Pivot drilling lathe question

[Buffomarinus]

G'Day,

I just scored a beautiful little C.W.Z. pivot drilling lathe (image below) and I'm a bit perplexed by the drill bit holders.

There is a hole in the nose of the holder to accept the bit and a notch in the shaft which I would think is for levering the bit out of the holder. The thing about this notch is that the hole in the nose does not seem to be drilled through to the notch.

Am I missing something here?

Any help appreciated.

Cheers,

Buffo

FNQ,Au

 

[Betzel]

G'day!

Always wanted to say that

Woops, just re-read the part about the hole not going through. It's not broken off inside or plugged? Same with all three?

This is a very nice, but antique, tool. It is not functionally obsolete, but may not be best or the easiest thing to use to do the job. Say you have a pocketwatch with a broken pivot. This was your go-to device! You seem to be missing the brass pulley with drive dog to turn the wheel and it's arbor. Is that just not shown? You can make one (or two) pretty easily.

Like facing in a lathe, the broken part has to first be prepared for drilling. I think guys softened the end as needed with a hand-held "combo" clamp that lets you anneal just the tip, but not the whole thing, and file or stone the original end of the pivot square to the center axis. A pair of dud tweezers would work too. Anyway, once you have that, you would clamp it in a vice, and then put the good side of the part you want to fix into one of the long, sliding rods that fit the piece the best (good side facing away from the revolver) then, slide that rod with the pully to guide the broken end of your abror into one of the revolver points (best fit) and clamp the long rod.

Once that's set up, old-timers used a bow kind of like a violin, but smaller. I think these were originally made of bone or wood (steel was a welcome relief?). The bow string wraps around the pulley one time and lets you spin the pulley, and the arbor, with a back-and-forth motion (like sawing) while the arbor is fit up between those centers.

If all is well, oiled up and fit correctly, and tight (enough), you would pop a spade drill bit into one of the short rods and "bank" it's flat side against the wedge cut in the back. Then, acting as if it were no big deal, and while rocking it back and forth, you would be drilling a hole the "right" size for your wire to replace the broken pivot. Pretty sure the jacot was used to final-finish the pivot, so you needed a list of tools, and a lot of guts.

After all ten minutes of that, you get on with the next job. Nobody had a Geneva with an offset runner that made this a bit easier, so nobody complained I will look for a few photos that may help. Something about a thousand words...

 

[Betzel]

Yeah. There's not much out there, but I ran across these old (I think German made) drills from a seller I have bought from in the past a while back.

Note how the ends have a flat dent at an angle which would mate up with the wedge in your (plugged up?) bit holders. The sad thing about this setup is the need for so many different sizes for the range of work you would have to do. These were unbranded, but I have seen them in sets branded as "Sphinx" who later sold tool steel bits with a single flute that are amazing. There are other sources, but Perkins has a section in his book on how to make these, step-by-step, including the proper rake angles. There is a small knob under the revolver that may have been used to hold very small bits. Have you opened it up to see what shakes out? If you're lucky, maybe one is still stuck in there. May need some solvent dripped in with a wire and a catch rag under. Good luck!

The other picture shows some guy's bench project, but just for the driver pulley, though after a few runs with a bow, you can see why he made it. Be careful with any industrial carbide bits, as most of them were made for circuit boards, and will break off after starting smoothly leaving you with a hole full of carbide that is not easy to get out. You may know this, but it might help others --or they can learn the hard way like the rest of us.

Looks like one of these is very worn or too small, but still has a nice handle if you wanted to make your own holder and stick it on the end? If all of yours are NOT plugged, I can only guess they were perhaps from another set (like the longer rods you have, but from a cheaper version) and the seller stuffed them in there. Do they fit really well, or are they sloppy? If they are solid and a perfect sliding fit, an even wilder idea is that you were supposed to drill them yourself the diameter of your favorite supplier's bit diameters. Maybe this is why there are so many of them?

It would be difficult to slam into a pivot shoulder, but a hard steel dead center could be a nice "spotting" technique? Does the bow kind of look like a lamb (or other suitable size animal) rib? Ancient art techniques worked...

 

[gmorse]

Hi Buffo,



When this picture of repivoting an escape wheel arbor was taken I was using a wooden bow strung with hair from a horse's tail, (I used to be on good terms with my horses), but now they've gone, I use 10lb monofilament fishing line in a steel bow, it's much less likely to break. Many of the antique bows were made of whalebone, which of course isn't acceptable any more.

The spade drills have two different tip profiles, as shown in the lower right of this old label.



The pointed ones are intended for softer metals and the rounded ones are for harder steel.

Regards,

Graham

 

[gmorse]

Hi Betzel,

Be careful with any industrial carbide bits, as most of them were made for circuit boards, and will break off after starting smoothly leaving you with a hole full of carbide that is not easy to get out.

