Need help with non automotive compression spring

Tradarcher

Well-Known Member
Joined
Mar 20, 2005
Location
Creedmoor, NC
Here's my dilemma. I have a high dollar video tripod head that has a compression spring in it that is interchangeable depending on the weight of the camera. Right now it has what I believe is the heaviest spring they make for 20+ pound cameras. I'll never find a lighter spring (i've tried) so I will have to make one. The image below shows the dimensions. It looks similar to a harley fork spring. I lowered a harley front end once and cut off about an inch but I must have thrown what I cut off away so I can't compare it. I am wondering where I might look to get another spring with a lower rate even if it is too long. I can shorten it if necessary.
 

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So if the spring wire is 0.22 inches, am I correct in assuming that it's a pretty heavy rate spring if it's made of steel? You need some calipers, an arbor press, and a bathroom scale to take some crude spring rate measurements.
 
zuke said:
Acxess Spring has an online calculator to figure out that one's cmpression rate, Then you can use that info to order a lighter one...

Compression Spring Calculator Instructions - Quality Spring, Affordable Prices


(I Came up with .890 when I put in your figures, but not sure how to figure out what material that thing is actually made of...)
Click to expand...

That's what I got but if I understand spring rate that means it would only take .890lbs to compress this spring 1 inch. There is no way this spring is that light. IMO it would take more that 100lbs to compress it.
 
Not sure what I might have done wrong the first time, I know I counted the coils wrong (Should have been just 2 active coils, I'd put in 4) But I ran it again and got these figures;



Rates & Loads
Spring Rate (or Spring constant), k : 2,469.043 Lbs/In
True Maximum Load, True Fmax : 302.278 lbF
Maximum Load Considering Solid Height, Solid Height Fmax : 302.278 lbF
 
zuke said:
Not sure what I might have done wrong the first time, I know I counted the coils wrong (Should have been just 2 active coils, I'd put in 4) But I ran it again and got these figures;



Rates & Loads
Spring Rate (or Spring constant), k : 2,469.043 Lbs/In
True Maximum Load, True Fmax : 302.278 lbF
Maximum Load Considering Solid Height, Solid Height Fmax : 302.278 lbF
Click to expand...

Yeah when you put in 4 coils it gives you a warning saying that the numbers aren't possible. That's more like it. Minimum order $69 :(
 
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You can kind of ballpark it with the geometry of the camera mount. There will be a distance between the pivot and the estimated CG height of the camera, and a distance between the pivot and the spring centerline. The forces will likely be roughly equal at maybe half of the compression of the spring, (if I'm understanding how the mount works), so there will be spring travel in both directions with the camera is balanced.

That should be a good starting point, based on some measurements you can take directly from the camera mount thingy...
 
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You need someone with a valve spring compression tester .I have a RIMAC one but an pretty far from ya . Might could find someone in your area with one.
 
Tradarcher said:
av4you.com - Tension Spring

Found a replacement spring. $55 :eek:
Click to expand...


Wait...is this $55 option the right size that you want to end up with?


I mean lets be fair, best case scenario you spend a couple hours, find an alternate spring, for $20...then spend another hour modifying it to fit, hoping you dont ruin the $20 spring.

In the end you have risk and 3 hours of work for $35, tops.
As long as you make $10/hr just work 2 hours of overtime and buy the right tool for the job and enjoy your extra hour of life.

(Yes I am an asshole)
 
Ron said:
Wait...is this $55 option the right size that you want to end up with?


I mean lets be fair, best case scenario you spend a couple hours, find an alternate spring, for $20...then spend another hour modifying it to fit, hoping you dont ruin the $20 spring.

In the end you have risk and 3 hours of work for $35, tops.
As long as you make $10/hr just work 2 hours of overtime and buy the right tool for the job and enjoy your extra hour of life.

(Yes I am an asshole)
Click to expand...

That is too sensible. I forgot to add that I could probably sell the one that is currently in it for at least $50.
 
I thought this might be a little easier. I actually walked into the hardware store and they had a good selection of compression springs but not quite what I was looking for. I was hoping I would be able to locate a place to drop in and go through a bunch of bins and get what I need like Wilders or something. I remounted the spring and didn't put as much preload on it and it is a little better. The tripod has some age but is top of the line and still has some value and use. Cameras have come down in size and weight so a hd counterbalance spring is not necessary for a mobile tripod that would probably be supporting a dslr.
 
Could you add some ballast, like a steel plate under the camera?
 
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