Mechanical Engineer

October 10, 2013

MECHANICAL ENGINEERING JOB INTERVIEW QUESTIONS

1.)What is hydraulic jump ?

Ans: It is a natural phenomenon in open channel. It is an abrupt reduction in flow velocity by means of a sudden increase of water depth in the down stream direction. Through a hydraulic jump, and high-velocity supercritical flow is changed to a low velocity subcritical flow.

2.)What is conicity ?

Ans: The ratio of the difference in diameter of the taper to its length is termed conicity.

3.)On what parameters the head developed by a centrifugal pump depends ?

Ans: It depends upon the impeller diameter and its rotative speed.

4.)What is the difference between dressing and trueing of a grinding wheel ?

Ans: Dressing is the process used to clear the cutting surface of the grinding wheel of any dull grits and embedded swarf in order to improve the cutting action. Trueing is the process employed to bring the wheel to the required geometric shop and also to restore the cutting action of a worn wheel.

October 8, 2013

Nagada Sang Dhol Baaje Lyrics from Ramleela

Nagada Sang Dhol Lyrics

Hey dhin tadaak dhin tadaak
Aaja ud ke saraat
Pairon se bedi zara khol
Nagada sang dhol baaje, dhol baaje
Dhaayn dhaayn dhum dhum dhaayn
Nagada sang dhol baaje, dhol baaje
Dhaayn dhaayn dhaayn dhum dhaayn (x2)

Re khat-khat haan khat-khat
Baaje dastak woh na ab tak aaya
Re tab se haan tab se
Haan dekhe raahein
Ki ab tu khol baahein aaja
Umad-ghumad ghumein
Re machle re mora mann
Goonje re baalam ke bol

Nagada sang dhol baaje, dhol baaje
Dhaayn dhaayn dhum dhum dhaayn
Nagada sang dhol baaje, dhol baaje
Dhaayn dhaayn dhaayn dhum dhaayn

Hey dhin tadaak dhin tadaak
Aaja ud ke saraat
Pairon se bedi zara khol
Nagada sang dhol baaje, dhol baaje
Dhaayn dhaayn dhum dhum dhaayn
Nagada sang dhol baaje, dhol baaje
Dhaayn dhaayn dhaayn dhum dhaayn

Leeli lemdi re
Leelo nagarvel no chhod
Parbhu parodh na re
Maar gher uttaara karta jaao
Utaaro nahi karun re
Maar gher Sita juve vaat
Sita ekla re
Juve ram-lakhman ni vaat

O pal-pal re pal-pal beet'ta jal-jal
Naach ab chal aaja
Re tharr-tharr tharr-tharr
Haan kaanpe tharr-tharr
Haan darr darr jee se darr ab na na
Baagon mein bola, bola re bola
Morey badla re dil ka bhoogol

Nagada sang dhol baaje, dhol baaje
Dhaayn dhaayn dhum dhum dhaayn
Nagada sang dhol baaje, dhol baaje
Dhaayn dhaayn dhaayn dhum dhaayn

Hey dhin tadaak dhin tadaak
Aaja ud ke saraat
Pairon se bedi zara khol

Nagada sang dhol baaje, dhol baaje
Dhaayn dhaayn dhum dhum dhaayn
Nagada sang dhol baaje, dhol baaje
Dhaayn dhaayn dhaayn dhum dhaayn (x2)

Leeli lemdi re
Leelo nagarvel no chhod
Parbhu parodh na re
Maar gher uttaara karta jaao
Utaaro nahi karun re
Maar gher Sita juve vaat
Sita ekla re
Juve ram-lakhman ni vaat

Hey.... ho dhol baaje!

October 6, 2013

TYPES OF SPRINGS

This section will tell you about other types of springs that can be made. Where it's possible for you to make them easily, I'll tell you how. Otherwise, your best bet is to have these types of springs made commercially.

Made from Round Wire:

Buckling columns: Get the idea of a plain coil of very fine wire with no loops or hooks on the ends. Get the idea of one end of this coil being held in place, while the other end is approached by something. When the 'something' hits the other end of the coil, the coil will support it until the load passes a certain point, and the the coil will buckle. Here's what it looks like:

Buckling columns are also used as sensors that send an electrical signal when something gets close to it. You can make buckling columns very easily with a drill: just follow the procedure for making fine-wire extension springs.

