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  1. #1
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    Default Practice Turning a Balance Staff

    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. #2

    Default Re: Practice Turning a Balance Staff (RE: bbodnyk)

    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. #3
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    Default Re: Practice Turning a Balance Staff (RE: bbodnyk)

    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

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    Default Re: Practice Turning a Balance Staff (RE: bbodnyk)

    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

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    Default Re: Practice Turning a Balance Staff (RE: bbodnyk)

    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

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    Default Re: Practice Turning a Balance Staff (RE: bbodnyk)

    Quote Originally Posted by bbodnyk View Post
    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
    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
    Attached Thumbnails Attached Thumbnails DSCN2666.jpg  
    Last edited by Jerry Kieffer; 03-29-2012 at 10:20 AM.

  7. #7
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    Default Re: Practice Turning a Balance Staff (RE: bbodnyk)

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

    Bruce
    Attached Thumbnails Attached Thumbnails Image1525.jpg  

  8. #8
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    Default Re: Practice Turning a Balance Staff (RE: bbodnyk)

    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.
    Attached Thumbnails Attached Thumbnails IMG_1556-2.jpg  
    Rob

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    Default Re: Practice Turning a Balance Staff (RE: bbodnyk)

    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
    Attached Thumbnails Attached Thumbnails elgin_bal_staff_857.pdf  

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    Default Re: Practice Turning a Balance Staff (RE: bbodnyk)

    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
    Attached Thumbnails Attached Thumbnails staff_2.jpg   staff_1.jpg  

  11. #11
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    Default Re: Practice Turning a Balance Staff (RE: Jerry Kieffer)

    Quote Originally Posted by Jerry Kieffer View Post
    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.
    Jerry Kieffer
    Took me a minute and then the light came on...!

    Excellent tuning technique..!

    RJ
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    Dave Bowman: Where I am now.

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    Default Re: Practice Turning a Balance Staff (RE: bbodnyk)

    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.
    [Discovery is about to be destroyed by the birth of a new star]
    HAL 9000: I'm afraid.
    Dave Bowman: Don't be. We'll be together.
    HAL 9000: Where will we be?
    Dave Bowman: Where I am now.

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    Default Re: Practice Turning a Balance Staff (RE: RJSoftware)

    Quote Originally Posted by RJSoftware View Post
    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.
    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

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    Default Re: Practice Turning a Balance Staff (RE: bbodnyk)

    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. #15
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    Default Re: Practice Turning a Balance Staff (RE: bbodnyk)

    Click image for larger version. 

Name:	P1000197 75% 2.jpg 
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ID:	126977"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.

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