Spring making

[tkerrigan]

I'm getting ready to start making springs.  the method I am thinking of is to pull wire through two plates with a groove cut mounted in the tool holder in my lathe using using thread cutting set up to get even pitch.  Turning the chuck by hand.  Sure wish the lathe would turn slower than 70 rpm.  Then to heat treat in molten lead for temperature control.  My question is more to do with the proper wire to use.  I see that EBAY has Small Parts brand #2B ASTM A288 smooth finish full hard temper at a very reasonable price and a wide selection.  Is that a suitable material to use and if so, what temperature should the lead be at?  I want to do compression springs in the .063 to .067 range for hammer springs. I would appreciate any help I can get.  Regards, Tom

[rgb1]

A288 is the most widely used material, should work fine.
Also, the heat treat isn't necessary with wire this fine.

                                                           Ron

[Bill G]

A288 is the most widely used material, should work fine.
Also, the heat treat isn't necessary with wire this fine.

                                                           Ron

+1.   Although I have done a tempering after the spring is formed and finished.  450* for 1 hr and let cool naturally in the oven until room temp.  I haven't done ant quantitative study but it seem that it makes them less likely to take a set. could be voodoo. 

[lloyd-ss]

Tom,
I think these other guys have had better luck at making springs than I have, LOL. Seems to be kind of an art with a lot of tricks to learn.... which I never really mastered.
 
www.mcmaster.com  has lots of spring wire in the A288 and 302, 304, and 316 stainless, too.  Just search their site for spring temper wire.

But they also have a pretty decent selection of pre-made springs at good prices and you might save yourself some headaches if you can find what you want off the shelf.
Lloyd

[tkerrigan]

Well, I'm into it now.  I ordered 9 different sizes of A288 music wire from Amazon, much better price than MSC.  .016 through .080" diameter. I've wanted to get into spring making for about the last 10 years anyway.  I would have bought springs if anybody made them.  This spring I want needs to be .067" with about .2 to .25" pitch about 3.5" long, unobtainium.  Besides it helps justify the lathe and two milling machines I bought.  Certainly not cost efficient but sure handy to have around.
https://imageshack.com/i/pbrTWmLpj
Regards, Tom

[lloyd-ss]

Ha, ha. Past the point of no return !
Have fun, and you definitely will . 
Lloyd

[tkerrigan]

I've been retired since 2002 and I have plenty of time to learn this.  I also found and downloaded a 60 page manual on spring making, makes it seem pretty easy but I'm sure it will take some time.  Regards, Tom

[rsterne]

The method I use is very simple, and seems to work extremely well.... It results in a spring that will not subsequently collapse to a length shorter than you made it.... No lathe required, a vice, piece of rod for a mandrel, and some music wire.... and maybe a pair of gloves and goggles....   

1. I wind the spring over the appropriate diameter mandrel so that after it springs back the OD is what I want.... That takes some experimenting, but you are faced with the same situation using a lathe.... I wind the spring in a closed coil configuration, one coil right up against the next, like you would a tension spring.... Note, when you let go of it (intentionally or not), it unwinds a few turns and the end can bite you!....

2. While on the mandrel, or a rod of similar size, which must be several times longer than you need, I stretch the spring out so that the coils are quite a long distance apart.... ie the wire has been stressed past its yield point.... You will fell it "give" when you pull hard enough, and the coils will now be further apart.... You need to stretch it more than you think.... The coils at this point will be about 0.5 to 1.0 diameters apart, and may be unevenly spaced.... NOT a problem at this stage....

3. I then collapse the spring, still on the mandrel, until the coils are once again touching each other (coil bound).... When you release the spring, it will rebound to its SET length, and all the coils will magically be evenly spaced.... If you do this several times, the spring will no longer get shorter, it will always rebound to the same length....

4. I cut the spring to just over the length I need, close one coil on each end by bending with pliers (or bend a coil out at 90* to put a hook on the end if you need a tension spring), and grind it flat if necessary....

The key is stretching the spring MORE than the length it ends up, so that when you compress it, it shortens.... If it doesn't shorten when you do step 3, then you didn't stretch it enough at step 2.... Make a couple and you will see what I mean.... My Dad showed my how to do this, and the only variables are the mandrel size you wrap it around, the diameter of the wire, and the material you use.... I always use music wire.... Works every time....

Bob

[shorty]

I make springs a little different. I like to use PH materials as it easily forms at lower tensile <300k psi and can be tempered well over 400k psi like PH17 or 1RK91.

For proper coil spacing of a compression spring I always use a spacing guide when forming the spring on a mandrel.

Tempering is the key with any spring.... With 300 series steels you can increase tensile and yield strength by 17%. PH alloys increase well over 40%.

When ever you work (shape) a tempered alloy such as music wire the tensile will always decrease to the "as drawn" tensile hence needing to temper the alloy after shaping.

An extension spring "stretched" to act like a compression spring works but, it never works like a properly wound compression spring.

Here is a good spring making video that should help you:
http://www.instructables.com/id/Make-your-own-springs-in-seconds/
and
http://www.leespring.com/compression_spec.asp?springType=C&forWhat=Search

Have fun and be careful.

[rsterne]

"Properly wound" compression springs will very often "set" to a shorter length than they were formed at.... If they do, I submit they are pretty much useless as a hammer spring, for example.... However, you can definitely make weaker springs by spaced winding than the "stretch and set" method.... If your goal is a spring of a given length with the highest possible force and the shortest compressed length (giving the greatest travel).... my method gives you that, for any given wire.... and requires no special equipment to make.... but there are certainly other (more difficult) methods.... many of them requiring somewhat special equipment.... 

Bob

[shorty]

There are many way to make things that achieve "similar" results.

I disagree with some of Bob's comments because my work with wire and medical products do not allow for error. Take for example a pace maker lead made from Mp35n or a guide wire that has to have the repeatable "feeling" for the surgeon that is doing in-evasive surgery on you or even a heart valve.

All those pieces of wire in those devices DO NOT change for atleast 10's of years of use.

Most of those small "springs" in those devices are made on "what we would call" special equipment. I have seen and built these machine's and I design these alloy's and wire on a daily basis. Most are nothing more than the instructable with a twist.

Iam not trying to correct you Bob but when making a spring, the spring decreases in length because of the "spring back" of the wire or as you mentioned the mandrel needs to be smaller to account for the "spring back". As the coil springs back the ID and OD of the spring becomes larger than the mandrel resulting in a reduced coil free length.

Over extending an extension spring to turn it into a compression spring actually damages the spring. Unless 2 things are on your side:
1) The extension spring you made is in the "as drawn" stage and then stretch, and then tempered properly.
2) Tempering (you best have an oven that get get over 650f for a minimum of 1 hr to a max of 4 hrs.

Like I said,
There are many ways to make springs. Bobs way is the easiest. Heck, it's only a spring.

[tkerrigan]

The following two movies are very interesting.  Regards, Tom

http://www.instructables.com/id/Make-your-own-springs-in-seconds/