Feeding While Performing a Turning Op. 13" SB Single

[Janderso]

Question,
When I use the power feed (not the half nuts) what speed do you choose?
I just pick a threading combination that seems right. Is there a better more repeatable way of doing this?
I just started using the auto feed feature, pretty cool, easy too.
Thank you!

 

[Dave Paine]

This is the old "speed and feed" chart. The lathe should state the in/rev for each position of the QCTP. One of many links showing Speed and Feed data.

Speed and Feed chart

 

[chips&more]

I actually have no idea anymore LOL? I have been playing in my hobby shop for so long I just use my gut feeling...kinda. I think you will get the gist of it after time. And not need any chart or math. I can get good results at first but can always dial in the speed or feed if needed. I don’t sweet it, been doing it for to long…Dave

 

[Janderso]

Chips, I'm sure you are right. This is mostly new to me it's been so long. I was playing around over the weekend turning some cold rolled then switched to brass. I know I need to speed up for brass and I was looking at the threading levers for TPI trying to come up with the best speed for the auto feed=no half nuts just the apron gears driving the autofeed feature. I hope I am explaining myself correctly.
I was relieved to see oil coming out of the apron hand wheel. You know the fix to add an oiler in the cast iron at the hand wheel bushing? Not needed if the apron has oil in it and the felts are not compromised.

 

[Technical Ted]

I don't remember for sure, but South Bend's book How to run a lathe probably gives some general guidelines. Once you get some experience you will just go by feel. There are so many variables at work i.e. type of cutting tool (carbide, HSS and grades of each), tool geometry, nose radius, material types and grades, what surface speed you are running, the desired finish you want, how rigid your setup is, coolants/cutting oils used, etc. etc. etc.

Play and learn!

Ted

 

[benmychree]

The plate on the front of the change box shows both threads and feeds in thousandths one should never use the half nuts for feeding, as it puts extra wear on the half nuts and screw, and is a positive, (not) friction drive, so if something hangs up it ( the carriage feed) stays in motion until something breaks. Looking at "How to Run a Lathe" is good advice.