determining spring strength

[bad375]

How do you measure the strength(pounds) of a spring? Such as a recoil or magazine spring?




Thanks

 

[Chawbaccer]

Use a scale

 

[bad375]

ok I deserved that,

 

[Chawbaccer]

If you hook a spring to a scale and pull the spring, initially the spring will pull on the scale. After the spring stops pulling the scale and before the spring starts over expanding, you will have your weight of pull on the spring.

 

[krs]

People have constructed spring strength testers, even using rams , hydraulics, and pressure guagess to measure the amount of push before a spring begins to compress.

You might try googling with something like "spring rate tester" to see what pops up.

 

[HammerBite]

The weight of a spring is determined at its working length. So, in the case of a 16-pound recoil spring in a 1911, the spring exerts a force of 16 pounds when the slide is all the way to the rear.

Spring weight is best determined by a spring tester. Spring testers typically have a scale with which to pull or push on the spring and a frame to hold the spring, with a calibrated distance scale so that you know when the spring is at its intended working length.

The problem lies in knowing the working length in the gun under consideration. Gun springs tend to be located inside of guns, where they cannot be easily measured at working length! The working length can be determined by measurement of various physical features within the gun, but this is not usually a thing that is straightforward to do or casually done.

It would seem that you can determine the weight of a recoil spring by measuring the force required to draw the slide fully rearward, but you would have to keep in mind the drag on the slide from sources such as the hammer, disconnector and rails. You might be able to get a fair estimate for a loosely-fitted and well-lubricated (with light oil) gun if you first removed the hammer, disconnector and anything else that bears on the slide.

 

[bad375]

Thanks for the info guys

 

[Riss]

Other than testing its springiness as above, for two springs that are the same type you can use calipers to check the diameter of the wire. Assuming that the springs are the same material, and use, 1911 recoil spring calibration pack for example. If the springs have the same free length, same diameter, same number of coils (spacing), then the one with the thicker wire is stiffer.

 

[Jim Watson]

Layne Simpson did a chart of the WEIGHT of 1911 recoil springs as measured on a regular powder scale. More steel in the same size spring = more load. Can't mix conventional and "progressive", though.

 

[log man]

I find that measuring recoil springs and keeping a log is useful for keeping track and noting new weights at full recoil1.625" and battery 3.625" and checking after 5000 rounds. There are some surprises and tuning a spring can be enlightening. This is one of two that I've made for that purpose.

This is a 16# spring compressed to 1.625".



LOG

 

[krs]

Awesome, Log man. Above I was thinking of the gizmo that Hunter (I think it was) in M1911 devised, but he used a wooden frame and what looked like a common fishing scale. Someone else posted photos of their arrangement of a large lever, a yardstick, and a pressure guage.

There's a lot of ways to try to skin this cat, seems like.

 

[log man]

Exactly, the idea for me is to have total adjustment and hands free so I can bump both the spring and scale and get a repeat weight, the hand held are kinda painful and hard to maintain the pressure while reading it.

LOG

 

[bad375]

Thanks Log Man I feel totally inadequate now.
Seriously though the pics helped a lot, thanks