Practice Turning a Balance Staff

Discussion in 'Watch Repair' started by bbodnyk, Mar 28, 2012.

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  1. bbodnyk

    bbodnyk Registered User
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    I've recently been practicing with my 8mm lathe using both the cross slide and the t-rest with hand held gravers. I'm using w-1 drill rod to practice on. I have managed to be able to get down to 0.25mm in diameter. When making a balance staff, what diameter should I expect to be able to turn down to before using a Jacot tool to burnish the pivots smaller?

    Thanks!
    Bruce
     
  2. Madman

    Madman Registered User

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    I am used to turn a pivot down to about 0.15 or even less before finishing it on the Jacot tool with a sapphire file.
     
  3. bbodnyk

    bbodnyk Registered User
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    Thanks! Getting down to .25mm wasn't too bad. Getting down to .15mm will be challenging but now I have something to shoot for. Good thing drill rod comes in 36" lengths!

    Bruce
     
  4. watchwinder

    watchwinder Registered User
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    hi Bruce, i think if you harden the W1 and then let it down to blue it will turn much easyer. Or you can get some blue stock from a supplyer. Good luck
     
  5. bbodnyk

    bbodnyk Registered User
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    Thanks Watchwinder! The same thing occurred to me yesterday as yet another pivot broke off while attempting to turn it smaller, hardening the steel should allow me get down to a smaller diameter. I've ordered a graver sharpener and can't wait for it to arrive. I've been hand sharpening my gravers and it's impossible to get the end perfectly flat when holding the graver by hand. While I've got a ways to go until I get proficient, so far it's clear that keeping your gravers absolutely sharp is critical in making something this tiny.

    Bruce
     
  6. Jerry Kieffer

    Jerry Kieffer Registered User
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    #6 Jerry Kieffer, Mar 29, 2012
    Last edited: Mar 29, 2012
    Bruce
    Generally when you break a short pivot like a staff pivot it is because of three reasons.

    First, the cutting tool must be sharp with proper cutting clearances.

    Second, the cutting tip cannot be positioned above the spindle center line. If so, the tip will not cut and simply rub on the surface applying pressure on the pivot and sometime break it off.

    Third, if the cutting tip is to low on the center line, the pivot will grab the tip of the tool and try to climb over the top many times breaking the pivot.
    The cutting tool must be held at the spindle center line for cutting efficiency.

    It is far easier to demonstrate Graver use than describe it or at least for myself. A few will have natural talent while many will require years of use for a high degree of proficiency. If this is your chosen method, then in person instruction or practice will eventually resolve your issues.

    I have owned many Watchmakers lathe slides over the years and currently own a Peerless, Boley and Levin. Personally, I find them cumbersome to use and less than controllable/accurate when compared to a machine Lathe carriage/cross-slide. But again, thats a personal thing.

    This last weekend during the NAWCC Lathe workshop, each student was able to cut a .125 diameter staff pivot on their first attempt as follows. In this case the schools small machine tool Lathes (Sherline) were used in machine tool mode as staffs were/are manufactured.

    First, a USA made AR-4 brazed carbide lathe tool was used. The factory tip radius on tools like Micro-100 provides the base radius for the pivot with no modification required.

    Second, stock was placed in the spindle and a very sharp pencil point was filed on the rotating stock. This point was then used as a reference to set the Lathe tool cutting tip under magnification. The cutting tip must be adjusted or shimmed to the point BUT NOT ABOVE IT.

    Third, with the tool set, a .76 diameter roller section was machined on the staff stock.

    Fourth, in the next pass, a .15 mm x .64mm long pivot was machined using handwheel settings at about 2500 rpm. For this procedure, only the handwheels are viewed and slowly operated not the cutting of the lathe tool. In the next pass, the handwheels were reset and the staff was reduced to .125mm using the same procedure. further reduction in diameter in .01-.02 mm steps can be done by moving the handwheel only about the thickness of a graduation mark under magnification.