Nested compression springs: Sometimes, you'll need a compression spring that's stronger than any single spring can be. In that case, you can make nested compression springs — one spring inside the other — that will be a lot stronger than a single spring. Some automobile valve spring assemblies are actually nested springs: so are the suspension springs on railroad cars.

You can make nested compression springs easily: just remember two things:

Nested compression springs must be different-handed. If the outer spring is right-handed, then the inner spring must be left-handed, or vice-versa.
The outside diameter of the inside spring CANNOT be larger than the inside diameter of the outside spring. If it is, the springs will not nest.

Conical springs: You may want to make a compression spring that's smaller at one end than the other. This is called a conical, or tapered, spring. You can make these just like any other compression spring: the only difference is the arbor, which must also be cone-shaped.

The best way to make a cone-shaped arbor for light wire is to turn one out of wood. Get your arbor diameters for both ends by using the steps in the section on The Setup and turn your arbor like this:

Use good, hard wood — ash, for instance — and remember: wood is a lot weaker than steel. Don't try to coil long springs on a wooden arbor, and don't try to make a conical spring with wire heavier than about .125". It can be done, but with heavier wire, the wire will start to cut a groove in the wood. More important, the arbor may snap, which would NOT be fun.

The other thing to watch out for is that when you grind the ends of a conical spring, you have to hold the spring in your hands to get it ground square. Because the sides of the coil are sloped, using a grinding stage would not give you a square end.

Variable-pitch springs: Sometimes you'll want a compression spring that starts out ï¿½softï¿½ and after a certain load is placed on it, becomes stiffer. This is called a variable-pitch spring, and you can see springs like this in some motorcycle shock absorbers:

These are pretty tricky to make, but you can do it. Here's how:

Make your setup as you would for any other compression spring.
Find the right settings for your lead screw for each of the segments of the coil.
Start to wind the spring. When you've wound what you want at the first pitch, STOP THE LATHE and change the lead screw speed setting to the second position.
Continue winding at the second pitch until you've finished the spring.

The key is to have some way to remember TWO coil counts: one for the first section, and one for the second. Once you can do this, then you can change where you switch from one lead-screw speed to another and come out with the exact spring that you want.

Snap-rings: Snap rings are easy. Just coil an extension spring with the right diameter and cut off single rings, one at a time, with wire cutters.

Double torsion springs: You recall how torsion springs can be either left-handed or right-handed? Well, sometimes you'll want to make a torsion spring that's both. Such springs are sometimes found on clipboards, and they might look like this:

Making double torsion springs means making some pretty specialized tooling, and the best way to actually wind them is with a hand-winder. Here's how:

First, find the right size of arbor for making the coils. The arbor will have to be at least a few inches longer than the widest part of the coils.
Grind a flat spot on the arbor, narrower than the distance between the insides of the two coils.
Drill a hole through the arbor at the flat spot.

At this point, your arbor should look like this:
Make a short pin that'll fit into the hole in your arbor. The pin should be an inch or so longer that the arbor is thick, and have a bend in one end. The other end should be slightly rounded, like this:
Now, get a piece of flat stock as thick as the inside gap between the two coils of the spring. Grind it like this:
Drill a hole in this piece (the tongue piece) so that when you put the arbor, tongue piece, and pin together, they look like this:
Make TWO wire guides, one for each side of the spring. Make sure that the pins on the wire guides come out one to the left and one to the right.

Whew! You're about half done!
The next step is to prepare your wire:
1. The first step is to figure out how much wire you'll need to make a spring. Do this the same way you did for a single torsion spring, figuring out how much you'll need for ONE SIDE of the double torsion spring.
  
  Don't forget the fudge factor. When you're done, then just double your answer: that'll do for a start.
2. Take a length of wire and form a U in the center. (Your design may call for other bends in the center piece — I call it a 'U' just for simplicity's sake.) This will be the tongue of your spring, so make sure you get the inside dimension of the bend the right size. You can form the U using any of the bending jigs we've discussed.
3. Save this setup. After you make your first spring all the way through, you'll use it again to make as many springs of this design as you need.
Now it's time to actually coil the springs.

