Thread Problems Part Failure

As others have said, using a live center makes a delicate job into an easy one. Even 1/4-20 threads in brass are a piece of cake with a center.DSC_1105.JPG
 
1. Have a sharp tool with proper relief (both side and under the cutting edge) set at the correct height and angle (use fishtail)
2. Support the free end of your work with a center in a proper hole.
3. Compound, in this case set at 29.5 degrees.
4. Small cuts, .003-.005
5. At least on every other cut, take a pass without advancing the compound on small threads, light lathes and/or gummy material (brass/bronze)
6. Make your last few passes at .001

This SHOULD make your problem go away. You don't need a small lathe to cut small threads. I cut 6-40 threads on my 17 inch swing Nardini with no trouble.

Watch size threads...yes. THEN you would reap the benefits of a small lathe.
 
"CENTERDRILL FOR THE LIVE CENTER. NEVER JUST RAM THE CENTER INTO THE STOCK"
Billy G
 
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I will only say that I have been a machinist for almost 40 years. It is how I make my living. Worked around some guys that are damn smarter than most of us. Once again there are those who think they are the gift to this trade. Most of them are hobby trained. Have had a few of them come into the shop, and usually quit, or get fired because they can't handle the real world of machine shop work. I run the shop I am at now and didn't get here by being a hack.
Once again, I did not say jam the center into the end of the part, but to bump it a few times. It WILL leave enough dimple to hold a short part. If you are machining out away from the chuck, I would not even suggest this. Close to the chuck, it works like a charm.
I have not been a member of this group very long, but as a whole there is generally good info here for the novice, and a pointer or two even for us experienced guys. Generally the ones who think others ways are a hack usually just know enough to be dangerous.
 
You all are welcome to disagree with regard to the right way to do something. However the disagreement may not be insulting to anyone. Remember, we can disagree without being disagreeable on this forum. Thank you
 
You should be reducing your depth of cut as you progress in with the compound. The deeper the tool is in to the work then more of the tool flank is applying pressure to the work as it is cutting over a larger area.
Also, as you near the max thread depth it can be beneficial to take a zero cut with the compound, but advance in a thou with the cross slide and take a finishing cut on both flanks of the tool to clean up the thread and provide a little thread clearance.

Cheers Phil
 
Hey Paul. I was the one that used the word ram. But gently bumping makes perfect sense to me. I will try your method for it with save me a step of center drilling. Now I will ask you though, do you recommend on smaller dia. parts or even with larger dia. parts? Also, do you use a spring center or just a live center? Your experience is valuable to me and appreciated. But I do also know there is always more than one way to skin a cat. ;)
 
First off I will apologize for my rant above. Was one of those rare days I got surrounded from all sides :) (thank goodness, very rare). I love to teach people this trade, thought it is not for everyone. My hope is to throw out some ideas of what works for me. It's up to you to take it or leave it, agree or disagree, and go on. Mine to do the same with yours as well. So............
Larger parts will generally always get a center drill. Depending on how far out of the chuck they extend determines a lot. Set up rigidity, etc., etc.,...
One reason for 'bumping' just the center in on small diameter parts is at times it will keep the center just far enough out for clearance for the tool. I use a regular live center. Again, this method I use is for short, small diameter parts that just need a bit of support, usually not more than an inch or so out of the chuck. Any more than that you need the full support of the center drilled hole. HTH.
 
Paul in OKC said:
First off I will apologize for my rant above. Was one of those rare days I got surrounded from all sides :) (thank goodness, very rare). I love to teach people this trade, thought it is not for everyone. My hope is to throw out some ideas of what works for me. It's up to you to take it or leave it, agree or disagree, and go on. Mine to do the same with yours as well. So............
Larger parts will generally always get a center drill. Depending on how far out of the chuck they extend determines a lot. Set up rigidity, etc., etc.,...
One reason for 'bumping' just the center in on small diameter parts is at times it will keep the center just far enough out for clearance for the tool. I use a regular live center. Again, this method I use is for short, small diameter parts that just need a bit of support, usually not more than an inch or so out of the chuck. Any more than that you need the full support of the center drilled hole. HTH.
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Paul, same here, apologies for my comment which didn't help. A little background: I also have many decades (5) in this trade and also enjoy passing along whatever knowledge I have. In fact I was a Trade Teacher for 9 of those years.
I firmly believe the best thing to teach a novice is the proven, time-honoured, "correct" way to do something. If he decides to do it some other way, then that's his choice. And yes, we all develop our own way of achieving the end result, and others can try it or not, it's up to them.

There is no shortcut to proficient Turning (definitely NOT Lathing...see another thread), especially screw cutting. For a novice, the best place to start is to get a book and read it. I still refer to the South Bend book "How To Run A Lathe". It is THE classic amateur's lathe handbook, but there are others also. The section on threading is excellent, and tells you how it should be done. Then it needs practice and the more the better. And by all means, experiment and learn...

I assume Latheman has solved his problem by now!
 
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