Topics include, Machine Tools & Tooling, Precision Measuring, Materials and their Properties, Electrical discussions related to machine tools, setups, fixtures and jigs and other general discussion related to amateur machining.
earlgo wrote:Perhaps I misread this and you were referring to the positive rake reducing the cutting resistance as opposed to a neutral rake. If so, please excuse me.
--earlgo
Yeah, that one. The extreme positive rake cuts with much lower pressure, but also encourages hogging. It's also easy to burn the cutting edge, because it doesn't conduct heat well. A balance between an extremely sharp edge and front relief is often required to limit hogging.
It works, and works well. Something I learned early on in my training, and from a relatively young guy. He was in his mid 20's, while I was, at the oldest, 20.
Harold
Wise people talk because they have something to say. Fools talk because they have to say something.
Keep in mind that Harold's suggestion to add positive rake to your HSS parting tool will most likely result in a more free cutting tool then the Carbide insert tool. There is a possibility that you may not get away with sticking the stock out 6" when parting when using the Carbide.
Glenn
Operating machines is perfectly safe......until you forget how dangerous it really is!
Glenn Wegman wrote:Keep in mind that Harold's suggestion to add positive rake to your HSS parting tool will most likely result in a more free cutting tool then the Carbide insert tool. There is a possibility that you may not get away with sticking the stock out 6" when parting when using the Carbide.
Heh! I'm surprised he's getting away with the amount of extension, regardless of tool type.
Rule of thumb for turning is that unsupported extension should be no greater than three times the diameter. Doesn't mean you can't go longer, but it tends to be troublesome. I'd expect chatter, if nothing else.
I like to keep things choked up when working a similar job. Overall, there's far less trouble.
Harold
Wise people talk because they have something to say. Fools talk because they have to say something.
I use split point Screw Machine drills so they don't wander, and only stick the stock out just farther as I can drill. You can run a bit harder that way and still have good parts.
I use a lever collet closer, so having to extend the stock more often is not really a big time loss.
Even when making stuff for myself I like to challenge myself for efficiency. That's pretty much the biggest challenge to making stuff. Making good stuff efficiently without making scrap! "Efficently" being relative to what you have to work with.
Glenn
Operating machines is perfectly safe......until you forget how dangerous it really is!
LarryMck wrote:I used a dial indicator and trued my parting tool, set my cross fees to .0016 per rev, and shorted my material length to 4 inches past chuck.
I now am getting an acceptable finish and tolerance using the paring tool. I am still using the HSS parting tool. I made 25 spacers in an hour.
Harold
Wise people talk because they have something to say. Fools talk because they have to say something.
I have been messing around with “home machining” for 5 years and it is not following the basics or trying to take a short cut that tends to get me pour results. I squared my parting tool with a 123 block to the face of my chuck and was getting a unsatisfactory finish and shorten life on my tool. Once I used I dial indicator I increased tool life and got a great finish. In the past when I was making one part if I got a pour finish I would just face the surface and it was not so important. Having to make multiple parts has forced me to improve my methods.
I delivered some of the spacers Saturday morning and picked up some more work. Making some pitman arms that require cutting snap ring groves to retain a bearing and some tig welding. Again the material is 304 stainless.
Thanks again for all the help
Larry
SB Heavy 10 and Jet 14" Lathe, Bridgeport and Van Norman #12 Mill
