Tapping and Threading on a Lathe

[Mednanu]

Sorry in advance for the stupid question, but please clue me in on this one. When you have a lathe, do you need to purchase taps an dies anymore, or can you simply attach some sort of thread cutting blade, angle it for proper pitch and then cut any desired thread/pitch size you desire with it ?

 

[Rothrandir]

you can...

but taps and dies are much easier.

 

[tvodrd]

Mednanu,

Both! Taps and dies (in holders) are by far the easiest and fastest way to cut a very good thread. The size/HP/lowest speed of the lathe will determine whether you can do it under power. The one I use has 5HP and I have no problems with 1" dia threads. As sizes get larger, the price of the taps and dies $kyrocket. "Single-pointing" a thread requires multiple passes with a 60deg (included) cutter and lathes usually have a threading dial which makes it possible to repeat/synchronize sucessive cuts. Trying to cut the V-groove in a single pass only works for very fine/shallow threads and not particularly well then. Set up properly with the compound at 29 deg results in the tool only cutting on one side of the V. Kinda complicated to explain. Threading is one of the most challenging tasks with the lathe.

Larry

 

[Dan C]

[ QUOTE ]
tvodrd said:
Threading is one of the most challenging tasks with the lathe.

Larry

[/ QUOTE ]

Yeah, and also one of the most FUN things to do! There is something very satisfying about single point cutting a clean, shiny thread, a couple thousandths deeper on each pass, fitting them precisely with no discernable play between parts (can't do THAT with taps and dies). If you're not into production (and I'm not), mastering single point threading is very rewarding. Plus, you can cut any thread without the additional expense and hassle of running down oddball tooling that might only be used once or twice......

Dan C

 

[jtice]

I have to agree,
While it is alot more work, and takes alot longer, it really does feel great when you have accomplished it.

I know I surprised myself when I did my first threading.
I have only had to thread something twice, and both worked great.
2 for 2 isnt bad /ubbthreads/images/graemlins/grin.gif

 

[McGizmo]

It has been my experience that there are times when a tap or die can't be used since you need all of the thread to be full cut. I agree with Dan C's comments.

Now that I have a Hardinge Tool Room lathe, cutting thread is a real breeze, relatively speaking; no more thread dial and the auto feed is in both directions. There is a lever on the compound that pulls the cutting tool away from the thread, you back out via the auto feed, dial in a deeper cut and then go for another pass. There is an adjustable stop so the thread stops at the same point every time! Yes, I feel like I'm cheating, big time! But heck, I paid my dues! /ubbthreads/images/graemlins/tongue.gif /ubbthreads/images/graemlins/grin.gif

 

[jtice]

THATS how Gizzy cranks out all the cool stuff.
Super cool automated lathes !!

Nah, hes just the master. /ubbthreads/images/graemlins/rolleyes.gif


Those sound like REALLY useful features.

 

[Chief_Wiggum]

[ QUOTE ]
Now that I have a Hardinge Tool Room lathe

[/ QUOTE ]

/ubbthreads/images/graemlins/bowdown.gif /ubbthreads/images/graemlins/bowdown.gif /ubbthreads/images/graemlins/bowdown.gif

 

[Mednanu]

Thanks so much for all of the replies everyone ! It has cleared up a personal query about lathe's that I've had for some time now.

tvodrd - I totally get what you're saying about cutting half the V within the thread from your very good description /ubbthreads/images/graemlins/wink.gif - things in my head are wired very visually, so I saw a picture of exactly what you were talking about just from your explanation. It was something that I had never thought of before ( ie - only 1 'side' of the thread gets cut at any given time, then one has to cut the other side, to make a V in the thread). I could see how this would make things VERY challenging to get the tool passes aligned just right in order to allow the thread cut to complete successfully !

 

[tvodrd]

Mednanu,

To complicate thing just a little, your final/last pass should be a few thou with the cross slide and not the compound to get the full V profile. A set of thread measuring wires or if you're big bucks, a thread micrometer can be invaluable. Internal's require gages. I very strongly suspect that most of us thread one part and then keep trying it on its mate in progress until "ahhhhhh." /ubbthreads/images/graemlins/grin.gif (Of course there's the crapshoot if you're planning to plate or anodize. /ubbthreads/images/graemlins/grin.gif )

Larry

 

[Rothrandir]

also be careful about forcing it...

i've permantently adhered a custom head to a mag body /ubbthreads/images/graemlins/frown.gif
this was no sissy head either!