Chuck up your arbor in your hand winder. Leave enough room between the chuck and the flat spot to fit one side of the completed coil, the width of one wire guide, plus at least half an inch.
Slide the left-hand wire guide onto the arbor. That's the one with the pin coming out the RIGHT side.
Slide the tongue piece onto the flat spot on the arbor and put the pin through both to hold them together.
Slide the right-hand wire guide onto the arbor.
Hook your prepared wire onto the tongue piece and over the arbor. Hold it tight against the tongue piece as you catch each free end of the wire with the wire guides. Your setup should look like this:
With your left hand, put a little tension on the arbor -- enough to be sure that your wire guides have both caught the wire securely.
Then start to wind, holding both wire guides with your right hand. Keep a little pressure toward the center of the spring from each side. Spring coils should start to form on either side of the tongue piece. You can let them 'push' your wire guides outwards as you continue.
Stop winding when you have a little more coils down on each side than the finished spring will need. Back the winder off until the spring hangs free on the arbor.
Now, take the spring off the arbor:
1. Slide the right-hand wire guide off the arbor.
2. Use a finger to pull the tongue of the spring off the tongue piece.
3. Pull the pin out of the tongue piece.
4. Pull the tongue piece off the arbor.
5. Slide the spring free.

Then, check your dimensions and change the number of coils you lay down until you've got the right number.

Stress-relieve the coils and finish the ends like any other torsion spring. Note that because the two coils are mirror-images of each other, you'll probably need to make two setups to do any bending on the legs of the spring -- one for the right-hand coil and one for the left-hand coil.

Wire forms: Wire forms are any shape made out of wire — not just a coil. There are a jillion different kinds of wire forms: here's a common one.

You can make wire forms easily with round-nose pliers, or with a bending jig.

Bedsprings: These are basically hourglass-shaped compression springs in which the ends wrap around themselves. They're made on special automatic machinery — I hope you don't need one bad enough to try making it yourself — they can probably be made by hand, but it would not be easy.

Limited-travel extension springs: Sometimes you'll want to make an extension spring that only extends so far and then stops. You'll see these sometimes on screen doors:

As you can see, they're basically compression springs with a little extra added hardware. Here's how to make them:

Make the compression springs and don't grind the ends.
For each spring, make two wire forms that look like this:
Stick one of the wire forms through the center of the spring coil until the wire form sticks out the other end.
Slide one of the legs of the other wire form through the center part of the first one.
Flip the second wire form around so that the center part is aimed down the middle of the spring, and push it through.

There you go!

Braided wire springs: Howitzers and other military hardware use springs that have to handle sudden significant loads. Ordinary solid-wire springs would shatter under the stress of artillery recoil, so for these situations springs are made out of braided wire. I haven't seen any of these myself but I imagine that coiling such material would be similar to coiling solid wire.

Very heavy wire: What's the heaviest wire that can be made into a spring? Well, coiling cold, the heaviest is about 5/8". Most spring shops won't coil 5/8" wire cold, though, because it's too dangerous.

Springs made from larger material start as straight bars of steel with the ends tapered down. The bars are heated red-hot and then coiled on special machinery. I've seen 2-1/2" bars made into railroad suspension springs, and I've heard of 6" bars being made into compression springs that are used as shock absorbers for underground military command sites.

If you need a spring made with wire thicker than .375", I'd recommend going to a spring shop and having them make your springs for you. With a big enough lathe and a thorough awareness of wire safety, you can coil up to .625", but frankly, most springmakers you talk to will think you're crazy.

Very light wire: Common commercial coiling machines typically handle wire as fine as .010", but springs have been made with wire as fine as .002" using custom-made micro coilers. Winding extremely fine wire by hand is difficult because the wire tangles easily and cuts flesh even easier. Leave these to the pros, OK?

Springs Made from Other Materials:

Many springs are made from material other than round wire. Again, if you can make some of these with simple setups, this section will tell you how.

