Spindle wear

Betzel

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the diagram you posted as got me thinking....
For my "someday" projects I have two mothballed WW80 headstocks. One that is totally gone, and another might be saved, but only after a feasible plan can be developed, based on the failures experienced on the first one. Though the measuretwice home shop facility is something I could only dream about, I'm interested to see where your thinking goes :)

I have nothing to lose to experiment on the first and if that works, can perhaps save the second. Both have well designed deep oil channels from the gravity feed cups that preclude cutting the steel outers much farther. Having owned (but sold) one generic American headstock with soft (bronze) outers, it was amazingly smooth, almost with a vibration damping effect. So, I was thinking bronze (with its deformation tolerance) might be the best way out, but I still need a way to cut acceptably close short/small tapers in bronze and true up the spindle. It's a dream.

it refers to an old BHI page I think.
Yes. Thanks! They replaced their message board a few years ago and I suspect some of the original content was lost.

its a shame there isn't more of a record.
My books are all in storage, but maybe there is something in Jendritsky, Perkins, Levin or Goodrich that I missed. Also, Tony, the machine archive guy in the UK seems to have met some surviving members of the machining families in Esslingen, but he's a busy guy and hard to reach. Levin and Pratecma are still in business, but it seems they don't make hard spindles anymore, leaving only Bergeon doing these. Perhaps the chinese have a good system, but suffer from their focus on lower cost production methods.
 

wefalck

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Thanks, that's how I understood it, hence my comment.

A noted in another thread, the Austrian state gun-factory in the later 19th century made guns from what they called 'steel bronze', meaning a mechanically hardened bronze. They cast the gun muzzle up with a high hydrostatic pressure of molten metal on it, trimmed of the surplus, bored it out undersized and then rammed down a calibrated steel plunger down the bore. This hardened the bore, before the rifling was cut. So dropping a calibrated plunger with the correct taper on it into the bearing installed in the headstock would press it firmly into the headstock bore and at the same time harden the bronze. It then can be ground and lapped, say with a charged tin-lap or something that is softer than the bronze.
 

AlexandreVienna

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So my new 1942 Derbyshire Elect lathe has been taken apart. I dont know anything about spindle wear so i am curious what condition the spindle is in. I think it looks pretty good but i want advice. And now that i have it apart im curious to know if i should try to pursue and get the Hyspin E5 spindle oil from Mobil. If not i have on hand #10 that i can use. I am wondering if i should use #6 instead?

View attachment 636149 View attachment 636150
Does it bother you that the collet pin is missing?

4182C819-86A8-4A8E-B344-DECCF029F6CA.jpeg
 

Betzel

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A reasonable repair procedure is outlined in Archie Perkins' book.

In this condition (missing, rather than sheared off) oil will leak out, stressing the front bearing from loss of hydro static pressure from oil leaking out through the hole. It will also cause a vertical "daisey cutter" splatter from the oil when it eventually flies out at speed. Not good for the eyes. Most pins are sheared off when a tool (or the edge of the slide) hits a spinning jaw, the drawbar is not tight, and the pin shears off half-way, plugging the hole. Looking at all the keyway damage in used chucks online.

Usually, the pin is made of cylindrical unhardened steel to fit the precise width of the slot of the collets intended for the lathe, and is press-fit into the spindle and peened in on the spindle side. The trick is to not drift it when peening. Collet charts have most of the collet slot width dimensions, and you will have to decide depth, end-profile and fit. These are nice machines, but I don't know much about Derbyshire, as all my Lathes are German. Do you have original collets? If not, look up the size in a chart, or make the pin to match the collet set you do have.

Many will say you don't need a pin, as it slows them down. Except for roughing/production work, where you are not final-finishing in place, or don't need the accuracy, I disagree, and so does every lathe manufacturer that ever made a tapered, spring collet-holding lathe. Except turning between centers, all work is always off. The key helps in manufacturing and gets you close to "where you were" if the collet or material is put back identically to how it came out, which never, ever happens. Finish and part, or go between centers.

A lot of old lathes had collets (etc.) made up just for that one machine. Due to wear, I even mark my centers with the keyway for the collets they fit, as even those will run out.
 
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Brento

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There is a mark on the spindle nose like a sharpie line indicating where the key would be. I do have the same manufactured collets. I wouldnt mind doing it but im kinda nervous to do it and damage the spindle. I can prob make one pretty easy. How would you peen it without drifting it or marking up the spindle?
 

AlexandreVienna

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you have a hole Brento! The pin has to go into the hole! And the pin/hole matches the groove at the other end of the spindle. well, I do not need a mark on the spindle at least..

Maybe I misunderstand something again....
 

Brento

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I know the hole is there. I am saying that the precious owner or someone before marked where the pin hole is to line up the collets.
 

karlmansson

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As I mentioned in another thread, I made a new pin for my W20 lathe. Much bigger in all regards. It was a bit scary as if the pin works itself loose (if I left it a bit long and pushed it out with a collet that was slightly tighter in the cutout or so) if would mess up my front bearing in a heartbeat. The front bearing on my lathe is bronze though and your hardened steel bearing should probably handle a mishap better.

I ended up pressing and peening the pin from the outside and then filing it to final length from the inside of the spindle. Just trial and error and testing with a collet. So far so good!

Regards
Karl
 

Betzel

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Now that I think of it, a WW80 I repaired once originally used an inverted "T" with a crescent-wedge rounded toward the collet. Then, they peened, then did the cone grinding. How did it stay straight? Jedi magic. The stuff those guys did in the old days to make stuff absolutely perfect in places nobody sees. A pin is good enough though. It's only like 1mm proud or so. The keyway is not very deep.

