How to measure

Discussion in 'Watch Repair' started by Rob P., Nov 22, 2019.

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  1. Rob P.

    Rob P. Registered User

    Dec 19, 2011
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    I'm just going through my "to fix" drawer and for some reason I picked up my 16s Model 1860 Waltham to look at a little bit closer.

    It has a broken staff (both pivots). I have a new staff for it that is supposed to fit the 1860 model KW 16s, BUT, the new staff and the broken staff aren't even close to the same overall length. The new one is shorter than the broken one.

    The new one appears to be the same as the broken one in looks, it's just shorter. I can't drop the new staff into the movement to check the overall length because the pivots need reduced in size to fit the jewels. I'd need some kind of drive dog for my pivoting tool and I have no idea what I could use other than buying one of the dog sets which are a bit spendy.

    It's possible the broken staff isn't correct. It's also possible that NEITHER staff is correct. Most of the staffs for Waltham 16s movements are around 5.35mm but there's no info for the Mod 1860 KW staff that I can find. The broken staff with no pivots is 4.92mm and I added on some extra for pivots to end up with something around 4.97mm or so. The new staff is only 4.87mm.

    So, now I'm wondering how someone would measure for overall staff length from the movement. The only way I can think of is to pull the cap jewel off the balance bridge and run a wire down through the hole jewels to rest on the lower cap jewel. Bend the wire at the top of the upper hole jewel, clip it off a little bit long and trim until the wire is flush with the top of the upper hole jewel.

    That's a lot of fussy microscope work for not much result. Plus it'd be easy for me to screw up or break something else. Anyone have a better idea?
     
  2. Chris Radek

    Chris Radek Registered User
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    Apr 13, 2014
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    Measure over the installed cap jewels with your micrometer, then pull them both and measure them, and subtract.
     
  3. Rob P.

    Rob P. Registered User

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    Hah, I KNEW there had to be a better way.

    Not that this one is even close to being worked on. Next up is a Model 1888 Waltham that only needs cleaned and a set of hands. After that is a very nice 16s Bunn Special with a busted staff and crystal. After that is... well, you guys get the idea.

    However, for this afternoon, it's off to the "the drawer" with micrometer in hand.
     
  4. Bila

    Bila Registered User
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    The staff for this model is listed as being 6.27mm in length:)

    Erin
     
  5. Rob P.

    Rob P. Registered User

    Dec 19, 2011
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    Thank you.

    I looked up that length on http://home.elgintime.com/elgintime/StaffLookup and found something interesting.

    The overall length listed is 6.27. But, the lower length is listed as 6.5. :???:

    That's just crazy. The lower length cannot be longer than the overall length. Unless someone broke the laws of physics.
     
  6. Jerry Kieffer

    Jerry Kieffer Registered User
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    Rob
    I have also measured the overall length of a staff with a Micrometer measuring cap jewels for many years without issue.

    Since I machine staffs rather than cut them, I mount existing staffs or work pieces directly in a collet in the lathe spindle for such work if required or desired. Since there is no such thing as a perfect spindle or collet or work piece mounting, I have removed any collet positioning pins on my lathe spindles where I use watchmaker collets. This allows rotating the collet and workpiece each in different directions until a non runout work piece sweet spot is achieved. From that point it can be machined to a predetermined size by hand wheel settings. I have also constructed a tweezers for safely holding jewels for fitting while a staff remains in the lathe first photo.

    However, in the early days when I needed a drive dog, I machined one per the attached second photo.

    Jerry Kieffer

    DSCN2666.jpg DSCN3579.jpg
     
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  7. Bila

    Bila Registered User
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    That is totally incorrect Rob, so maybe a typo, dimension for the lower is 3.45mm and it is .61mm diameter for the roller table seat:)
     
  8. Rob P.

    Rob P. Registered User

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    You make the coolest stuff. :coolsign:

    Currently "The Plan" is to buy a Sherline after the first of the new year. Then it'll be a few hours spent turning tiny steel bits into mini-chips as I learn how to use it with both the handwheels and a handheld graver.

