Building a New Lathe

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PekkaNF:
Looks very good. Nothing wrong with the traditional construction.

Pekka

vtsteam:
Thanks Pekka. :beer:

i had problems with threading today -- will have photos tomorrow.

I might be following john vintageandclassic's and your lathe's example...... :(

vtsteam:
Okay so some problems......

I had the taper bore all done, and now on to the simpler job of threading the other end of the tailstock ram. Piece of cake because I'd made my own Acme tap, which had done a fine job on the cross slide and the carriage half nut. It was made from the same Acme all-thread as the leadscrew, case hardened with Kasenit, and tempered to straw color in the kitchen toaster oven. Quite proud of that tap...

Here I was innocently starting the tap by hand in the lathe:

vtsteam:
Right after that photo, I unbolted the three way chuck from the faceplate, and set it on the bench. I have a monster tap handle -- about 18" across, and grabbed that one. Everything seemed to be going well for the first turn and a half, when something gave....and the tap suddenly was easy to turn -- disaster, some of the starting teeth had broken off. Or I should say, sheared off. Though the case hardening was hard enough to cut steel, the unhardened interior of the teeth just weren't up to the task. Acme form teeth really take some pressure. Perhaps if I'd made the tap with a longer lead in.... Anyway, This was a major disappointment as I really liked that tap!

So checking the damage to the bore, I figured it was only at the start of the thread, and really just a nick, so I could still try to thread it in the Craftsman. I didn't have an acme tool so I had to forge, shape, harden and temper one out of 5/16" drill rod.

vtsteam:
It's been awhile since I threaded in the lathe. Like maybe 3 years. And an inside bore Acme 1/2" screw is not a favorite threading task. So I renewed the joys of searching for the right change gears, squinting to try to read the layout chart on the inside cover of the gear housing, getting blackened grease on arms, clothes and, as I discovered later at my family's surprised smiles, face. :loco:

With the gears finally set up properly, I pulled out the pin in the bull gear, flipped the gear engagement lever, checked for proper carriage travel direction, set the compound to 14 degrees with a magnifying glass, and loosened and engaged the thread dial with the leadscrew. I checked that the tool was square to travel, moved the cutter to the bore start, zeroed the two slide dials, and finally started a cut.

Well, things were going okay, at the the lowest speed the Craftsman was capable of. I was starting to think I hadn't lost the touch. The only problem was, I hadn't figured out what the compound's depth of cut should be for a 10TPI Acme thread at 14-/2 degrees compound. But Being the try and fit type, I did have my somewhat wounded tap, which I'd ground back a little, and I figured I would just test the bore periodically with that. Once it was close, I could use the undamaged part of the tap to make the final cut.

Things went well and the tap showed promise of getting near to the end of lathe threading. I was able to screw it in 1, then 2, then 3 turns with the lathe stopped. I kept working it in, and then backing off, gaining ground bit by bit, though it seemed to be getting tighter. But I felt the end was in sight so I applied a little more pressure -- not enough to break anything, but definitely putting some pressure on. It moved a little when I bumped it with my hand, but it never seemed to break through.

Then I noticed I was turning the whole workpiece in the chuck jaws. I guess I hadn't tightened those enough to resist this kind of mistreatment. So I was well, screwed ......again. The tap couldn't cut it, and now the threads were out of register with the lathe threading dial. I did the usual mistaken last hope in this situation -- trying to re-align the tool and slides and threading dial while taking the backlash out of the gear train. But as usual, all I managed to do was mess up the threads.

Time for a break! :loco:

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