Other options include plugging the hole (with brass, epoxy, wood?) and respecting the witness mark, like you do now. This is what I do on my WW83 because I am afraid to disassemble the head stock, so I can't say it does not work. It's just not right...yet.

I like Karl's idea of flaring the outer end and inserting toward the center. Brass might be easier, but you will shear it forgetting with a scroll chuck using hand force. A file should skate on the cone to get the external excess annealed carbon steel off, I would think. Or, how about mild steel?
 

measuretwice

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If you can get a really good fit with the hole, I'd loctite in some annealed (as you buy it) tool steel....say O1 drill rod. Key thing is the fit. The use of tool steel is because even annealed, its strong stuff than mild steel. I've done that with with new spindle shafts I've made and it worked well, but I had control over the hole I had to work with....with a hardened shaft you're stuck with what is there.

If the hole is rough and ragged so there isn't a good fit to be had, you may have to peen it in. I'd very exactly make a plug to back the pin while peening. Slot in the plug should ever so slightly shallower than that of a collet. peening could be done under magnification with found small punch vs the peen side of a hammer so you can get the impact force where its needed. I would not say it would be a cakewalk, but doable. I would concerned about possible distortion of the shaft, but there may not be much choice

Clean up under magnification with files and when close to the hardened shaft with stones or a foredom if you've got a steady hand.

afaik the most important function of the pin is to guarantee you can unscrew the drawbar without the tooling turning. I can maybe see some function in repeatability, but the key there is orienting the work in the collet. The collets aren't made in or matched to the lathe afaik....i.e. the eccentricity is with the collet's OD to its ID

Betzel, I agree with your well placed fear...that lathe as you know uses rolling element bearings. The rule with assembly is never put a force through balls. Which is about impossible for disassembly so there'd be a chance of damaging races/balls tapping it apart. If you do, I'd recommend the conversation to AC's.....P4 AC's are easy to find but really hard to find in the deep bearings the lathe came with
 
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Brento

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I can get some annealed drill rod and maybe loctite it in. I would be worried of it coming out and scoring up the bearings though. With peening the pin would you end up losing the peened material filing it away? I did think when filing it away if i used like clear wrapping tape to protect the spindle a little bit? How important would it be to have the pin? I have the lathe back together so i dont want to take it apart again if i dont have to atleast for a little while.
 

measuretwice

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as you peen it you are expand it in the hole, creates outward force making it an interference fit. Delicatingly...you don't want to deform the shaft. You then have to bring the surface of the pin to just below the bearing surface. As the spindle is hardened filling will only get rid of so much which is why I suggested stones (very fine) to carefull get it lower than the bearing. Loctiting will only work if the pin and hole are a very good fit. I agree with the comments above that it becomes a drain hole for the oil so imo you do want something there
 

AlexandreVienna

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Don't loctite it in and do not use a O1, too hard. Superglue is a chemical, whose reaction to metal and oil can't be good. The whole idea of a pin, who sheares and can be replaced is: hard metal versus soft metal.

And I disagree with getting the pin surface under the spindle surface: just get it flush.
Also disassemble your spindle regularly as you have to clean it. Get used to it. A good working lathe is very easy to disassemble. Because hard and soft metals are combined you have to clean the wear now and then.
 
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karlmansson

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I left the pin a little shy on the spindle of my W20 lathe. I copied the layout of the one that was in there, which I can only assume to be original.

Superglue is cyanoacrylate. I don't think superglue was the intended Loctite here but possibly 603, which from what I can tell is very inert after curing. I have seen it used in proximity of spindles by machinists far more accomplished than myself.
 

measuretwice

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Don't loctite it in and do not use a O1, too hard. Superglue is a chemical, whose reaction to metal and oil can't be good. The whole idea of a pin, who sheares and can be replaced is: hard metal versus soft metal.
as I described it the O1 is not hard, but its suitably tough. It's not shear pin, that's not its function. Your comments on the loctite are quite surprising. If you have mechanical experience it seems an odd thing to say. Its constantly used in oil immersed scenarios by manufacturers the world over. If the bore is true and round, it is the perfect way to make this repair with about zero chance of someone new to this buggering the spindle shaft

The surface of the shaft is a finely finished curve you don't want to disturb. Please explain how you would expect to get the replaced pin exactly flush with this curve without damaging/disturbing the curve? You have basically two choices, have it slightly proud of the curved surface or slight below it if you not going to avoid messing about with the shaft's bearing surface.
 

AlexandreVienna

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Yes sorry,
loctite is not a superglue but for securing bolts etc. My fault. (Especially Loctite 648). But about O1 I have a different view: it is a Mangansteel made for cutting tools etc. Its speciallity is you can harden it up to 64 HRC.

And yes Karl, you are right, I like your clear words - thanks
 
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measuretwice

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. But about O1 I have a different view: it is a Mangansteel made for cutting tools etc. Its speciallity is you can harden it up to 64 HRC.
You can harden it to 64 Rockwell C, but I suggested using annealed which is its state when you buy it and isn't much harder than mild steel. But its tougher so will last. Its an excellent steel for all kinds of uses not just cutting tools. In fact in the age of HSS and Carbide I'd think very little gets used for cutting tools however anything and everything a tool and die maker makes that is suppose to last, V blocks, dies, angle plates, vises, blocks as well as all manner of tooling gets made out of it. In its annealed state its an good material to use for things like this and most of us would have some kicking about so is convenient

But we're allowed to have different views :)

PS, I assumed it was a given but should have clarified, the loctite to use is not the thread stuff but cylindrical retaining compound, like a 603.
 
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