Measurements

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  • #49127
    chris mabbott
    Participant
    • Topics Started: 119
    • Total Posts: 1525

    Here’s the question of the day…
    I was drawing out my diagrams for a few broken staffs, in case I have to make them..

    I’m having a hell of a time with measuring the various lengths..

    Yes I’ve tried rulers, calipers etc, but they aren’t accurate simply because there exists an error factor!

    Example… The length is no problem, neither are the 4-6 outer diameters… Child’s play :ugeek:
    But the length of the pivot to where it meets the body, then that part, the the rivet length etc… That is the SOB 😯

    Suggestions other than purchasing an optical comparator or other expensive tool are welcome 😆

    #58591
    randy
    Participant
    • Topics Started: 39
    • Total Posts: 594

    Chris,
    I have a JKA-Feintaster bench mike.
    Something like that might meet your needs.
    I picked up a nice one for under $300 on Ebay.
    I’m thinking that it’s cheaper that an optical comparator ??

    I also think that you will be logging the dimensions,..but when you go to make one, you’ll still have to “ease into” the final dimensions with various tools.

    Best,

    Randy

    #58592
    chris mabbott
    Participant
    • Topics Started: 119
    • Total Posts: 1525

    Hey Randy,

    Yeah I have a bench mic but like the vernier, there is an error factor as you have to physically hold the staff against the anvils/jaws to approximate the various stepped lengths.
    To me it just seems a bit sloppy when we’re using precision tools to obtain accurate measurements. There’s probably a formulae somewhere that will use the length plus diameters :?

    #58593
    willofiam
    Moderator
    • Topics Started: 75
    • Total Posts: 1437

    Chris, how about using the actual parts that will go on the staff for figuring these dimensions, for instance, after turning the balance seat where the balance will be riveted on, put the balance on the new part and scribe a mark to give the overall balance shoulder, take the balance off and turn to the hairspring collet size. as long as you have enough for a rivet. reading Frieds watch repairers manual he says “the shoulder should exceed the thickness of the balance arm by .10 to .15mm depending on the size of the balance.” As far as your question it looks like you can measure the thickness of the balance arms and add the .10-.15mm.
    From what I have been experiencing in learning to make a balance staff a new one could be fashioned without any measurements and just by “fitting” to the parts of the watch. The cool thing is if you mess it up you get to start over, how fun is that!!!!! :D Now remember I am a greenhorn in making these so please look for expert advice…….Oh and by the way, now you can dig up one of those coffee cans and justify getting a optical comparator, bench mic, and several other expensive items 😆 becoming efficient in making staffs has been on my mind lately, thanks for the thread. William

    #58594
    Bob Tascione
    Moderator
    • Topics Started: 38
    • Total Posts: 1552

    Hey Chris,
    Yes an optical comparator would be real nice but sometimes Mucho Dinero!
    Another easy way is to make a few guages. You can go as simple as using different diameters of round stock rod to hold up against the shoulder you are measuring. By filing them in half you can get them right up against the shoulder. Under hi-mag this works very well. Also automotive feeler gauges work well for comparison measuring. You can also take some brass or steel plates and file them down to various thickness and drill different sized holes in them. Stamp the thickness on these plates and you have some valuable guages that work great.
    Hope this helps,
    Bob

    #58595
    willofiam
    Moderator
    • Topics Started: 75
    • Total Posts: 1437

    See, didnt even think of what Bob suggested, great ideas..thanks Bob….you know….sometimes I can make it much more complicated than it has to be 🙄 . William

    #58596
    Bob Tascione
    Moderator
    • Topics Started: 38
    • Total Posts: 1552

    :D Actually William,
    I rarely use gauges for measuring staffs. I do it exactly as you posted earlier! When making a new staff it’s much easier for me to use the movement and balance and roller for measuring and fitting. But if you have some staffs that you would like to get dimensions off of for categorizing then gauges are the way to go for me.
    Hasta la vista…
    Bob

    #58597
    arutha
    Participant
    • Topics Started: 85
    • Total Posts: 1536

    Daryn taught me to do it by eye, just hold the old staff up to the new bit of material and cut away ;)
    i found when I first started on cutting staffs i was spending more time measuring stuff than turning. it is amazing how accurate your vision is when it comes to comparing stuff!
    One other thing you will read a lot about is when you come to turn the balance staff round to keep it concentric it has to be then fitted into a wax chuck. If you have good collets and your tailstock lines up correctly you dont have to worry about a wax chuck, when you part off your piece of pivot steel (before you start turning the balance) just turn a cone down on each end. When you have turned the first half of the staff you can then turn it round, put it back in the collet and check it against the tailstock to see if it still lines up. some times it may take a bit of moving in the collet to get it straight and obviously make sure your collets are spotless!
    Paul.

    #58598
    Bob Tascione
    Moderator
    • Topics Started: 38
    • Total Posts: 1552

    Hi Paul,

    Daryn taught me to do it by eye, just hold the old staff up to the new bit of material and cut away

    Exactly. If you have the old staff it becomes the perfect comparison gauge for measuring lengths. It can also be rotated in the opposite direction and placed up against the stock in the collet to establish perfect collet shoulder and balance hub heights. Then for the missing pivot you can just fit it to the movement.

    Bob

    #58599
    david pierce
    Participant
    • Topics Started: 90
    • Total Posts: 1360

    Chris,
    You may be able to make use of the equipment you already have. Your milling machine can also be used as a coordinate measuring machine by chucking a fine point (sewing needle) into the spindle and fixturing the staff along the X axis. With the spindle off, as you move the needle to different positions on the staff (observing with magnification), record the measurements from a dial indicator or your digital readout. The best way to check the diameters is with a dial indicator fitted in a fixture with specialized tips which you can make from low cost standard tips. This is where the Unitron Staging Microscope really comes through. It can nail those measurements to about .0001 inches but you should be able to get good results (close enough for watch work) with the stuff your have.
    david

    #58600
    chris mabbott
    Participant
    • Topics Started: 119
    • Total Posts: 1525

    Hey guys,

    thanks for all the great suggestions and David, of course, I never thought of that but it makes perfect sense now you’ve mentioned it :)

    I hear & agree with what some of you are saying regarding shooting from the hip, or making a new staff by line of sight, the problem I’ve been facing and still am facing, is that some if not most of the parts books (if they exist at all) for Rockford, South Bend, are not accurate OR the staffs have been modified by someone. If they do have a description, it’s only of the part number..
    The other problem is that I’ve had a fair number of watches with NO staff, although luckily the hardware has been present, which leaves me scratching my head, not hair 😆

    The reason I want to make detailed diagrams is for the future so that I have my own source of info, so that if I, or anyone, should need these measurements, then I have them available.
    I would rather have the exact dimensions and make as close to an original part as possible while trying to avoid making one on “best guesstimate”, then fit it, adjust, fit it again, adjust etc etc.. That is a time consuming exercise that can be made a lot less painless by having a simple well measured drawing :)

    Thanks again gents..

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chris mabbottMeasurements