- Joined
- Aug 26, 2013
- Messages
- 1,061
If you want a dedicated aluminum bit, try 25 to 30 for the back and 15 or so for the side.
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Making chips with HSS
- Thread starter Jack C.
- Start date
- Joined
- Jul 27, 2013
- Messages
- 295
Regarding rakes;
Rake is designed to get the tool to cut, obviously. If the sides are flat, the tool just rubs and the edge is never activated (unless you are talking a high HP/RPM machine with carbide where you plow it in deep. Let's not go there!). Beyond that, you get into the object material in question and how aggressive you want/need to be. If you are working with HSS in a soft material, you can use a larger rake because the edge does not need the material underneath it to support/cool it as much. For instance, 10*+ will dig right in on aluminum or especially brass and really hog without problems. If you try that same setup with steel you will very likely overheat the bit and loose the edge rapidly, unless you back well off on the feed. A steel rake might be only 5-8* depending on how aggressive you get with feed/speed. The harder material needs more edge support (material directly under the edge, i.e. a lesser rake) for the cutter. If you get REALLY technical about it, you need to look at the shape of the chip you are getting and profile your tool so that the chip will break short instead of very long. In general, the longer the chip, the higher the heat on your cutting edge, and the quicker it will fail. If you are talking steel, watch the color of the chip as well as the length. If you see long and/or blue, your HSS tool may in jeopardy.
Don't get the impression I have a lot of experience with this. I don't, but I've been studying!
Take a look at this thread. Not all of it is directly relevant, but there is an absolute ton of Gold here, from some really experienced guys.
http://www.practicalmachinist.com/v.../where-buy-lathe-tooling-uses-inserts-278566/
Rake is designed to get the tool to cut, obviously. If the sides are flat, the tool just rubs and the edge is never activated (unless you are talking a high HP/RPM machine with carbide where you plow it in deep. Let's not go there!). Beyond that, you get into the object material in question and how aggressive you want/need to be. If you are working with HSS in a soft material, you can use a larger rake because the edge does not need the material underneath it to support/cool it as much. For instance, 10*+ will dig right in on aluminum or especially brass and really hog without problems. If you try that same setup with steel you will very likely overheat the bit and loose the edge rapidly, unless you back well off on the feed. A steel rake might be only 5-8* depending on how aggressive you get with feed/speed. The harder material needs more edge support (material directly under the edge, i.e. a lesser rake) for the cutter. If you get REALLY technical about it, you need to look at the shape of the chip you are getting and profile your tool so that the chip will break short instead of very long. In general, the longer the chip, the higher the heat on your cutting edge, and the quicker it will fail. If you are talking steel, watch the color of the chip as well as the length. If you see long and/or blue, your HSS tool may in jeopardy.
Don't get the impression I have a lot of experience with this. I don't, but I've been studying!
Take a look at this thread. Not all of it is directly relevant, but there is an absolute ton of Gold here, from some really experienced guys.
http://www.practicalmachinist.com/v.../where-buy-lathe-tooling-uses-inserts-278566/
I am a newbe to using a lathe . I purchased a 1936 south bend C I have been working to build a bench and getting lathe set up . I have tore the lathe down cleaned and replaced wicks . I am now getting ready to make some chips undecided on what cutting tool to use or the best way to learn how to grind or sharpen the tools any suggestions on how to get started thanks.
- Joined
- May 5, 2013
- Messages
- 310
Stan, look on YouTube for Tom Techniques, Mr Pete 222, and Ox Tool. The 3 of them have EXCELLENT videos on grinding HSS lathe tools.
At the beginning it is very confusing, stick with it. Being able to grind special tools is what it is all about. One day it will just click!
At the beginning it is very confusing, stick with it. Being able to grind special tools is what it is all about. One day it will just click!
This is my current cutter, I have made a lot of chips with this, a little touch up and keep truckin.
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See the very tip of this cutter, how it's black. I severely over heated it. When grinding a high speed cutter it is super important to take your time, dip your cutter very often in water. You never want to get the cutter so hot that you quench it, and harden it. Also avoid colored chips, you can heat your cutter up on the lathe. This is one of the most important things I have found for consistently getting a good finish.
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I made a fly cutter for a mill yesterday. I need to grind a piece of 3/8 hss for a cutter in it. Any pictures or advise for making this type of cutter? It's a 11degree fly cutter btw.
- - - Updated - - -
See the very tip of this cutter, how it's black. I severely over heated it. When grinding a high speed cutter it is super important to take your time, dip your cutter very often in water. You never want to get the cutter so hot that you quench it, and harden it. Also avoid colored chips, you can heat your cutter up on the lathe. This is one of the most important things I have found for consistently getting a good finish.
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I made a fly cutter for a mill yesterday. I need to grind a piece of 3/8 hss for a cutter in it. Any pictures or advise for making this type of cutter? It's a 11degree fly cutter btw.