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Does anyone what what proceedures spring manuf. use to obtain spring rates?

Does anyone what what proceedures spring manuf. use to obtain spring rates?

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Old 01-06-2013, 06:38 PM
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Default Does anyone what what proceedures spring manuf. use to obtain spring rates?

I'm testing springs and while I'm somewhat close to their test results I'd like to know what technique is manufacturer approved or standardized (if any) for testing spring rates. As of now, I'm using my jig to test at each 1/2" and 1" compression 3 times averaging the results. To compensate for variances in spring height I start each spring at 1oz of preload and then subtract that from the final scale display.

IE, I put a spring in my jig, I set my fixture to 1 oz. of preload and then zero my caliper. I then will move my jig 1.000" down and record the measurement minus 1g. Then divide that by 16 to get lb/in. if at 1" compression. If at .500" I'll divide that by 8, etc. My results are very repeatable so I can at least compare all of my springs but I'm very curious as to the spring manufacturers test proceedures.

Do they measure at only 1", average rate through 2 points, 4 points, 18 points up to 1 inch, 2 inches? Until coil bind?

Any input is appreciated.
Dave
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Old 01-08-2013, 12:09 AM
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Anyone?
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Old 01-08-2013, 01:58 AM
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I think spring rates are calculated and not actually measured. The spring manufacturer probably does some actual rate testing as part of their QC process similar to what you are doing. But the actual rate is calculated by a formula of spring length, diameter, wire diameter, number of coils, and type of material used. A lot of springs are coated for corrosion resistance but that leads to inconsistencies in rate from batch to batch since the coating can be thicker on some than others which affects actual rate.

I've done some testing using the same method as you are and rarely see a result that matches either the calculated rate or the claimed rate from the manufacturer. Sometimes they are fairly close, other times off as much as .4 lb/in. So I don't know if the method is wrong or there is a large variation in springs.
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Old 01-08-2013, 04:40 AM
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Originally Posted by rcgod View Post
I've done some testing using the same method as you are and rarely see a result that matches either the calculated rate or the claimed rate from the manufacturer. Sometimes they are fairly close, other times off as much as .4 lb/in. So I don't know if the method is wrong or there is a large variation in springs.


I'm waiting for a RC/spring mfg to release "preset" and matched springs like they do in 1/10th on road. However, I doubt the general off road RC consumer is willing to pay $35+ on 2 springs. For now kyosho seems to have the most consistant nonmatched (that I know off) 1/8 buggy springs on the market.
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Old 01-09-2013, 12:17 PM
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Originally Posted by rcgod View Post
I think spring rates are calculated and not actually measured. The spring manufacturer probably does some actual rate testing as part of their QC process similar to what you are doing. But the actual rate is calculated by a formula of spring length, diameter, wire diameter, number of coils, and type of material used. A lot of springs are coated for corrosion resistance but that leads to inconsistencies in rate from batch to batch since the coating can be thicker on some than others which affects actual rate.

I've done some testing using the same method as you are and rarely see a result that matches either the calculated rate or the claimed rate from the manufacturer. Sometimes they are fairly close, other times off as much as .4 lb/in. So I don't know if the method is wrong or there is a large variation in springs.


I don't feel so bad now. This is exactly where I'm at. Even comparing my results to another person w/ the same spring are off (Kyosho X gear included). I do realize every spring testing jig will be different and rates will vary greatly so what i've been doing is testing the rate of every spring I can get my hands on and document it. This info is helpful for me but probably useless for anyone else. At least I'll know that if I want to go stiffer than my Xgear yellow I can go to an Avid (insert color here) despite what the advertised numbers may be.

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Old 01-09-2013, 12:44 PM
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Originally Posted by TT_Vert View Post
I don't feel so bad now. This is exactly where I'm at. Even comparing my results to another person w/ the same spring are off (Kyosho X gear included). I do realize every spring testing jig will be different and rates will vary greatly so what i've been doing is testing the rate of every spring I can get my hands on and document it. This info is helpful for me but probably useless for anyone else. At least I'll know that if I want to go stiffer than my Xgear yellow I can go to an Avid (insert color here) despite what the advertised numbers may be.

Dave
With the springs you have on hand, whats the repeatability/sampling been like between the same set of springs rates from "X" manufacturer. Also, you should do a test on new springs then retest them after so many hours of use to see how much fatigue/springset occurs.
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Old 01-09-2013, 12:49 PM
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Originally Posted by nv529 View Post
With the springs you have on hand, whats the repeatability/sampling been like between the same set of springs rates from "X" manufacturer. Also, you should do a test on new springs then retest them after so many hours of use to see how much fatigue/springset occurs.
Repeatability of one spring is =/- .01 lb/in. Testing between a pair of springs sold together was actualy =/- .2 lb/in if I recall. I'll have to double check this data though. I'll have my rc stuff back from the track tonight and can double check. I also got some RB5WC "kit" springs which I'm curious to test tonight or tomorrow. THey are pink front/red rear I think but people speculated that they were not xgear springs so we will see as I have some official pink xgear fronts to compare to, not that that seems to matter any.

I've not been able to test any new springs to make a comparison new vs. used spring rates unfortunately.

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Old 01-09-2013, 03:09 PM
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Originally Posted by nv529 View Post
I'm waiting for a RC/spring mfg to release "preset" and matched springs like they do in 1/10th on road. However, I doubt the general off road RC consumer is willing to pay $35+ on 2 springs. For now kyosho seems to have the most consistant nonmatched (that I know off) 1/8 buggy springs on the market.
Avid does, but i'm not sure how they measure it. My guess is that they plot load versus deflection and fit a line to the data. The line is the rate in lb/in.
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Old 01-10-2013, 11:48 AM
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not sure I follow you completely.
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Old 01-14-2013, 08:27 AM
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Figured I'd update this. I spoke with Avid and they've been very forthcoming w/ information. It appears you were on to something w/ the averages. This is what they've told me thus far.

AVID springs are the closest to the label on the package in the industry. Gil Losi Jr. said he runs AVID springs because they check out the same as the label!

We have a Chatillon Spring test machine. We pre-load the springs and check them at several steps up to 1 inch for rears. The rates on the package is the average rate for our sample set.
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Old 01-14-2013, 08:34 AM
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Originally Posted by TT_Vert View Post
Figured I'd update this. I spoke with Avid and they've been very forthcoming w/ information. It appears you were on to something w/ the averages. This is what they've told me thus far.
Is that what you were getting when you did the tests on my avids?
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Old 01-14-2013, 08:58 AM
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I didn't average your results but that would make my results very similar to their rates. I want to test all your avids agian next time you are at the track. I'm trying to find out what deflections they are checking at so I can directly compare my Xgear to them. I need some stiffer front and rear springs.

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