FAIL! Collets 101

[farmersammm]

I made that fancy collet to grab the bush hog shaft, and it didn't work

I dont gots any pics.................CAUSE I LOST THE OLD ONES.

Anyways, I'm looking at fixing the doggone collet so it HOPEFULLY will work. Can't have just one slot, it needs as many slots as there are jaws on the chuck. I THINK

Can't take the runout out of the setup on the lathe..................so it's gotta be that the collet, only having one slot, is catching on two jaws, but preventing the other 2 jaws from closing properly and eliminating runout. Once the collet is closed, the remaining circumference is "locked up" so to speak. IT'S GOTTA HAVE 4 SLOTS.

[farmersammm]

News at 10

[farmersammm]

With only one slot, the chuck jaws can't grab it right, in order to close it evenly around the shaft. At least that's what I'm thinkin'. I fooled around a lifetime trying to do the setup, and this has to be the problem. All that time down the drain today. Even put the shaft on v blocks to make certain it's straight. Gawd what a clusterfk

Cut 3 more slots this evening, and see if it works out. GEEZ!!!!!!!!!!!!!!

I shoulda been clued in when the shaft kept trying to walk. Interesting phenomenon to see a live center spin with a wobble

[MinnesotaDave]

How about just turn the diameter thinner?

Should have nuff power to grab then?

[M J D]

How about just turn the diameter thinner?

Should have nuff power to grab then?

I don't think that would help. A better way would be to cut 3 slots equal spaced but leaving about 1/4-1/3 of the length uncut. By design or lack of , the singular cut forces an out of round condition. Individual protective pads on the jaws would be another option.

[Munkul]

Use a 4 jaw chuck?

[farmersammm]

Almost 4:00AM, and I'm just draggin' my butt into the house

I sliced the collet into 4 sections. One for each chuck jaw.

Placing the 4 slices on the threaded portion of the shaft was a booger. I finally taped them so I could get the whole mess in the chuck without little slices falling all over the place

I literally spent the whole stinkin' night chasing a few thousands. GEEZ!!!! I could not get the runout down below .020 at the far end of the shaft, no matter how I fooled with it. The first bearing journal was coming in at about .0015 runout, but that damn far end was whipping around like a NOODLE. And the tailstock was only able to take a few thousands wobble out of the shaft.

I finally got fed up, and frustrated. Sat down in front of the lathe, and just looked at it................like I might be able to divine some hidden secrets from the metal

For S&G's, I turned it on while I was sitting there, and REALLY looked at how the shaft was spinning. THE END OF THE TAPER RIGHT NEXT TO THE CHUCK WAS MOVING LIKE A SNAKE................EVEN THOUGH THE BEARING JOURNAL WAS RUNNING TRUE.

I was getting almost .010 at the the very end of the thin part of the taper, about 1/4" from the chuck. HELL.................that don't look right!!!!

So, I figure WTH, might as well try to set the runout at the face of the chuck on the taper. Fought it for a doggone long time, and finally settled on about .002 runout..............which is A LOT for a 4 jaw. I just couldn't get it down to .001ish.

This brought the runout at the far end down to about .010 . Hell, it's better than .020...........................

Switched to a dead center in the tailstock, instead of the live center, and slammed 'er into the shaft center. BROUGHT THE RUNOUT DOWN TO .004 On a shaft that's been beat for almost half a century, that's pretty friggin good. I can turn it fairly concentric at that runout, or at least get close.

I was able to turn it down to the next thread size. It was 1 9/16-18..................I was able to salvage enough of the metal to come in at the proper diameter for 1 1/2-18 . There's just a ghost of the original thread on the surface, but it's within .002 of the maximum major diameter. KEWL!!!!



I'm glad I ordered the 1144 Stressproof. The original nut is hard enough to resist a file. 1144 comes in at 100Ksi tensile, and a fairly hard Brinnell/Rockwell. It should be close to what's needed.

Anyways............it's almost a waste of time goin' to bed at this time of the morning

[farmersammm]

For short lengths, I'm forced to buy off of Ebay. Alro will have the proprietary grade/brand with MTR's, but they won't sell short lengths unless you show up with an armored car full of greenbacks. Niagara is the maker of the real deal, 1144 is the industry generic.

http://www.niagaralasalle.com/product-stressproof.html

2.50x12.00 piece cost $42 including shipping. Cheaper than a new shaft, if all goes well.