Square and flat wire: All types of coil springs can be made from either square or flat wire. Using these materials gives you a stronger spring than if you use round wire for the same design.

You can use these materials to make your springs: the only change to your setup is the wire guide. Besides the wire guide that fits in the tool post of your lathe, hold the wire in a crescent wrench, in front of the tool post.

As the wire coils onto the arbor, it'll try to ï¿½rollï¿½ in a clockwise direction. To prevent this, keep a counterclockwise pressure on the wire with the crescent wrench. Then, the wire will lay down flat on the arbor.

Tubular stock: You can also coil tubing into spring shapes for cooling coils and so forth. Tubular stock is very soft, though, compared with solid wire, so a couple of extra steps are needed:

All tooling parts which come in contact with the stock should be ï¿½dishedï¿½ to accommodate the stock. That means the arbor should be made with a shallow groove:

And the wire guide, ideally, should be a roller with a groove in it, gimballed to allow it to swing:
To prevent the stock from collapsing during bending, fill it with fine sand before you start. Be sure the sand is packed tight — the tighter the sand, the less the stock will deform.

Leaf springs: Leaf springs start out as bars of flat stock, which are then heated red-hot and formed, either by machine or by hand. If you need leaf springs, best bet is to go to a spring shop that specializes in making them.

Belleville washers: These are just like regular washers — flat metal donuts — except that the inside of the washer is higher than the outside. Belleville washers are mounted in a pack and with a bunch of them together, make a very strong spring. Belleville washers are made by a stamping process that's best done in a spring shop.

Clock springs: Some springs are made from wide, flat stock and coiled up like the shell of a snail. These are called clock springs, and the material they're made from is called 'blue clock', because the color of the steel is blue.

Springs like this are found inside clocks, retractor reels, and other machinery. Take apart an old thermostat and you'll see that the sensor element is basically a clock spring. You can make them on a lathe, but you'll need special tooling that's not easy to make. Your best bet, again, is to go to a spring shop and get them made for you.

On the other hand, you can always give it a shot. I've written up the basics here.

October 5, 2013

TORSION SPRINGS

This chapter will tell you how to make torsion springs. Before you start, read the section on The Setup, and have your setup done (spring coil diameter correct).

Don't forget that torsion springs come left-handed and right-handed. Be sure to make your setup for the correct hand. If you're making a left-handed spring, remember that the setup and the motion of the chuck and arbor will be OPPOSITE to what is described.

Wire length:

When you're ready to start coiling, the first thing you need to do is figure out how much wire you'll need to make your spring. Here's how:

Take the outside diameter of the spring and multiply it by 3.3.
Take the result of this and multiply it by the number of coils in the spring.
Figure out about how much wire you'll need to form each end. Allow a couple of inches on each end to grab onto when making your bends. Add those two numbers together.
Add together the results from steps 2 and 3.
Add in a fudge factor (about 10%, but not less than 6").
Write the result down. If you're WAY off, you can save yourself a lot of wire by cutting it closer. By writing down what you think you'll need, you'll know how much you can change this figure and still have a margin for error. When in doubt, err on the side of safety and plan to use more wire, rather than less.

Coiling the First Trial:

Now you're ready to actually start.

Cut yourself a piece of wire to the length you figured out above. Be sure that anyone else in the area stays out of danger while you do the rest of this. Also, get your oven heated up.
Put the wire into your setup. Let the 'front' end of the wire stick out beyond the pickup pin for as much as you need to form the SHORTER of the two ends.
It may be that your short end will need more wire than will clear the ways of your lathe or (if you're using a hand winder) your workbench. If this is the case, you can bend the wire by hand so that it will clear and then straighten it out by hand once the coiling is done.
Move your wire guide to the left as close as you can to where the pickup pin is, but not so close that the pin will hit the wire guide as it comes around on its first pass.
Your setup should now look like this (these diagrams will show both a hand-held wire guide and a tool post-mounted wire guide):

