This is the method (more or less) employed by the magnificent Gogglerman in many of his designs. In some areas this method is even an improvement. I do not pretend that my finished product is anywhere near the same league as Gogglerman. The man is a true artist; a savant even in the way he solves design problems.
But where the master shows off his work he does not like to spend time explaining his process. Many who comment on Gogglerman's work complain (rather aggressively) that he does not give step by step instructions on how to make what he's showing. I intend, only, to fill that void.
This is my first instructable, so constructive criticism is, of course, welcome.
Keep in mind please, I am an artificer not an artist. The techniques I describe can be used with greater skill and creativity than I possess to create works of art. They are employed by myself only to solve a problem and the final product is often aesthetically inelegant.
Step 1: Design
In this example I'm making goggles that are about 2inches in diameter. It's not all that important (to me) if that number is a little off, so long as both eye-cups are the same dimension. If you demand precision, it is a simple matter of taking much more time with your mensuration.
The diameter * PI = the circumference as well as the nominal width of our template. the 'length' of the eye-cup will be about 3 inches which is also the height our template must be. For reasons I will describe later, I add about an eighth of an inch to each side of the pattern,
To conform to our face the goggle eye-cup will need to be shorter at the bridge of the nose than it is near the temple.
To do this center a ruler horizontally against the bridge of your nose, centered vertically on the pupil of each eye.
Take a rounded straight object like a pencil (eraser end) and hold it against the face about an inch from your pupil. This is the point on the temple side. Mark the distance between the face and your ruler at this point and measure it.
Draw a line on a piece of paper the same length as the eye-cup circumference, in this case about 6.3 inches. At each end draw a perpendicular line up the page the length of the measurement we took earlier.
Mark the halfway point on the horizontal line and then draw a nice sine connecting the top of the 2 vertical lines. You can get fancy and measure the contour of your face perfectly but it's not really needed.
Now extend each of those vertical lines below the horizontal line by the 'extra' length you want for your eye-cups. By extra I mean the part that extends past the bridge of your nose. My pattern added about a half inch for this.
Add an eighth of an inch to each side and cut it out.
What we have now is a sheet metal pattern for the eye-cups that puts the seam on the outer extreme of the goggles, nearest the temple. For aesthetic reasons or a host of other kinds of reasons you may wish the joint to be somewhere else. To do this, cut the pattern where you would prefer the seam and join the two longest edges. Do this before you add the two eighth inch bits to the edges of the pattern.
Step 2: Tools and Materials
Every tool used in this process you either have already or you should have it, don't have it, and need to go buy it. No expensive tools. Read through the guide and find out what you need and go get it. I'll wait.
I'll call the tools out as I go instead of listing them all.
I use copper almost exclusively. In many ways it's easier to work, than brass. If you really want brass knock yourself out.
Something you might not have already is silver brazing material. Do not get 'Silver Bearing' solder from the hardware store. You need what is called hard-solder or brazing filler. Probably have to get it from a welding supply like airgas.
I strongly recommend 'Stay-Silv 5' made by Radnor and sold at most welding supplies. The reason I like it is it is very high temp (1600F) solder which makes doing follow up brazings or repairing a brazing less likely to open a pre-existing joint. (more on that later). Also, the Stay-Silv 5 is a phosphor bearing alloy which makes is self-fluxing when you are joining copper to copper. I still flux and recommend the stay-silv white flux but a bit of borax will work too.
If you have sheet metal, great. I don't. It's expensive and hard to come by for the average guy.
Luckily copper pipe is plentiful and cheap (compared to the cost of sheet copper).
For this pattern I need a piece of sheet that is 3 inches wide. When you buy copper pipe the 'size' is what's called the nominal size and has stopped having any relation to the pipe's actual size generations ago. 3/4 inch copper pipe is actually about 1 inch diameter. 1 inch times PI equals 3.14 inches. Perfect.
For this pattern we need sheet that is about 6.5 inches long. Easy. Get your pipe cutter and cut 2 6.5 inch lengths of your copper pipe. While you're at it cut another 2 sections of pipe about 4 inches long. These will be the flaring that contours to the face.
Now we have all that, the next step is to make sheet metal.
Step 3: Making the Sheet Metal Pt. 1
Annealing copper (or brass or bronze) is easy to do and should be done often if you are working the metal a lot.
All it entails is heating the metal up to a dull cherry red glow for a few seconds. A propane torch works fine for this but one using MAPP will work better. MAPP comes in the yellow canister and burns a fair bit hotter than propane. It's also not really MAPP anymore if anyone cares but the stuff that's in the yellow can works.
Once you have had the whole piece glowing (doesn't have to be all glowing at the same time) you can dunk it in a bucket of water to quench it.
Use pliers to move the metal. It's hot.
Common misconception about quenching is that it makes the metal brittle. It doesn't. Not on base metals.
Once the metal hits the water it sheds all of its heat and is cold to the touch almost instantly.
Step 4: Making the Sheet Metal Pt. 2
Cut a straight line the length of the pipe, then open the pipe up with pliers and tap it flat with a hammer. I use a small anvil but the back of a vice or a decently sturdy workbench surface will do.
The final picture in this step shows the 2 sheets for the eye-cups and the 2 sheets that will be used for the flange.
Step 5: Mark and Cut the Eye-cups.
Using tin-snips or some kind of shears, cut out the pattern as well as possible. The tight curve can be tricky, use a Nibbler to finish the curve if need be. The nibbler cutter punches a tiny bit of metal at a time and can make very tight cuts.