Get to threading later in the day.............gotta go inspect some used S8 beams (around $350 for 3 20' sections)

[123weld]

I made that fancy collet to grab the bush hog shaft, and it didn't work

I dont gots any pics.................CAUSE I LOST THE OLD ONES.

Anyways, I'm looking at fixing the doggone collet so it HOPEFULLY will work. Can't have just one slot, it needs as many slots as there are jaws on the chuck. I THINK

Can't take the runout out of the setup on the lathe..................so it's gotta be that the collet, only having one slot, is catching on two jaws, but preventing the other 2 jaws from closing properly and eliminating runout. Once the collet is closed, the remaining circumference is "locked up" so to speak. IT'S GOTTA HAVE 4 SLOTS.

theshop i worked in the 90's, was one of the biggest shops around, they had about a quater mill in tooling alone. for ur setup, i woulda walked over to a can, that had various strips of lead intended for the jaws , cut about .5+ wide, and about .125 thick. just lay b/t jaws/thread (whatever), and were reused many times. it worked great

[farmersammm]

theshop i worked in the 90's, was one of the biggest shops around, they had about a quater mill in tooling alone. for ur setup, i woulda walked over to a can, that had various strips of lead intended for the jaws , cut about .5+ wide, and about .125 thick. just lay b/t jaws/thread (whatever), and were reused many times. it worked great

Probably be a good addition to the tool drawer. I've always used folded up beer can strips to protect smooth surfaces, but the thread had me worried. That collet was a ton of work. Luckily,, in the end, it worked out.

[farmersammm]

The chips from removing the threads were short, with very little curl. I have no idea what Rockwell the shaft is. I can't dent it with a file. The carbide insert screamed a bit at the end of the cuts when it hit the shoulder. Because of the keyway, I kept the speed down to 190rpm, with a slow feed. Was worried about ruining the insert on the interrupted cuts.

With the thread removed, and the surface machined barely below the minor diameter of the old thread, the metal appears softer. I can dent it with a file. But with effort.

I'm thinking that maybe the shaft isn't through hardened, and I may be getting near the case boundary. Even at this depth, I kept the depth of cut to .005 to be safe, and not hit the keyways too hard.

If I'm coming out of the hardened area, into some softer material, I'm having to make a decision between HSS, and carbide, for threading.

I like HSS, but if this stuff is too hard, I'm worried the bit might dull before the thread is finished..........then I gotta pick up the thread when I sharpen the tool. Not something I care to do if the thread is near completion. So.....................................I guess it's carbide. Carbide doesn't work well on the 1018 I'm used to working with, but I'd wager the shaft metal is a more machinable alloy, so the carbide should do fine. (I hope)



I have a sort of obsolete on-edge threading tool that I picked up as part of the NOS Dorian toolpost deal coupla years back. I used it when trying to repair the thread, and it cut the material really nice. AND IT'S INDEXABLE SHOULD I CHIP A CUTTER.

The old tool takes TNMC 32NV inserts, which are still out there, but seeming to be going away.

I'm looking at the Kennametal NT3 insert on edge system (Top Notch I think they call it). It's modern, and has a good availability of inserts in different grades. One grade, in particular, is made for turning hardened steel..........grade KU25T. Maybe Santa will drop one down the soil stack K'kins always gets me a ton of feed for Xmas

[123weld]

That collet was a ton of work.

i bet, and u'll probabaly never use it again, it was too much work to ever throw away - so it'll become a desk paper weight, or hang it on the wall.

[farmersammm]

Wound up working into the night again. Last night messed up my sleep pattern, took a nap that was supposed to last an hour............and wound up sleeping till sometime in the afternoon

It all started fairly good Then it rapidly went down the crapper.

The keyways almost killed the lathe, and destroyed 3 inserts (all 3 cutting edges on each one)

When the tool hit the keyways (2), the shock broke the tips of the tools, and drove the cross slide back against the leadscrew...NOTICEABLY. Whole damn cross slide started bucking. WITH A STINKIN' .005 DEPTH OF CUT AT 70RPM When the tips held up, they cut, and no problems other than slamming the leadscrew. Dropping the DOC to .003 helped, but the tips still broke. This is some miserable hard material

Cranking the lathe manually solved the problem No shock to break the tip of the tool, and it cut smoothly. But you can't hand crank a lathe that has splash lubricated bearings........eventually they run out of oil if the machine isn't running at speed

Got the Dremel out, and ground infeed ramps on both keyways. Solved the problem if you kept the DOC at .003 . Still trashed an additional insert though.