READ THE NEXT STEP ALL THE WAY THROUGH BEFORE YOU START IT.
Start your coiling. Move the chuck DEAD SLOW until you have completed your first full coil. When you have your first coil laid down on the arbor, you'll then need to do two things at the same time.
1. First, bring the wire guide a little to the left. You want there to be a gap between the first two coils as the wire lays down on the arbor, but you don't want the gap to be big. In fact, the smaller, the better, as long as it's always there. The gap should look like this:
2. Second, start counting your coils. Count “one” each time the pickup pin passes top dead center. Stop winding when you've wound one coil MORE than your spring should have when finished, or when you run out of wire. DON'T LET THE “BACK” END OF THE WIRE PASS THE PIN ON THE WIRE GUIDE!
When you've stopped coiling, mark the top of the chuck with a chalk line, and write (on the chuck) the final coil count. You can rig up a pointer out of tie wire that will indicate when the chuck reaches the exact stopping point as marked by the line.
Back off the chuck SLOWLY until the spring is loose on the arbor. Don't let the pickup pin or one of the jaws of the chuck catch on the front end of the wire and start to “unwind” your spring! When the spring is loose, slide it off the arbor and cut the excess off the “back” end, leaving yourself what you need to form the longer of the two ends.
Put your spring into the oven and relieve the stress. For this trial, you can leave it in the oven for half an hour: all you want to do is make sure you have the right diameter.

The process of baing out the stress in the wire may change the dimensions of your spring. Stainless steel coils will generally expand slightly when heated: music wire coils will generally contract slightly.

When you've finished this process, let the spring air-dry and measure it to see how close you came to what you want. Check the diameter first. If it's not OK, don't bother going any further: you'll need a different arbor, which will change all the rest of your dimensions.

If the diameter is OK, count the number of coils in your spring. You should be pretty close: if you're only making one or two springs, being an eighth of a coil off either way is OK — you can always strip out or add a small amount of coil by hand. If you're more than an eighth of a coil off, figure out how much more or less you need and change the chalk mark on your chuck so that the next time you wind a spring, you can stop coiling at the right spot.

Lastly, look at the coils themselves. They should all lie flat against each other, all the way out to the ends of the spring body. If you see gaps in the body of the spring, that means that you let the wire guide go too far to the right while you were coiling. If you see a gap at one end (usually the “front” end), that means that when you started coiling, your wire guide was too far to the right of the pickup pin.
Finally, set this spring aside to use in setting up for bending the legs. If needed, repeat the coiling process again until you get what you want. At this point, you're ready to begin work on the ends.

Torsion Spring Ends:

When you coil your springs, it's a good idea to wind up a few extras so you can practice making whatever bends you need to the legs. When you have one spring that's exactly what you want, bends and all, stress relieve it again, doublecheck all your measurements, and, if possible, test it where it'll be used. Then, make all the bends in as many springs as you need.
Take the extra springs to figure out how best to form the ends the way you want them. There are a million different ways to form the ends of torsion springs, so what this section will tell you is general principles to follow.
Start with straight ends. If you're using light wire, the curve of the coil will probably make the ends of your springs curved. The curve is called “cast.” You can straighten it out by running the wire over your thumbnail or by bending the wire in the direction opposite to the cast by hand.
Heavy wire usually doesn't have this problem, unless it's stainless steel. To straighten heavy wire, secure the spring in a vise and use a pipe for leverage, straightening the wire by hand a little at a time.
Make your bends gradual. This is the difference between a gradual bend and a sharp bend:

A sharp bend may cause the wire to break when a load is placed on the spring. As you figure out how to form your ends, keep this in mind. The best tool to use for light wire is round-nose pliers.

Always relieve the stress in your springs again after you form the ends. A second stress relief won't likely change any dimensions, but it will allow the bends in the formed ends to stay in the shape you put them in when they're under load.

Easy Bends:

Here's a quick way to make torsion spring ends. It's not too precise, but then again, maybe your spring doesn't have to be, either.
Find a rod that you can use to make the bend. Try not to have it skinnier than twice the diameter of your wire.
Mount the rod in your vise, along with a pickup pin. Put the end of the spring between the pickup pin and the rod. Measure the distance so that when you're done, it comes out right.
Using a wire guide or a bending pipe, bend the end the way you want it. (With very light wire, you can do this by hand.) If the spring slips as you bend the end around, put some pressure on the coil body so that the pickup pin grabs it solidly.

