# Thread: Any Mechanical Engineers on this site?

1. ## Any Mechanical Engineers on this site?

Loads of people moan about the trigger pull on the X Bolt. I have managed to get my hands on a new spring but need some assistance to specify a lighter spring.

Any help appreciated.

2. These guys may be able to help. They sell A-Bolt springs.
Wolff Gunsprings - Firearm Springs for Semi-Auto Pistols, Revolvers, Rifles, & Shotguns
~Muir

3. The expression linking the force applied to a spring (F) and the amount the spring extends/compresses (x) is usually:

F = kx where k is the spring constant

k effectively defines the stiffness and could be specified as N/m, lbs/inch etc.

To be useful though you'd need to be able to calculate k for your existing spring if not already known.

Alex

4. Well it looks like you just beat me to it Alex thats just what I was ging to tell him ??

5. Sure I've seen that formula on 'T' shirts somewhere's

6. Originally Posted by csl
The expression linking the force applied to a spring (F) and the amount the spring extends/compresses (x) is usually:

F = kx where k is the spring constant

k effectively defines the stiffness and could be specified as N/m, lbs/inch etc.

To be useful though you'd need to be able to calculate k for your existing spring if not already known.

Alex

Um, yeah, like whatever.
I was more going along the lines of; I have the dimensions of the current spring and if I change the thickness of the spring then how much difference is it likely to make if I was to change it by say .1 of a mm.

7. most springs you buy for a specific application will have a known "spring rate".
if the coil length (bit like twist rate in barrels) is constant from one to the other then a finer wire will obviously reduce spring rate.

unless someone is selling a specific kit for your rifle it would be difficult to measure accurately other than by the wet finger in the air approach.

TBH in applications this small with any adjustability in the trigger already I would just "suck it and see".
fit a finer, lighter spring and try it out.

8. For the replacement spring to work, the outer dimensions will need to be about the same so that it will fit the same, the diameter will need to be the same, the free length must be enough so that it doesn't totally go limp in use, but not too long that it totally compresses.

You be able to find a spring that is similar enough to your current spring, just wound with lighter gauge wire, if it's a bit too long, you can truncate it with some cutters.

9. Originally Posted by csl
The expression linking the force applied to a spring (F) and the amount the spring extends/compresses (x) is usually:

F = kx where k is the spring constant

k effectively defines the stiffness and could be specified as N/m, lbs/inch etc.

To be useful though you'd need to be able to calculate k for your existing spring if not already known.

Alex
Are you telling me they sent you home while you are delirious

10. I did a quick search and found this:
http://www.leespring.co.uk/pdf/compguide.pdf

It explains in more detail about the dimensions, I doubt you'll need to worry about the internal diameter. The 'spring rate' is what Alex was talking about, you need to find one which is less that what you've currently got, though I doubt very much that you'll be able to measure your current spring very easily, though you might be able to measure the diameter of the wire which should get you close.

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