DIY spring rate test/calculation thing

[Gridgway]

I need to work out the spring rates of the springs on my radical (ssshhh).

 

Is there a way to do this with the stuff I have in the garage? DO I just find a really heavy weight to balance on the spring and measure the compression? They are not rising rate.

 

And what does a rate mean? Eg what compression does 170lbs mean? An inch, foot, mile?

 

Tks

Graham

PS the reader should assume I have a fairly normal set of tools n stuff in the garage, but excluding a spring rate compression tester gadget!

[philwaters]

A spring rate is the force required to compress the spring by 1", so 100lb spring will get shorter by 1" under a 100lb load - apply another 100lb (i.e. 200lb) and it will compress a further 1" = 2".... and so on.

 

Phil Waters

[Paul Richards]

Springs are normally measured over an inch. So for your 170lb spring it is the weight needed to compress the spring 1 inch.

You can make a primitive gauge using bathroom scales. Put the spring on. Rig up a ruler to indicate when the spring has been compressed an inch - Put appropriate weight on spring and read off the scales. Obviously in practice it's very difficult to accurately perform just using your body weight, especially if they are heavy (strong) springs. I suppose you could try to rig up some kind of frame and a lever to compress the spring or some sort of threaded system to compress the spring.

Rising rate - springs which normally get "stronger" the more they are compressed. e.g. to compress 1 inch may take 170 lbs and the next inch 250lbs etc. These springs are normally recognised by coils being closer together at one end than at the other - as per standard rear springs on many 7s.

Hope this helps.

 

Paul Richards

Area Representative - L.A.D.S. (Lancashire and District Sevens)

LADS Website

Growing old is compulsory - Growing up is optional

[Bricol]

Use a drill press - sit the scales on the base, with nice load spreading pas on top. Stick spring on pad. Wind table up / space scales off base so spring contacts chuck.

 

Place ruler on scales - note positon of top of spring. Ruler has to be on scales to measure your spring deflection only, not the scales deflection too.

 

Lean/pull on handle to pull the chuck down one inch on the ruler - read scale.

 

Et voila - one spring rate in ibs/in.

 

Bri

 

 

[Richard Price]

The spring rate can be calculated, if you can measure the wire diameter, the diameter of the coils, and count the number of active coils, with a calculator like the one on this page here

 

 

[Rob Walker]

The spring rate is normally engraved on one end face of each spring.

[Gridgway]

thanks all, put one 13st weight on the spring and measured approx 5/8th deflection. seems to be 300lb springs. One of the 4 had what looked like 300 engraved on it.

 

Graham