Springs and things

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Deanofid

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Hi all;

I haven't had any engine stuff to post for a month or two, 'cause I have some real jobs to do.
Thought I would put this part of a job up, since it does pertain to something that needs to be done in
the shop now and then. I do quite a bit of machining stuff during the course of my regular work.




1.jpg


I make my daily bread working on old cameras. Stuff that was made before anyone ever thought of
taking film out of cameras and replacing it with a computer. Most of my work involves purely
mechanical cameras, made even before cameras needed batteries, much less chips and memory cards.

I was a full time welder and part time "machinist" for many years, but my body protested after years of
bucking iron, so I made a change of direction some time in the early 90's. I have no idea how I put
camera repair together with welding and machining. It seemed sensible at the time.

One of my typical jobs is repairing shutters, which involves taking them to pieces, like the one in the
picture above.





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This particular unit is a German made Synchro Compur, and this type was last made about 45 years
ago. The screwdriver is pointing to the end of the broken mainspring. I'll bet lots of repair shops, of
any type, rely on a fair percentage of problems caused by someone just not listening to their bit of
machinery, whether it's a camera or a car, or whatever. Something else was originally wrong with this
shutter that wouldn't let the last operator cock it, so they forced it.

So, on to what this is really about. A quick demo on making small springs.




3.jpg


With the spring out of the shutter, it can be measured for a number of need-to-know things. Mainly,
the wire diameter, the coil diameter, how many coils, and whatever other notes may be useful, like the
direction of any hooks or eyes/loops needed on the ends of the spring.

The original spring is shown in the center of the picture, above. The wire size on this spring is .014"
diameter. There are a couple of sources of wire suitable for this type of spring, shown here. One is
guitar strings, which are really just tarted up music wire. The other is regular music wire that is sold as
that, or some times called spring wire. It's all music wire, as far as I know.

Guitar strings are really easy to get in almost any town. They're very good for small springs of almost
any type, but they only come in a limited size range. For most modeling needs, you probably would
not need much outside the range that guitar strings offer. If you want a quick assortment of spring
wire, go buy every different sized solid steel guitar strings you can find, and you'll have a good start.

Wire that is sold as music wire is basically the same stuff, but it doesn't usually come polished like guitar
strings. (You don't need polished wire, unless that's what you want for appearances.)

Regular music wire is usually black, and you can get it at hobby stores that sell supplies for RC airplanes
and the like.






3a.jpg


The two wire sizes I had on hand were both slightly different sizes than the original spring. One was
almost .015", one about .0135". I'll make a few spring blanks in both sizes. I always make extras for
a particular job, in case "someone" goofs.





4.jpg


This is the basic setup I use for making SMALL springs. This way only works well with small wire sizes,
up to about .025". Larger wire sizes absolutely must be done using a winding jig, for your own safety.

The first consideration here is the size of the arbor that will be used to form the spring coil diameter. I
do it the simplest way I know how, which is to check the inside of the broken spring using different
sizes of wire. When I find the wire that fits, I use that size to judge what I think will work. The spring
wire usually has to be wound smaller than the size spring you actually need, because as soon as it's
done being wound, it springs open a little bit.

For an example of what I mean, the nearest sized wire I had that fit close inside the broken spring was
.062" dia. If I wind the new spring on that size arbor, the new spring might be too big in dia.

So, I used the next size smaller wire I had as an arbor, which was .055" dia. I did make a couple using
an .062" arbor too, because of a peculiar thing that happens to the wire that will be noted a little farther
down in this post.

In the picture above, the winding arbor has been mounted in the chuck on the left, with one of the
chuck jaws pinching on the spring wire. The chuck on the right is not tight on the wire. Just closed
down enough to keep the arbor from bending when the spring is wound, but still loose enough that the
arbor can spin freely.

Some safety things that have to be said;

Safety glasses! Tiny wire will go right into your eyeball, just like a needle.

Gloves are okay as long as you are not using the power on your lathe.

Start with a piece of wire that will be enough to make your spring, of course, but don't have wire
hanging out and drooping down to the floor, (unless you need that long of a spring). Keep it short as is
practical.

Don't let go of the wire when winding until you have let it relax. The small wire size being used here
won't break anything if you should turn it loose, but it's not good practice, and if you were to do it with
larger wire, it will scare you at the best, scar you at the worst.





5.jpg


The piece of wire is now gripped tightly with pliers, and the headstock pulley on the lathe is turned by
hand to form the coils. Unplug the lathe, turn it by hand, when using this method.

As soon as a coil or two are formed, the wire is moved to the left, as shown in the picture above. This
keeps the coils tight against each other. At the same time this is being done, pressure is kept on the
wire, pulling it back toward the operator. You have to pull pretty hard, and keep an eye on the coils to
make sure they are staying tight against each other.

When the coils are long enough to make the length of spring you need, give it a few more turns, then,
slowly turn the arbor backward until all the tension on the new spring is released. It will relax a little and
open up slightly. You must not just let go of the wire when the spring is as long as you need it. If you
do, the wire will be pulled back toward the chuck, and make a rats nest, not to mention flailing around a
bit when it does so.