Yes, even with the support of the hollow cone runners, the flutes are much too long and they're designed to cut the circuit board material, not steel. I've given up with them and now buy good quality industrial grade carbide bits, which have much shorter, accurately profiled flutes, (as Jerry Kieffer always recommends), which make precise and accurate cylindrical holes. They're expensive but my breakage rate is now far, far lower.

Regards,

Graham

 

[Buffomarinus]

WOW! Thank you Betzel and Graham !

Betzel thanks for your excellent response to my question. You've truly provided me with the "manual/instruction" sheet I've been looking for ! I have two examples of these brass frame pivot drilling lathes. One lathe with a turret and one, more basic, without the rotating turret. Both pivot lathes are cased, in excellent condition and came in at an unbelievably low bid price on Ebay. I actually have a complete 8mm Lorch accessory that I modified for my IME watchmaker's lathe that will do the same job and more, but these little brass pivot drilling lathes have always fascinated me ever since I developed an "addiction" to restoring old watches.

Thanks especially for your info on the drill runners. Yes, both the runners must be blocked by broken drill shanks. I'll attempt to clear them, but if I can't, I'll turn up a couple of replacements suitable for the bits that are readily available on line. Both drill runners included in the case are a "snug" fit in the brass frame.

Graham, as always, thank you for responding to my question too. I've re-haired a few violin bows in the past, but I must admit I never considered driving a "lathe" with the same resource ! If you don't mind me asking, where do you source your good quality, industrial grade carbide bits in the >1.00 mm sizes ?

While I have your expert ears on this, one more question... How are the two slotted runners (below photo) that are included with these pivot drilling lathes used ? With one the slot extends to the tip. The other doesn't extend to the tip and has a circlip. I'm guessing the circlip holds the brass pulley with it's drive dog in position, but the slots have me mystified, especially the one extending to the tip.

Thanks again, both Betzel and Graham for enlightening this "newbie."

Cheers,

Buffo

 

[gmorse]

Hi Buffo,

How are the two slotted runners (below photo) that are included with these pivot drilling lathes used ? With one the slot extends to the tip. The other doesn't extend to the tip and has a circlip. I'm guessing the circlip holds the brass pulley with it's drive dog in position, but the slots have me mystified, especially the one extending to the tip

The one on the left looks like a safety centre, but these don't usually have that ring on them and I expect you're right that it's been added to retain the loose pulley. The one on the right has been modified with the slit, but I don't know why; the runners with these tools usually have just female cone centres. The pulley doesn't need a retainer if you're careful with how you use the bow.

I usually buy my carbide micro drills from Drill Service (Horley) Ltd here in the UK, they sell all sorts of cutting tools, but there must be a supplier of these products a little closer to you!

Regards,

Graham

 

[Betzel]

Well, in my Wolf-Jahn (similar, if not identical to Lorch equipment) tapered tip-set, and some of the 7mm tailstock runners, there are many with these parallel, separated slits from those older days, likely cut with a small, round sawblade. But, they never extended axially all the way through to the edge. The more modern ones in my Leinen set have a wedge ground perpendicular into them such that you can see clear through the hole, but not enough room to do any work on the pivots like those hard, thin discs on a true jacot. Never drop those! Most safety roller fine inserts share these center-holes.

With no manual (that's what this forum is for?) this is how you can introduce and maintain a steady supply of clean oil to extend in to the conical contact points to avoid turning issues with close dead center work. I use light sewing machine (mineral) oil, as it's cheap. Today, we have "live" centers which are great for larger work, but if you have real 60 degrees included on all four sides and are turning with a dog between hard dead centers (like the turns) I've found there is an extremely fine line between flopping (too loose) and binding (too tight). The slot lets you add fresh oil and almost operates like hard cone lathe bearings - the work (kind of like a spindle) is perfectly suspended in a bath of light, clean oil against the bearings. That's my $.02.

The one on the right has been modified with the slit, but I don't know why

My guess for the one on the right is that it was a hack job. It's cut all the way through to allow for a spring-fit of work that was too big for the original end, but he did not want to cut a new tip just for one job. So, it spreads a little under pressure and if you're quick, it gives just enough tension to hold the workpiece steady (enough) in a tip that's actually too small. I wonder if the ring actually belongs on the fully slitted end, as a tensioner? Out in the boonies, you gotta make do. Removing the saw burr on the inside of the cone would have helped. Goes to show you can never have too many sizes of hollow female centers?