    When personally fitting a pivot to a balance jewel, I machine the pivot to a sticky fit to the pivot per above procedure. It is then polished and or burnished to proper fit. Holding a balance jewel for fitting in the lathe was an issue. For that, some years ago I built a tweezers with two small rings silver soldered to the tips to resolve the issue. Attached photo.

    A good quality small machine lathe can be a option for those who have difficulties or do not have the time to master traditional repair procedures.

    Jerry Kieffer
     

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  7. bbodnyk

    bbodnyk Registered User
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    I'm down to 0.20mm now. It's not pretty but that's what practice is all about!

    Bruce
     

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  8. R.G.B.

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    I've got a few practice pieces myself. :) Funny how they go from looking chew turned to fairly decent in a few days practice. With gravers on a T Rest I find myself going back to good HSS. They're quicker to sharpen and for me seem to cut smoother.
     

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  9. bbodnyk

    bbodnyk Registered User
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    Enough practicing! I'm ready to try and make a "real" balance staff. I choose an Elgin 18s staff for my first real attempt. Attached is a pdf of the dimensioned drawing of the staff which will give me something to shot for. The second sheet of the drawing is so I can easily mark off the blank on my height gauge.

    Bruce
     

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  10. bbodnyk

    bbodnyk Registered User
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    I think I might be getting the hang of this. Here is my latest attempt. I had to use a carbide graver as my hhs ones wouldn't cut it. I've ordered a few collets so I won't need to use the Jacob chuck to hold my drill rod and once they arrive I should be all set to make a "real" staff.

    Bruce
     

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  11. RJSoftware

    RJSoftware Registered User

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    Took me a minute and then the light came on...!

    Excellent tuning technique..!

    RJ
     
  12. RJSoftware

    RJSoftware Registered User

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    Hey Bruce. Looks like you are making same progress as me. Wanted to ask you if you got a countershaft so to reduce speed and increase torque..?

    I had made the mistake of not using a countershaft and was cutting making dust chips instead of peelings.
     
  13. bbodnyk

    bbodnyk Registered User
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    I have a foot operated variable speed control to control the rpms rather than a countershaft with a bunch of pulleys. Learning to vary the speed thru the foot control is almost as challenging as learning to use hand held gravers, especially since I'm sort of doing both at the same time. I've been meaning to take the foot control apart to see what electronics are inside and then make a speed control with a dial rather than the foot control. I'm thinking it might be easier to dial in the speed I want rather than using my foot to control the speed.

    I wonder what others use to control their turning speed?

    Bruce
     
  14. Skutt50

    Skutt50 Registered User

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    I have stolen a motor and foot pedal from a sewing machine. Old Singer machines are sold for peanuts at flee markets and I have collected some 2-3 motor/pedal sets. The speed controol consists of a variable resistor made from hundreds of stacked small graphite chips. There is a spring changing the tension between the chips thus varying the resistance..... I have tried using a thyristor to control the speed but with poor result. I can adjust the speed and set it, but when I apply the graver (load the motor) the speed slows down. My next project is actually to get some extra wheels and gear down, running the motor at "full" speed.....
     
  15. Kevin Scott

    Kevin Scott Registered User

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    P1000197 75% 2.jpg "I wonder what others use to control their turning speed?" quote


    This is the lathe I mostly use. Not the best set up, but have not got around to making the changes I have in mind. Have many improvements in mind. Want to get rid of Borel stand.

    On a Borel stand. When doing work with high magnification, I raise stand up on blocks, so to maintain proper posture.
    The auxillary lense magnifier works very well. Easy to swing out of way, and very fast to reposition and be in proper focus. Also gives me a greater working distance. Combined with my clip on to glasses loupe, I have about 7-8x magnification with about 5'' focal working distance. Tried quite a few mounting systems for the auxillary magnifier, and until I came up with this one, they were far more trouble than they were worth. This system still could use some refining, but works great.

    The Moto Stat combined with the Variac speed control can give me lower speed than I need, with good torque that does not stop motor.
    Show in tailstock of part of Freid's Wig Wag system to guide lap, file, or burnisher, to keep pivot or other diameter of staff etc at proper angle. Don't need a chuck holding tailstock for the system.
    Have on-off switch next to headstock. My right hand is near there usually anyway, so I can use it without even looking.

