Machining fusee Links

Discussion in 'Horological Tools' started by Jerry Kieffer, Mar 31, 2013.

  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  1. Jerry Kieffer

    Jerry Kieffer Registered User
    NAWCC Member

    May 31, 2005
    2,424
    232
    63
    Male
    wisconsin
    Country Flag:
    #1 Jerry Kieffer, Mar 31, 2013
    Last edited: Mar 31, 2013
    One of my current projects requires a tiny roller chain that is only a tiny fraction of what is available commercially. I started out making Stamping Dies for the dog bone links, but scale link thickness and available material did not produce the results desired.
    I have now decided to machine the links as I have done in the past when I needed Fusee links and even a complete chain.
    I hope this will be of interest to some since it was easy to take photos while setup.

    In most cases, now and in the past, Fusee links for chain construction have been stamped. There are of course some early chains that were filed. However, if one needs a few links for repair or possibly enough for a single specific size chain, constructing dies and filing may not be the most attractive option especially making dies for only a couple of links.

    Personally, I have found that machining dog bone links is a very easy, fast and highly accurate method that almost instantly adapts to any size of link required.

    My personal method is as follows.

    (1) I first center mount a rotary table to the Mill spindle in the horizontal position as shown in the first attached photo.

    (2) Next, stock just large enough to allow construction of the link is mounted vertical in the rotary table and two holes are drilled in the stock. These holes are of proper size and spacing for the link to be machined and drilled deep enough to allow 4-5 link blanks to be parted off. This procedure can be seen in the second attached photo.

    (3) From this point, the stock is removed from the rotary table and placed in the Lathe. Once in the lathe, round link blanks of the proper thickness are parted off. Per the third attached photo.

    (4) Next a larger piece of stock is mounted vertical in the rotary table per the fourth attached photo. Then a Endmill is set about .150" deep and most metal is machined away by rotating the table until what is left is about twice the diameter of the link blank as seen in the photo. From this point two identical spaced holes to the blanks are drilled in the machined raised section and two pointed pins were installed. Then the link blank is placed over the pins. With the endmill centered to the pin holes, it is brought up to the blank and set at a depth that will generate the proper radius of the dog bone link. In this case, the blank was rotated 115 degrees in one direction and then 115 in the other direction machining half the link. The link is then flipped over on the pins and the process is repeated to complete the link. The half cut link in the photo was raised on the pins so it can be seen.
    The rotation distance and endmill size determines the valley shape in the center of the link.

    (5) The fifth photo providing they come out in order, shows a completed link that is sized somewhere between a watch and clock size fusee link. It was machined in the setup shown.

    Initial setup of center mounting the rotary table and finding suitable pin material took about 15 minutes. The actual drilling, parting and machining takes about 7-10 minutes from start to finish. In most cases I am machining at least 4 links at a time on the pins. So in that case, each link takes about 2 minutes give or take when 4 are machined at the same time. Watch links are done in the exact same manner by simply using smaller tooling as required and optics on the same equipment and setup.

    Jerry Kieffer
     

    Attached Files:

  2. D Magner

    D Magner Registered User
    NAWCC Member

    Dec 27, 2004
    382
    30
    28
    Male
    Georgia
    Country Flag:
    Region Flag:
    Hi Jerry,
    Very Neat. Thanks for posting procedure with pictures.
    Do you use a "spacer bar" behind the saddle of the mill? Is it just to help stabilize the table? Do you "bump" up against the rod , then lock the bed and indicate the rotary table while tightening the clamps for the rotary table?
    David
     
  3. Jerry Kieffer

    Jerry Kieffer Registered User
    NAWCC Member

    May 31, 2005
    2,424
    232
    63
    Male
    wisconsin
    Country Flag:
    David
    Thanks for pointing out the rod behind the "Y" axis. Actually it is not used for this procedure. I use it to quickly bump position the Mill bed to the center of the spindle when installing accessories and re-finding center as you surmised. It is left in position when the mill is not in use so it is handy and I forgot to remove it for the photo.

    Jerry Kieffer
     
  4. wefalck

    wefalck Registered User

    Mar 29, 2011
    453
    18
    18
    Male
    Paris
    Country Flag:
    Actually, I would have jumped step (3) and milled the stock to shape right away, before parting off. What is the advantage of first producing circular blanks ?

    wefalck
     
  5. Jerry Kieffer

    Jerry Kieffer Registered User
    NAWCC Member

    May 31, 2005
    2,424
    232
    63
    Male
    wisconsin
    Country Flag:
    Wefalck

    Thanks for the suggestion


    While it is possible to do what you are suggesting, it adds additional levels of complication and setup along with greater potential for inaccuracy.
    Or at least the way I had done it.

    As currently setup, One hole of the link is centered to the rotary table. This allows the link to be rotated providing the correct ark and ark distance required to complete half the link. To machine the second half of the link, one would have to reposition the stock on the rotary table so that the second hole was
    center to the R/T rotation. In addition, the two link holes would need to be positioned parallel to the Mill "Y" axis or the forming ark distance would need to be recalculated in order to properly blend the outer arks. Flipping the link disc blanks on the pins was a simple easy and highly accurate method of eliminating this issue.

    One way of doing what you are suggesting would be to add an additional off set indexer on top of the rotary table. Once one side of the link was machined with the R/T movement, the stock was then rotated 180 degrees in the indexer and the other half is machined with the R/T. I have tried this method, but have found the method described in the first post to be more accurate and efficient. One issue can be the size of endmill required for forming the link. If small, you may only be able to machine deep enough to part off 2-3 links including parting space that is not an issue when parting discs from round stock. Added complication always seems to cause issues.


    Jerry Kieffer
     
  6. wefalck

    wefalck Registered User

    Mar 29, 2011
    453
    18
    18
    Male
    Paris
    Country Flag:
    Jerry,

    I had missed that you flip over the link after milling the first half. Good point.

    On a CNC-mill, repeatability would not be an issue, but on a manual mill your procedure makes all sense.

    wefalck
     
  7. Jerry Kieffer

    Jerry Kieffer Registered User
    NAWCC Member

    May 31, 2005
    2,424
    232
    63
    Male
    wisconsin
    Country Flag:
    Wefalck
    CNC would be an ideal method of doing this, however it would need to be equipped with automated change tooling to save time over manual. In addition, the system woulds have to be delicate and accurate enough to handle micro tooling when making watch size links. Unfortunately, In most cases, the cost of CNC equipment accurate enough for watch work far exceeds what is practical in a small repair shop.

    Jerry Kieffer
     

Share This Page