I want to mention again here, you can only make springs that use small diameter wire with this
method. And again, .025" wire is about the max. Anything larger than that needs a winding fixture.

Serious!

I have a small setup for winding springs that use larger wire. I'll show it another time.





6.jpg


When the spring is long enough for your needs, let it relax slowly, and cut off the tail. Then you can
take it out of the lathe and off the arbor.




7.jpg


I made five blanks for this job. Ideally, I'll only need one, but since the next step takes a while, and I
don't want to repeat it if I should mess up when bending the eyes, I make extras. I've been making
springs like this for ten years or so, and have learned it's easier just to make a few more than you need
than to start the whole thing over.

You can see a couple there that have a loose coil. That's the reason those two are longer than the
rest. I just made them a little longer when I saw the bad coil, and I can cut the bad part off later and
still have a usable spring.





8.jpg


This next bit, including the following few pictures show the method I use to heat the springs. They have
to be stress relieved after the winding process, or they won't hold their shape well. If you don't do this
step, the springs won't be as springy as they should be, and can easily be stretched out of shape.

I make a nest for them using steel wool and foil. Put the springs on one half of the steel wool.





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Fold the steel wool over to make a sandwich.





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Fold the foil lightly around the wool to make a loose packet.





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Pop it in the oven. This little toaster oven does a good job on music wire. I put it on its highest setting,
which is 450f, and leave them for an hour, then turn off the oven and let it cool naturally.

It takes about an hour and a half, and that's why I make extra springs. The five springs took me about
10 minutes to make, but 1 1/2 hours to cook and cool. If I only made one spring, and messed it up
after cooking, I'd have to start all over again.

There is another way to do the heating thing. You can use a small can, like a tuna can, fill it half full of
brass shavings, put the springs in, and fill it the rest of the way with shavings. It does the same thing. I
find the steel wool way more convenient.





12.jpg


This is what you want to see when you open the packet. The steel wool should be somewhat blue
from the heat treatment. The springs that were shiny to begin with will be slightly off color. The springs
that were black will still be black.

Here's where the peculiar thing I mentioned earlier comes into play when sizing the arbor for winding
the spring. When you heat this stuff to stress relieve it, it gets a little smaller. The diameter changes
just a touch. So, if you need a spring that has to be an exact diameter across the coils, you'll have to
experiment a little with the arbors you use to wind them. If someone had asked me before I had ever
done this, I would have thought they would get larger. But, they shrink.


Something you married folks should probably know before you do this step in the house. Steel wool
has a tiny trace of oil on it, to keep it from turning to a ball of rust between the time you buy it and the
time you get around to using it. That little bit of oil does make a slight odor when you cook it. My dog
doesn't care about that odor, or, if she does, she doesn't mention it. A spouse may not feel the same
way.





13.jpg


Here's one of the heat treated springs, ready for the final sizing and pulling out the eyes.
The two brass pieces are for holding the spring. They each have a small round bottom channel filed in
them so they won't rock around on the spring once it is positioned between them. I've made a lot of
this size spring over the years. You can see some grooves that look similar to threads have started to
wear into the slots where spring coils bear against them.

The little tail on one end of the spring is clipped off with flat nosed wire cutters, and it's then positioned
between the blocks.




14.jpg


The first eye is pulled up. The spring has to be put between the blocks just so, in order for the end of
the coil to end up in the correct place. You'll have to figure that out for what ever spring type you're
making.

Then, using a small rod filed to the shape of a screwdriver end, it's wedged between the end coils, and
levered up to bring up the eye. The clamp has to be pretty tight on the spring to do this, in order to
keep the second coil in line from pulling up with the first one. Once it is pried up a little, I put a rod down
the center of the spring, and pry against it a little to get the eye pointing straight out.





15.jpg


Here's the new spring, and the old one. In this shot, I'm just getting a sense of the position for the
second eye needed on the other end. The the eye pulling process is repeated.

The new spring looks somewhat fatter in this picture. It's a trick of the camera, though. The new one
is within .001" dia. of the old one.





16.jpg


Well, that's it. The new spring is done, and by now, it's in the old shutter, ticking away.

Thanks for having a look.

Dean
 

1hand

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Dean,

That's awesome! :eek:

And how timely. You have any tricks on making Compression springs? I need some for a prosthetic thing I'm doing now. I have ordered a bunch of different springs, but having trouble finding what I need. They need to be .240 by .375 long and have a compression load of 5 to 6lbs. Any Ideas.

Matt
 

10K Pete

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Dean,
That's great information on small springs. I've only made a couple and have never
reduced the process to the 'science' you have. I've never known about the heat
treat, but now it's clear why I've had trouble with the springs not holding their shape!

Please post about the winder you use for larger wires.

Thanks,
Pete
 

Shopguy

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Dean
Very informative.
I've never had much luck making my own springs in the past, but with your method there is some hope for the future.
Thanks for posting.
Ernie J
 

AlanHaisley

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Dean,

The annealing is a surprise. In addition to releving stress in the wire, I guess that it makes it just the right springiness.