    After that, who knows where it'll lead.
     
  9. Rob P.

    Rob P. Registered User

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    Thank you. With that additional data I can machine a staff (once I get a lathe and some practice working that small) if what I have isn't correct for the movement.

    When I get to that point I will definitely be asking more questions.
     
  10. Rob P.

    Rob P. Registered User

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    #10 Rob P., Nov 23, 2019
    Last edited: Nov 23, 2019
    Ok, more weird stuff just because.

    I measured across the top plate and the bridge by using a small piece of 1/8" square bar as a spacer so the micrometer jaws will clear the rim of the plate. Then I pulled the caps jewels and measured them.

    Besides discovering the fact that some ham fisted gorilla wearing boxing gloves has worked this movement over in the past, what I found is turning out to be very interesting. In a watch nerd-y kind of way.

    The overall outside measurement is .401" Subtract the .1245" thickness of the square stock (as measured on the actual 2 sides used) and you end up with .2765".

    Both cap jewels are .033" thick for a total of .066".

    That leaves .2105".

    Convert to MM and you get just under 5.35mm for the overall staff length. (5.3467mm)

    I took the original numbers last night and scratched my head. I took them again this am because I didn't want to be mistaken because I was tired. Those are the numbers I got both times after a full double check each time.

    I was confused at first because this doesn't compare to the published data. But, there IS a shoulder on the underside of the cap jewels. Ahah! A 6.27mm staff can go in there is if the cap jewels are recessed in their bezels on the underside by .0017" each. I have no possible way of measuring that. (Ok, I could if I had a small enough sphere but without sphere in hand...) so, basically, I going to assume that it's .0017".

    In the end, I have the gross measurements I needed. What I'll probably do is machine a dummy Delrin "staff" to to specs without the pivots and put it in between the hole jewels. That way I can verify the overall height, roller table height, balance seat height, and the HS collet seat height. As it stands neither staff I have will fit this movement. Which also tells me that the RT on the current staff may not be the correct one and I'll need to measure the hole diameter before final machining the new staff and using that hole diameter instead of the published data for the dummy staff. That way I can verify that the RT is the correct diameter to properly put the roller jewel in the fork. Otherwise I have to make a RT too.

    I am so glad I don't do this for a living and trying to get it done by a customer deadline.
     
  11. Jerry Kieffer

    Jerry Kieffer Registered User
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    Rob
    Thank you for the compliment.

    It should be noted that the Sherline Lathe and other machine style lathes are not designed for, or well suited for Graver work (Of course it can be done) when compared to a Watchmakers Lathe.

    Much in the same way a Watchmakers Lathe and Cross slide are not designed for the use of Micro tooling and dimensional machining when compared to a machine tool.

    The Good news is that a Watchmakers Lathe for just Graver work is quite inexpensive if it is something you wish to continue doing.
    However, if you must, the attached photo shows my early fixture (Lower half of photo) for mounting various watchmaker lathe slide rests to a Sherline Lathe. If it were something I used on a regular basis, I would redesign it for more flexibility, but it gives the general idea.

    Also, it would appear that the NAWCC beginners Micro Lathe class WS-117 will be held in California again next year if you have issues.

    Jerry Kieffer

    fullsizeoutput_482.jpeg
     
  12. Rob P.

    Rob P. Registered User

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    At this point the Sherline is "The Plan" Right now I'm doing all my machining on a GIGANTIC Southbend Heavy 10 that has more bearing and leadscrew play than the machining tolerances I'm working to. (The chuck on that monster weighs almost 30 lbs!!! ) Working to tight tolerances on that beast is a challenge to be sure and there is no way under the sun that I can machine a staff on it. Mostly because I am NOT spinning 30 lbs of solid steel fast enough to get the kind of surface speeds I'll need to work that small. The air displacement from the jaws acting like fan blades would create enough wind that it'd be like trying to work outside during a cyclone or hurricane and I AIN'T putting my face anywhere near it neither!!! Absolutely NOT happening.

