Originally Posted by
DaveW
Maybe i should state it THIS way.
1)The thinner the wire size, the larger the ID of a linear compression spring should be, for it to be able to do its job effectively and stay on axis. It still isnt a progressive rate spring though... the value of the spring stays constant.
2)Im sure this is difficult when you are trying to mass produce a product for the market, and sourcing good but reasonably priced materials to get the job done.
3)Theres a reason AE springs have been on the 'chopping block' for years. You could pull 5 of the same color and would be lucky if any of them were close in a simple hand compression test... much less a metered compression test. Are you telling me this is a fault of the wire material consistency, the wire coil, or AE's math... ? If it is as complicated as you make it out to be, then AE's springs should be on the money and EVERYONE should be scooping them up.
Dont get me wrong... ive been die hard AE since the first day i first dropped an RC car on the track. BUT when i got into TC and started having to compare variations in products for consistent repeatable handling... AE springs went in the trash.
1) Not exactly, if you make the wire diameter thinner, then you have decreased the spring rate. Then if you also make the diameter larger, then you will have further decreased the spring rate for a given number of coils. If by "staying on axis" you are refering to buckling, then the wire diameter does not effect this. But the increase in coil diameter does reduce its tendancy to buckle, since the buckling calculation is a function of the spring free length divided by the coil diameter. If this number is greater than 4 then it is safe to say that it will not buckle during its travel. If this ratio is less than 4 then it will have a tendancy to buckle, and given two springs of equal free length and coil diameter, the one with a higher spring rate will buckle with even greater force making it even harder to collapse axially.
2) Yes, having a good spring manufacturer is very important because a spring can obviously be designed for an exact spring rate, yet manufacturing tolerances will make that difficult to achieve consistantly, especially since some of the parameters can be so sensitive!
3) I think that it is tougher to get the same tolerances on a more slender spring that has a smaller wire diameter, especially when it is close in number of coils to a big bore spring for a couple of reasons.
1) The total length of wire on the slender spring is less! This then makes all of the other geometric parameters of the spring even more important that they have good tolerances because you have less material that you are working with that needs to absorb the same energy.
2) Given a certain diameter tolerance that a spring manufacturer can achieve say .05". Now lets say you have two springs, and one has a larger diameter (say .5" and .625"). The spring with the smaller diameter will be more greatly influenced by this .05" tolerance because it is a greater percentage of the diameter and results in a greater variance in spring rate (10% for .5" and 8% for .625, in this case)
3) The number of coils is another and the toleranceson that .
A couple other factors might be how straight the spring is wound, the length, and powder coating.
All these factors are what introduce all of this spring rate inconsistancy. I think a BB spring is inherently better because it does have more wire length for an equivalent spring rate as well as a larger diameter wire, and this helps reduce the stress in the spring when compresed and overall is just better spring design. I am sure they guys at AE have done their math right, there are a lot of pretty sharp guys over there with lots of experience. But it ultimately comes down to the manufacturers tolerances and cost. Kyosho is able to get very fine spring increments with minimal tolerance overlap and variance...but you pay for it!