[Newbie] When Is It Good/safe To Engage The Power Feed Lever

Yeah, that's what I'm doing, and I've watched a bunch of youtube videos on doing it. Using a HSS bit, larger stock and a faster speed has mostly eliminated the tearing [it'll look bad after the 'bad' cut (when it takes off a big part of the thread), when the saddle seems to have shifted over a bit for whatever reason].

I'm pretty close to getting it right, it'll get 80% of the way done, then it seems like the saddle jogs over just a smidge and I get pointy threads. Next time I'm going to try using the carriage handwheel to take up the slack in the threading screw before each pass.

Doing the reversing thing instead of releasing the half nut/using the thread dial is working ok for me, one less thing to get wrong, and I have to do this anyway when I get to doing metric threads.

Fixing the shear pin definitely helped [as I could move the thread screw laterally with the carriage handwheel with the halfnut engaged and the saddle against a stop].

Using layout dye sounds like a good trick I'll have to try, I'll have to go get some.
 
If the shear pin sheared you don't have to line it back up to remove it. Just pull the coupler off the shaft and drive out the pieces.


Steve Shannon
 
Yeah, I got it apart. The shaft had to pull out of the coupler, and there was still pretty good friction from the part of the shear pin in the shaft with the couple [it was still able to drive the saddle back and forth, I had trouble rotating the two parts using pliers]. I did get them apart using the saddle with the half-nut engaged and drive out the original bits and then reassemble and put in a new one.

There still seems to be a little play between the thread screw and the coupler [the pin fit snugly in the thread screw, but a little loose in the coupler]. I'm going to drive it out, expand the ends a little and then drive it back it so they are fixed together. The old one was like this [one end had clearly been expanded].
 
And now, after googling around a bit about lathe shear pins, even though the previous split pin did shear before anything else, I think it will be better if I made a shear pin out of brass for it instead.
 
And finally, victory!
IMG_0504.jpg

Depicted are the previous trials, the final one, along with the winning tool bit [HSS that I ground to the right angles], and the victory coffee.

Even with light passes (.005 on the compound slide), the carbide tipped tools I had would lose their tip pretty fast, but this HSS kept it really nicely. As well, taking up the lateral play in the threading screw/half nut by moving the saddle handwheel towards the endstock [as well as replacing the shear pin for the threading screw] seems to have fixed the problem of pointy threads and the slight offset of the cutting tool between passes.

Now to repeat the process with a metric thread and then I'll begin my project to make a grinder for sharpening lawnmower blades.
 
Congratulations! Thanks for taking us along with you. It was a trip down memory lane for me.
Am brewing a coffee to toast you, Tim Hortons will be for another day, its winter out there.
Mike
 
Thanks. It's fun learning new stuff. It's too bad I didn't get into doing more things like this when my dad could show me how to do it.

But the people who visit here are also pretty helpful.
 
woohoo. one and done.
IMG_0505.jpg

M10x1.5 thread

Things learned:
-double check that all the gears and levers are right, don't "remember" what the gears are...
-double check that the levers on the front are correct...on my lathe, you have to bend over and look squarely at the levers to make sure they are right, and then fiddle with the levers a bit to make sure the gears are actually engaged
-do a test pass where you graze the surface, so you can visually check that the pitch/tpi is at least in the ballpark [it wasn't until the 3rd try that I got the lathe set right for 1.5]
-need to be careful with the parting tool, this was a different scrap rod, and seems harder than the other one, and even with it supported with the tailstock, the bar bent at the relief cut and the tailstock ruined the threads at the end [which is why they are ground down so I could get the nut back on again].
 
Good stuff. Looks like you are having fun. Are you keeping a log book of your experiments and lessons learned or relying on memory?
 
Hey, that's a good idea. This is something that I probably won't do that often, so writing it down would help in the future. And just writing it down also helps with remembering it as well...
 
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