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Thad in AR. 
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 Topic: Machinist question
Posted: 01 Feb 2024 at 5:29pm |
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I have a 1 1/4” shaft. I need to cut 6 inches off of it and machine a snapping groove in the end.
It’s too bog to slide through the head on my lathe.
I’m thinking Chuck the end to be cut off in the Chuck
Machine the snapping groove and then cut it off.
The shaft has a key way full length. What I need to know is can I run this with my steady rest having ng that key way?
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steve(ill)
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Posted: 01 Feb 2024 at 5:47pm |
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i would take a key 2 inches long and set in the way where the steady rest will ride.. Hold it on with a hose clamp, then grind it down smooth with the shaft.. You dont want any lip that can be caught... I dont thing .020 inch step will hurt you, but i would not try a 1/4 inch deep keyway... better safe than sorry.
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steve(ill)
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Posted: 01 Feb 2024 at 5:50pm |
I have also made a SLEEVE to slide over the shaft and epoxy it into place where the steady rest can ride on the SLEEVE.. can be brass or steel... When your done, use a cutoff wheel to split the sleeve where the key way is, then spread and it will pop off.
You might even be able to drive a little wood dowel into the key way to SNUG the sleeve , and not need the epoxy.... Not a lot of LOAD on the sleeve from the steady rest jaws.... little oil goes a long way.
Edited by steve(ill) - 01 Feb 2024 at 5:52pm
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Like them all, but love the "B"s.
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Codger
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Posted: 01 Feb 2024 at 5:50pm |
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Clamp a snug shaft collar to the shaft for the steady rest to bear against, or use a centering square to find center the shaft, and using a center drill, bore a tapered pilot for your tailstock to bear against. I have done it without any special attention but using little pressure on the steady rest feet bearing upon the shaft. A snap ring groove doesn't need to be absolutely precise but it is preferred.
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Thad in AR.
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Posted: 01 Feb 2024 at 6:08pm |
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I like the idea of a sleeve and the ground down key way.
I have bearings that go on that shaft but I bet they’re bigger than my steady rest will go to?
Codger the shaft is hollow 1/4” wall chrome Molly . It’s longer than the bed so I can’t use the tail stock.
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desertjoe
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Posted: 01 Feb 2024 at 6:39pm |
Well,, I believe I like the idea of the sleeve like Steve suggests to make sure the steady rest has a no obstruction spot to run into,,,,something that long can become a dangerous wayward missle,,,if it hangs for an instant,,,?? 
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Codger
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Posted: 01 Feb 2024 at 7:02pm |
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Easy enough to machine you a collar to slip fit over the shaft bored to 1.255 internally and turned externally to dimension your steady can bear against. A recessed set screw to lightly bite into the shaft keyway to keep everything rigid will easily clean up with a file after completion.
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A career built on repairing and improving engineering design deficiencies, shortcomings, and failures over 50 years now.
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jaybmiller
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Posted: 02 Feb 2024 at 6:22am |
outside the box thinking here.... slide a bearing whose ID is 1.25' onto the shaft,use electrical tape either side to hold in place,put steady rest around the OD of the bearing ??
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desertjoe
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Posted: 02 Feb 2024 at 6:49am |
Years ago, the youngest son of the Refinery Mgr and crew were replacing the mechanical seal on a 150 HP vertical transfer pump out in the field. The shaft on these electric motors could be removed vertically and had been raised about 10" for clearance to replace the mechanical seal. The motor was still bolted to the pump body. After replacing the mechanical seal,,the crew chief bumped the starter to verify seal set and disaster struck!! The 2" motor shaft instantly came to speed at 3600 and centrifugal motion bent that 2" shaft OVER and hit the worker in back of head!! In the following OSHA investigation, the instructor took a office type electric eraser, pulled the eraser out halfway and "bumped" the switch and showed everybody how that fatality happened in a blink of an eye.
Be very careful with this type of possibllity!!!
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Thad in AR.
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Posted: 02 Feb 2024 at 11:25am |
 jaybmiller wrote:
outside the box thinking here.... slide a bearing whose ID is 1.25' onto the shaft,use electrical tape either side to hold in place,put steady rest around the OD of the bearing ??
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My thoughts as well. Right now my wife has a broken leg so I was cool and cleaner and never got a chance to see if the steady rest will go that big? I’ll try tonight or in the morning.
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Thad in AR.
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Posted: 02 Feb 2024 at 11:29am |
desertjoe wrote:
Years ago, the youngest son of the Refinery Mgr and crew were replacing the mechanical seal on a 150 HP vertical transfer pump out in the field. The shaft on these electric motors could be removed vertically and had been raised about 10" for clearance to replace the mechanical seal. The motor was still bolted to the pump body. After replacing the mechanical seal,,the crew chief bumped the starter to verify seal set and disaster struck!! The 2" motor shaft instantly came to speed at 3600 and centrifugal motion bent that 2" shaft OVER and hit the worker in back of head!! In the following OSHA investigation, the instructor took a office type electric eraser, pulled the eraser out halfway and "bumped" the switch and showed everybody how that fatality happened in a blink of an eye.
