Threading without the end groove

All discussion about lathes including but not limited to: South Bend, Hardinge, Logan, Monarch, Clausing and other HSM lathes, including imports

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whateg0
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Re: Threading without the end groove

Post by whateg0 » Thu Apr 12, 2018 9:42 am

drmico60 wrote:
Sun Mar 25, 2018 11:28 am
I made an electrical autostop for my minilathe, see:
...

Mike
That's what the ELSR on my 10ee does. I only recently got a decent VFD installed so that the spindle doesn't coast to a stop, and haven't had a chance to try it out yet. I've been withdrawing the tool and not using a runout groove on the parts I've made recently, then follow it with a die.

Dave

Oldboy1417
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Re: Threading without the end groove

Post by Oldboy1417 » Sun Oct 21, 2018 10:30 pm

Hi
Could you help me with a treading problems. I'm trying to thread a back plate for my 6" Chuck for my atlas12" late 1 1\2" x 8 threads per inch .national coarse thread series what I need is the (major dia) (the minor) (thread pitch) and the OD of the hole for 1 1\2" x 8 tpi i don't have a thread chart that show the thread I need
Allan

Harold_V
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Re: Threading without the end groove

Post by Harold_V » Mon Oct 22, 2018 1:42 am

Lets start with the thread size, which is NOT in the national course series. If it was NC, it would be six threads/inch.
That said, what you have is likely considered to be an N-3 (class three) thread. Pitch diameter for that particular thread would be 1.4188"/1.4251".
Minor diameter, which is the size of the hole you'd thread, is 1.3647/1.3795. This information is based on a 1½"-8 pitch internal thread.

If you don't happen to own a Machinery's Handbook, I highly recommend you purchase one. The information provided was taken from an old one (15th edition). It was purchased new, by me, way back in 1958 and has served we perfectly well for years. A more modern version will have more information within, including threads that were not commonplace when the 15th edition was printed, but unless you're involved in CNC machining, a current edition (which appears to be #30) isn't really required, and they're not cheap. With rare exception, you'd be served perfectly well with an older edition, say something in the mid 20's, and they're reasonably priced. Just sayin! :wink:

H
Wise people talk because they have something to say. Fools talk because they have to say something.

John Hasler
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Re: Threading without the end groove

Post by John Hasler » Mon Oct 22, 2018 7:05 am

Newer editions of Machinery's Handbook are actually less useful for manual machining than old ones. They started deleting some of what is considered obsolete data to make room for more CNC-related stuff so that the book wouldn't get to be a foot thick.

I wish they'd put out an electronic-only edition with everything in it.

Harold_V
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Re: Threading without the end groove

Post by Harold_V » Mon Oct 22, 2018 2:37 pm

John Hasler wrote:
Mon Oct 22, 2018 7:05 am
Newer editions of Machinery's Handbook are actually less useful for manual machining than old ones. They started deleting some of what is considered obsolete data to make room for more CNC-related stuff so that the book wouldn't get to be a foot thick.
Yep! I agree, although Patio (one of our readers and contributors) gifted me a newer edition when we discovered that my old 15th didn't have any information on the thread used for speedometer cables (non-standard), which the newer edition contained. It's out in my shop and I'm not there right now so I can't say for certain what edition it is, but it's in the 20's, towards the lower end.

It gets complicated when trying to dispense advice. Most of the home shop types are limited to manual machines, but not all. My entire career on machines was limited to manual operations, and that's where I can help. Once it gets to CNC operations, I rarely can offer anything of substance, instead finding myself the student trying to learn.

The machining arena is huge. No one can know it all. Thankfully, we have wide representation on this board, so most issues can be addressed by those with experience, for which there is no substitute.
I wish they'd put out an electronic-only edition with everything in it.
Heh! Talk about a foot thick book, that would surely be the case. What little education I got in regards to electricity and electronics came in high school, when solid state wasn't yet known (at least in the commercial world). Even without that consideration, I can only imagine how thick an all-inclusive book might be. A great idea, though. I know that Machinery's book has bailed me out countless numbers of times. I relied on it almost exclusively for thread data when I ran my commercial shop. The machinist's bible, for sure.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

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neanderman
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Re: Threading without the end groove

Post by neanderman » Tue Oct 23, 2018 10:44 pm

I have four editions of Machinery's Handbook: 10th, 1940 (my Dad's first); 13th, 1948; 15th, 1954; 17th, 1966 (Dad's second). The middle two I bought at a used book store that were going out of business. With a 3.5 story house, I keep one on each floor (with the newest one in the shop) -- that way, I don't have to hit the stairs every time I want to look something up. I might also have a problem... :D

I'd watch eBay or search ABEBooks. Just be careful not to confuse the 'Guide' with the actual manual.
Ed

Le Blond Dual Drive
US-Burke Millrite MVI
Atlas 618
Files, snips and cold chisels

Proud denizen of the former "Machine Tool Capitol of the World"

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4gsr
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Re: Threading without the end groove