    So, like I said; there's a Sherline in my future. Once I have the new lathe, I'll be asking more how-do-I-do-this type questions that will cover a very broad range of topics from best place to get materials, to annealing, to sharpening, to just about everything else. In the meantime, there's this 18s Waltham that would fit very nicely in my pocket if it were clean and running (and had some hands).



    ps: Where can I get the details on the NAWCC class?
     
  13. karlmansson

    karlmansson Registered User

    Apr 20, 2013
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    I'm not really sure why this is, but there is a general consensus that for really small stuff, watchmaking size at least, the surface speeds and feeds are somehow thrown out the window. In general a slower speed is preferred in order to avoid burnishing the work. And as far as I can tell machining has been just fine at slower speeds for me at least. Sharper tools and light tool pressure are key though.

    But yeah, a Southbend Heavy is probably a little oversize :).

    Regards
    Karl
     
  14. Jerry Kieffer

    Jerry Kieffer Registered User
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    I see that it has not been listed under Education and class schedule yet.

    I would suggest, contacting the NAWCC and ask for Ext 237 under Education. They will make sure you are aware of the courses when it is scheduled. For Micro machine Lathe such as Sherline, Ask for WS-117.

    Jerry Kieffer
     
  15. geo.ulrich

    geo.ulrich Registered User

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    the South Bend is available with collets
     
  16. Jerry Kieffer

    Jerry Kieffer Registered User
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    Karl
    The procedure that you have described is generally associated with the use of a Graver and or watchmakers cross slides where small amounts of metal are removed under optical observation. Its success is of course based on operator skill development.

    On the other hand, Micro machining on machine tools as utilized in industry is a totally different process. It is used by those wishing predetermined dimensional accuracy and surface finishes often encountered in commercial parts in a timely fashion. This of course requires capable equipment that can utilize proper tooling in a way it was designed to be utilized for the materials it was designed to be used for. This type of machining requires high speeds and the use of cutting fluids as recommended by the manufacturer. Personally, I have found the "Mist" systems to be ideal for small shop use.

    The ball/roller bearings as used in machine tool spindles are very rigid as are tool and work piece holders. Again with proper setups and tools, cuts made are very clean leaving no friction thus no burnishing (Per typical Horological definition) at slow or high speeds. Burnishing will only occur with equipment and or tooling failure and would eliminate predetermined dimensional accuracy. In addition, if were allowed to occur, it would decrease machine tool capability.
    An example of this can be seen in the attached photo that I recently posted on another topic. In this case, a .002" or .025 mm rod is being machined in a singe pass as is often common in dimensional machining. If the equipment, tooling or procedure were to permit burnishing, the rod would immediately disappear in mid air.

    Jerry Kieffer

    fullsizeoutput_58.jpeg
     
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  17. Rob P.

    Rob P. Registered User

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    A Heavy 10 will swing 10" and take off 1/4" from mild steel in a single pass without complaining. Trust me, those chips get HOT! and will stick to you as they burn and blister. BTDT, got the T shirt complete with charred holes and thank goodness for face shields.

    This isn't really the lathe you want to use for miniature machining. The smallest I've done on it is around 1/8" and that was nerve racking to be sure the runout didn't ruin what I was working on. It really is a beast of a lathe.

    I was offered time on a 16" once and turned that educational experience down. 12" is about as big as I personally care to go because I really don't see any need for me to be spinning material the size and weight of a small bus.
     
  18. praezis

    praezis Registered User

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    Sensational, Jerry. But I suppose, it is just a typo?

    Frank
     
  19. Jerry Kieffer

    Jerry Kieffer Registered User
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    Frank
    My math teacher in high school was 23 years old, a very good friend and we were team mates on a small bore rifle team. As such, I suspect I was not forced to be as sharp at math as I should have been.

