PDA

View Full Version : Why Make A Spring Like This?



john hobdeclipe
01-16-2013, 07:10 PM
What would be the reason for making a coil spring like the one in the pic, made up of multiple strands wound together, then wound into a coil? This one is about 1-1/8" OD and about 12" long.

http://www.auldooly.com/imagehost/P1160080-13.jpg

Mike Burdick
01-16-2013, 07:44 PM
One advantage is that multi-strand springs will remain functional even when one or more of the strands break.

One disadvantage is the strands may rub together causing a shorter life span.

.

glenj
01-16-2013, 07:56 PM
The spring above will have some degree of built in damping from the wire to wire friction. Wear will decrease life as mentioned.

A.K. Boomer
01-16-2013, 08:52 PM
That is crazy, unless is ornamental? or it's ornamental and still needs to be somewhat functional...

Toolguy
01-16-2013, 09:03 PM
That type of spring is more resilient. It can extend and compress further than an equivalent single wire. It is also less likely to break. Several semi auto pistols have springs like that for the recoil spring that operates the slide. There is little to no wear from the individual strands rubbing on each other.

Bob Fisher
01-16-2013, 09:24 PM
Makes sound engineering sense, the smaller wire dia is less stressed at an equal deformation, but does not have much force. Multiple strands will increase the output but without the higher stress that a larger wire would incur. I have no experience with the inter coil friction or life. Very interesting, nonetheless. Bob.

A.K. Boomer
01-16-2013, 10:32 PM
That's amazing TG, never seen one,,, it's very cool looking for what it's worth,

in a related subject my high performance brake and shift cables that I use on my bike pull there stranded cable through a die that crunches down all the external rounded area of the individual strands - the results are they slide as friction free as a single large strand in the sheathing yet still adapt to bends and curves just fine - if you take the individual strands apart they are not round internally either - they all get formed together inside as well giving great surface area to rub on and hold oil,
don't think it would work with radical bends like a spring though and would ruin the torsion bar effect that all wound coils need to function properly...

flylo
01-16-2013, 11:16 PM
The main springs in AKs are somewhat wound like that & claimed to be very reliable.

Mike Burdick
01-16-2013, 11:29 PM
A couple of things I noticed about the spring pictured...

The strands are "woven" together. If they weren't, the strands would "separate" when the spring was in compression.

Another advantage I see is that one could very easily make a "variable" spring simply by adding additional strands along its length.

All in all, the idea is a clever one!

duckman
01-16-2013, 11:47 PM
I have seen these in isolation mounts.

dfw5914
01-17-2013, 12:07 AM
Damping effect would probably be the main reason for the multi strand design.

chipmaker4130
01-17-2013, 01:07 AM
A couple of things I noticed about the spring pictured...

The strands are "woven" together. . . .

Mike, all I can see is a simple twist. What am I missing?

A.K. Boomer
01-17-2013, 01:50 AM
Damping effect would probably be the main reason for the multi strand design.

Could very well be - that's a darned good point - possibly keep things from being hammered back to fast the other way and wearing out stops and such...

oldtiffie
01-17-2013, 01:55 AM
http://www.google.com.au/#hl=en&sugexp=les%3B&gs_rn=1&gs_ri=hp&cp=24&gs_id=2o&xhr=t&q=multi-strand+coil+spring&es_nrs=true&pf=p&tbo=d&output=search&sclient=psy-ab&rlz=1R2IRFC_enAU360&oq=multi-strand+coil+spring&gs_l=&pbx=1&bav=on.2,or.r_gc.r_pw.r_qf.&bvm=bv.41018144,d.dGY&fp=9ec91d6d9ae929f&biw=1280&bih=545

Wirecutter
01-17-2013, 12:17 PM
That looks a lot like the slide return spring from a Sig P226 9mm or .22 cal.