Post by 4gsr » Tue Mar 26, 2019 5:08 pm

If you ever worked in a oilfield machine shop, most of the threads are cut up to a shoulder and pulled out next to the shoulder. Rotary shouldered connections are cut on a 2" or 3" taper per foot and as coarse as 3-1/2 threads per inch. And can you imagine threading at around 160 something RPM on a diameter that varies starting out around 3" and at the large end of the thread around 4-1/2" and about 4" long? That shoulder comes up pretty quick, and you better be quick on kicking out the half nuts and retracting the cross slide to within 3/8" of the shoulder. They do make air kick outs that will dis-engage the half nuts and retract the cross slide if you were lucky to own a lathe equipped with such. I don't miss those days one bit! KenS.
Ken

drmico60
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Re: Threading without the end groove

Post by drmico60 » Tue Mar 26, 2019 5:37 pm

My solution to this problem was to make an autostop that is linked to the lathe motor, see:
http://mikesworkshop.weebly.com/autostop.html
http://mikesworkshop.weebly.com/lathe-m ... ntrol.html
This system works especially well when used in conjuction with a swing up toolholder, see:
http://mikesworkshop.weebly.com/swing-u ... older.html

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Bill Shields
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Re: Threading without the end groove

Post by Bill Shields » Tue Mar 26, 2019 7:28 pm

All of this discussion is why there are lathes with a 'quick retract' lever on the cross slide...so that you don't have to worry about kicking out the 1/2 nut...you just yank the lever and out comes the cross slide..

I have seen this feature more on European machines (UK and Italy) than from north america
Too many things going on to bother listing them.

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liveaboard
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Re: Threading without the end groove

Post by liveaboard » Wed Mar 27, 2019 4:57 am

My ancient lathe has no threading dial, no brake, no clever pull out gizmos.
And as a newby, my skills are [shall we say] still in development.
So I've had my struggles.
A trick I found; a white paint mark on the work really helps. I count the rotations and pull out the tool as the paintmark makes the numbered pass.
When the work is short and desperate, I reverse the motor for an instant to stop the machine [a trick I learned from watching an experienced guy in India]. Even that needs a little practice.
When the tip gets broken it sure is a pain, and time consuming, to get it all lined up again.
and again.
So I use a grove whenever possible.

Harold_V
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Re: Threading without the end groove

Post by Harold_V » Wed Mar 27, 2019 3:51 pm

Bill Shields wrote:
Tue Mar 26, 2019 7:28 pm
...so that you don't have to worry about kicking out the 1/2 nut...you just yank the lever and out comes the cross slide..
Unless the half nut is disengaged simultaneously, that often isn't enough to be of much help. If the shoulder is much larger than the thread diameter, you're still going to hit the shoulder. As I've not experienced such a lathe, can you make your comment more clear? Does the half nut get disengaged along with the compound retraction?

One thing should be mentioned. One acquires the skill of threading manually by repetition. If one avoids the activity, when it's mandatory, it most likely won't be successful. Also, while one is free to provide a thread relief at the end of the threaded portion, that may or may not be an option when working to a print. Learning the process and honing the skill of single point threading is very much a part of one learning to machine. I highly recommend it not be circumvented.

The art of tool extraction and half nut disengagement can be practiced safely by simply stopping at the same point time and again on a straight piece, no shoulder. If destrection of the tool is an issue, practice can be achieved by machining some PVC pipe, whish is soft enough to avoid destruction of the threading tool when the disengagement occurs beyond the target position. It's cheap, and machines very nicely. A great choice in material when practicing technique.

Assuming the most common right hand thread, external, orient the cross slide so the handle rests @ 10:00, with the dial set @ 0. That way, you achieve the most travel of the cross slide with the same motion, which, by using this process, is just a down motion. The half nut is disengaged at the same time the handle is pushed downward, all in one, smooth motion. Try it. It works quite nicely.

One thing. If one uses random cross slide locations, such that the handle may require pulling up instead of pushing down, in a panic, the wrong direction may be chosen. Make a habit of using the 10:00 orientation for that reason.

And, checking pitch diameter with wires? Don't make that hard by doing stupid things, like holding the wires with any kind of restraint.

First, clean out your chip pan/tray before using wires. That way if you drop one it is easier to find.
Place the third wire between your lips.
Set the micrometer slightly larger than the expected reading.
Place two of the wires on the top of the part to be measured, centering them on the item so they don't fall, and separated such that the spindle of the micrometer spans the two wires.
Place the micrometer on top of the wires, which will hold them in place.
Grasp the third wire and place it between the top two wires, but at the bottom of the part. The wire should be free to slide in the thread, but not be able to move side to side between threads.
Once in place, the diameter can be read by tightening the micrometer appropriately.
Repeat the process after taking additional cuts, until the target diameter is met.

Don't hold wires by any means that will prevent self orientation. It takes very little misalignment of the wire to yield an erroneous reading. Even a small amount of tape holding the wires is enough. Learn to use the wires individually. It's not hard once mastered.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

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4gsr
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Re: Threading without the end groove

Post by 4gsr » Wed Mar 27, 2019 4:03 pm

One tip we used to use when checking threads by M.O.W. Take a dab of grease and apply in the thread where the wires will be placed and do this at 180 degrees from each other. Now, place the wires in the thread, the grease will hold them long enough to get a measurement. Haven't yet lost a wire using this method. KenS.
Ken

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