Do i need to scrag the main spring

[gingernut]

Knew a girl like that.

[Black Beard]

Your spring will slowly fatigue if you have overcompressed it so the metal exceeds about 0.5 of the yield . The more times and harder you do it, the more it fatigues and the sooner it fails. Go above yield and you will only get a few cycles until it fails (and since it is taking on a set, you have done this when scragging).

So scragging the spring will prevent the spring power from dropping a little as the spring beds in (but everything else loosens up and the power goes up anyway). It will take out any badly made springs. But it will also fail sooner. With modern springs, I wouldn't bother.

[vbull]

OK, so with modern springs it seems to me unnecessary but what about the original Webley MK3 spring I've just bought from Dave, scrag it or just put it in the gun and get on with it ?

[Benelli B76]

Knew a girl like that.

You lucky man, must have been the red hair.

[wonky donky]

I think you will find all quality springs are double scragged during manufacture.

My springs are made at the same factory as a leading UK Airgun Tuner uses using the same specification wire & process, but different dimensions. That's good enough for me.
I know of some springs in rifles tuned during the late 80's still giving the same power as the original tune, having had many thousands of cycles, with just piston & breech seals needing replacing every few years.

So to me you fit the spring, get the power level you want & forget it.

[TonyL]

Agreed.

I have quite a few Weihrauchs that were tuned by Dave and Ivan from the mid-eighties to early-nineties.

All maintaining power to this day.

Back at the June Springer Bash, I had UK Neil look over my Lazaglided HW80. Built in 1990/91. When he had checked it I asked him his thoughts; I was expecting, at the bare minimum, a quick re-fresh-re-lube.

Power, bang on. Nice and smooth.

"Leave it as it is!", was the verdict.

[Benelli B76]

If good springs are already double scragged during manufacture why are we discussing doing it again on this thread ? Seems to be an unnecessary requirement to repeat the process.

Baz

[MarcDV]

Rickenbacker has given the correct answer to the spring scragging question, i.e. buy good quality, modern springs . If you are replacing an OEM spring in a cheap weapon, expect a cheap spring and therefore one made with poor material, inconsistent heat treatment, sampling instead of 100% inspection quality control and inferior, straight carbon steel. You will not get sophisticated stabilized alloys for a low price. Modern, high quality springs are made with considerable science and knowledge. We have computer programs which can tell us everything there is to know about a spring, including how long it will last and accurately predict the rate of degradation. Airgun springs almost always fail due to lateral bucking. They operate under the extreme condition of being compressed to almost solid height which can put the torsional stresses in the steel close to the material yield point. Scragging will do absolutely nothing to prevent this condition. If you want the spring to last longer, do three things: 1) Reduce the pre-load. This will lower the torsional stress in the material. 2) Fit a thrust bearing under one end of the spring. This will lower the combined stress in the material. 3) Buy the best alloy steel spring you can find.

MarcDV.

[Benelli B76]

Marc, fitting a thrust bearing sounds like like a good idea. Will try to find correct size for my springer.

Baz