Last night I had some time to kill while waiting for a guy to pick up his bike so I thought I would cross another item off of my list of things to do. I had wanted to make a larger die holder for my tailstock threading die holder for years and never seemed to get around to it. I didn't have one for 1.5" round dies so I grabbed some 1144 round stock out of the rack and cut a 2" long piece of 1.75" diameter off in my new to me Jet 7x12 horizontal bandsaw that I finally refurbished and got up and running.
Turning one half down to 1.00" diameter to fit precisely into the smaller die.
While machining this part I decided to focus on getting more familiar with my new lathe and seeing just how accurate it is and how repeatable I can make cuts. Like everyone else, once you get a feel for your machine you have a much more precise idea of what kind of roughing cuts you can make and how close to your final dimensions you can get prior to your finishing cut(s).
Here I removed .080" (.040" actual DOC). Machine didn't even flinch. Keep in mind that this is only a 1300 pound/2hp lathe, not one of the 3k pound/5+ HP monsters that some of you guys may have.
Now I decided to push it a little and take half a dial revolution and measure for accuracy. Here is a .050" DOC, .100 total diameter removal. This dial is taking some getting used to but I am getting much more comfortable with the total diameter markings vs. what I was used to with dial markings signifying crossfeed movement. Prior to this cut I had a measurement of 1.331" and after this cut I had landed at a measurement of 1.229", .002" difference from target to actual.
Okay now I decided to take that measurement and make one complete revolution of the crossfeed dial in two consecutive cuts, each cut taking .100" material removal for a total target of .200" material removal. Starting measurement was 1.229" and after one complete dial revolution in two .100" cuts I landed at a measurement of 1.031". Only .002" shy of my target in one revolution of the crossfeed dial, I'll take it. I am completely satisfied with that. Now I am at least getting a very comfortable feeling for the machine to rough out and get within .010"-.020" before taking another measurement and dialing in on the final dimension.
After measurement I offset my dial to the final dimension and took a final cut of about .014" and faced out.
My target was 1.000" and after the final cut of .014" here is my actual dimension. Sorry, I should have grabbed a micrometer for this but was too lazy to walk to the toolbox and get another measuring tool out for something that had some margin. I was more trying to make a target dimension and shoot for it to get a feel for the machine.
Final measurement was 1.0005". Half a thou off from target. Very satisfied.
Breaking the edge and throwing a chamfer on each of the two sharp edges.
Test fit into the smaller die holder prior to turning around and machining the other half.
1.5" round thread die drops right in. All I have to do now is drill/tap for my retaining screws.
After chamfering the outer edge and the inner bore.
And after all cleaned up and ready to be put to bed for the evening.
Mike.
