Building a New Lathe

[vintageandclassicrepairs]

Hi Steve,
I have been following your build with interest and admiration

On the making of the tailstock I happened to notice that the thread on one of my lathes is a seperate phosphor piece fitted into the end of the ram, On the old lathe i used to have the ram was cross bored and a cylindrical PB piece fitted in,  this had the thread for the jacking screw through it
I presume this would have allowed for any minor misalignment in the casting machining or wobble in the jacking thread??
Making the threaded part seperately  also means it could be replaced when required
I remade that piece which was an interesting job !!!

John

[vtsteam]

That's interesting John, I haven't seen that before. Both the Gingery and the Craftsman I own just have a threaded ram. In both there is a clearance bore between the threaded portion and the tapered portion.

I started to bore the ram today, but quickly ran into a problem using the trial and error taper adjustment method -- there was already too large a bore at the taper end (from using that same piece of stock as a bearing while boring the headstock). What I mean by too large is it is close to the finished size of the wide end of the intended taper (MT2). Therefore I can't just bore and try a MT2 tapered center to see how close I am, and then re-adjust my steady rest to get a closer angle.

I really needed to start out with a small hole, and gradually enlarge it by taper boring a small amount, blueing the MT2 taper center, trial fit it, and adjustments to the steady rest set-over according to what gets scraped off the blue. But there's a big hole, so not at all possible.

Dumb, should have realized. Oh well...... not a super big problem. I have more 1-1/8" ground stock. I just thought it would be great to use up the piece I had used elsewhere during construction.

Now if I had an MT2 reamer, and a calibrated lathe and cross slide already, I'd probably be able to make do with this piece of metal (if I was careful and lucky). But I don't. So we'll start fresh with a new piece of stock tomorrow. enthusiasm waned for this job today, because I have to break down my set-up, re-mount the chuck and drill out the center of a new piece. Then re-set up the steady, etc.

[PekkaNF]

Hi Steve,
I have been following your build with interest and admiration

On the making of the tailstock I happened to notice that the thread on one of my lathes is a seperate phosphor piece fitted into the end of the ram, On the old lathe i used to have the ram was cross bored and a cylindrical PB piece fitted in,  this had the thread for the jacking screw through it
I presume this would have allowed for any minor misalignment in the casting machining or wobble in the jacking thread??
Making the threaded part seperately  also means it could be replaced when required
I remade that piece which was an interesting job !!!

John

I think my lathe has same construction, but just ironmetal insert for tailstock nut, the tread rod ejects taper tooling when retracted fully home.

Pekka

[vtsteam]

Yes, Pekka, if the jack screw is long enough, it ejects the tapered tool when the ram is retracted- works the same way in the Craftsman and Gingery lathes. Otherwise removal would be very difficult;

Sleeping on problems often seems to create solutions. This morning I woke up realizing that I could probably just plug the existing hole. The plug  would eventually be bored out completely......I think....I'll have to measure.

[PekkaNF]

Myford ML10 has thread outside of the ram and gives a good drilling stoke in a very compact format.



To eject taper tool: insert a rod from the tail end and give it a gentle tap with a hammer. I found it pretty usefull. Used sometimes the hole to blow air/coolat mixture trough ER collet to remove swarf/cool the drill.

Pekka

[Neubert1975]

An other interesting, to me at least, way it rack and pinion.
if any of you know Stefan Gotteswinter on youtube he has made it on hes lathe.
https://www.youtube.com/watch?v=n1ytS1lhVFg
i have been thinking of making the same om my own lathe, that is similar to Stefanīs

[vtsteam]

Interesting stuff, guys!

On this one I'm going conventional -- in fact I'm just going to copy the Craftsman ram, since that's the casting.

I started boring the taper this afternoon:

[vtsteam]

Trying the blued MT2 tapered center in the bore:

[vtsteam]

The light area towards the end means that the steady rest needs to move towards me to lessen the bore angle.

[vtsteam]

After adjustment, and a couple more passes, the pattern is spreading, but the steady rest still needs less set over:

[vtsteam]

The set over is now correct, though I need a few more passes to even out the pattern. When you reduce the set over, it cuts deeper in the back initially making a double pattern due to the springing of the necessarily thin boring bar. It evens out after a few passes at the same setting.

[vtsteam]

Once the angle was right, I put the blued center into the original Craftsman tailstock ram, and scribed it where they met. Then I used that to test for the proper bore depth in the new ram. When boring passes allowed the center to  reach the same line, below, I knew I had bored to proper depth.

[vtsteam]

Once the bore was finished, I needed to drill for the relieved section between the taper bore and the threaded back section of the tailstock ram. To re-center the steady rest, I loosened the steady's slot retaining screws, popped the MT2 center back into the tailstock and brought it up to the new ram bore. Applying a small amount of pressure with the handwheel centered the bore, and I tightened the steady rest down again.

[vtsteam]

Then I relieved the mid-section of the ram with a 1/2" drill bit to leave 3/4" at the rear of the ram for threading to take the jackscrew.

[vtsteam]

And here is what the business end of the ram looked like after finisheing the taper and midsection relief:

[PekkaNF]

Looks very good. Nothing wrong with the traditional construction.

Pekka

[vtsteam]

Thanks Pekka. 

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. 

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! 

[vtsteam]

So, what to do, what to do. I didn't fancy boring a new tailstock ram. Hmmmmmm. Wait a minute Didn't Vintage and Classic, Pekka, Neubert on this very forum mention using an insert for the threads in lathe rams? Why yes, they did!

Of course.... 

[vtsteam]

So, on with the show.....

Bore out the old wrecked threads and open out to .7495"

Check.

[S. Heslop]

No hope of finishing up the mostly cut threads with what was left of the mangled tap?

[vtsteam]

Sorry to say Simon, no the tap wouldn't budge further. I later found the cause to be that the relief section was slightly eccentric, because it had only been drilled (not bored). This jammed the tap, I believe. The relief section was a tricky problem, because I wanted to preserve the Morse taper's small end (as much as possible) yet relieve for a 1/2" jack screw at the other end. This really required an odd size drill that I don't have. I have a full range up to 1/2", but then it jumps to 5/8". Unfortunately, 5/8" would eliminate a lot of the narrow end of the Morse #2 taper. I was hoping that an older 1/2" drill, cutting a little oversize, would work in the hardest to reach section of the relief bore. But obviously, it didn't.

Anyway, I forged ahead with the insert plan, I found an old piece of 1" OD bronze bearing material that I had bought years ago, and never used. It coincidentally was bored almost exactly to the tap drill size for a 1/2" 10 TPI Acme thread. Sheer luck!

So I chucked that up in the lathe and started turning the outside down to get a light press fit in the tailstock ram.

[vtsteam]

While turning, I noticed its bore was not on center with the OD. Since I had to consider that bore as final, I stopped the lathe, and readjusted the chuck off-center to match the bearing bore. This proved out one of the really great advantages of my faceplate-3-jaw chuck setup! It was a piece of cake to clock in the bore, rather than the OD.

Then I continued turning the outside down, I got it to .750 and parted it off.