If you're just making a few springs, you can probably get away with doing each one by hand.

If you want to make a lot of the same kind of spring, go ahead and make a more sophisticated bending jig — see the section on tooling for how to do this.

Extended hooks:

If you're making an extension spring with extended hooks, like this:

you'll need to treat the ends as if the spring was a torsion spring.
The first step in forming extended hooks is to make sure that the ends of the wire are straight. Having done that, the next step is to lay the ends over. Here's how you do this:

Take the narrow plate with the knife edge that you made when you were making tooling and shove it in between the coils of your spring, like this:
Put a spacer plate the same size as your wire across the bottom of your spring.
Put the layover plate you made across the end of the spring, a little below the center of the coil. At this point, the spring and the three plates should look like this:
Chuck the three plates — with the spring, if possible — up in a vise.
Using your hand (for light wire) or a pipe (for medium wire), bend the end of the spring down over the bending plate. While you do this, hold the spring down with your other hand so that it doesn't pop off the knife plate. You'll need to bend the wire MORE than 90 degrees to get a 90- degree bend.

The two most common bugs that happen when doing this are A) the end comes up outside the coil and B) the end hooks in toward the center of the spring.
To fix these errors, A) raise or B) lower the spacer plate.

This procedure will give you ends that come straight off the ends of the coil, and fom here you should be able to form hooks or loops, as you wish.

October 3, 2013

SETTING UP FOR COILING

This is the first of five pages that will tell you how to make springs. The information covered on this page is necessary, no matter what kind of spring you want to make.

The next pages, covering torsion springs, extension springs, compression springs, and finishing techniques, will round out the subject.

To get the most from these pages you should have your wire, your tools, and the design in mind for a spring you want to make. You should also print out this page and the page relating to the type of spring you want: that way you can get started right away.

The Arbor

Making springs by hand basically consists of bending wire around a rod called an arbor or mandrel. The arbor is secured in the chuck of a winding machine (typically either a drill, a hand winder, or a lathe). This section will tell you how to get the right diameter arbor, but it's also important to get the right length. Correct arbor length is important because it's difficult (not impossible, but difficult) to coil a spring on an arbor that's not long enough. Here's how to figure out how long your arbor has to be.

Estimate the amount of arbor you'll need to accommodate the spring itself.

Know that spring wire wound on an arbor will take up more space than the same spring will after it's off the arbor. How much more depends on the number of coils and the size of the wire. Generally, the more coils in the spring, the more it will contract after coiling. Also generally, the smaller the wire, the more space it will take up on the arbor. And lastly, the larger the arbor, the more room you'll need to accommodate your spring while coiling. A couple of examples might help with all this:
- A heavy torsion spring with 5 coils will generally not uncoil more than about 1/2 a coil after winding. Giving yourself as much slack as you can, your arbor might be 6-8" longer than the spring, plus whatever length you need to chuck it up.
- A similar torsion spring made from very light wire (same diameter arbor) will lose more coils, and take up more room on the arbor when coiling. Because it's short to begin with, though, the 6-8" addition to the arbor length should still be okay.
- A long extension spring (like on a screen door) should be wound on an arbor at least a foot longer than the spring itself, again plus whatever you need for the chuck.
Add in the amount of arbor you'll need to secure it safely in the chuck.
Add in a fudge factor — 10% will do — just for the heck of it.

Remember that your arbor should be at least the length you figure out here: there's no real maximum length until your winding machine won't support the weight.

The First Coils

Once you have your arbor, make a few coils to check the diameter. How you do this depends on what kind of machine you're using to coil your wire.

