your lathe is not rigid enough or powerful enough to allow that then chip breakers will make little difference, at least in my experience.

I did a lot of experimentation with chip breakers at one point (in HSS and inserted carbide) and found that you need a relatively healthy depth of cut and faster feed rates to make them work. The reason for this is  simple; it takes a fairly heavy chip to break. If you watch aluminum coming over the tip of a HSS tool with a chip breaker, the chips from a light cut flow right over the chip breaker; don't take my word for it, try it and see. This is especially true if the tool is ground with conventional rake angles and the user relies on the chip breaker to handle the chip.

The reason faster feed rates work better is because it causes the chip flow to be directed into the chip breaker valley, where it hits the back side of the valley of the chip breaker and has a better chance to break off. How fast is fast? Well, you have to experiment to find the right feed rate and if you power feed, that may or may not be what your gearing allows. If you want to find the right rate, feed manually.

Coolant also makes a huge difference, perhaps even more than the chip breaker itself, because it reduces temps at the point of cut and makes the chips break easier. Actually, quite often the chip will not break; it will coil. You will especially see this when boring; chips will turn from stringers into coiled chips that eject easily just by using adequate amounts of coolant, and this happens with inserts with or without chip breakers. If you're cutting aluminum with a heavy depth of cut and a fairly fast feed rate then sulfur-bearing cutting oils can make a big difference (vs something like WD-40) in the chip because it hangs around long enough to actually cool the material at the point of cut, thereby helping the chip to break/coil.

On my Sherline lathe, I found that larger amounts of side rake and back rake on my HSS tools did more for me than chip breakers. Rake improves chip flow, thereby lowering cutting temps. Add more cutting fluid than I normally use also helps. When I take a decent cut in aluminum, 0.050" to 0.065", I don't have stringers; I get coils. The same is true on my Emco lathe. When taking light finishing cuts, I still produce stringers but they are fine and not bothersome, especially if I use coolant.

I guess the bottom line, for me, is that chip breakers are not worth the time it takes to grind them. Roughing heavy, feeding faster, using coolant, and aggressive rake angles work better for me.


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## sanddan (Feb 15, 2017)

Here's a good video on grinding chip breakers


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