    For over 20 years used foot pedal rheostat. From the start, knew there was a better way. Finally changed over. Had no problem getting used to new system. Wish I had done it 20 years sooner.

    Also shown is a hand rest. Not so much for keeping hand from getting tired, but for support and helps in keeping graver to proper geometry to work.
    Another advantage of the Moto Stat is it is very easy to adjust belt tension when changing pulleys etc. But unlike a regular countershaft, can't use with a milling or grinding etc attachment.
    From reading this forum, a router speed control seems the way to go versus the Variac. Can mount close to headstock, does not take up much room. Also cheaper.
     
  16. Kevin Scott

    Kevin Scott Registered User

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    Reread my post. Made a mistake.
    Says right hand is near there anyway.. Should have said Left hand.
     
  17. bbodnyk

    bbodnyk Registered User
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    Per Kevin's suggestion I ordered a router speed control to use with my lathe. I have a hard time with the foot control and am finding I am probably using too great a speed much of the time. Since the diameters of a balance staff are relatively close I should be able to dial in the speed that works best and hopefully leave it there.

    I'm hoping to also be able to use the speed control with my Dunmore Hi-Speed drill I got a short time ago. It turns at 17,000 rpm and a speed control should allow me to get a lower speed for drilling larger holes.

    Bruce
     
  18. Kevin Scott

    Kevin Scott Registered User

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    Bruce, I think you made the right move with the speed control. If you have a good motor, and a good belt, you should be able to have enough torque at low speed without a countershaft.
    Also, when doing staff work, after rough out, try adjusting the lathe belt as loose as possible, especially when working on the pivots. With a quality belt, don't need as much belt tension to avoid belt slippage.
    With motor off, adjust belt so that turning motor pulley by hand turns the lathe pulley without slippage. A looser belt will allow motor to run at lower speed, and still have the torque needed.

    Looks like you are making good progress.
     
  19. RJSoftware

    RJSoftware Registered User

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    Not to be argumentative, but I also had a speed control on mine. But, mine was a lightbulb dimmer switch which might have been the difference. Maybe not enough watts. But funny isn't lighting/speed control just reduction of power? (zero to full )

    But the only way that I really knew what was going on was comparing the chart that someone displayed here about "feed and speed" and the suggested rpm.

    I was lucky enough to have found a lathe speed indicator at one time. So I found that without the countershaft my lathe speed was way too high.

    But trying to compensate with the rheostat for me was scetchy. True it takes little to no belt tension as since things are small no heavy torque is needed. But adjusting the rheostat down simotaneously reduces power AND torque. For me, it was either too fast creating a chipping dust cut or just too little of power -no cut -stopped.

    There is an easy way to establish a countershaft. You can make a bracket that fastens to one of the motor bolts. Use strap steel and have one axle made from a bolt for a double pulley to spin on right above the motor pulley. You bend the strap steel in whatever configuration establishes the bolt for the double pulley so that it is centered above the motor pulley.

    I see double pulleys on lawnmowers but suppose ebay would be a good source. If you have a wood lathe you could turn one.

    When I use to thread rigid pipe as an electrician, we would use an electric pipe threader. The thing ran slowly but had soo much torque it could break your arm off if it wasn't handled correctly. The peelings from the threading action was in curly ribbons. So it is the same here when your cutting at correct feed and speed. The blade has to bite in enough and the torque has to be strong enough to create the cutting. Else at high speed you get chatter/dust which creates a sloppy unreliable cut.

    You know when you got a good cut going when you see a long thin curly ribbons coming off. It also saves the HSS blades from needing to be sharpened soo often. What happens is the stock spinning at high speed when HSS graver doesn't cut it instead burnishes and rock hardens the metal and the HSS stops cutting and continues to burnish and heat up and get dull REAL QUICK.

    The carbide goes ahead and forces the cuts/chips at high speed but the cut is sloppy and produces a dull chipped and WEAKENED surface. I think that it actually fractures the stock, not sure.

