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Never Have I Ever

T

Tecnico

(Dave)
Premium Member
Never have I ever............ turned a piece of steel and gotten a mirror like finish like I get from turning aluminum with a new indexable insert tool.....until today!

I was getting set up to make a doodad to mount my mill DRO display and deciding which of my HSS, brazed carbide or insert tools to use on a piece of cold rolled bar. I've never been satisfied, often I'll get a decent finish, sometimes it turns out pretty good usually with HSS but I've never been truly happy with the result. It's usually the typical gummy steel part that's decent and functional.

On a whim tonight I took @Dabbler 's advice and dressed the flanks and nose of an indexable carbide insert with a diamond EZE Lap and was blown away with the result. Like night and day even after I've stepped up my HSS grinding & polishing.

OK, I'm a detail guy so: .030 DOC, .002 feed with a SOWA DCMT21.51-F2P insert, 1-1/2" cold rolled bar running 720 RPM so ~280 SFPM. The finish was actually better for the first cuts & not quite as good as the diameter decreased. The chips were coming off between brown and bright blue and HOT on the hand waiting to disengage the carriage feed (ouch!). It was coming off in chips too, not ribbons.

Oh, and the DRO saved a lot of jigging around with carriage stop/dial indicators and stopping to take measurements. I think I'm going to be using the micrometer more and calculator less with the DRO.

Never stop learning.

Anyhow, I just had to share. :)

D :cool:
 
YYCHM said:
Need Pics....
Click to expand...

Ask and you shall receive! The part in question:

TW-22.jpg


For scale, the threads are 5/8-11 - single point cut using the hand crank. EDIT: To my chagrin I found that the nice indexable tools I bought for threading and haven't tried out yet don't cover threads as deep as these therefore the fallback to a ground HSS tool. :(

D :cool:
 
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I suggest you buy some DCGT CCGT inserts and try it on steel, Forget doing .030 DOC - But a nice shallow finish pass ( relative to your nose radius ) and a semi slow feed ( .003 IPR ) will yield the same. More or less.
At the highest RPM you can muster. ( relative to your part of course )

If you are chasing those tenths, Consider using a HSS shear tool, https://gadgetbuilder.com/VerticalShearBit.html


Gluck
 
Tecnico said:
For scale, the threads are 5/8-11 - single point cut using the hand crank.
Click to expand...

Ya........ I'm REALLY LIKING THAT CRANK! If I had made that part, the OD would look good too, but that would be a relief at the shoulder, not a nice fat shoulder.

Of course, somebody on here is gunna say something like just thread in reverse. But, that still makes a start groove. With your crank, the thread just ends - prolly even better than cnc. Yup, I'm a fan!

My crank isn't gunna happen overnight. But it's gunna happen!

Good on you for such an amazing innovative idea!

And ya, nice finish too..... :rolleyes: LOL!
 
Proxule said:
I suggest you buy some DCGT CCGT inserts and try it on steel, Forget doing .030 DOC - But a nice shallow finish pass ( relative to your nose radius ) and a semi slow feed ( .003 IPR ) will yield the same. More or less.
At the highest RPM you can muster. ( relative to your part of course )

If you are chasing those tenths, Consider using a HSS shear tool, https://gadgetbuilder.com/VerticalShearBit.html


Gluck
Click to expand...

I've read about using the DCGT on steel, haven't yet made the leap to try them - note to self; move it to the To Try List.

I've also seen reference to the shear tool but never an explanation that actually describes how it is ground and works, thanks for the link! One more item for the To Try List.

D :cool:
 
Susquatch said:
Ya........ I'm REALLY LIKING THAT CRANK! If I had made that part, the OD would look good too, but that would be a relief at the shoulder, not a nice fat shoulder.

Of course, somebody on here is gunna say something like just thread in reverse. But, that still makes a start groove. With your crank, the thread just ends - prolly even better than cnc. Yup, I'm a fan!

My crank isn't gunna happen overnight. But it's gunna happen!

Good on you for such an amazing innovative idea!

And ya, nice finish too..... :rolleyes: LOL!
Click to expand...

LOL! I can't take the credit for the hand crank, somewhere in the deep depth of knowledge of the UK Myford users someone invented it or re-spun it from something they saw. Very good idea though. I believe you can get a Hemingway kit for it.

I do have to put my thinking cap on though, mine can slip when I get into the last passes in deep threads like the 5/8-11. No notches or features on the tail end of the spindle to key to like you have though and I am NOT modding the spindle. I think it'll be a mod to the split angle.

OK, fessing up. The lack of relief groove is not by design, I had intended to do one but I also got the bug to cut the thread last night during quiet time so I couldn't run the machine. I hadn't cut the grove yet so I went ahead without it., lack of patience........turned out fine though. The part will pass though a bushing before it engages the threads so no functional issue.

