Introduction: How to Make a Round Thing Without a Lathe (plus Model Making Tips)

Picture of How to Make a Round Thing Without a Lathe (plus Model Making Tips)

You want to make a model of something that you've seen in a film, but it's round and has lovely compound curves and you don't have a lathe. Don't worry, this instructable will show you how you can use a simple profile and some car resin filler to get a lovely round shape with out using any machines at all.

For me I used it to make this alethiometer from the book Northern Lights (aka the Golden Compass in the US) and shortly to be released as this Christmas's big hit, the Golden Compass. Which looking at the trailers is a mixture of Riven (the game for those that know), Steam Punk and a bit of Round the World in 80 Days thrown in for good measure.

Full instructions on how to use this instructable to make a Golden Compass can be found on my website dadcandohere, including free printable templates for all the graphics and an accurate profile template guide.

But then you can make loads of round things using this method... I'm sure you'll think of them. Post pictures here if you do, we'd love to see them.

Step 1: Make the Basic Shape

Picture of Make the Basic Shape

In this case I wanted a flat disc a little bit like a large ice hocky puck or in fact a pocket watch, to match the shape of the device drawn on the front of the book. I made my basic shape out of cardboard, but really you can make it out of anything.

Model Maker's TIP #1

If you model is of something that has weight, i.e. it is made out of metal, plan to fill it with some ballast. This will make the final model much more realistic and fool people into thinking that it has been made out of metal, or has more of a quality feel to it. But be careful not to stick anything over the centre hole area, you are going to need to be able to poke something through the card right there in the next step.

In this case I cut two discs and then used up right spacers to make sure they were at a constant space apart and then wrapped a piece of card round the assembly to give me the disc shape.

Step 2: Make and Insert a Spindle

Picture of Make and Insert a Spindle

Using a piece of straight coat hanger wire push it through the cardboard disc so that it is on the axis of the shape you want to "turn", i.e. it is as close as possible to being at right angles with the top and bottom surfaces. If you have trouble pushing it through, make a (very) small nick in the surface with a craft knife first (just to break the surface) and to get started.

It should be a nice snug fit, but be able to turn. This is what you are going to stick you profile on to.

Step 3: Stick a Rough Handle on the Bottom

Picture of Stick a Rough Handle on the Bottom

Model Maker's tip #2 Think how you are going to hold the project while you make it!

Model makers often run into into the problem of how to hold something small or fiddly or awkward shaped when making, finishing or painting a model. The way they get round it is they stick a handle on to the model that they are going to remove later in a place that no one will look, or in a place where the mark left when the handle is removed can be covered up later.

For small things this might mean super gluing (cyano-acrylate) a cocktail stick to the edge of something small, right up to resin gluing a piece of doweling or a metal bracket to something big.

In this case you are going to need some way of turning the disc when it is covered in wet filler, so this handle will do nicely. later in the model we will remove it and cover the mark with some flat filler.

Obviously don't put the handle over the centre hole area. It needs to be central but not over the place where the hole is going to be and clearly not overhanging the edges, because we are going to be making a profile there.

Step 4: Cut Your Profile

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Measure the crucial dimensions of your basic form (you should already know them from making it to the right shape. But if you are anything like me and make it up as you go along... now is the time to get measuring. Draw up your profile on a piece of paper. and cut out and offer up to the basic form. if it fits and can rotate around the axis without fouling any where (being stopped turning), then the profile is right and you can stick the paper to a piece of plastic and cut it out.

I always like to use what I have lying around, and the plastic I used for this model profile was from an old detergent bottle that had reasonably straight sides from which I could cut a big enough shape to hold.

Glue your profile to the wire coat hanger making sure that it is nice and square to the rotation axis of the basic form. I used glue gun glue and then sticky tape to make sure that it stayed put. You don't want it coming off half way through the exercise.

NOTE: I tried cardboard for the profile, but it could not keep a clean edge.

Step 5: Mix Up Some Filler and Start Spreading It Round With the Profile

Picture of Mix Up Some Filler and Start Spreading It Round With the Profile

It's magic, you shape starts to appear immediately. try to make the shape as clear as possible, but you don't need to do all the shape at once. In fact this is almost impossible so don't try it. You are going to be building your shape up over a few goes. ( I have pictures of each step). Given the resin only takes about 10 minutes to go off, this process won't take that long, even if you have to do 6 layers!