If you're using a drill:

First, make sure that your drill is mounted solidly. Best bet is to mount it in a vise. DON'T TRY TO HOLD ONTO A DRILL THAT'S BEING USED TO COIL WIRE!Mount your drill so that if you're standing with the drill in front of your left shoulder, the top of the chuck spins away from you when you turn it on.
Next, chuck up your arbor. The diameter of the arbor should be a little less than the inside diameter of the spring you want to make.
Get a piece of wire maybe a couple of feet long. Cut it off from the coil and make a 90-degree bend in one end, giving you a dogleg end about an inch long.
Put your wire guide onto the arbor. Hold it with your right hand and position it an inch or so away from the chuck.
Stick the dogleg end of your wire between the two topmost jaws of the drill chuck. Shove it in as far as the bend in the wire.
Bring the wire guide near enough for the wire to catch in the groove in the pin. Keep the wire guide away from the chuck. At this point, your setup should look something like this:
READ THIS STEP ALL THE WAY THROUGH BEFORE DOING IT!

When your setup is done, go ahead and turn on the drill. Keep the speed LOW, and keep your finger on the trigger. All you want to do is make a few coils, to check the diameter.

As the arbor starts to turn, two things will happen. The wire guide will “kick” upward: you can steady it with your right hand. It will also try to slide away to your right: let it slide for an inch or so, and then move your right hand to the left until the coils of wire lie flat against each other. What you're looking for is this:

Stop the drill before the “back” end of the wire reaches the pin in the wire guide. The gap in the diagram, by the way, is a good thing. If you see it while the coils are laying down, that means the coils will be tight up against each other when you're done. (In an extension spring, how tight the coils are is called “initial tension.” There's more info on this on the extension spring page.)
Reverse the drill SLOWLY until the coils hang free on the arbor. If you can't reverse the drill, you can grab the coils tight near the chuck and pull the dogleg out of the chuck. Loosen your grip on the coils slowly and let them unwind themselves until they're not under any tension. Then let go.
Slide the wire guide and the coils off the arbor. Check the diameter of the coils and see how close you are to what you want. Remember, if you need an exact diameter, the size of the coil may change when you relieve the stress in the spring. See the page on finishing techniques for information on this.
If the diameter is not what you want, go to a different size arbor, repeating steps 2-9 until the arbor is the right size.

That's it.

If you're using a hand winder:

First, make sure that your hand winder is mounted solidly. Mount it in a vise, or bolt it onto a workbench. Mount your hand winder so that the handle is to your left and the chuck is in front of your left shoulder.
Next, chuck up your arbor. The diameter of the arbor should be a little less than the inside diameter of the spring you want to make.
Get a piece of wire maybe a couple of feet long. Cut it off from the coil and make a 90-degree bend in one end, giving you a dogleg end about an inch long.
Put your wire guide onto the arbor. Hold it with your right hand and position it an inch or so away from the chuck.
Stick the dogleg end of your wire between the two topmost jaws of the drill chuck. Shove it in as far as the bend in the wire.
Bring the wire guide near enough for the wire to catch in the groove in the pin. Keep the wire guide away from the chuck. At this point, your setup should look something like this:
When your setup is done, go ahead and start turning the handle. Turn it so that the TOP of the chuck moves AWAY from you.

As the arbor starts to turn, two things will happen. The wire guide will press upward: you can steady it with your right hand. It will also try to slide away to your right: let it slide for an inch or so, and then move your right hand to the left until the coils of wire lie flat against each other. What you're looking for is this:

Stop turning the handle when you have three or more complete coils side by side on the arbor.

The gap in the diagram, by the way, is a good thing. If you see it while the coils are laying down, that means the coils will be tight up against each other when you're done. (In an extension spring, how tight the coils are is called “initial tension.” There's more info on this on the extension spring page.)
Turn the handle the other way SLOWLY until the coils hang free on the arbor. Don't unwind so far that one of the jaws of the chuck catches the wire dogleg and starts to unwind the spring for you!
Slide the wire guide and the coils off the arbor. Check the diameter of the coils and see how close you are to what you want. Remember, if you need an exact diameter, the size of the coil may change when you relieve the stress in the spring. See the page on finishing techniques for information on this.
If the diameter is not what you want, change your arbor, repeating steps 2-9 until the spring is the right size.

That's it.

