Suspension spring specs?

MuseChaser

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Feb 5, 2019
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Thank you for tuning in to this week's episode of, "Musechaser's Stupid Questions!".....

When looking up and ordering supsension springs, I took the number, i.e., .0036" for most standart Kerns, .004" for Schatz 49s, .0023" for 53s, etc., to reference the thickness of the spring. .004" is approximately 0.1mm.

The springs have three measurements...length which is obvious and we cut them to fit, width which is next largest dimension measured across the flat surface of the spring, and thickness which is ...what it sounds like....the thickness of the metal itself, or gauge, if you will.

Going strickly by memory, the thicker springs seem to be not only thicker, but also wider, than the thinner springs, i.e, a .0023" spring appears to be narrower, in addition to being thinner, tha a .0036". Is that true? My most precise measuring device, other than a pair of very used Mark V Eyeballs, is a 12" ruler also marked in mm...which obviously isn't up to the task.

If it IS true, would not the width of the spring have just as much, if not more, to do with its torsional strength as its thickness? I ask because recently I installed a .004" spare spring I had on a clock that needed a .0036", which I didn't have on hand. Figured it would give me some hands-on experience seeing the effects of a too-thick spring, and also allow me to try thinning a spring which I hadn't done previously. Having read the cautions about thinning only taking two or three "swipes," I proceeded gently at first. In reality, using 600 grit wet/dry paper, it took almost 30 increasingly strong swipes along the entire length of the spring to achieve enough thinning to get the pendulum speed in range to keep good time. I was thinning the thickness, and not narrowing the width...can't see how you could narrower the width without seriously buggering up the spring.

Comments and thoughts appreciated. Thanks for tuning in. On next week's episode of "Musechaser's Stupid Questions," we'll be discussing "Epoxy....why isn't it a good long term lubricant?"
 

KurtinSA

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I've never paid attention to spring width nor have I even tried to measure it...haven't figured out a way to do that. Having always ordered spring from the Horolovar Store, I just accept that they will be right. I actually thought that the widths were all the same and that the thickness is what varied. The overall cross section is what contributes to the torsional rigidity, so both dimensions play a role in that. I seem to recall John Hubby mentioning that the Terwilliger designed springs...which is what I thought the Horolovar Store springs are...are not square in cross-section. He said that the corners are slightly rounded to help keep them from cracking due to the sharp edge.

In my brief conversation with Chris Nimon years ago, he said that he has numerous dies that he pulled the source material through to create the dimension needed. I don't think he has a "hot steel mill" to pull molten steel, so he must take rolls of something that is close and use the die to cut the base material down to size...I'm guessing here. As part of this process, he said he would take a sample of cut springs for say, 0.004", and set them up in a test machine to see if it oscillated the proper amount with a specific weight. If it did, then the batch was considered ready for packaging.

In terms of thinning, I too have used 600 grit sand paper and it does seem to take a lot of swipes to make a change in the spring. I leave the bottom block on and slide from the bottom all the way off the other part of the spring. The most important part of the thickness is going to be that between the fork and the top block. John cautions about having uneven pressure with the fingertips which I guess I can understand. At one point, I glued the sand paper to popsicle sticks and taped one end of them together...that way I could sandwich the sticks together to create more uniform pressure. But the sand paper gives up too quickly and I figured I'd be regluing new paper over and over. So I just use my fingers. But I thin for a number of strokes, rehang my suspension unit (top and bottom block only) and check how long it takes for 8 beats. That way I can sneak up on the dimension I need.

Kurt
 
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Wayne A

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Just checked a few Horolovar suspension spring sizes with a micrometer and they all are as close as I can measure .0165" wide. Not real easy to measure these but had read that they are uniform in width and its a method to identiy the Horolovar brand. Also they start out as the proper size wire for each spring size and are cold rolled to thickness which leaves the rounded edges.

Sanding to size I always use Popsicle sticks with the paper glued on, 320 and 1000. Using fingers alone its posible to introduce a curve in the spring from un even pressure.
 
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shutterbug

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There are two metals used in suspension springs. The genuine Horolovar springs are the only ones you can use with the 400 Day book. The others (Nylor?) are wider, and you find them on most of the complete units sold now, except by Horolovar themselves - if they are going to stay in business since the owner's death recently. They don't work as assembled because they take into account the thickness but not the width.
 

MuseChaser

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Thanks for the kind, informative replies! I've ordered packs of springs from Timesavers on two occasions so far, in various sizes ranging from .0023" for some of my mini and midgest clocks, through .003, .0032, .0036, and .004. The listings for all of these describes them as Horolovar products and shows the exoected red cardboard Horolavar holder encased in plastic. However, the .004" springs, unlike the other sizes, arrive placed by hand in a white corrugated plastic holder wrapped and taped in a plastic bag. This has happened on two occasions. They work fine, but sure appear wider than the .0023" springs in Horolovar packaging. Can anyone confirm that these "unmarked" springs are still Horolvars? Anywah to tell visualIy? 'll see if I can remember to snap a side by side pic later today.
 

shutterbug

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I believe they have a more golden color.
 

shutterbug

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That's what my memory says. I'm not sure I can always trust it though :D
 

MuseChaser

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I snapped a pic of three pieces under magnification. Left to right ... Horolovar .0023", Horolovar .004", non-Horolovar .004" (Nylor? Bronze? Don't know). Looks like you all were correct and my mind was playing tricks on me..the width looks pretty constant between the two Horolovars.

IMG_20210301_173750231_1.jpg
 

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