    To me, when the HSS cuts it's a lot nicer feel to it. Feels professional, more controlled. So I know what you mean when you say your glad they where cutting again.

    So you see where sorta at the same crossroads.

    This is the typical thing I am running into too. I start out cutting and making good time. I can take time to fit parts to the staff as I am cutting and measuring. I can do that in a couple few hours.

    But then it's time to get the pivots closer to size...

    As things get smaller and smaller I am less able to bite with a blade and speed gets slower too. The speed gets slower cause the surface area is reduced. It would seem to be as simple as speeding things up, but what I find is that when it gets real real small I am not so able to hold the cutting edge at the proper height. I do mine free hand without the slide. For now I find the slide too awkward and time consuming to set up. I feel I should be able to do this free hand anyway. Guess I'm stubborn.

    The time cutting to get those pivots reduced down to near size goes up drastically. Next thing you know it's 2 am and I'm not done yet. Not only do I have to hold the blade edge at precisely center of the stock, I have to avoid the overwhelming desire to push at all. Only touch no push.

    One push too much or too high or low and snap,,,, time to start over. I can't tell you how many times Ive seen my graver roll past underneath or overtop and the pivot break off instantly.

    But now I realize that a watchmaker pivot file and/or ruby/saphire file should be the solution. I have not bought one yet. But looking forward to it.

    Here is the part of that, that makes sense. I also have a Jacot tool. It's difficult too. Plus mine is a little less than complete. The thing is, with the pivot file the ridges I am told are smaller than the pivots we create. But using them requires PUSHING. So they are really intended to be used on the Jacot tool because that tool has slots in the head that prevent the pivot from breaking off. So you can push.

    The saphire or ruby stone, from what has been said is able to cut/reduce without pushing........!!!!!!!

    So to me that seems very ideal as I can leave the work on the lathe and simply "touch" up the pivots.

    I have tried to use my other stones to include my best arkansas ones, a west virginia slick too. What happens is the pivot just digs a rutt into the stone and the cutting / reducing action is next to nill.

    I have tried using a diamond wheel flat against the spinning pivot and sorta same thing happens. The diamond dust just sorta pops off the diamond wheel. It is glued on I suppose. But at any rate spinning a pivot against one does no good either.

    What I realized about that is although the diamonds are harder and do cut the metal, it relies on IT'S spinning action to cut, so that a multitude of diamond dust acts as the abrasive against the pivot instead of the pivot finding space to squeeze inbetween diamond dust glued to a stationary (non moveing) surface.

    So I tried my best to hold a spinning diamond wheel to the spinning pivot. That cuts real quick...! But the unreliable flap of uneven diamond wheel is too critical to hold. Might make a good milling operation. Especially if one could get a higher quality watchmaker diamond wheel...

    But anyway, still sounds like the best practicle approach is to obtain a piece of ruby or saphire and make one. I'm not into spending big money unless later on this trade turns out to be real lucrative... :)

    I see big giant chunks of saphire on ebay. Looks like real crude gems quality. Then I see rings with high quality saphire (real blue) or whatever. Don't have a clue which to pick...

    I feel quite confident that I could shape the stone adaquate to the purpose and fit it in nice wood handle. Prepping is another consideration. I'm not sure what to do about that. I suppose just rub it on a stone.

    Let me know how your progress goes.

    RJ
     
  20. David S

    David S Registered User
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    There is no question that if you wish to retain power with adequate torque, it is best to use a gear reduction of some sort. The simple fact with universal motors is that if you reduce the voltage by half, hence half the speed, you reduce the power by 4. There are some motor and controller combinations that use speed feedback to maintain torque.
    David
     
  21. Kevin Scott

    Kevin Scott Registered User

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    RJsoftware,
    From what you are saying it seems to me are are on the right track with your thoughts.

    1) countershaft: what you describe making is what I have pictured in post #15. Yes, it does allow me to go even lower speed than I need, and still have adequate torque. But I was able to cut and finish balance staff pivots before I got it. But you need a good motor and and a proper belt. I use the green bumpy belting. And some sewing machine motors I suspect are not good enough for this work.