Between each layer trim off any wayward prongs or bulges that impede the easy rotation of your profile, i.e. stick up in the way of the profile, If you are using car filler resin (see below) then the best time to do this is when the resin is in the gelling phase as it is going off. Be quick, the gelling phase is only about 30 seconds to 1 minute long. This type of resin is called a "snap cure" and once the setting reaction gets going it is a driven by what is called an avalanche effect at the molecular level. Once it is set the only real way to remove lumps and bumps is by rasping, filing or sanding. (note always wear a mask when doing this to avoid inhaling the dust). In the gelling phase the resin is hard enough to keep it's shape but cuts like rubber, so quick gross modeling is possible then. However, be careful, before it is set it is not stuck that well so you can also dislodge what you have just made, if you cut to aggressively.

As for the filler I used... My favourite is two part auto body repair filler (resin car bodywork filler). You mix it up from a big pot of resin and a tiny bit of hardener.

Model makers like two part fillers because they set very hard very quickly and can be sanded very smooth and take paint well.

Model Maker's Tip #3 Use two part car filler to make nice fillets round you models, and even cast the odd detail (if you have a suitable mould pattern).

TIPS...
Don't put the mixed up resin covered spatula back in the pot to get more, the hardener on the tip will set off a reaction that hardens the whole tin.

Be ready with your profile before you mix up, once mixed up, the resin is going off and will become very hard so you don't have much time to get things right

If you want it to go off quicker mix a tiny bit more hardener, but be careful too much and it will set as you are mixing it.

CAUTION
It sticks to anything and once hard is impossible to remove, either wipe it off straight away when it is semi liquid or wait till it is in the gelling pahse and chip off quickly (very quickly) before it is stuck.
It gives off fumes so open a window when using resin filler

Step 6: Put More Filler on and Shape With Profile

Picture of Put More Filler on and Shape With Profile

In total I did about 6 applications of filler. I have shown pictures taken at stages 2-3-4, here. Looking good. I took the profile out after each application so that I could chip the filler off it between each application so that I got a neat shape.

At step 4 the handle fell off the back. I just glue gunned it back on, it was only cardboard after all, and I still need it for a couple more goes.

Step 7: Put Filler on Shape With Profile and Sandpaper

Picture of Put Filler on Shape With Profile and Sandpaper

Stages 5 - 6
Maybe you already had a quick go at sanding down between each application. if not now is the time to start doing that. Start with coarse paper P80 or P100 go with the curve and don't worry too much as you know that the next application will fill all the scratches left by the grit on the paper. After the final application you will want to move first to about a P200 and then finally to a really fine paper. I used P600, but that was only because that was the finest I could get in my hardware / DIY store.

You might note the slight colour change from the photos as we go along, this is just my digital camera and the fact that the sun was going in and out. These pictures were taken at each stage so that you can see how much filler went on and how much the shape evolved at each stage.

Looks nearly done now (shape wise that is).

Step 8: Finish Off the Back

Picture of Finish Off the Back

If you want a curved back then really you have to do the same again, on the back. For me, I was happy having a flat back, so I just pulled off the handle (carefully), filled in the hole with filler, sanded, filled, sanded and that was that.

It looks soo cool now I could almost each it.

Step 9: Spray or Paint the Project

Picture of Spray or Paint the Project

What you do now depends on how eager you are to finish it off, or whether you are prepared to do a perfect job. If it's the latter you want to go for then you should spray with undercoat first and sand down with very fine paper, say P800 or finer, between each coat.

For me I just wanted to get on and I had no primer anyway.

As you can see here I sprayed and then sanded off, because I sprayed too much and it started to run. If that happens to you. bite the bullet and remove at once using thinners and a rag. make sure you don't get a load of lint fibres and dust stuck to the surface. Rub down with sandpaper till fine and start again.

Model Maker's Tip #2 (yes I know I have already had a tip #2) But this is the same one.

Remember the tip? find someway of holding the model so that you can spray it and then leave it to dry without it getting stuck to something or getting marks on it. I guess the tip here is THINK of this before you start to spray and not half way through when it is wet! In this case I gently rested the disc on a coat hanger wire poked into the hole that was left in the top, as the hole in the base was filled.

You could use any bit of spare real estate. In real models, witness marks (the marks left when where something that was holding the original moudling is removed) are usually covered by a label or another component.

