Spring Making - One nailed one failed, please help

[Matthew Machinist]

Hi, I am making springs for a firearm project, I am using Music Wire as per the part blueprints.

The first spring I made, a torsion spring came out pretty good if I do say so myself, it is by no means perfect but it will do the job. I made a small mandrel to wind this around and it came out as expected first time. Here is a blurry photo (sorry)-

http://s1056.photobucket.com/albums/t379/matthewdd3/?action=view&current=spring1.jpg

With this spring I made the mandrel the coil ID, the coil is quite small so there was virtually no spring back to compensate for.

The next spring I need to make is a rather large compression spring. It actually uses the same diameter wire as above which is .063" or 1.6mm.

http://s1056.photobucket.com/albums/t379/matthewdd3/?action=view&current=spring2.jpg

This has been a disaster so far, before attempting this project I did do some background research, namely I read a book called Spring design and manufacture by Tubal Cain, he mentioned that Music Wire does not need to be hardened and tempered. This effectively changed the method I was going to use to make this. I was originally going to make the mandrel to the spring I.D then harden and temper using my electric furnace. With this new method I had to turn the mandrel down to well below the spring I.D to allow for spring back, I actually had to turn it down about 6mm less than the ID to allow for the spring back. The spring I am making is 245mm long and 26.5mm O.D with 17 coils.

So in the photo at the top is the wire I was using to get the mandrel diameter correct during testing. In the middle is the mandrel, which you should be able to see the screws I used to tighten down one or both ends as well as pen marks which I passed the wire over to get the spacing right, and at the bottom is the failed attempt or should I say sorry excuse for a spring.

I have learned a lot from this failure. Firstly when I wound this spring and measured the O.D I found it is a whole millimeter smaller than the test piece, I can only assume this is because the spring was fatigued more during the actual winding than it was on the test wire so I will need to make a new, larger mandrel to compensate. The spring also got shorter by about 10mm when I released it from the mandrel, this is common sense really because as the spring releases and unwinds sightly it will get shorter as it gets wider. So I will make the new mandrel longer to compensate.

The one problem I am not really sure how to fix is the fact that the wire seems to have a mind of its own, even when I was winding it (I wound it by hand with one end of the wire clamped in the vice) it wanted to snake around and twist, I found I was having to contort myself round to try to take the twist out of the wire as I would it. Ultimately it was all for nothing because, as you can see in the photo when I released it from the mandrel the wire went where it wanted to go.

Afterwards when I re read Cain to find out the problem he mentions the importance of getting the wire straight in the first place(getting rid of the kinks he calls it), this sounds feasable however past experience tells me that straightning very high tensile wire of this diameter will add a few coins to the swear jar! And he doesn't actually mention how. I have considered winding it on the lathe but with a 15mm pitch it cant really be done. The other option would be to use a spring winding tool as pictured in Cains book in conjunction with the lathe. However I am not really sure that this alone will take care of the kinking problem. Does that device actually straighten wire before it is bent?

Can anyone help with advice on how to proceed, my best guess will be to straighted the wire as much as I can (I doubt I will ever get it perfectly straight) and try extra hard to get rid of the kinks as I wind, which I don't think will be easy.

If anyone else is interested I found that the 1911 blueprints call for Music Wire springs, unlike Cain the 1911 blueprints call for the Music Wire springs to be "stress releived" after forming in particular the "Spring, Helical Compression" calls for .045" diameter music wire to be stress releived at 450F for 20min minimum. I applied this process to my torsion spring and thus far all I can say is it still works like a spring i.e. hasn't been put into service yet. so I can't say if it is an improvement over not stress relieveing but I have to believe the US Govt knows its stuff when it comes to designing small arms.

 

[MrCleanOK]

I don't have any spring making experience, but did study some spring theory and do have some metallurgy experience. You can work around your compression spring going wild when you take it off the mandrel by heat treating it before taking it off the mandrel. You'd have to make a new mandrel for the finished size of the spring, out of a material that can go in the furnace too. This may be easier than the trial and error it would take to try to straighten your music wire, then allow for spring back off the mandrel.

Sent from my ADR6350 using Tapatalk 2

 

[dirtyjim]

I've made a few oddball springs from flat wire on the past. The wire I used was annealed & was a pain to keep flat on the mandrel. I also heat treated it on the mandrel.
Now I just spend a couple hours searching mcmaster-carr till I find something close enough to work

 

[james layman]

spring making

After you get the size you want, this worked for me. Not very scientific. Heat spring cherry red. Dip in motor oil. Remove immediately and set fire with a flame. Let cool slowly. Let us know your resolution.

 

[Jim K]

That is essentially just annealing the spring, returning it to dead soft, then re-heat treating it after it is shaped to the required diameter. As noted, that does not need to be done with music wire, which is already a spring, but sometimes is the best way.

Depending on the use, it is sometimes possible to just buy a spring assortment (Wolff's, Brownells or some big box stores) and find one that will work. That is what most gunsmiths do, buying/making one spring may be less expensive.

Jim

 

[Zeke/PA]

Actually, when using Spring Wire and winding around a mandrel,no heat treating is necessary as the wire is already at that point.
Spring winding is time consuming and frustrating with quite a bit of "expirementation" involved.

 

[Jim K]

One trick is to use drill rod for the mandrel and drill a hole through it crossways. Then you stick the end of the wire through the hole, insert the hole end into the headstock and hand turn the headstock. (Using power is not recommended; being whipped by a length of music wire is not really a lot of fun.) Getting the spacing right is a matter of practice, but a tool can be used.