    2) I agree with your thoughts about breaking pivots, work hardening the surface etc. when using the graver.
    Slow speed lessens these problems. Graver must be very sharp. Must have proper graver to work contact. To reduce breakage, set tool rest close to work very carefully adjust the height carefully. This is also where the armrest pictured in post #15 comes in. It sort of forces me into one contact position of the graver to work geometry.
    Also, to avoid pivot breakage with the graver, light pressure is applied with the graver moving towards the headstock. Do not apply pressure perpendicular to pivot.

    3) "digging rut into stone". Should not have this problem if you are always moving stone in opposite direction of work rotation, and with stone lubed.

    4) Cost of sapphire, and what and where to buy: Reread post #15. You can get them for free... easily.

    5) Carbide gravers: What you are experiencing sounds about right if you do not have the proper finish on them. After sharpening with the diamond wheels or laps that mount in the lathe, they will cut very well, but will not have the control and finish you get with steel and HSS gravers like you are experiencing. To solve problem, use a plexiglass lap with a small amount of ~1200 grit (same as comes with Barkus system) diamond paste embedded in lap. Sharpen edges along line of, parallel to graver cutting edge just two or three times. Now your carbide graver will leave a finish and handle like your steel and HSS gravers, or close to it. But still, I only use carbide when I have to, to remove work hardened glaze, or on some very hard factory american staffs.

    6)Buy Freid's book, The Watch Repair Manual, if you don't have already. Read the section on his "Wig Wag" system. Part of it is pictured in the picture, post #15, mounted in the tailstock, and explained in the post. This forum is great, but don't expect to learn this without reading and studying books. And they don't cost much, and are easy to find.

    Keep practicing, read and study the good books, and soon you will be cutting pivots with a hand held graver to .12mm diameter quickly, with a good finish, that can be quickly finished by grinding and burnishing to size. Well, grinding and burnishing quickly to size, without going undersize is another subject. But you are well on your way there.

    Also, it seems the best pivot work is done without abrasives or stones. Fine for other staff diameters. But pivots should be finished with files and burnishers: sapphire, steel etc. Again, another subject, and open to argument.

    Also, I suspect sewing machine motors and even the quality traditional lathe motors are not as good for this work as the newer type motors like sold with the newer Sherline lathes. DC current versus AC current. But have not used one. Again, another topic and open for discusion.
     
  22. DaveyG

    DaveyG Registered User
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    I have tried an ordinary watchmakers lathe system, belonging to a friend, with a DC motor and speed control and found that the motor kept a constant speed, whatever setting was applied, regardless of the load applied, definitely much superior to the AC motors usually used. The DC motor is able to provide much more in the way of torque. Why haven't I got one - because it cost an arm and two legs, although I'm sure, with a bit of effort on my part, I could achieve the same set up at much less cost.
     
  23. RJSoftware

    RJSoftware Registered User

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    Hey Jerry. I have seen you post this image before. I had been meaning to ask you, do you have some kind of clipping or retaining ring or something to maintain the jewel in the tweezers so that you don't accidentally drop the jewel..?

    I imagine a simple slip ring that slides up tweezer prongs gradually squeezing tighter would suffice, but probably would be better if a threaded nut and bolt where applied it might be safer not to apply too much pressure.

    Also confirm with you about what was said in reguard to the pivot file vs the saphire. Neither I have yet.

    The pivot file requires pressure to cut and therefore requires use of the Jacot tool. The saphire file requires less pressure so it can be used while stock remains in lathe.

    Both bennefit from Jacot tool but one could complete the pivots on the lathe with the saphire, true?

    RJ
     
  24. bbodnyk

    bbodnyk Registered User
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    I took a short break on my practice to make holders for my gravers. I'm using 1/8" HHS tool blanks and was holding them by hand and quickly realized I needed a better way of holding them. Borrowing the idea from my Waller carbide graver set I turned an aluminum rod to .375" diameter 4" long for the handle. I drilled a 0.182 hole about 1 1/2" deep to allow a recess for the extra tool length and then drilled and tapped a 5/16-24 thread on the end.