Be very careful with this type of possibllity!!!
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I’m taking note. I’ll be running the lathe on the slowest speed and use a parting tool to cut the snap ring groove. I’ll use the same tool to cut the shaft off but I’ll not cut all the way through. I’ll finish the cut with a hack saw and dress the end with a file.
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Tracy Martin TN
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Posted: 02 Feb 2024 at 6:37pm |
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How long is the shaft to be machined with snap ring groove? Will it fit between centers of lathe? I don't understand the problem I guess. If you can chuck it up, put a center in the end to be machined. HTH Tracy
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steve(ill)
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Posted: 02 Feb 2024 at 7:44pm |
he has a 4 ft shaft and a 3 ft lathe............ thats why the steady rest..
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Like them all, but love the "B"s.
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BrianC
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Posted: 02 Feb 2024 at 8:18pm |
Sounds like make that sleeve. Doesn't have to be pretty. It is 3 feet from the groove, a little wobble, it's just a snap ring. Remove tailstock. Chuck end with snap ring. Add steady rest. Make the groove. Cut off tool to partly cut through, finish with hacksaw.
I used to have a large lathe with big 3" hole through head stock. How delux. Now I have a little 10" lathe, much more limited.
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desertjoe
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Posted: 02 Feb 2024 at 10:10pm |
i hate parting,,,,i hate parting,,,,i double dog hate parting,,,,DID i SAY i hate PARTING,,,?????  i KEEP THE PARTING TOOL IN A ,RAZER SHARP SHAPE,,,,USE CUTTING FLUID,,,go slow CUT EVEN SLOWER,,,,, aND MOST TIMES WIND UP USING A HACK SAW or my 4 1/2:" grinder, TO FINISH THE CUT, i fRIGGIN hate PARTING,,,,!!!!!!
Edited by desertjoe - 02 Feb 2024 at 10:11pm
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Walker
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Posted: 02 Feb 2024 at 11:27pm |
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Put your cut off tool on center.
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Thad in AR.
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Posted: 10 Feb 2024 at 8:00pm |
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Got it done.
Turns out there was a space in the middle with no key way.
I set the steady rest there.
Cut the groove and cut it most of the way with a parting tool. Finished the cut with a hack saw. I then clamped in on the mill and tried the cut on the mill.
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desertjoe
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Posted: 10 Feb 2024 at 8:32pm |
Well,,now ole Buddy,,,you must know they invented the parting tool to use instead of them dang hacksaws,,,,,,,Did I say I HATE PARTING TOOLS,,I DO,,,,I DO,,,,!! I'm glad you got er done tho,,,, 
Edited by desertjoe - 10 Feb 2024 at 8:33pm
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Thad in AR.
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Posted: 11 Feb 2024 at 6:27am |
desertjoe wrote:
Well,,now ole Buddy,,,you must know they invented the parting tool to use instead of them dang hacksaws,,,,,,,Did I say I HATE PARTING TOOLS,,I DO,,,,I DO,,,,!! I'm glad you got er done tho,,,,
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If I didn’t have 3’ of shaft hanging out there I would have parted all the way through but you see my ole buddy DJ got me nervous. I must have gotten a good grind on that parting tool cause it was cutting smooth and quick.
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DaveKamp
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Posted: 14 Feb 2024 at 10:32pm |
There's three things that make the parting tool a challenge of geometry:
First is the cutting area and depth. A normal lathe cut skims off a very small area... but the parting tool takes an order-of-magnitude GREATER in the cut width... and significantly more depth. The tool's height reinforces against that cut load, but still, it's alot of pressure.
Second is reach. The tool needs to stick out long enough to reach halfway into the part, so it's hanging out there unsupported.
Third is speed... in order to cut, the SURFACE speed needs to be properly set for a cut to work... but on a facing or parting cut, we start at the outer radius, and as we work inward, the DIAMETER of the cut surface gets smaller, so it's Surface Feet Per Minute falls off rapidly. Those of us with variable speed just twist the knob a bit... but those with mechanical spindle speed settings, it doesn't work out that way.
Finally, kerf clearance. The parting tool cuts through, and even the best geometry still leaves very little room for interference between the tool and stray spoils. Easy to jam that tool, shatter it, and send pieces flying at your eyes...
The alternative to a parting tool, is the Milwaukee Porta-Band, mounted into a toolpost... or a slitting tool on the toolpost grinder (with a significant decrease in feed ratio, of course). Using the slitting saw, spinning slow, against the chucked workpiece, again when slitting slow, will always yield a good square end.
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