D :cool:
 
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Tecnico said:
LOL! I can't take the credit for the hand crank, somewhere in the deep depth of knowledge of the UK Myford users someone invented it or re-spun it from something they saw. Very good idea though. I believe you can get a Hemingway kit for it.
Click to expand...
Yes lathe hand crank accessories has been around model engineering circles for a long time. I'm pretty sure I've seen it in ME mags in the 60's. Not just for controlled threading but 'indexing' with headstock or chuck mounted gears, spring winding & other useful purposes. Always useful to see these techniques because as time goes by they can become forgotten.

Back to hand crank threading up to a shoulder, one thing going for them at the time was HSS cutting tools which are considered more forgiving than carbides given the very slow surface speed & maybe slightly uneven Armstrong rpm. Because everyone knows, threading with carbide on a non-cnc hobby machine causes Biblical floods, volcanic eruptions & Goats raining from the sky.
 
Tecnico said:
LOL! I can't take the credit for the hand crank, somewhere in the deep depth of knowledge of the UK Myford users someone invented it or re-spun it from something they saw. Very good idea though. I believe you can get a Hemingway kit for it.
Click to expand...

I used to enjoy discussing how innovation happens with my research and academic colleagues. It seems like most often, it is the product of a young uncluttered mind unschooled by the discipline and rote of established methods and formulas. But sometimes a cluttered mind is required to provide enough cross-fertility for synthesis to arise spontaneously. Perhaps it's that piler / filer thing again. Other times, I think it's driven by raw need, or just building on other new or existing ideas.

At any rate, I had found myself wondering how that crank idea arose in your mind. What in the world led you to that idea.....

I had thought maybe you were trying to fill a specific need, or perhaps you were using a chuck wrench to rotate the chuck and got tired of it.....

In any event, I had raised my image of you to compare with one of those rare geniuses like DaVinci or Gallileo.

Now I discover that you just saw it on a board in England. Alas, you are not a DaVinci anymore..... Just another amazing Machinist doing ordinary things like making fine machines out of iron ore.

Ya, I'm still impressed. Just only mount everest level now, not a super god on mount olympus. Insert big sigh here......

No worries about whether you planned the shoulder or not. That wasn't my point. My point was that it was possible at all!

Feel free to ask about shear tools, I make and use them all the time. When nothing else will produce a good finish on mystery metal while creeping up on a dimension, a shear tool will. Look them up on our forum here too. There has been some good discussion.
 
Tecnico said:
single point cut using the hand crank.
Click to expand...
I read this statement a couple times, and couple other members replied, and I'm, "what in tarnation are they talking about?". I've never heard of that. Of course I had to Google it. Ok, I get it.

I had to do something similar on an internal trapezoid thread in a blind hole. Yes, I ran it in reverse, but because its metric, couldn't disengage the half-nuts, so had to pull on the motor drive belts to bring it back to the starting point. But I don't think a hand crank would have worked because I was in low gear, lowest speed with a 14" 4-jaw. I could barely hand turn the chuck.
 
I’m stuck with my Harrison, threaded Chuck, no lock and no reverse either. I miss having a Voest Lathe and a Snap-Tap, thread, reverse forward set dial, repeat, right to a shoulder, at high speed.
 
PeterT said:
Yes lathe hand crank accessories has been around model engineering circles for a long time. I'm pretty sure I've seen it in ME mags in the 60's. Not just for controlled threading but 'indexing' with headstock or chuck mounted gears, spring winding & other useful purposes. Always useful to see these techniques because as time goes by they can become forgotten.

Back to hand crank threading up to a shoulder, one thing going for them at the time was HSS cutting tools which are considered more forgiving than carbides given the very slow surface speed & maybe slightly uneven Armstrong rpm. Because everyone knows, threading with carbide on a non-cnc hobby machine causes Biblical floods, volcanic eruptions & Goats raining from the sky.
Click to expand...

Oooh, you poked the goat, look out for the locusts too!:p

I was looking forward to trying out the indexables just to avoid the fun of grinding and tweaking the HSS but it worked out fine. Maybe another job.;)

D :cool: :
 
thestelster said:
But I don't think a hand crank would have worked because I was in low gear, lowest speed with a 14" 4-jaw. I could barely hand turn the chuck.
Click to expand...

The closest I've ever come to @Tecnico s crank is to use the jaw tool in the drive holes and turn the chuck and spindle with that. But I never thought to cut threads that way.

I don't think you need to have the spindle in low gear. You can cut threads or turn the chuck manually in a higher easier to turn gear.

But I'm making myself a crank. I'm gunna bolt mine to the spindle ( because I can) and I'm going to make the crank a ratchet wrench so I can leave it engaged for the entire threading operation. I make make the spindle drive a simple 1/2 female square drive. To accept various wrench ratchet styles.

Of course, after I install a VFD and can run at 1 rpm, I may not care about wrenches anymore.....
 
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