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When only a watchmaker will do Restoration of Omega Jump Seconds Clock
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Notes on Lathes and Collets Under construction Sept 25, 2017 The first machine tool required for restoration work is a lathe. There are a bewildering number of lathes and I remember drooling over DeCarle's Watchmaker Lathe. In a nutshell, it comes down to a WW lathe (8mm or 10mm), a toolmaker's or second operations lathe (Schaublin/Habegger/Simonet 102s, Hardinge, South Bend) and the dead center lathe. Each lathe is designed for a certain class of work, and the primary functional difference is the size of the work that can be performed. For example, a WW lathe excels at balance staff and stem work, turning work less than 10mm OD and 15mm long. You can also use a WW lathe for large plate or ring work with an appropriate chuck. The headstocks are designed for the operator to be close and personal, and if mounted on an aluminum plate they can be positioned for best access to the work. Size Matters! When making your choice for your lathe, it is important to understand that "swing" refers to the maximum size work that can be mounted on the headstock. A lathe is designed for a work piece maximum that is one half the swing! So a WW lathe (with a 100 mm swing, 50mm center height) is best used on work below 50mm (2 inches). Once you try to work on a clock barrel with its long overhang from the headstock, you will understand this limit. You can use a polishing attachment for decorating wheels and can even cut WATCH wheels and pinions with a milling attachment. Archie Perkins (may he rest in peace) wrote the definitive book on uses of the WW lathe and I highly recommend you find a copy before it goes out of print. Leaving the details to Archie, the main disadvantage of the WW lathe is the dilemma of the apprentice carpenter who only owns a hammer. There is a tendency to use a WW lathe far beyond its design specs with comparable poor results. You also need to make sure you acquire a set of quality collets from a single manufacturer. Hardened collets ring when they are plucked; cheap collets do not. As far as I know, only Schaublin, Levin and Derbyshire continued to make hardened collets into the 21st century; and new, they are pricey. The reason to have a set of collets from a single manufacturer is tolerances. One manufacturer's No. 8 can be another's No. 9. But within a manufacturer, the runs will be consistent. The 10 mm lathes by Levin and Derbyshire are very similar to their 8mm lathes. Too similar to be of use to a watchmaker who owns an 8mm WW already. These are really the first lathe of choice for someone working on clocks. Then come the second operations size lathes, usually with a 200mm (8 inches) swing as opposed to the WW lathe's 100mm swing (swing is the maximum OD that can be mounted on the lathe). These lathes are essential for making tooling, larger and longer pieces and such. You can usually find the basic machine (head, bed, tail, slide rest and drive) for not much money. The issue is finding the collets and accessories. For this reason I suggest starting with a Southbend (even issued to subs in WWII; was the ubiquitous American lathe), one of the Schaublin/Habegger/Simonet 102s, or the Hardinge. I have experience only with a 102 so that is what I will detail here. (102 refers to the center height.) The reason I group the Schaublin, Habegger and Simonet together is because they are essentially identical and all accessories interchange precisely. They generally use W20 collets which have a max through capacity of 9/16 inch. They can mount work up to 8 inches. They are the lathe of choice even today in Swiss production. They were used in all the watch factories and in any company that required machines that could work to close tolerances. These came configured with precision roller bearings or cone bearings. Both work well. BUT, if the bearings are shot it is much easier to replace the roller bearings. I bought my Habegger in the late 1990s. Used it for 15 years with no issues. Finally, I could never use a parting tool without the work jumping over the cutter. Bearings! There are specialty houses that will repair spindles. I had a customer who was a custom machinist who offered to do the install if I bought the bearings. Bearing were $800. BUT, I have a 102 that is as good as factory. The major maintenance on all these lathes is to ensure they are lubricated. WW cone bearing lathes usually have oil cups over the bearings or you remove the endcaps. If these are hardened steel cones (as opposed to bronze) they will last forever if