    I turned a piece of brass to match, putting a 5/16-24 thread to screw into the handle, drilling a 0.182 thru hole and drilling and tapping a 2-56 hole for my set screw. I'm actually using a socket head cap screw rather than a set screw. I find it gives me a reference point on the graver when I'm using it.

    Regards,
    Bruce
     

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  25. Kevin Scott

    Kevin Scott Registered User

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    You confirm what I suspected. How much does a DC current Sherline motor cost? Maybe for someone that needs a motor, it is worth the extra cost.

    About 20 years ago Horological Times had a article about converting a standard AC current watchmaker's lathe motor to DC, and solving the low speed torque problem. I will see if I can find it.
     
  26. Kevin Scott

    Kevin Scott Registered User

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    Made a mistake again. Should say: in thread about "filing down newly cut staff pivots" post #14.

    Very sorry for any confusion it caused.
     
  27. DaveyG

    DaveyG Registered User
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  28. DaveyG

    DaveyG Registered User
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    From memory my friend paid £800 for the whole set up, transformer/rectifier, hand speed controller, dc motor et al.
     
  29. Kevin Scott

    Kevin Scott Registered User

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    horo times.jpg

    Rewiring motor, from AC to DC?, for low speed torque. Not sure if that is the difference between being wired parallel or in series.

    DaveyG, seems for 800 english pounds you can buy a complete Sherine system, and have money leftover.
     
  30. Jerry Kieffer

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    RJ
    I have never had a need to lock the jewel tweezers in place. In fact I prefer not to lock it since I like to have the jewel find its own way when fitting to a pivot. However a lock would be a very simple modification.

    Personally, I feel if you need a pivot file when sizing or finishing a staff pivot, your probably in trouble. This is one of the reasons I no longer use a watchmakers Lathe or Jacot tool when cutting staffs in favor of machining staffs on a machine type Lathe.

    When I machine a Staff, it is machined using high quality brazed carbide tools and handwheel settings. Once close to size with a couple of cuts, I then advance the tool about .01 mm per pass until desired fit is achieved to the balance jewel using the mentioned jewel tweezers. At this point I take a couple more additional high speed slow passes at the same cross slide setting that will brightly finish/burnish the pivot requiring no filing and minimal sapphire finish work.
    If machined from properly tempered steel, a short staff pivot should not need support for finish work unless it is very crude requiring a lot of work.
    However, If support is required or desired, it is not an issue since my machine Lathe has a tailstock that is adjustable in ALL directions. Highly accurate alignment adjustment allows the use of a tailstock mounted pivot runner for pivot support. The leadscrew controlled tailstock allows the runner to be accurately advanced or retracted for Optical pivot inspection and or jewel fitting. In addition, with the lathe turning the staff, I can concentrate on finishing the pivot without distraction. Again personally, when compared to the machine lathe procedure above, I find the Jacot cumbersome and inefficient in comparison.


    Jerry Kieffer
     
  31. flynwill

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  32. Kevin Scott

    Kevin Scott Registered User

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    If you don't need a countershaft for a milling attachment or for a rotary grinder - polisher, etc, the Sherline system is cost effective at that price. Add cost of good motor, countershaft, rheostat, price is about the same. And Sherline seems to have excellent customer service etc.
     
  33. bbodnyk

    bbodnyk Registered User
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    Since I started this thread I figured I'd ask a different question but still related to turning a balance staff.

    I'm using w-1 drill rod which I heat treat with a Map torch over my kitchen sink. I heat a 1" piece until it reaches what I hope is the critical temp then drop it into a saucepan of cold water. I then temper it in my oven to a blue color.

    From what I have read, when the steel reaches a cherry color that's the critical temp. My question is what kind of cherry are we talking about; Bing or Marachino? :) If I heat til a dull cherry color and temp til blue I can cut it easily with my HHS tool steel. If I take it to a brighter cherry color and temper til blue I can only cut it with my carbide gravers.