Alan
 

Deanofid

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Hiya folks;

Thanks for your nice comments.

Matt, I'm pretty sure there is a formula for figuring exactly what you want, but I don't know it!
I have made compression springs, yes, but not quite as many as extension springs.

You need to use your lathe as you would for cutting screws if you want consistent results with them. You also need a jig that is pretty simple to make. It fits in your tool post, and guides the wire as the arbor turns.

The strength of the spring you want to make is pretty stiff. How much can you allow for the hole in the center of the spring? That, and the OD will dictate the maximum thickness of the wire you use. Machinery Handbook may well have the info you need for wire size, and the number of coils for a given travel and compression weight.

Pete;
I'll do my best to get a post up about the jig and using lathe feeds for doing springs with a heavier wire. Some time in the next week or so.

Dean
 

rudydubya

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A great post Dean. I've made a few small springs, but never heat treated them. I'll try your heating method next time. And I never thought about going to the music store for music wire. Story of my life... Thanks for the tips!

Rudy
 

joeby

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Well done, and very useful information, Dean.

Thank you!

I've dealt with all sorts of springs over the years, as I'm sure many here have also; but never attempted making my own. Knowing how to wind springs would certainly remove some limitations on design.

A constant source of amazement in the machining world is realizing that all the things you have learned over the years have barely scratched the surface.

Kevin
 

gbritnell

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Hi Dean, thanks for the great write-up. We had a bench spring winder in our shop. As an apprentice I was taught how to make springs but nobody ever mentioned about heat treating them. I had just assumed that the tension in the wire was constant even when the spring was wound. I make my own springs from time to time and for compression springs I wind a tight coil for an expansion spring like you have done and after I take it off of the mandrel I grab both ends with needle nosed pliers and then pull. It's not very scientific but it seems to work. The hardest part is getting the end coil to lay flat against the next one. Any tricks for that?
Thanks,
George
 

cobra428

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Dean,
Thanks for taking the mystery out of spring making and annealing :bow: :bow:

Tony
 

mklotz

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Dean mentioned the problem of determining the correct size of spring winding mandrel to obtain a required spring inside diameter.

Kozo Hiraoka, the genius who wrote all those books on the construction of Shay locomotives, has worked this problem. He wrote an article (HSM, July/August 1987, pg. 30) detailing an algorithm for calculating the required mandrel size.

I've used his algorithm numerous times to make spring winding mandrels and the results have always been spot on. Highly recommended.

I incorporated his calculations into a computer program that's available for free on my website. Look for the MANDREL.ZIP archive and download it.
 

ChooChooMike

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BigBore said:
That is , simply put, a great post! (copy/paste/copy/paste)

Thanks a lot.

How many "K's" in Karma? ;)

This post should be copied to a "Tips Best Of ..." thread !!

EXCELLENT !! :bow: :bow:
 

Deanofid

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Thanks again for the comments, folks.

It looks like Marv has something for us spring maker types. I won't get to look at it today, but it sure is nice of you to figure up all these useful programs, Marv. Thanks!

I've never used a formula to figure arbor size or wire size. All the springs I've made are usually trial and error, unless I have a reference spring, as I used for this write up.

gbritnell said:
The hardest part is getting the end coil to lay flat against the next one. Any tricks for that?
Thanks,
George

Hi George, and thanks.
When I make a compression spring, I do it with one of the lathe feeds used for threading.

At the first part of the spring, I make about two turns with the coils right next to each other, like for an extension spring. Then, engage the lathe feed and run the length you need for the compression part of the spring. The lathe feed will get the spacing right for you, so you don't have to pull the spring apart with pliers. Of course, you have to figure out the lathe feed ahead of time.

When the compression coils are wound to within one coil width of the end of the spring length I need, stop the lathe feed, and let it wind another two coils nice and tight against each other. Let off the tension and cut the wire.

Take the spring off the arbor, and cut one of the close coils off each end. At that point, the ends will be almost flat, except for where you cut the wire. I use a Dremel tool with an abrasive disc to touch up that last coil on each end so it makes a flat surface, like a long bevel on about 1/3 the diameter of the end coil. Don't get the metal red when you do this.
Then bake it, and it should be good, providing you have got your arbor size figured right.

Dean
 

kendo

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Hi Dean
That was one really impressive write up, Just loved it, and very easy to
understand. That's what makes this such a great site, are guys like yourself
sharing their experience with others.
I've always wondered how i could make some springs, this I've just
gotta try. Thanks for sharing.
Ken

PS well deserves a Karma or Ten
 

itowbig

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hey big bore could u please send me the pdf of this with permission from dean first of corse this was very nice write up and i really enjoyed reading it to the end i want to thank you dean for this great write up it was wonderful.
 

itowbig

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oh thank you guys so much thats was fast . i have received the pdf and a very big thank you
such a wonderful place here all this great learning and great people make this a great place :bow: :bow: :bow: :bow: :bow:
 

putputman

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To add the PDF file to a post, click on the "additional options" on the bottom of the reply page, then click on "browse" and select your PDF. You can add 4 files.
 

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