lubed with Mobil light spindle oil. WW Lathes The WW ball bearing headstocks are bulkier than the cone bearing headstocks (hardened bearings to be preferred over bronze bearings). The cone bearing headstocks are easier to use with a 10x loupe; but there is no difference if you use a microscope. WW lathes with preloaded angular contact bearings are lubricated with a paste grease like Kluber Isoflex. This is done when the bearings are installed. You need to read up on installing precision bearings if you have a ball bearing lathe. The precision bearings of these lathes were lubricated for the "life of the lathe". Oh well. If your bearings start to chatter read up on replacement of back to back angular contact bearings. If you are reading my stuff, you are a watchmaker working in a clean environment and have the skills to do this; requires a press and such but most watchmakers can do this. One word of caution here though. The early Levin round headstock 10MM lathes used SHOULDERED New Departure bearings which are no longer made. People seem to have overcome this, but you would have to research this. But the square 10mm Levin headstocks used modern bearings without the shoulder. The Swiss 102 lathes mostly need Mobil Spindle oil (I do a shot every use). Even those with preloaded angular contact bearings! WARNING! The oil ports look like grease gun ports. THEY ARE NOT. The same with the slide rest ports. There is a special oil pump made for delivering oil to these ports. The nice thing I know about the Swiss 102s is that they are made to be disassembled for cleaning and reassembled back to their original locations. Whether the spindle, slide rest, or milling attachments, they come apart easily! Alignment of Headstock and Tailstock There is a difference between how Swiss lathes and American lathes were manufactured. Levin sight bored the head and tailstock as a set; in other words there was one tailstock that was perfect for that headstock. Of course others will line up as well, but that is not by design. The Swiss OTOH, made their lathes by tight control over tolerances. Each piece was adjusted to a master reference. This almost guarantees that any Schaublin tailstock will line up with any Schaublin headstock. Big reason for buying a Swiss 102. My lathe is Habegger (head/bed/tail). Everything else is Schaublin. I even have a Schaublin Capstan Drilling Tailstock that lines up. The advantage is that you CAN find virtually anything for these machines although the price is rising as these machines disappear from machine tool auctions and used equipment dealers. A Fool's Discovery I found (by ignorance) that fittings for the spindle noses of American lathes (1 1/2 inch 8TPI) fit the spindle nose of the Swiss lathes. I have 3 and 4 jaw chucks mounted on new American backplates and instead of paying $100 for a Schaublin spindle nose protector (even aftermarket were $100), I paid $15 for one from a Southbend. Absolutely irreverent, but I never had a stuck chuck and the 3 jaw registers on center every time. My friends in Europe think I am nuts. Just saying. For a number of years I was naive enough to think it was ordered that way for use in the USA. You can see with thread gauge that it starts to close up, but the thread length is too short for that to happen. Power For the larger machines, I recommend staying with their 3-phase motors and using a Variable Frequency Drive from Dealers Electric in NYC. A TECO VFD drive for these 1 hp motors is less than $200, allows speed control without belt changing, works off 120VAC and takes up little room. You can even program the time it takes to ramp up to full speed (highly recommend) and dynamic braking (uses collapsing magnetic field of motor to induce a "reversing" current into the motor for almost instant stops). All of my smaller machines are powered with Sherline Permanent Magnet motor and speed control. I install a reversing switch in the housing. These have great low speed torque. You will also see I use a handwheel only on the turns. Learned the value of this in WOSTEP. When I was originally taught by Roy Hovey, he advocated driving the turns with a motor. But the handwheel gives much more control. Speed Kills! American do love speed. Everything has to be in the fastest time. This accounts for many discouraging results. Slower speeds on the WW or Turns often result in a better finish. There are times when I pull directly on the drive belt on the turns for final cuts! When it comes to drill for repivoting, high speed is certainly a job killer. It dulls the drill, burnishes and hardens the bottom of the hole and the heat expands the drill in the hole resulting in seizing and