found a new way to be hard on my lathe tonite....

[alinwa]

Pete, don't be fooled by how things "appear". Yes, rigidity and HP are a plus when doing heavy work. But there is no reason a guy can't do good work (turning, drilling, parting-off) using a 10"-12"- 13" swing lathe (that includes bench lathes,,, and you probably won't be drilling any 2" holes unless it's in nylon/plastic). You just have to take into account that you may not be able to do it as fast. Proper tool geometry, proper spindle speed and feed rate, proper set-up, good work holding (chuck or collet) and good tool holding all make a difference in the final outcome, regardless of machine size. There's no reason on earth why a guy can't part-off half a dozen pieces on a manual bench lathe if he has observed all that I mentioned above, even to include feeding the parting tool with the power feed. These are "basic" principals, traceable back to the beginning of the industrial revolution. Ignore the "basic principals", whether chambering a barrel or parting-off a 1" piece of 12L14, drilling a hole of any size or turning to a given size and the trouble begins!

Interesting that you mention use of the power feed for parting. This one I haven't got licked, you're better than me. Much better.....

Due to the changing surface speeds I feed by hand, by 'feel' while parting, even with cheater-stock like 12L14. Pretty much always I feed by hand once I think about it, for parting. Even for one piece...

Just last nite I was making weights for pool cues, parting off 1" hunks from 1" diameter barstock. Exactly like your above illustration. I managed to get 6 (your "half a dozen") from one setup by seriously feathering my in-feed, basically making the first 3-4 parts all at different rates. Of course the last couple I could have walked away...

BUT....6 was my limit. I made about 20pcs. I don't think I could do 7 pcs without messing up my end cuts and finishes.

 

[shortgrass]

Interesting that you mention use of the power feed for parting. This one I haven't got licked, you're better than me. Much better.....

Due to the changing surface speeds I feed by hand, by 'feel' while parting, even with cheater-stock like 12L14. Pretty much always I feed by hand once I think about it, for parting. Even for one piece...

Just last nite I was making weights for pool cues, parting off 1" hunks from 1" diameter barstock. Exactly like your above illustration. I managed to get 6 (your "half a dozen") from one setup by seriously feathering my in-feed, basically making the first 3-4 parts all at different rates. Of course the last couple I could have walked away...

BUT....6 was my limit. I made about 20pcs. I don't think I could do 7 pcs without messing up my end cuts and finishes.

After machining for 40+ yrs a guy is bound to learn a few things IF he keeps his eyes (and mind) open. 17 of those 40yrs were spent in my own shop working for customers that just kept coming back for more..... I spent many of those years tooling, setting-up, and operating multiple spindle automation screw machines (NO! I didn't make screws, unless they were real special).

 

[Pete Wass]

I grew up

Pete, as many on this Forum know, I own a Machine shop with some rather large equipment. We also have small equipment. We perform a large array of machining operations on a wide variety of parts involved in our primary mandate, serving the Marine Industry.

You are correct. The amount of metal you can remove without any overloading of a particular machine is directly related to the overall size, rigidity, and power of that machine.
The picture is our largest a radial Drill. If needed, it will punch a 3 inch hole through mild Steel with no problem at all.

http://benchrest.com/attachment.php?attachmentid=18586&stc=1&d=1477841494

We make a lot of Stainless Steel Steering Pins for Push Boats out of 3inch diameter stock. We used to saw them to length. Now, with insert parting tools and new heavy duty 20 inch lathes, such as the one in the picture, we can part them off at a speed of 300 rpm.

http://benchrest.com/attachment.php?attachmentid=18587&stc=1&d=1477841875

Among folks who were what today are called Lumbermen. A comment they use to make about their saws when they were bragging them up was " That baby will really haul shavings". I think of that sometimes when I watch the big chips coming off that old Iron.

It does appear that tooling has made great advances and enables a lot of the big work they do. That lad in Kentucky has a G&L boring mill that fills up two semi beds which he plans to set in his Barn/workshop that he is slowly putting together. 30" of travel in it's spindle. He plans to use it and has work lined up for it. Good to see the Old Iron being used still.

Pete

 

[James Lederer]

The tang!

I could be totally wrong, but the purpose of the taper is to lock the tool in place, provide positive repeatable location, and to transmit torque to the cutting tool.

The primary purpose of the tang, is to eject the taper when the quill is retracted or through the use of a wedge. That's why it is called an ejection tang. A secondary purpose of the tang may be to prevent further rotation if the taper slips, but chances are on a big machine you will just end up with a broken tang and a messed up quill. If you are having trouble with the taper not holding, it's time to investigate why.

If you are drilling a large hole, even a small lathe is capable, but this is the key to making it work. If you are drilling in steps and are taking too small a bite (for instance going from 7/8" to 1"), you are asking for the taper to slip. This is because you have a large diameter with high torsional loads, yet it takes very little thrust to feed the drill. The thrust is what keeps the taper locked.

If you need to drill a 1" hole, it will work better to drill a pilot hole slightly larger than the web on the drill (1/4" should be plenty) and then drill the hole in one step in back gear. If your lathe stalls or breaks the drill, you can go up a little larger on the pilot hole. In other words the key to preventing the taper from slipping is to make sure there is adequate thrust on the drill. This is totally counter intuitive, but it works.

 

[Pete Wass]

I have noticed

With older drilling machines, machines a bit larger then what we consider drill presses today, all of them have spindles with a slot for knocking out the drill or drill adapter, one. I kinda got the drift from that that perhaps the tang was indeed there for preventing slippage as well as disengaging the drill or drill adapter sleeve. Perhaps this is wrong thinking but if it's there anyway, why not ensure that the dang things don't slip?

I understand James and have experienced the same as you have described. Better to slowly punch a big one than fool around with the steps. Sort of like threading. There are a number of new instructional vids on threading. Eye openers, they are.

Pete

 

[coyotechet]

Drilling

I use my Heavy Ten to do lots of heavy drilling with 1" drills and also power feed when parting.
Chet

making cats head for lathe thread spindle.

 

[jackie schmidt]

The "Tang" on a Morse Taper is the primary positive driver, or in the case of a lathe tailstock spindle, (where one is present),or a position on a tool holder of a Turrent Lathe, it is the primary anti rotation device.
Notice the word "positive". That, in machinery terms, means failure would be predicated on the actual destruction of the piece, as in twisting off of the Tang.

A clean dry taper will offer a certain amount of grip and prevent turning in light load applications, but that is not it's primary purpose when heavier radial loads are encountered.

It is built on a 5/8" nominal taper per foot to facilitate easy removal while at the same time provide a firm and slack free mount.

A #50 milling machine spindle taper has two recesses on a flang that serve the same purpose when using cutters that are subjected to lots of cutting torque, such as multi cutter stabbing mills.
http://benchrest.com/attachment.php?attachmentid=18620&stc=1&d=1478050318