George, I think I now understand your avatar better. Hair from horses and whale bones, eh? I tried the violin once, and was always amazed at how they got all those hairs to stay together and how well it all worked with rosin. Also, I think that winged lion with a human head was the "Sphinx" or "Eureka" brand, or trademark, which later came in a very nice reddish wood box in a big set, and then moved from spade/round to single fluted. Boley, GMBH still sells the single flutes, but they are Bergeon-pricey. Here is a link to another members' personal site showing the various kits: Lathe Tools

Buffo, looking again at the back side of your good holders, there is no evidence of any kind of a hole in the back that would need to be drilled through. So, I now suspect you have a rare "virgin set" that was never touched. If your closer look reveals just a centering hole on the front, and you are into it, I am almost certain they were intended to be drilled to final size by the owner to fit their favorite brand of bits.

All you need is to find a really nice set of bits that you can self-sharpen as well as get replacements for, and drill one to suit? Good luck!

 

[wefalck]

Couldn't the ring on the left centre rather go onto the right thingy and in this case it could be shop-made drill holder. You have cylindrical hole, say for the standard 1 mm or 1.5 mm drill shanks, but the outside slightly tapers so that when you push down the ring the slot closes onto the drill shank. The pivot drill holders in the Lorch tailstock attachments work on a similar principle.

 

[Betzel]

Maybe. But both appear larger in diameter than the brass handled "holders." Perhaps they will fit into the hole on the far side of the revolver? I think you can only drill from that side.

One of the two shafts is cross-drilled and both are slotted. Some old 1880's (?) catalog might show what these originally came with. These "revolver" versions seem to be the best of the series, as I've seen. I have one like it in storage, probably missing half of the thingys, and another one marked Wolf, Jahn & Co. which I think is older and has even fewer original parts. Not that that's a problem!

What was I thinking? Probably of finding a whale bone and a horse to give it the old college try

 

[Buffomarinus]

G'Day NAWCC mates,

Thanks again for the link to the source of good carbide bits and the tool site showing the original style of bits that were/are possibly used in my two pivot drilling lathes.

Cleaned up and on closer examination, the runner with the long slot (RH) has been definitely "butchered/hacked." The tip of this runner has a rough dish shape that almost looks like it was sheared off. I think Betzel is spot on in saying that someone in the past made a rough modification to suit a job they had at hand.

The concept of using the slot or in some cases the round hole to act as an oil reservoir when turning between centres without the advantage of a 'live" centre makes perfect sense. In fact, I may even adapt several of my lathe tools so that I can use this same concept.

Betzel wrote:
"What was I thinking? Probably of finding a whale bone and a horse to give it the old college try"

I haven't come across a beached whale as yet, but a kangaroo rib might do the trick. As far as the "driving" hair goes, the neighbor's horse occasionally grazes along the fence line.

Thanks again for all the excellent responses,

Buffo

FNQ,Au

 

[Betzel]

In fact, I may even adapt several of my lathe tools so that I can use this same concept.

All the best with the kangaroo thing.

The circular-saw slots works okay to get oil in, but if you're going to adapt tips to do dead center work, I'd suggest the "zapfenschonern" design below with the flat bottomed "D" cutouts. Oil flows like solder on flux. The arbor runs tight and true in a thin film of oil with no heat. You can almost part off at the tip of the pivots-to-be if you're good.

Cutting a small female dead center is not easy (for me), but you can modify the regular ones. They used to sell blue steel blanks for benchmade balance staffs. Convenient to have on-hand with well polished 60 degree male points. The blueing wears a ring from running inside the cones perfectly.

 

[Buffomarinus]

G'Day Betzel,

Thanks for the excellent tip. It sounds a lot more efficient than what I originally had in mind and what I am currently doing to eliminate the lubrication and heat problems when turning between centres.

Cheers,

Buffo

 

[Betzel]

Saw this recently. Not all tools are identical, but it suggests the slot was likely cut past it's original end by a previous owner. Why, we may never know...

And, I think the revolver was a better design, but this (older? less expensive?) version also works. And many a 4th wheel arbor was long for the sweep seconds (would a chronograph center fit in there?) so maybe the longer pivots were intended to fit into the slotted side better and the regular pivots just used the cross-drilled idea? Another mystery

 

[Buffomarinus]

G'day Betzel,

Thanks for that followup and the photo... very interesting !

I just turned up a drive pulley (below) using the wire from a mandolin string for the drive dog. I might also replicate a new runner or repair the original along the line of the one you show in the photo. I can't see an advantage to a slot going right through to the tip.

I've scored, locally, some reasonable carbide micro drill bits with three mm shanks. If I turn/grind the shanks down to 2.25 I should be able to use them with the tool. I'd like to try to repair an English fusee that has a sheared pivot on the pallet lever.

Cheers,

Rob

 

[Betzel]

...I've scored, locally, some reasonable carbide micro drill bits with three mm shanks. If I turn/grind the shanks down to 2.25...