breakage. When I drill on the WW, I drill at the lowest speed the motor will turn. I can see the the collet make its revolutions. Will give other hints at drillin sub millimeter holes in a future section. Foot Control! All my machines can be operated via a foot controlled on/off switch (normally open). This allows two important functions. The first is it is a "Dead Man" switch. If I fall into the 102 it shuts off before I get eaten. Secondly, once I set a speed I just turn the lathe on with the foot switch (WW or 102) with no hunting around for the previous speed. I have each motor set up with a mil type connector so that it can either plug into its foot switch or into a dummy connector that is wired to provide constant power to the machine. This is important on my drill and on my overhead drive for the 102 milling attachment. COLLETS can become a real headache. At one point I owned sets of 8mm, 10mm, Schaublin F8, Deckel, R8 and ER 32 collets. I had a Schaublin drill press (F8), used the R8s in my floor mill, and the Deckels for my tool grinder. Now I am down to the W20s for my lathe and tool grinder, 8mms for my WW and Levin drill press, and the ER32s for my floor mill. Once again I switched my drill press to the Levin since it used my 8mm collets! (I have switched between Schaublin and Levin at least 5 times. Either is "close enough and the collets make the final difference to me). My W20 collets are Imperial in 1/64th increments. Never had an issue with finding a fit so I never bothered with trying to find a metric set. Small stuff is done either on the 8mm lathe or on my turns. So that could be why. ONE CAUTION ABOUT WW COLLETS! Be aware that not all 8mm collets are the same. Derbyshire Large collets can only be used in a Magnus headstock. There are a bewildering number of 8mm collet styles and threads. Here, your best bet is a copy of Goodrich's "Watchmaker's Lathe." Collet sets require space and are one more thing to think about. Simplify! Standard W20 Collets can made to order or purchased from stock at Southwick and Meister in Connecticut! (once needed a collet for square stock). Proably others, but you would have to look at their website. Assessing Quality The initial presentation and the seller will give you a lot of information. If it has a fresh coat of paint, be very careful. May be good, more likely something is hidden. Is the bed itself dinged up? My Habegger bed was used as an anvil at one point but with the highpoints taken down the effect is cosmetic. Still, it is an embarrassment and I have been looking for a replacement bed for 10 years. Is the setup fairly complete? I have found the more complete the setup, the less likely it was "put together" for the sale. You also get better value buying a more complete setup. What happens when you put male centers in the head and tail stocks? Do the points line up? Capture a piece of mainspring between them. If it hangs plumb then it is ok. Are the controls smooth? Is there evidence it was in a flood? (Walk away, never going to be right again). Are any modifications professional looking or jury-rigged? Does the seller know what he is selling? How long has HE used it? Ask about lubricating (if he gives wrong answers, look over the equipment again). Finally, try it under power. Listen to the bearings with a poor man's stethoscope (a stick, screwdriver or tool handle pressed between your ear and the bearing housing). Do the bearings sound smooth or do you hear clatter? Works on any sized machine. Take a heavy cut after making sure the cutter you brought is properly centered. Do this on soft steel at low and high speeds. (Remember however, all machines have a speed range at which they resonate and shake). Does your tool chatter and does the work jump around? Be sure the work is big enough for a fair assessment; both in ID and length. Get and read the Tubal Cain series of Argus books. You now have the info needed to put the odds in your favor. And NEVER buy a machine sight unseen and to be delivered. If you see something you like on eBay, leave a down payment if needed; but go SEE it, pay cash and rent a trailer. I bought several things from a sketchy dealer in CT who sold on eBay with about a 15% complaint rate. But I always drove up and took delivery myself. He was not unhappy because he got paid in cash. My Personal Favorite, The Dead Center Lathe OK.
SHERLINE IS NOT A TOY!! z
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OMEGA RECOGNIZED SERVICE PROVIDER WOSTEP CERTIFIED For shipping or ordering information, contact: Dewey Clark 410.592.9998 Email Contact: Historictimekeepers@gmail.com Site Created and Expanded since 1999!! (Watch my hair go grey) |