View Full Version : Spring weight tester???

June 11, 2009, 08:04 PM
Is there a tester, sort of like a trigger pull test, to see what your spring weights are. so that you know what weight replacement springs to order.

I wasn't sure what to call it.

June 11, 2009, 10:10 PM
Solid Height

Solid Height = (Number of
Coils – 0.25) x
Wire Diameter

For example, for a spring with 14 coils and a wire diameter of 0.5”, the Solid Height would be calculated as follows:

Solid Height = (14 – 0.25) x 0.5
= 6.875


Rate = Load (lbs.) ÷
Deflection (in.)

For example, if a spring deflects by 2.75” under a load of 300 lbs, the Rate would be calculated as follows:

Rate = 300 ÷ 2.75
= 109

Deflection = Load (lbs) ÷ Rate

For example, a spring under a load of 300 lbs with a 109 Rate, the deflection would be calculated as follows:

Deflection = 300 ÷ 109
= 2.75


Load = Deflection x Rate

For example, a spring with a 109 Rate and a 2.75” deflection, the load would be calculated as follows:

Deflection = 2.75 x 109
= 300

Combined Spring Rate

This is used when two springs are stacked on top of each other.

Combined Spring Rate =
(Spring Rate 'A' x Spring rate 'B')
÷ (Spring Rate 'A'+Spring Rate 'B')

For example if the rate for spring 'A' is 200 and the rate for spring 'B' is 500, the combined rate is calculated as follows:

Combined Spring Rate =
(200x500) ÷ (200+500) = 143

Bill DeShivs
June 12, 2009, 01:37 AM
I'll make it easier.
It's called a scale.
You need different scales for compression and expansion springs. I believe Brownell's sells them.

June 12, 2009, 07:24 PM
Scale seemed wayto easy, I have looked at Brownells but could not find it. Now that I know what to call it I will look elswhere too. Thanks

That first response from Brewman is great information but made my head spin reading it :D

June 12, 2009, 08:37 PM
How precise are you talking(that is like how much money do you want to spend)?

I might spell it wrong,but there is an outfit named Chatillion that makes such gages for QC purposes.

However,you might look at scales to weigh fish.

extension springs,obviously you pull on,but to compress

Suppose you drilled a hole in a board.put a long eyebolt or the equivalent through the hole,thread on the spring,then put a fender washer and nut on it.Hook the fish scale to it and pull.Now,there are many ways you could vary this,but it might get you thinking.
Heck,you could put the board horizontal,the spring on top,with a washer on top,something thru the spring and hang a bucket on it.Pour in water till you get whatever compression you want,and weigh the bucket.

Don't forget the tare weight of whatever you hang.

June 13, 2009, 07:01 AM
OK, maybe I should have posted the reason I am looking for one. How do you know what pund replacement springs to order for your semi auto guns?

I have a customized 1911 I purchased used (the smith that built it is dead can't ask him) I want to know what pound springs to order as replacents because what ever they are they work and I did not want to guess. So how do you guys order springs?

June 13, 2009, 07:46 AM
Springs are cheap enough to order a set in different pounds to find the one you need/want and works for your gun/loads.
Wolff Springs sells sets and individual springs for all sorts of guns and purposes.

Bill DeShivs
June 14, 2009, 01:06 PM
If the springs work, why would you replace them?

June 14, 2009, 08:10 PM
Springs do wear out so that is why there are replacements available.