Use the newly cut sheet as a template for the second sheet. Cut that one out as well.
Once you have them both cut, clamp them together and use a file or grinder wheel to true them up to each other.
You can see a 1.5" grinder wheel chucked into my drill-press. A drill-press is a shop necessity. The one I use most is $50 at harbor freight and works fine. In high-speed it spins at 3100rpm which is a respectable speed for grinding and buffing.
Step 6: Form the Cup
To achieve this I am using a style of joint called 'Cramping'. With a cramped seam both of the edges are hammered to half their normal thickness and then a series of cuts is made along one or both edges.
The cuts form tabs that are then alternately bent in and out. The second edge is either left uncut or is prepared in a similar manner so that when put together the 2 edges mesh and overlap. Before bringing the edges together clean them with a wire wheel and lay a thin coat of flux,
To form the cup I use a small length of 1 1/4 inch steel pipe as a mandrel. It's not important to get a perfectly round shape at this point. More important is getting the 'cramped' edges to mesh properly. If things aren't perfect, don't sweat it. The grinding wheel can atone for many sins.
Once the edges are nicely joined, press the tabs flat with pliers and hammer then tight against the mandrel.
Do that for both cups.
Step 7: Braze the Eye-Cup Seam
Brazing is not rocket science. Work needs to be clean and bright, throw some flux in the general area, add enough heat to get the copper glowing dull red, and run the tip of the silver solder into the seam. When you're done, quench it and wipe of the soot with a rag and hold it up to the light. If light leaks through, polish that bit up again, flux it and go to it. Try to keep the heat localized to where you are repairing, but with this high-temp solder it's much easier to do.
The Stay-Silv 5 I mentioned specifically is formulated to fill gaps. It works.
The pictures show the finished joint, and again after a quick trip to the wire wheel.
Personally I like the looks of it, rather like a sutured wound. Some don't. It can be covered by a strap of metal or leather. Or, as I show later, it can be filed and sanded flush so that the seam disappears.
An alternative to this style of joint would be a simple 'lap joint', where the two edges overlap a bit. I have to caution against this as it's impossible to hold the joint tight enough while brazing it to make a good bond.
Mechanical joints, instead of brazing, are an option. I rather think a row of rivets would look nice. But they wouldn't be as strong and if I really want a row of rivets I can add them as a decorative flourish to this joint.
Now that the seam is done round out the eye-cup with the mandrel.
Step 8: Making the Flange.
Take a sheet and lay the eye-cup on it as shown.
Trace the interior hole, then design the shape of the flange around that hole.
I do one half first, cut it out and clean it up a bit (not perfect) then use that to mirror the second piece.
When both are cut out, true them up to each other and clean up the edged of the eye-cup and the flange.
First bend the flange into a tighter curve than it really needs. This is so it will fight you when you tie it to the eye-cup.
Use steel wire like a twist-tie to hold the pieces together. Use a pair of pliers to twist the wire and it will draw the two pieces tight.
Flux the joint and fire up the torch.
Use the torch to heat the metal then let the metal heat the solder.
Be careful not to burn the steel wire early. Once a few spots have been done it should hold well.
You can layer the solder somewhat to fill gaps. Getting the gaps closed tight before you start brazing is a better plan.
Step 9: Rounding Over the Eye-Cups
More importantly it adds strength to the finished product and preserves the round shape.
I accomplished this with my trusty 6 inch length of 1 1/4 inch steel pipe. I have it planted vertically in a milling vice but any old vice will work.
Place the top piece so that the edge is about a quarter inch above the top of the pipe. then tap it in with a small hammer.
Do a little at a time all the way around the piece until you are hammering straight down onto the pipe to put that last flattening face on the goggle.
Last step in this process is to grind off any extra material from the flange where it meets the eye-cup. It's unlikely that the hole you cut in the flange sheet and the hole in the eye-cup came out a perfect fit, so where the flange intrudes past the soldered joint it will need to be removed. The 1.5 inch grinder works well.
Note: Grinding copper produces a great deal of heat which can sneak up on you. Keep a bucket of water near the grinder and quench the piece regularly. You will hear it sizzle.
The last pic of this step shows both pieces at this stage of the process.
Step 10: Some Finishing Touches Then You're on Your Own
You could drill a zillion holes and sew it to a leather mask. I won't judge.
You can hinge the two halves together or join it with a rigid connection of bar-stock and screws. Or Rivets. Or maybe you made the whole flange out of one piece of metal.
You can rivet a loop at the sides for a strap. Or notch a slot right on the piece to feed the strap through.
As I mentioned, the pics below show the cramp seam after it has been ground flush on the wheel and polished a little. If I had used a little more care and attention in laying the seam it could have been made to disappear completely.
If you are just married to the idea of brass goggles, you have two choices. You can electro-plate the copper.
An easier choice is to get a bit of plumbers solder. It is 95% tin. Heat the copper up til glowing and lay down a bit of the tin. Brass is an alloy of copper and zinc, but bronze, which is just as cool, is an allow of copper and .... tin. Doing it this way creates a very thin plating of the alloy.
So... get to it!
If you are flat out stuck on the idea, Zinc can be bought cheaply and applied just like the tin but it's a much more finicky process and if it gets too hot the zinc will burn like a magnesium flare and give off poisonous gas. Fun!
Step 11: [Update!] Epilogue
I should probably cut a leather strap for it and put some lenses in and decide on a surface finish for it (patina, sandblasted, wire brushed, hammered, or high gloss). But that will have to wait
I'm looking for someone to take them off my hands and that person may have a preference. I don't. So it can wait until then.