Step 10: Spray or Paint the Final Top Coat

Picture of Spray or Paint the Final Top Coat

Oops sprayed my thumb, but oh joy... it's finished, and boy doesn't it look trick. Don't get impatient now. All this hard work will go to waste it you handle the finished thing before it is dry. Find some way of propping you work piece up while it is drying. In this case i used a small desk top vice to grip the coat hanger wire, but a hole in the top of a scrap of wood would work just as well. Make the stand or place to rest the piece BEFORE you start spraying. Don't make it anywhere it will get disturbed, and leave it for as long as possible to make sure the paint is really hard and dry. over night should help, somewhere warm would be good... you get the picture.

Woo Hoo, but... this is just the basic shape of my Alethiometer. Theres a whole lot more to be done to make it in to that model... but that is another story and for the full instructions of how to make the Alethiometer and all the templates needed, you can get them at dadcando right here. But then this is only one of the 100s of things you could make using this simple technique.

NOTE: for the glorious paint i just used a can of BRILLIANT metallic paint which in my hardware / DIY store come in both gold and chrome and gives the most outrageous finish, if the surface is nice perfectly smooth, perfect for showing off all those lovely complex curves.

If you make something don't forget to post a picture of it.

Comments

bigb0986 (author)2014-06-20

How can i get DIY Magazines Plz Help I am from pakistan

padbravo (author)2013-10-02

great way to do it!

I'll try to remember (and bookmark this) for the next project...

throbscottle (author)2011-07-02

This rocks! I shall try the technique to make pulleys!

verdastel (author)2010-12-26

A state of art indeed!

underkill (author)2010-03-18

 Absolutely brilliant tutorial.

KaptinScarlet (author)underkill2010-03-18

thank you

jamwaffles (author)2010-03-15

This is genius man!

KaptinScarlet (author)jamwaffles2010-03-16

glad you like it... it's a time honoured technique, I'm just passing the baton on

jamwaffles (author)KaptinScarlet2010-03-17

well its been passed on in style. Also, i'm guessing this would work using a lost-foam (instead of lost-wax) technique?

cheers

billhorvath (author)2010-03-15

A laser cutter would be the perfect tool for cutting the profile to spec, if you have access to one.

great idea

Blakeney (author)2010-03-14

You are absolutely brilliant! I've been wishing forever that I had a lathe for small jewelry projects but don't have the money to buy one or the time for the learning process right now - will have to give this a try. I remember your Harry Pottter wand tutorial on dadcando - another amazing use of humble resources!

KaptinScarlet (author)Blakeney2010-03-16

thanks that's nice

iminthebathroom (author)2010-03-14

Awesome - This is one of those instructables you go back to a year later when the need arises.  Its like the maker version of learning how to tie a tie.  Simple, yet elegant technique that breaks down a daunting task for the first timer.  Thanks!

thanks, that was the idea

Patent Dragon (author)2010-02-04

This could be JUST the technique I need for a similar prop device I have in mind. I'm sure that, once I read through the instructions several times, AND check out all the comments, I should have all I need to know. I discovered this instructable quite by chance, and I'm so glad I did!

Glad to hear it. this is an old modelmaker's technique for making complex shapes using filler and a former. This instructable uses a roiund one, but basically if you want to make complex curved surfaces then a former and repeated sanding and filling (using the former) is definitely the way to go.

Thanks for the comments.

kaptaink_cg (author)2010-03-14

Pretty clever!

thanks

Broom (author)2010-03-14

You're brilliant, your work is beautiful. Kudos! And thanks!

KaptinScarlet (author)Broom2010-03-14

thank you, that is a very kind thing to say. Cheers

mg0930mg (author)2009-02-17

I found an error in step 10, the stuff is not free....

KaptinScarlet (author)mg0930mg2009-02-17

Sorry about that, now corrected. I had to start charging (only a small amount) for dadcando as it was costing me too much to offer it for free. It's only £9.95 per year or 95p per project, which is not much really. But thanks for spotting that mistake.

mg0930mg (author)KaptinScarlet2009-02-18

Cool, any new projects coming soon. Also do you know how much that would be in american dollars.

KaptinScarlet (author)mg0930mg2009-02-18

$14.17 at today's exchange rate I believe. Loads more projects coming up. Going to be working on some projects with a National Newspaper here in the UK This week I am trying to get a new paper plane done. I try to keep the new projects coming over a wide range of ideas. What's your favorite type of project??

mg0930mg (author)KaptinScarlet2009-02-18

I may pay it if I get money soon.... sigh, although I do need to make some stuff to sell... ANYWAY, enough babbbling. My favorite projects, have to be movie props, or book props, or anything cool like that .I like a lot of your projects, almost all of them.