/ubbthreads/images/graemlins/mecry.gif

 

[Chief_Wiggum]

[ QUOTE ]
i've permantently adhered a custom head to a mag body

[/ QUOTE ]

/ubbthreads/images/graemlins/blush.gif /ubbthreads/images/graemlins/blush.gif /ubbthreads/images/graemlins/blush.gif

I bashfully admit to doing the same. If it won't thread on easily, it aint goin on. If it does, it aint comming off /ubbthreads/images/graemlins/icon15.gif

If it's too tight you can try to make a pass at the same infeed to clean things up, or advance the cutter in 0.005" increments until it fits just right.

Make sure to deburr the threads with some sandpaper or a fine file.

 

[Mednanu]

Thanks for all the replys everyone !

I've actually been looking at something like this, but fear that it might be too much of a 'kiddie lathe', rather than the serious tool of mass destruction like I'd hoped. I totally like the idea of the modular design being able to be reconfigured into a lathe, drill press, horizontal milling machine, etc. Probably a bit too weak and inaccurate for serious jobs, but I really like the versatility and modular, upgradeable design of the whole unit.

 

[KC2IXE]

Don't buy the Unimat 1 - the OLD Unimats were better, but still pretty much a toy

With a lathe (and mill for that matter) you really have to ask yourself the following questions

1)How much room do I have
2)How much am I willing to spend
3)Do I have the time to learn to use it

Another thing to remember as a rule of thumb - you will spend a price EQUAL to the price ot the lathe buying the basic tooling for the lathe - chucks, centers, etc

The basic 7x10s get OK reviews. The Old Atlas/Craftsman 6x18s are a good starter lathe (do NOT get a dunlop/AA Craftsman) I hear the Taig lathes are OK - the Sherline lathes were not bad, and their baby mill was my first mill (still have it - going to turn it into a cnc test bed "one of these days")

Just remember, if you have the ROOM, and you look long enough/put the word out, you can often stumble across lathes/mills cheap - one time I missed 2 lathes - a 10 SB and a 12" LeBlond by a day - cost? "take them - they are taking up too much room in my garage"

 

[Mednanu]

I'll keep looking to see if I can score a deal on something better - at least I'm not in a rush buy one just yet. I simply have a serious case of lathe/fabrication envy. ...I've found that Dremels are great, but you can only go so far with them once you move into the arena of fabrication, as opposed to repair or modification.

 

[ABTOMAT]

Do you plan on threading on a lathe? You need one with a power-traversing carriage and a gearbox or changegears.

How much $$ do you want to spend for versatility? If you can have a machinist friend make sure it's not junk (a lot are) an import 3-in-1 machine is good for smaller stuff. A namebrand like a Smithy is better but more expensive. I'm not really a fan of combo machines, but they do save space and can be pretty cheap.

The Unimat-1 really is a toy. I have a Unimat SL2000 from around 1965, back when they were very high quality. As nice as it it, it's still tiny with few features. Can't turn anything very wide, no threading, etc. Nice for really tiny stuff, though.

KC2IXE, what do you have against the AA Craftsman lathes? The only real problem with them is the undersized spindle bending. Most folks have made their own solid ones now. Just treat them as a 4" (never should have been made in 6" sizes) and you're fine. Of course, they're pretty pricy now the way very small vintage lathe prices have gone.

 

[KC2IXE]

[ QUOTE ]
ABTOMAT said:
...snip...
KC2IXE, what do you have against the AA Craftsman lathes? The only real problem with them is the undersized spindle bending. Most folks have made their own solid ones now. Just treat them as a 4" (never should have been made in 6" sizes) and you're fine. Of course, they're pretty pricy now the way very small vintage lathe prices have gone.

[/ QUOTE ]

You about summed it up - too many folks I know found bent spindles, found problems buying new chucks for the small spindle, and they cost as much as the Atlas version, which is a lot more lathe for the buck.

As you say, if you treat them as a VERY light duty 6, or as a 4" lathe, they are OK, once you check things out. Solid spindles limit you

Me? I have a 12" "commercial" Atlas with almost every tool that was offered (yes, even the lever collet closer and turret tailstock) - Just about the only thing missing is the BED turret. I "stole" the basic lathe, in PERFECT condition for $450, and have since tooled it up

The BIGGEST limitation of that lathe, and the thing that drives me nots about most small lathes is the size of the hole through the spindle. It's 3/4" on the 12", and once you put the lever closer in, it's 1/2". I run a production job that would be PERFECT for the the lever closer, except it takes 5/8" stock /ubbthreads/images/graemlins/frown.gif

One day, probably in the next few years, I'll replace the Atlas - I'm thinking 10ee or HLVH- the big problem there is lack of length between centers. I don't have the room for the LONG 10EE. Another choice I'm thinking about is a Sheldon. The BIGGEST problem with all of these is ROOM - My shop is in the basement, and rigging the stuff down (and UP) isn't fun /ubbthreads/images/graemlins/icon3.gif