Are they 3.175mm at the fat end with about 7 spirals, 10 in a plastic box? If so, those are the ones that will snap off about 4mm in and leave you heartbroken, even with oil and a "perfect" feed rate. So, start thinking now about how you will get the broken off part(s) back out of your fusee arbour. If not, have you ever tried to turn carbide? or hold a finished bit on center while reducing its shaft diameter? It's not impossible, but...you really have to try those tool steel Sphinx bits to appreciate them.

I don't know how to buy, but boley GmbH If you want carbide, these seem the gold standard.

That pulley is a total champ though!

 

[Buffomarinus]

" Are they 3.175mm at the fat end with about 7 spirals, 10 in a plastic box?"

G'Day Betzel,

Variations on these are all that's readily available here in Australia. I recently purchased individual sets of specific >.5mm sizes which are different in that the actual tip and spirals are shorter, but I reckon they are still basically the same Chinese product. I have contacted Boley to see if I can get some prices on their Swiss manufactured equivalent. I'll check on the Sphinx bits and see what the possibility of scoring a suitable set is.

Thanks again,

Rob

FNQ,Au

 

[Chris Radek]

A few disparate thoughts:

I use carbide PCB drills and don't have a problem with them. If you're buying those be sure you're not getting resharpened bits, or if you do, at least check them carefully to make sure the point is right and the flutes are clean.

I really like that they are much harder than any watch part. You have to be careful and watch with the microscope to see that chips are coming out. If they stop, stop immediately and clear everything out.

Do you really drill more than 4mm deep? On what kind of repivot job? Even for a very large pivot of 30, that would be 13 diameters deep.

The last English pallet arbor I did was just a long taper, with pivots. If yours is the same, it may be better to just remake the part. But if you want to practice repivoting, doing it on a part you can remake if you break off carbide in it is great! I agree a part with carbide stuck in it is generally ruined. (The only way it isn't is if you have sinker EDM, and if you have that, why not do the repivoting that way?)

 

[Buffomarinus]

G'Day Chris,

I agree, 4mm is more than enough depth. I just practiced on a bit of 2mm drill steel using a .3mm PCB drill. Like you mentioned, I closely observed the flow of chips and didn't push with any force. I also carefully cleared the hole often and fed a drop of kero mixed with light oil on the working bit. The 2mm drill steel will be a replacement insert for the damaged runner (the end with the saw cut) on the antique pivot drilling lathe.

As far as the pallet arbor on the English fusee goes, it would be a better proposition to just make a new one, but I'm keen to see if I'm skilled enough to do the job with the old brass pivot drilling lathe.

Thanks for the added advice.

Regards,

Rob

FNQ,Au

 

[Chris Radek]

Some pictures for fun: This is the kind of swarf I got when drilling the pinion of a wristwatch sweep wheel. The pcb drill is .0067 (#95), 0.17mm

 

[gmorse]

Hi Buffo,

If you search for industrial drill suppliers as opposed to just horological, you may have more luck; there must surely be someone in Australia who sells these items.

One clue to whether the drill is correctly sharpened is the swarf from each side being the same. If only one side is producing swarf, there's something wrong.

Jerry Kieffer posted a very useful method of ensuring a true centre and controlling the drill some time ago.

Regards,

Graham

 

[Betzel]

All excellent points. You can have success with these, especially in larger "beefier" sizes. Until you don't. As you know, brass is very soft and wants to grab and suck anything inward. Like spinal traction. Many regular bits work better in soft material with a "zero rake" modification, but I would not try that on these. Looks like you made it!

I believe it is --any-- sudden change that leads to heartbreak. Best results happen with sharp bits, no "slop" (in any axis) and a combination of lubricant, proper feed rate, swarf management, full concentration and of course good karma

All the best!

 

[Buffomarinus]

G'Day Chris, Graham, and Betzel

Chris, beautiful swarf on the micro drilling! I tend to get "chunkier" material with my attempts.

I did manage to resurrect a new steel runner insert for the brass pivot lathe, replacing the end that had the crude saw cut (see below photo) . Using a .5mm pcb bit with great care, I got a 6mm deep hole in some 2mm drill rod without breaking the drill bit ! Not only is the new tip now useful, but the alignment of the runner is perfect.

The original bit holders on the old brass pivot drill lathe are truly "cactus" (broken or useless). I removed the original brass knurled knobs from both holders. I'll grind/machine down a couple of suitable pcb drill shanks from 3.17 to 2.15, install the knobs and use them with the old pivot drilling tool. I'm really curious to see how well the old tool will perform. These days the little pivot drilling lathe is more a "museum piece" than a really useful, practical tool, but, like with pocket watches, I really enjoy the restoration process.

Graham, thanks for the Jerry Kieffer post. I have been mulling over a way to make the tailstock on my little IME more useful for drilling. Jerry has some excellent suggestions in that post.

Cheers,

Buffo (Rob)

 

[dave-b]

Sorrry - fat fingers.