Kaiven (author)2009-01-23

Haha! I found another error! Step 8, I can almost each it xD

Kaiven (author)Kaiven2009-01-23

And step 10, prpping you work piece.

mweston (author)2009-01-03

After step 7 you could get a machine screw and nut then place the screw through the center hole and tighten it with the nut. Put the remaining screw in a drill and use it as if it were a lathe to sand down the sides and top - I did this all the time when I made circular wood... thingys Cool project otherwise, the bondo mold was pretty creative!

AnarchistAsian (author)2009-01-03

woahhh, my sister would like this too... curse you for making stuff my sister likes

foobear (author)2008-04-23

I'm impressed by your ability to make such a uniformly smooth object out of this stuff. After an hour of sanding, mine went from looking like a stone birthday cake to a crude pitted wheel made by some prehistoric tribe. I guess I need Sanding 101 or Bondo 101 class. It would be interesting to see a video of how you did the bondo step. You made it look easy, but I'm finding it isn't.

KaptinScarlet (author)foobear2008-04-23

OK, you need to start off with coarse grit paper, and I mean coarse 40 or 60 I think. then when you use the form to sweep round you do it lots of times and sand a bit between each time. To start with the shape looks rubbish but each time you do the sweeping round with new filler, the form makes sure that all the old gaps and cracks are filled by the filler. Don't try and put too much on to start with. when a layer has set, sand off coarsely until you can easily turn the form round without it snagging. Then mix up some more stuff and smear it on again. When you are putting stuff on that is smoothly going in the scratches of the previous snadpaper it's time to switch to finer grade sandpaper. It might seem tricky, but it's just a step wise process. However, the filler is tricky to handle when it has just been mixed up and it can be to fluid and then once it starts curing it goes off very quickly (it is called snap cure), so some practice is needed. Don't get too disheartened, I had to chuck my first one away, because I used wood filler and it wasn't smooth enough, nor easy enough to sweep round. BTW, this is one of the standard ways in which model makers make flowing curves on their models. AND yes, those styrene vapours over the years have probably killed off many brain cells and totally wasted my sense of smell, but it is an odour that reminds me of all my model making, so it is a happy smell for me. Good Luck, do get back to me and tell me how it's going, and send pictures in if you have them.

foobear (author)KaptinScarlet2008-04-26

Well, I finally did it. I could not resist trying to make it "work" (fingers making quoting gesture). So, here it is. I had to enlarge the pattern to allow for the workings inside (composed mostly of a pc fan and a meter needle from an old analog meter). I could not achieve the beautiful perfection of your finished piece. I struggled quite a bit with that. Maybe I could come up with some sort of old beat up tarnished look for it to make the blemishes just look like wear and tear. To your instructions I would add that the detergent bottle plastic for the profile is more of a necessity than nicety. I didn't get a clean edge as you mentioned until I used that. I also used a mask while sanding the bondo, which is good because I found that my entire work room is coated with a fine particulate dust of the stuff everywhere! So, if I were to do it again, I'd try to cover everything up with some cloth or something first. When I get a little more time and motivation, I am going to redo the faceplate and figure out how to make the crown glass part come out right. I just need to purchase some ink jet transparancies I think.

KaptinScarlet (author)foobear2008-04-27

That's amazing. The forming thing has worked really well. I know what you mean about the plastic forme. I would be even better if you were to make a profile from a thin sheet of acrylic, but I am fixated by making things from junk... mostly. However I'll look at the instructions and modify them. I love the video and the motor inside is a real bonus and innovation and very brave. How do you power it? BTW... I am redesigning dadcando at the moment and within about a month there will be a facility to upload pictures of your projects and each week I will be giving away prizes for the best. So keep an eye on dadcando, as this project looks as if it would definitely win!

foobear (author)KaptinScarlet2008-04-27

Yes, making things from junk is a great idea. The thick plastic of the detergent bottle worked great and was flexible and soft. Acrylic is too hard to cut I think, for me it shatters. The computer fan inside the contraption is powered by a little 9 volt rectangular battery. Turns out I only need one moving hand for it to work "correctly", so I might revamp it to work the way it's supposed to. I was at a loss as to how to solve the problem of the opening in the back/bottom for putting the parts in and changing the batteries. So I just put a thin wooden sheet in the back that I could lift in and out, but it doesn't look so nice as yours does. Ooh a contest, love those. Thanks, I'll keep an eye out on your site.

foobear (author)KaptinScarlet2008-04-26


Here is a video of the thing in action. Like all magical devices, it is frequently reluctant to work until the energies are right. :)
foobear (author)2008-04-21

I'm trying to find the filler you mention: two part auto body repair filler (resin car bodywork filler). Does it have a brand name?