    1. What cherry color am I trying to achieve?

    2. When tempering, do you take it out immediately upon reaching the blue color? Does leaving it in the oven longer affect anything?

    3. Should I be using Cobalt tool steel or should regular HHS work?

    I realize I can buy staff wire from the material house suppliers but if I can figure out this heat treating drill rod should work just as well or is the staff wire superior to drill rod?

    Thanks!
    Bruce
     
  34. technitype

    technitype Registered User

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    Is "w-1" carbon steel or tool steel?

    As for the color, it is better to use the lower temperature- heating steel really hot increases the risk of burning the steel.
     
  35. bbodnyk

    bbodnyk Registered User
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    The drill rod is w-1 tool steel with a hardness of 55-68 Rockwell C
    before tempering. Looks like I'm tempering it to around 58.
     
  36. RJSoftware

    RJSoftware Registered User

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    >> If I heat til a dull cherry color and temp til blue I can cut it easily with my HHS tool steel. If I take it to a brighter cherry color and temper til blue I can only cut it with my carbide gravers.

    Interesting. Never had noticed. I don't imagine you timed the two different processes.

    500 degrees is blue. You may have come close to with your second staff but not quite 500 and then the time element.

    OR you accidentally burnished the staff and dulled the graver...
     
  37. bbodnyk

    bbodnyk Registered User
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    Actually checking back on the various bits of used rod lying around I've come to the conclusion that the brighter cherry color is what I need to watch for, not the dull cherry color. The ones I heat treated to a dull color I don't believe actually reached the critical temp and I can mark with a file. The ones I heated to a brighter color, a file just skips across the surface so I believe I now know what color to heat treat to.

    Now I need to explore the tempering a bit more. I know what color to watch for, I just don't know whether the length of time the metal stays at that temp has an effect on the tempering.

    I think I'm going to order some of the Cobolt tool steel blanks. Hopefully they will cut the hardened steel better than my HHS ones.

    Bruce
     
  38. flynwill

    flynwill Registered User
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    The proper temperature varies a bit with the alloy as well. A google search will turn up the recommended hardening process for the common tool steels W1, O1 & A2. W1 seems to have the lowest temp at 1425-1475F, O1 slightly higher at 1474-1500F and A2 a lot higher at 1750-1800F. One guide I found lists 1400F as "red" and 1500F as "Bright Red" which I think is what is often referred to as "Cherry red". The temp need by the A2 alloy is closer to orange.

    Bottom line, if you don't have a temperature controlled kiln to do the work in, the try it and test the result method you used to learn the right process is probably the best answer.
     
  39. technitype

    technitype Registered User

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    I have been thinking about turning a staff out of "air-hardening" steel while the blank is still soft, and then heat-treating the staff inside of a small cast-iron container.

    That ought to be a lot easier than trying to cut tempered steel.
     
  40. bbodnyk

    bbodnyk Registered User
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    Though I am hardly the one to be giving advice here, while unheat treated steel is easier to turn I have difficulty getting my pivots down to a reasonable size and they tend to break eventually. Using heat treated steel taken to a bright red (marachino cherry not bing) and tempered to a blue color I've managed to get my pivots down to about .18mm using carbide gravers. This leads me to the conclusion that turning heat-treated steel is better.

    You would also have the potential problem of the turned staff warping from the heat treating process.

    Again, I'm just learning myself! I'm awaiting the arrival of the router speed control I ordered. I've also come to the realization that my foot control isn't sensitive enough and I'm turning at too high a speed. At times where the foot control cooperates and I've managed to keep a relatively low speed I've found I can hog out quite a bit of material. Hopefully this indicates that the torque will still be high enough at a low speed using the speed control. I will certainly report on my findings when it comes. Maybe today?

    Regards,
    Bruce
     
  41. technitype

    technitype Registered User

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    I am inclined to think that "warping" is a result of the quenching process, and not of heating.

    You do have a point that turning small pivots is likely easier on heat-treated steel.
     
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