HSS might have held up better, but we'll never know. If the tool had broken, or dulled.........................good luck trying to come back in on the thread after removing the tool from the holder. Maybe at the beginning of the process, but not near the end.

Anyways..........got 'er done finally The material cut like crap, resulting in a lot of work cleaning up the threads, but I can live with it.............Hell.........I gotta live with it

[farmersammm]

Missed my pitch diameter by slightly less than .004, which resulted from a grabby spring pass. The material is so hard that the tool either tends to rub, or if it catches a good edge, will cut to a depth deeper than what you set the compound for. The spring passes were a total nightmare............tool rubs instead of cutting, forcing you to advance the compound to try and dig in.................THEN THE DAMN CUTTER GOES ALL THE WAY TO CHINA Basically a combination of hard material, and a less than rigid lathe. I don't see at as a major issue, because this is a one-off with a custom nut. I can smoogie the nut a bit tighter when I make it.

Was a pleasure to finally take the collet off. End of story, outta here, get lost, don't let the door hit ya on the way out............................................... ...

Like suggested..........I might just hang these up somewhere to remind me of what a PITA this has been



One more fly in the ointment.......................................

Downsizing the thread diameter isn't a problem, nor is making a new nut..................but the damn lock washer is too big now. When I make the nut, I'll have to leave a lip in the center to centralize the washer against the pinion. Otherwise, the tab that sits in the keyway will wander , and the nut won't be locked. I might get lucky, and source a washer that's the correct size, but it's a gamble.

[M J D]

Fitting a piece of keystock and temporarily retaining it with loctite may have helped that situation if it fit tight enough before you turned the diameter. I had an internal bore on a hub I had to enlarge and that worked well.

[ghost_walker]

jb weld or similar in the keyway? take the shock loading off the tooltip?

[whtbaron]

You've got a welder. Gob snot some metal on the high side and grind it to fit into keyway. Make it look like a farmer fixed it, damnit...

[farmersammm]

Maybe I got lucky

https://www.fastenal.com/products/details/0437819

https://www.qualitybearingsonline.co...nch/#tech-data

[whtbaron]

$24 for a lock washer? I'd still gob snot it with the welder...

[M J D]

$24 for a lock washer? I'd still gob snot it with the welder...

That is a pack of 10. But knowing Fastenal they would put about 20$ worth of shipping on it to get it to the store.

[whtbaron]

just saw that... lol.... I'd still gob snot it to save me the trip...

[farmersammm]

Fastenal was for "availability"

Bearings Online store was for actual per piece price in the real world

Ebay is for the bottom dollar price at my mailbox https://www.ebay.com/itm/13383775083...75.c101224.m-1

Or.........I'll just wander down to the local parts store and pay about maybe 10ish dollars.

Hard parts start with an image search, narrowed to sellers that have dimension specs in their description, then you look for the cheapest version of that particular part number. The Uranus Global Procurement Division is on the case

[Munkul]

The engineering is sound, but I still hate your solution. I'd have thread filed the originals and made it work.

For what it is... heck I'd probably have welded the nut back on, after all, you hope it shouldn't fail again in your lifetime...!

[farmersammm]

Everything ground to yet another screeching halt yesterday.........just at the point of finishing up.

I lost the lathe thread center gage. Looked for over 2hrs for it, and no luck. I finally gave up, and called it a day. 100 mile round trip to get a stinkin' $5 gage today I guess. And havin' to do it draggin' that stinkin' trailer full of pipe.

Gotta haul pipe anyway, but the tool place is way off the highway, and I get miserable mileage off highway. And I'm too long to get in their parking lot access driveway. Have to park the damn thing on the street, and WALK.

I probably lose at least an hour a day losing things. It's getting worse.

[farmersammm]

I did, however, find my nice 6" satin chrome 4r ruler yesterday Was at the smoke shop, and sitting there waiting for the gal to get my carton, I looked sort of down at the dashboard........................and there it was.............tucked into the corner between the windshield, and the dashboard. Impossible to see unless you looked directly at it. It was just showing the thin edge.

So....................I figure I ought to find the center gage sometime in December