KaptinScarlet (author)foobear2008-04-23

There are various brands, but i bet they are differnt in the US (from the UK), but any body filler should do the trick, like this one Get an easy sand one, that will be one with more talc and less resin in the mix. A quick search on the web for body filler should find something. you want two part epoxy so that it sets really fast. Read the instruction before mixing it up. you'll only need a $10 or less can for this project, and even then you'll have loads left over for the next project!

foobear (author)KaptinScarlet2008-04-23

Thanks, I found some bondo auto filler two part stuff at the auto shop for $11.00. My god, how do you cope with the vapours? I wore a new two cartridge organic vapor mask and I could still smell the ghastly heady smell of the bondo through it, while working outdoors. Phew!!

benide (author)2008-04-18

Great instructable! Thanks, I think I'll use your tips this weekend. BTW, I've found that I can get a really smooth sanding job by using a piece torn from a paper bag. It like the equivalent of P1200 -1400, and very cheap and easy to obtain.

KaptinScarlet (author)benide2008-04-23

good idea about the bag, but only when you have flatted off the shape with coarser grit paper, otherwise you will be there forever!

GorillazMiko (author)2008-01-27

I forgot, what was the program you used again to make the awesome pictures? And how do you take such great photos, they're awesome!

I use Macromedia Freehand, but Illustrator would do, or in fact any vector line drawing application. The Photos, light carefully using natural light, not too harsh tho and then loads of retouching in Adobe Photoshop to try and get the best out of the images. easy really, just takes a bit of time and practice.

mg0930mg (author)2007-12-01

I just saw the sneak preview tonight it was awesome can't wait to make this.

KaptinScarlet (author)mg0930mg2007-12-03

I've seen clips of the film, but I have yet to see the whole film. I guess that when I do I am going to have to make a new alethiometer to match the one in the film rather than the one in the book! BUT yes the film does look awesome.

KaptinScarlet (author)2007-11-19

yup. and if you go to dadcando you'll find the whole Alethiometer project described with full instructions and a print out of the dial

smokehill (author)2007-10-01

A very clever approach, and well-explained. For most things, though, I think I'd probably just use my electric drill to turn the object, sort of like a lathe. Or pick up one of those old electric shoe-buffers, or an old record player, at a yard sale. I used one of those hand-held shoe buffers to polish the brass on my Army uniform for many years. The "moving part" is usually a 3 or 4-inch plastic disk that revolves, so I'd just put a loop of masking tape (sticky-side-out) in the middle of the disk, turn it on, and touch a ballpoint pen somewhere near the middle of the sticky tape to find the exact center --- much easier than it sounds, once you try it. Then I'd stick the brass (a flat brass circle the size of a quarter, with a hole in the middle) on the sticky tape, centered as well as possible, fire up the machine, and hold the polishing cloth against the spinning disk. In a couple of seconds you can then hold a clean cloth against it to finish it off, and the shine is spectacular. Since everyone else's uniform brass was polished normally, with random motions, mine stood out, throwing rainbow-like symmetrical reflections in the sunlight. I like your low-tech approach, too, but am too lazy to use it when I can pick up an old phonograph turntable for five bucks and have a lot of fun playing with it as a potter's wheel, or low-speed lathe, etc.

Edgar (author)2007-09-25

You DID saw this last post of mine, with the correct "The Boy mechanic" Link, below?

Edgar (author)2007-09-22

Just saw dadcando, and I'm green with envy!

Great site, man! Great Site!

You know, you can take a look at my Site,
Bulid your own Prototype and if you find any good idea, add it for your site, to build stuff for kids!

Edgar (author)Edgar2007-09-24

Had a catch there, sorry, it was "the boy mechanic", just click this:
http://www.gutenberg.org/etext/12655
Everything from a Tesla Turbine to a neat 12 cannon balls out of a bowling bag trick, I know the kids will love that!

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Bio: Eldest of five, son of two doctors, 10 years in Graphic Design and marketing, then retrained as a Biomedical Materials Engineer, don't ask me ... More »
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