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Spring tester


orangeman711
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Built one similar to the commercial designs.   Tried the cheap electronic scale,  nope.

Went to a spring scale with a sliding max indicator.  Better.

Ended up machining a vertical compression tester that uses a electronic platform scale.

Mark on the rod at 1.625".     Not perfect, but it will repeat within 2 oz.

Amazing how far off some recoil springs are from the label.

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  • 2 weeks later...

When I get springs usually they are unequal length so its harder to test but within a half pound the difference is negligible to me behind the gun. I do however notice when 2 10lb springs are both brand new but one is shorter do to a different brand. Gun feels a little bit different at the beginning of the recoil impulse.

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On 8/14/2021 at 8:58 AM, open17 said:

Built one similar to the commercial designs.   Tried the cheap electronic scale,  nope.

Went to a spring scale with a sliding max indicator.  Better.

Ended up machining a vertical compression tester that uses a electronic platform scale.

Mark on the rod at 1.625".     Not perfect, but it will repeat within 2 oz.

Amazing how far off some recoil springs are from the label.

What spring scale did you use?

  I have a digital but it is too difficult to get a steady reading.

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built one this morning, stainless and aluminium, uses a digital trigger pull gauge  with a positive stop you can move, so you can check max and find the rates, anyway  it appears accurate to about +/-  1 oz on 15 tests.  first thing I learned is stick to well known springs and chuck the off brand in the bench box ....lmao  explains a .2 grain powder difference I had in cycling slides on 2 exact guns  springs measured 1 pound 1 oz different ( both marked the same from same vendor/brand)  anyway more stuff to check now 

Edited by Sinister4
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I strangely had exactly the opposite experience.  Wilsons (ISMI?) were consistent, but low.  Springco were 10% to 20% low.  Wolf was most consistent, always within <5% of the label.  It's frustrating because once you have a tester, you'll know what weight you want for a happy gun.  At that point, you just want a brand that delivers springs that test to spec.  If a brand (or your tester) was consistently a certain weight or percentage off, you could account for it.  For brands that are inconsistent, you just waste time and money.

 

$12 luggage scale from amazon, some plywood scraps, and misc hardware.  I verify the scale on occasion using calibration weights and some water jugs against a fairly reliable (to about 0.5 oz) postal scale.  Repeat tests on the same spring are always +/- 0.1 pound.

 

Guiderod is 1/4" because it matches the ID of the spring almost perfectly.  Threaded enough to hold a washer and nut on the end.  There's another washer in the end of the PVC (held there by the cap) to give the spring something flat/square/even to sit on at both ends.  I have marks on the side of the board to quickly measure the relaxed length of the spring...should be ~6.5" new.  Slots in the lower stop allow adjustment of compressed length for the jig.  Short piece of pipe is cut to exactly 1.625" and is used to set compressed length of the jig.  Using the jig I know I'm compressing to the same length every time, which is a step up over the handheld versions where you pull to a measurement mark.

 

I'd make a spacer for the difference between commander and govt compressed lengths if that was something I dealt with.

 

It's not my finest woodworking project, but it took the guesswork out of dealing with my 9mm guns (not feeding if springs get too weak) and 45 guns (fail to lockback if spring to stiff for whatever ammo.)  With a tester...at least you know what the spring is.  Makes random, unlabeled springs on your bench less or a problem.  With an ever changing collection of 1911s this was a game changer.

 

 

 

tester1.thumb.jpg.e5b07dff1147d3bc5accef41f37cd571.jpg

 

tester2.thumb.jpg.70914fa61ecbb84477df03808aec83d4.jpg

Edited by johnmyster
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Having an automotive background helps me too see other ways of doing things or having ideas.   Try this?   A valve spring tester.   It will give reading based on compressed length.   They are not as low cost or as portable, but give better readings.

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Part of the issue (or non issue) with springs with a shorter length can have a higher tension rate with the same compressed # reading.   The coils can be the same number (in a shorter spring), but less diameter giving the same compressed length.

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Lyman trigger pull gauge, cleaning rod with handle, screw and a couple washers.

 

Slip spring onto rod with a washer on each end 8/32 screw in the end of cleaning rod.

 

Pull rod between the jaws of my vise (using the trigger pull gauge) with the one washer on the end of the vise.

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