Jaakko Fagerlund
01-17-2013, 12:35 PM
http://www.google.com.au/#hl=en&sugexp=les%3B&gs_rn=1&gs_ri=hp&cp=24&gs_id=2o&xhr=t&q=multi-strand+coil+spring&es_nrs=true&pf=p&tbo=d&output=search&sclient=psy-ab&rlz=1R2IRFC_enAU360&oq=multi-strand+coil+spring&gs_l=&pbx=1&bav=on.2,or.r_gc.r_pw.r_qf.&bvm=bv.41018144,d.dGY&fp=9ec91d6d9ae929f&biw=1280&bih=545
You forgot this: http://en.wikipedia.org/wiki/Spring_%28device%29

Black_Moons
01-17-2013, 01:00 PM
http://www.google.com.au/#hl=en&sugexp=les%3B&gs_rn=1&gs_ri=hp&cp=24&gs_id=2o&xhr=t&q=multi-strand+coil+spring&es_nrs=true&pf=p&tbo=d&output=search&sclient=psy-ab&rlz=1R2IRFC_enAU360&oq=multi-strand+coil+spring&gs_l=&pbx=1&bav=on.2,or.r_gc.r_pw.r_qf.&bvm=bv.41018144,d.dGY&fp=9ec91d6d9ae929f&biw=1280&bih=545

Omg, What is this google thing! I have never seen it before and had no idea how to use it! </sarcasm>

A.K. Boomer
01-17-2013, 01:32 PM
That looks a lot like the slide return spring from a Sig P226 9mm or .22 cal.

yeah but did you see the o.d.?

ikdor
01-17-2013, 02:33 PM
Omg, What is this google thing! I have never seen it before and had no idea how to use it! </sarcasm>

Well, at least he didn't add a link explaining every English word having more than two syllables.
http://en.wikipedia.org/wiki/Explain
http://en.wikipedia.org/wiki/Syllable

:rolleyes:
Igor
(sorry, I couldn't resist)

Jaakko Fagerlund
01-17-2013, 04:27 PM
yeah but did you see the o.d.?
Hah, would be for more like 2.2 cal ammo :D

Wirecutter
01-17-2013, 06:10 PM
yeah but did you see the o.d.?

I couldn't really tell. (Doh! It says right in the post. Never mind.)

john hobdeclipe: Where did that spring come from?

(OT: The Sig P226 offers a change-up system for multiple calibers. Eject the mag and remove the slide, and it can be changed to a number of different calibers by replacing the slide and magazine. I think that's a pretty slick setup, but I doubt it's unique to Sig stuff...) The spring in the slide for the .22 caliber setup is a normal, single wire. This is from a 9mm. This one has an OD of about .375".

http://i70.photobucket.com/albums/i106/wires99/sig_spring_zps3cbe23f6.jpg

John Stevenson
01-17-2013, 06:15 PM
Dunno, never seen one, let me ask Zebadee

demerrill
01-17-2013, 10:34 PM
Damping of spring surges in automatic gun action springs.

http://www.dtic.mil/dtic/tr/fulltext/u2/741949.pdf

David Merrill

demerrill
01-17-2013, 10:49 PM
Also: http://www.spring-makers-resource.net/advanced-spring-design.html

David Merrill

john hobdeclipe
01-18-2013, 11:28 AM
This is all very intriguing to me. Thanks for all of the thoughts and ideas.

AK, at first I thought this may be a decorative thing, but the springs are too dirty for that to have been an issue.

I have about 2 dozen of these. They were in an auction lot, a pallet of boxes full of springs, hinges, old paint, etc. I think someone had the old Depression mentality of "never throw anything away" in addition to a mild spring fetish. There must be a zillion springs in these boxes!

I was looking a bit more closely a few minutes ago, and some of these appear to have been used. They have little rub marks on both the inside and outside.

More accurate dimensions are: 1-1/16 inch OD, 15 inches long, and 22-1/2 turns. I don't have a good way to measure the spring rate, but they are pretty stiff.

Maybe I can make a nicely damped Pogo Stick.