Valentine's day jewellery project

Making stuff, breaking stuff, tearing stuff apart. Doing stuff is fairly easy, the hardest part's to start.

Valentine's day jewellery project

Postby mars-red » Wed Feb 13, 2013 2:05 pm

It seems like every year I tell myself I'm going to make something for my wife for Valentine's day, and every year I run out of time and my plans fall flat. Well this year it looks like my plans might actually come through. I had the idea on the way home from work last night and started on it after the kids went to bed. This will be a little heart shaped locket, but instead of the usual precious metals it will be made from mostly tool steel and a tiny amount of brass. To make this a simpler project than it otherwise might have been, I decided no hinges. The two halves would separate completely after being unlocked. I decided to use 3 steady pins - 2 to locate the plates to one another, and the 3rd to fit into an eccentric cam housed in the opposite plate. When the cam is turned (by a key, or a small screwdriver), it will bind against the mating pin. With the other 2 steady pins being a perfect fit, that will keep both halves locked together. It was a simple enough design so I felt I had a shot at getting it done (or at least presentable) in the two evenings I had left to do it (including tonight).

I started with just some rough sketches to help get the design worked out in my head, and to help come up with a plan for the order in which to make the parts and perform the various operations.

For material, I started with some flat ground O1 tool steel for the plates, that I sawed off from leftover scrap I had from another project:
Image

I covered one plate in blue permanent marker and then used a small pair of dividers, machinist's rule, and scribe, to lay out heart shape and the locations for the steady pins:
Image

With the two plates clamped together, I used my small benchtop drill press to drill the holes for the steady pins:
Image

Then turned 3 steady pins from brass (when making steady pins, a slight taper must be applied for a proper fit) and drove them into place in one of the plates:
Image

On the opposite plate, one of the mating steady pin holes needed to be turned into a counterbored recess where the little eccentric cam piece would fit. Every time I make a counterboring drill bit for some purpose, I bag it up and store it away for future use, and I was able to find one I made previously that was a good size for this. Here is the mating plate, with the counterbore formed for the eccentric cam:
Image

Then I chucked a piece of W1 drill rod into the jeweler's lathe and turned the blank that would become the eccentric cam lock. I left the overall length, and the length of the shoulder in the middle, oversized:
Image

Now I needed to drill a hole part way through it, that was off center. I chucked the part back into the lathe, with a piece of 0.007" diameter spring wire between the part and the collet on one side (making it 0.007" off center). I started by using a small center drill to start a pilot hole:
Image

Then I followed with a 0.059" diameter machine length drill (machine length drills are nice and short, which is usually ideal):
Image

I then turned the length down until it was a perfect fit in the plate:
Image

The head of the locking cam, that sticks through the plate, needed to be slotted (so a tiny screwdriver or key could be used to lock and unlock it) and in this case the easiest way was to use a jeweler's saw (carefully!). If I had been thinking, I would have done the slotting before reducing the length of the part, which would have let me perform the slotting using a slitting saw in the milling machine. Here's the head of the locking cam, after slotting - crude, but effective:
Image

Next, I needed the mating brass pin for the cam lock to be a little smaller in diameter, and slightly off center. I carefully filed it down by hand until I had a nice fit and a good locking action. Here are a couple of pictures of the two plates locked together using the cam lock, from each side:
Image

Image

By this time, it was quarter past 3 in the morning and my eyes were starting to burn so I called it a night. It'll be another late one tonight, but I think I can get it presentable in time for V-day. I need to mill a shallow recess in one plate, to hold a tiny photo or whatever, make a little retaining screw to hold the cam lock piece in place when the locket is open, then saw and file to the heart shape scribed onto that one plate, bevel and polish it, then heat treat it to a nice purple color and clear coat it to prevent rust and keep the color from wearing off. Not sure exactly what I'll do to allow mounting a jump ring (so it can actually be worn) - probably just drill it, but we'll see.
User avatar
mars-red
 
Posts: 21
Joined: Tue Aug 21, 2012 11:48 am
Location: Barrington, NH

Re: Valentine's day jewellery project

Postby mars-red » Thu Feb 14, 2013 11:19 am

Got it mostly finished last night - at least, enough to be presentable and give to my wife. I still need to make a small retaining screw to keep the locking cam in place when the locket is opened, and I really screwed up making the key (it's functional but I'll be re-making it).