    Good catch, It should have read .05 mm. per attached photo. Thanks for the photo.

    In case anyone is curious why someone would do this, it was for a local university professor who was researching a special electrical fuse.

    The request was for work pieces that were .002" or .05mm diameter and about .250" or 6mm long. They were from four unique alloys that I cannot spell or pronounce at the moment. Two from each alloy were requested.

    Jerry Kieffer

    fullsizeoutput_59.jpeg
     
  20. praezis

    praezis Registered User

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    This 0.05 mm is still amazing!

    I think, it depends what units you are used to. With metrics I know immediately what a figure means, with inches I have no idea a must reach for the calculator.

    Frank
     
  21. geo.ulrich

    geo.ulrich Registered User

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    I have worked in machine shops for 50 yrs. and I am familiar with the heavy 10's if machine is fairly tight you can go much smaller than 1/8" you are not going to take animal cuts, light cuts and SHARP tools on center and throw an indicator on cross slide for actual cut depth you will be surprised. I'm not saying this is the easiest or most productive just it can be done ...
     
  22. Jerry Kieffer

    Jerry Kieffer Registered User
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    #22 Jerry Kieffer, Nov 26, 2019
    Last edited: Nov 26, 2019
    Frank
    Thanks.

    Actually, the machining process itself is of the most basic and can be accomplished by a beginner on there first attempt with only some verbal instruction.

    The key to the process is the use of proper quality tooling Properly setup. For critical work such as this, I setup Lathe tools in stand alone tool posts perfectly centered to the center rotation of the spindle under optics. This takes about 30-45 minutes per tool, but they remain in their own tool post until the end of their useful life and are never reset.
    Each time they are used, the tool post with the tool in it is installed on the lathe and it is up to the Lathe to maintain that alignment through out its range of travel. If not, the lathe is readjusted for one more chance and if it fails, it is permanently removed from the shop.

    In post #19, I meant to say "Thanks for the correction" not " Thanks for the Photo ".

    Jerry Kieffer
     
  23. geo.ulrich

    geo.ulrich Registered User

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    Jerry, A little quicker setup to get you real close we use a block that was ground to correct centre height off bed ( hardinge tool room lathe) and sweep indicate from block to high point of tool. you can even adjust height with indicator in place for really small adjustments. a gage block stack would work as well but don't like to use them for this purpose...
     
  24. Jerry Kieffer

    Jerry Kieffer Registered User
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    Thank you for the suggestions.

    I have used similar methods on my larger machines with great success.

    On my smaller machines for general machining, (Sherline and Cowells) I use standard manufacturer tool posts designed for 1/4" tools. When using quality brazed carbide tools, I simply scrape or file the paint off the bottom of the tool and I am generally ready to go.

    However, for micro machining, I go to the extreme that can easily be considered anal.

    Without going into pages of detail, each machine has its own little quirks that must be accounted for. Settings are evaluated by observing actual cutting performance under Zeiss Optics and feel of the machine. Final settings to find the exact "Sweet Spot" desired, can be as little as a slight change in tool post mounting torque that is recorded for future mountings.

    Thanks Again
    Jerry Kieffer
     
  25. Rob P.

    Rob P. Registered User

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    Most Heavy 10's these days are long past their prime and the toll on them from wear and horrible maintenance makes machining to super tight tolerances nearly impossible. The one I have access to has some bed wear and leadscrew slop that I have to compensate for. However, I have done some remarkable things (at least I think they're remarkable) with it.

    One of the hardest things was making an expanding collet to hold a wrist watch case so I could machine away the integral interior dial opening lip and then make a new one to press fit in its place with a smaller dial opening. The centering ability of the collet and the holding ability of the fingers was, needless to say,, EXTREMELY important. The final machining of the replacement insert to the tolerances needed to achieve a press fit was nerve racking. Especially using 3/8" tooling. I had to try twice to get the replacement dial opening ring to spec.
     
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