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Spring measurements?
Ray B
Member Posts: 11,822
In cleaning a used gun that I recently obtained I dismantle it to basic pieces, clean and reassemble. Problem is, when I put it back together I was missing a spring. I don't know if it wasn't in the gun or not, but it isn't there now. I am going to see if I can find a similar spring and I know what the outside diameter and length should be and brackets on acceptable wire diameter; but I don't know how springs are measured. Is the wire diameter measured in actual width or gauge? Is there a system for force needed to compress? etc??
Comments
Usually if you get the diameter of the spring and thickness of wire right you'll be close enough. To get closer still count the number of turns per inch. Wolff Springs will have what you need if you can describe it.
If you can find the firearm at Gunparts.com (Numerich) then you may find an exploded diagram or even the part you need sometimes.
The coil spring kit from Brownells is handy.
http://www.brownells.com/gunsmith-tools-supplies/small-hardware/bulk-spring-kits/no-71-compression-gun-springs-prod26216.aspx
In cleaning a used gun that I recently obtained I dismantle it to basic pieces, clean and reassemble. Problem is, when I put it back together I was missing a spring. I don't know if it wasn't in the gun or not, but it isn't there now. I am going to see if I can find a similar spring and I know what the outside diameter and length should be and brackets on acceptable wire diameter; but I don't know how springs are measured. Is the wire diameter measured in actual width or gauge? Is there a system for force needed to compress? etc??
Answering this backwards, in a case like this the best thing to do is usually just to get a replacement for the specific spring in question. Assuming the gun isn't too obscure, this is usually possible and not terribly expensive. Sounds like you've done this already, sort of mooting the rest of the question.
On the first part, springs are assigned a "K" value, which represents the amount of force necessary to compress them a given distance. As mentioned above, Hooke's law is the physical law that describes this relationship mathematically.
It might help standardize things if they were, but in practice, I don't think most springs used in guns are actually described this way. Pistol (eg 1911) recoil springs sometimes are, as one example, but the hammer springs aren't. Wire gauge/thickness and number of coils/inch, along with dimensions seem to be more common ways of measuring/communicating these things.
Anyway, as mentioned above, if you can match the external dimensions, approximate wire thickness, and number of coils, that's probably good enough for most applications.
Also, if a spring is too weak, there usually isn't much you can do, except maybe try to cram in a longer one or find a stiffer one. But if an individual spring is too stiff, there are certain tricks one can use to "tune" it. For example, you can cut off individual coils, or even in some cases thin the outside of the the spring metal on a belt grinder to reduce its "K".