If you're using a lathe:

If this is the first time you're using the lathe, make sure you're familiar with it. Know how to stop the dang thing before you turn it on! Also, make sure you have a clear space around you (common sense).
Next, chuck up your arbor. The diameter of the arbor should be a little less than the inside diameter of the spring you want to make.
If you're using a four-jaw chuck, you'll have to center your arbor. Do this by turning on the lathe and holding a piece of chalk in your hand, right next to the tool post. Move your hand slowly towards the arbor until the chalk leaves a mark. Then, stop the lathe and adjust the jaws of the chuck so that the arbor moves away from the mark. Tighten the jaws and do this again, until the arbor is close to being centered (it doesn't have to be exact).

Next, back off one of the jaws of the chuck and put your pickup pin between the jaw and the arbor. Let it stick out past the end of the jaw about twice the diameter of the wire you'll be using (see the diagram below).
What type of wire guide you use depends on how heavy your wire is. For medium and light wire, you can use the same type of guide as for a hand winder or drill: for heavy wire (over about ¼"), use a tool post-mounted wire guide. If you're using light wire, you can read the directions for this step as if you were using a hand winder (above). Otherwise, complete this step as below.

Put your wire guide into the tool post. It should be positioned just a little under the top of the arbor. With small wire, the distance between the arbor and the wire guide should be fairly close; for medium wire, 3-6"; for heavy wire, 6-12". The groove in your wire guide should also be fairly close to the tool post: the heavier the wire, the closer it should be. Cinch the wire guide down TIGHT.

This is what your setup should look like edge-on from where you're standing:

Note the horizontal clearance between the right end of the pickup pin and the left end of the wire guide.
Get a piece of wire a few feet long (the heavier the wire, the longer the piece: also, the bigger the arbor, the longer the piece). Cut it off from the coil.
Position the pickup pin of the lathe at the top of the chuck and thread your wire UNDER the wire guide, OVER the arbor, and UNDER the pickup pin. At this point, your setup should look something like this:
READ THIS STEP ALL THE WAY THROUGH BEFORE DOING IT!

Before you start the lathe, make sure you have one hand on the motor control and the other on the lead screw lever. (If you're coiling without a lead screw, see the section oncompression springs on how to control the motion of the tool post as you coil.) Reach UNDER the wire with this hand, so that if the wire guide breaks, the wire will not snap upwards and catch you in the armpit.

Start the lathe DEAD SLOW so that the TOP of the chuck moves AWAY from you. Keep the tool post steady and watch the “front” end of the wire as it comes around. It should clear the ways and the wire guide.

As the arbor starts to turn, the wire will close up on itself. Keep the tool post steady until a small gap appears in the coils, like this.

When this gap appears, let the tool post move slowly to the right and continue coiling until you have about three full coils side by side on the arbor:
Stop the lathe and run it backwards SLOWLY until the coils hang free on the arbor. Don't let the “front” end of the wire catch on the jaws of the chuck as they come around.
Slide the coils off the arbor and check the diameter to see how close you are to what you want. Remember, if you need an exact diameter, the size of the coil may change when you relieve the stress in the spring. See the page on finishing techniques for information on this.
If the diameter is not what you want, change your arbor, repeating steps 2-9 until it's the right size.

That's it.

Left-Handed Springs:

There's one more little oddity you should know about: torsion springs come left-handed and right- handed:

Depending on what you want your spring to do, you may need one or the other, or both. The setups described above tell you how to set up for a right-handed spring. If you want to make a left-handed spring, you'll need to make a left-handed setup because a right-handed setup will not work for a left-handed spring!

Left-Handed Spring Setup:

Everything you read about setups for right-handed springs is exactly the same for left-handed springs, except for two things. When winding a left-handed spring:

The wire will travel OVER the pin on the wire guide, UNDER the arbor, and OVER the pickup pin.
The top of the chuck will be going TOWARD you as you make your coils.

The basic setup for a tool post-mounted wire guide will look like this:

The only tooling modification you'll need is if you're using a hand-held wire guide: the guide pin will need to stick out in the opposite direction from what was shown above.

The only difference this will make is that your first coil count will be somewhat of a guess, because you won't be able to see when the gap passes bottom dead center of the arbor. On your second trial spring, though, you should be able to correct this exactly with your chalk mark.

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