building suspension spring blocks

Discussion in 'Electric Horology' started by DC Kelley, Jul 12, 2009.

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  1. DC Kelley

    DC Kelley Registered User

    Mar 16, 2006
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    This a rather odd question about how suspension spring blocks were mass produced and assembled.

    I am interested in building up a lifetime supply of the small suspension springs used in the Kundo electric. This is a simple block with four brass plates riveted top and bottom over the suspension spring metal with an alignment pin. In modest quantities (i.e just making one or two), one can just used a few brass taper pins and grind the resulting overhang flush with the brass plates.

    This seems very wasteful in terms of sanding operations for any sort of jig set up so I am wondering how the manufacturer would have done it. I don't mind developing a few custom tools to stamp the parts out and assemble them in a jig, but I don't see an effective way to deal with placing and holding four rivets that are each less then 3mm in length.
     
  2. shutterbug

    shutterbug Moderator
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    Oct 19, 2005
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    DC - jump over to the 400 day area. I'll bet someone over there can help you :)
     
  3. Steven Thornberry

    Steven Thornberry User Administrator
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    Jan 15, 2004
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    I have moved this thread to the 400-day area for better exposure.
     
  4. DC Kelley

    DC Kelley Registered User

    Mar 16, 2006
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    Please move the thread back. This is not a 400 day problem, it is for Kundo electrics which use a what some might call a French style short suspension spring with riveted brass blocks. But suspension construction of the type if relevant to many other clock types. [Almost all 400 day blocks are screwed in place because of the need to replace the wire at times, this type is typical bought from the normal sources ready-made and about .6" on a side]

    My question has to do with how to effectively use such small rivets. I have more or less convinced myself that the "rivet" is in fact 20 gauge soft bras wire, but drilling this hole and setting up the wire before a "smash and sand" operation does not seem effective. If I have a die and punch made up, perhaps it can also punch the 0.032" hole required.
     
  5. doug sinclair

    doug sinclair Registered User

    Aug 27, 2000
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    If this is a "ATO" type, battery powered Kundo with the arc-style pendulum, I would wonder why you don't buy the suspension spring you need, in quantity? Seems to me to make more sense than going to the expense and taking the time to make them. I realize this doesn't answer your question, but sometimes you have to ask a question in order to answer one.

    I have a strong suspicion that if you took a factory suspension spring apart, you'd likely find the steel suspension springs are actually one spring, stamped out to resemble two springs. this would substantially simplify the process of assembling these springs. You'd have to produce some kind of die to stamp a spring like that. Then you'd need a jig to hold the bits together, all in their correct position while the rivet holes are punched, and while the rivets are fitted. Not something I would try to do.

    If this is indeed an ATO clock, it should be in the ELECTRIC CLOCK MB.
     
  6. DC Kelley

    DC Kelley Registered User

    Mar 16, 2006
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    It is (ATO and Kundo used the same spring assembly)

    I have done this before (at $10~12 each) but as I need at least 50 of them for my own needs, and suspect I can run off a batch of several hundred for sale to others, the die route appeals to me. Invested some time on the drawings yesterday and found that: Raw costs for a 500 lot run came out to just under a dollar plus labor as long as I can punch these four holes. If I have to drill them then the cost of micro bits becomes the dominate factor. The die set (as you noted two are wanted, one for the brass, one for the steel) will run a few hundred. Considering the total investment it makes modest sense but I can not figure out the best way to do this sort for the rivets, hence the question if anyone knew how it was done in production.
     
  7. doug sinclair

    doug sinclair Registered User

    Aug 27, 2000
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    I suspect that the setup used by the manufacturer of these springs would be much more elaborate (read expensive) than would be practicable for a small run of even several hundred. I'm sure the manufacturer would have dies that could be re-set to produce a wide range of different suspension springs, thereby making the expense of the ddies practicable. The other consideration would be as regarding how you would market your production over and above your requirements. If you were in the market for 50 of these springs, you might find the price to be negotiable to the point where buying them would be the better option. However, if you look at making these springs as a source of pleasure, then hang the expense of setting up to produce them.
     
  8. Steven Thornberry

    Steven Thornberry User Administrator
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    Moved back. Sorry for the slip up.
     
  9. DC Kelley

    DC Kelley Registered User

    Mar 16, 2006
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    Many thanks, hope I get a reply with how these tiny rivets cans best be done. In the meantime, here is the working drawing I am using to bid the dies and which may be of some value to others if you need dimensions to build one of your own (as other have noted, just buy it unless your a real die hard).
     

    Attached Files:

  10. lifeisgud71

    lifeisgud71 Registered User

    Jul 30, 2008
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    I have been successful taking these springs apart (carefully) and using the top and bottom portions of the spring for the sides The brass portions snap together and have held quite well. I have 2 clocks that have been running for months with this repair.
     
  11. praezis

    praezis Registered User

    Feb 11, 2008
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    This steel spring only is available here in Germany for repair purpose exactly as lifeisgud71 described:

    98.jpg

    A remark to DCKelley's drawing: the total thickness of the assembled brass part must not exceed 0.85mm, original parts have a spring of 0,04..0.06mm (drawing: 2x 0.8mm and 0.07mm).
     

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