The first thing I wanted to do last night was create a photo recess in the back plate. I thought at first that I would mill it out, then I thought about making a very shallow counterbore drill to do it, then I remembered I had started making a combination faceplate / tailstock vee block / drilling table for my jeweler's lathe some time ago, and never finished it. I decided to drill a couple of holes in the faceplate and tap them for M6 threads, to allow me to use the faceplate to hold the work and turn the recess using the lathe. I used a center drill in the tailstock to help locate the center of the plate, and drilled into it a tiny bit to keep the work located while tightening the bolts:
Image

Here is the recess being turned:
Image

Here is the finished recess:
Image

Next I hacksawed and filed the heart shape, using the marks I had scribed into the front plate way back at the beginning. I did this with both parts clamped together, to ensure a nice seamless join between the two parts. Here is a picture part way through filing it to shape:
Image

After filing, I grained the edges using a tool room finishing stick. With the edges done, I finished the front and back surfaces. Here was the front, after finishing:
Image

With that done, I cleaned up the parts and then heated them to get the best wine/purple color I could on the front surface. It came up pretty well, the pictures don't really do it justice. The back, since it was closer to the heat, ended up being a bright blue. Here's the color I got on the front:
Image

To clean up the edges, and to give a bit of contrast, I lightly beveled the front edges using a pivot file:
Image

I had a great idea for making the key, but it turned into a disaster so I'll need to remake it. The key does function for now, though. Here is the key blank that I turned, on the penny:
Image

And here is the key, pretty much ruined but functional. If you look close, you can see the almost screwdriver blade shape filed into the end:
Image

I even managed to find a picture to put into it. Tiny!
Image

It was a hit, my wife loves it. She wants to wear it as a pendant so I'll be adding a jump hook of some kind to it. I also need to clearcoat the front and back pieces to protect the finish - that oxidation is pretty delicate and will wear off quickly. If you notice, I have an extra hole drilled next to the recess for the little cam lock and that is where the retaining screw will go, once I make it.
User avatar
mars-red
 
Posts: 21
Joined: Tue Aug 21, 2012 11:48 am
Location: Barrington, NH

Re: Valentine's day jewellery project

Postby mars-red » Sat Feb 16, 2013 3:59 pm

The other day I worked on the ruined key a little bit and turned into something somewhat acceptable ... it's even kind of cute. I'll still be re-making it, but at least for now it looks alright. The purple temper came out really nice:
Image
User avatar
mars-red
 
Posts: 21
Joined: Tue Aug 21, 2012 11:48 am
Location: Barrington, NH

Re: Valentine's day jewellery project

Postby mars-red » Wed Feb 20, 2013 11:11 am

One more post to wrap up the loose ends, so to speak. A few days ago I counterbored and threaded the hole I had left in the back plate for the cam lock retaining screw, then made a retaining screw. I also drilled through both plates, near the top of the locket, for a jump hook to go through. That allowed it to be put on a chain, and it also keeps the two halves while they are separated. I finished it off by clearcoating the heat-colored parts, then bending and soldering a little jump hook from sterling silver wire.

To counterbore the hole for the cam lock retaining screw, I needed to make a little counterboring drill bit. I made one from W1 drill rod, then hardened and tempered it to straw:
Image

Here is the back plate with the retaining screw counterbore formed:
Image

The screw itself is the shortest screw I've had to make, so far. It has M1.2 threads and the threaded part is 0.040" long. The head is 0.025" thick. The screw was threaded with a die, and the slot was formed using the jewelers lathe with a parting tool held sideways in the toolpost, then using the cross slide like a shaper to form the slot taking off about 0.001" at a time.

Here is the screw being made, just after threading was done:
Image

And this shows the method I used for slotting (it worked really well and gave a nice, crisp slot):
Image

And the completed screw, before it was polished to remove the machining marks:
Image

All of the pieces:
Image

The cam lock and retaining screw in place:
Image

Here is the assembled locket, from the back... the cosmetic blemishes bother me a little but it's only the back so I guess I can live with it: Image

And the assembled locket, from the front (if you look close you can see I didn't have it snapped shut all the way before taking the pic - oops!):
Image

In that last picture the front plate looks very blue, the way the oxidized steel reflects the light is really crazy and often difficult to capture in pictures. In real life it looks really not blue at all, but a sort of dark wine color.
User avatar
mars-red
 
Posts: 21
Joined: Tue Aug 21, 2012 11:48 am
Location: Barrington, NH


Return to Projects

Who is online

Users browsing this forum: No registered users and 1 guest

cron