JIm

 

[rcmodel]

no heat treating is necessary as the wire is already at that point.

What he said.
Spring wire/music wire is already work hardened from drawing it into wire.
It is not further tempered or heat treated by the factory.
It is not really the right kind of steel for heat & oil tempering into a spring.

What you need to do is wind them the right size in the first place and leave it at that.

rc

 

[Jim K]

I suppose winding springs is OK for a one-off, but for a gunsmith, it is a bit hard to think of a coil spring that would not be available from a parts place, Wolff or in one of Brownells assortment kits. The cost would be higher, but the spring would work the first time and to anyone but a hobbyist with time on his hands, that is important.

Jim

 

[Aderondacker]

To make coil springs you need to wind the spring around a v cut thread screw. If you had a lathe you can make any size coil spring you need by cutting threads on a mandril of the correct size. If you don't have a lathe than you have to use the standard screw sizes or metric sizes available. The threads per inch of a screw makes the coils per inch spring by following the threads on the screw. The trick is to have tension on the wire you are winding onto the selected screw to keep the coils the same diameter.

 

[Matthew Machinist]

Sucess

Hi Guys

This springmaking project has gone from a half day project to one which has now consumed the best part of two weekends so I thought I had better do a write-up to let you all know how I have got on. Firstly I should tell you all that for the project I am working on I was able to purchase many of the springs off the shelf. I have to make one torsion spring (finished), a recoil spring (the subject of this thread) and a magazine spring (read about this one below). The wire I am using is from a roll of precision brand music wire, which I purchased for the project. O.k. if I looked really hard on the internet I probably could have purchased something which might work, however I am hoping to become a gunsmith one day so this is as good a time as any to actually learn how to make springs, in my case I am learning the hard way…

My first instinct was that MrCleanok and Dirtyjim were right, that I would need to anneal the wire, wind it around a finish size mandrel and heat treat, temper. However I decided to give it one more try, so I made a new mandrel. This mandrel I turned to 18.9mm, (the last one was 17.3mm and resulted in a spring with an o.d. of 25.6mm, with this mandrel I also made it around 10mm longer to compensate for it getting shorter when I released it from the mandrel.

I also took some of the advice given by Jim K and wound this spring on the lathe, I couldn’t cut a groove to wind it in as suggested by Aderondacker due to the pitch limitations on my lathe. However winding it on the lathe was a godsend, so much easier and less painful. However I pulled out all the stops, I spent the time to straighten the wire by hand before starting. I also machined a shallow groove in a piece of steel and mounted this in the toolpost, by using the screws on the toolpost I was able to use this to tension the wire as I wound it, helping to keep it straight. You can see all this in this photo (note the piece of steel I mentioned sitting on the ways showing the groove)

http://s1056.photobucket.com/albums/t379/matthewdd3/?action=view&current=2002_0101springs0001.jpg

As you can see I still wasn’t able to get the spacing exactly perfect so I suspected this would still be a write-off, however when I released it I was quite surprised –

http://s1056.photobucket.com/albums/t379/matthewdd3/?action=view&current=2002_0101springs0003.jpg

Not perfect by any means but it looks a lot better than my last attempt, and after trimming the ends and playing with it a little I was able to make it straight enough. So this result encouraged me to continue with this method, the only problem with this spring I had made was –

The diameter was now 29.3mm (I’ve gone from too small to too big)
I wound it with 17 coils – when it released it I ended up with just 13 coils
The length is now 10mm too long

So I tried again, I turned the mandrel down to 18.2mm and made the mandrel 10mm shorter (its now back to the 245mm starting length), I also wound this attempt with 20 coils to compensate for the fact that you loose some when releasing it from the mandrel. This resulted in a spring with 15 coils, 245mm long and a diameter of 27.5mm.

So I tried again, I turned it down to 18mm, and I wound it with 22 coils. I ended up with a spring the right diameter with the right no. of coils (17) and 10mm too long. I am basically happy with this one, I don’t think the extra free length will matter.

The three springs in order from top to bottom –
http://s1056.photobucket.com/albums/t379/matthewdd3/?action=view&current=2002_0101springs0005.jpg

So in the end I would call this a painful success. I really appreciate all of the advice you guys gave, the only bit of advice that I think was wrong was the chap who said to make the mandrel finish size and leave it at that – you only need to look at the photos provided or the data provided to see how wrong that is. However I will say that that advice is very true IF you are making a small diameter spring, for example when I made my torsion spring I made the mandrel close to finish size and experienced very little spring back. With this larger diameter spring the mandrel ended up being about 5.5mm under finish size.

This process clearly has limitations, namely many attempts may need to be made before getting it right. I have also realised it wont work at all for rectangular springs like the magazine spring I am making now (have a good laugh at this one) –
http://s1056.photobucket.com/albums/t379/matthewdd3/?action=view&current=2002_0101springs0006.jpg
http://s1056.photobucket.com/albums/t379/matthewdd3/?action=view&current=2002_0101springs0007.jpg

Basically after I released it from the mandrel it ended up triangular rather than rectangular due to spring back. Unfortunately there is no way to compensate for spring back with a rectangular spring so I will have to try the anneal and heat treat method with the magazine spring.
I’ll let you know how I get on once I find some data for heat treating music wire - temp, time etc.

Thanks again,
Matthew.