'Omega' bracelet
 

I made this bracelet for my wife for Christmas. I have called it Omega. I designed it in Fusion360 and used the Fusion360 CAM function to create the GCode. This is the fifth cut. It took a few go's to get the process right. I learned two techniques that made the manufacturing process work.

1. no matter how carefully I measured I had problems with the double sided registration. Omega is 40mm wide and I had to machine it from both sides. I ended up drilling a registration hole right through the material at the origin. I also moved the origin from the outside of the work with all work axes positive to having the origin in the centre of the work. This meant that minor error in registration when working the flip side were halved over having the origin in the bottom right corner outside the work.

2. I tried to machine the piece right through on the side B operation. When the tool broke through the work would break lose and shatter or smash into the tool and shatter. I got the job to work by leaving an onion skin in the middle between each side machine operation. Then I just used an old jewellery screw driver to crack through the onion skin around the outside. And, leaving the onion skin in the middle made the job really robust for sanding. the outside before finishing off the inside.

Surprise and Delight: How flexible and soft it is. Blackbutt is really hard but the design lets the material move and the finished bracelet is almost alive its almost squishy.

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Dale that's real cool:D I like it

Very nice.
Another item for the 'One of these day's' list

Very nice work & design !
Care to share your cutting strategy ?
It’s always interesting to analyze someone machining process ( feed, speed, depth, tool....etc )
Later ;)

Very nice, thanks for sharing!
Mark

Hi Robert, Sorry about the delay for this post. You know, Christmas and then the back log of work when I got back to it. Anyway.

Tool: endmill 3.175mm x 20mm flutes
Feed: 750mm/min
Speed: 24000rpm
Material 40mm

Work was milled from both sides. I don't think I'll do that for these bracelets in future. I'll just make them 20mm wide instead of 40mm wide. Flipping the job was a pain in the ass to get alignment. Also I ended up using an onion skin in the very middle of the work. Without the onion skin the moment the material cut through the bracelet would contract and become damaged on the tool, particularly near the ends of the loop. The bracelet is very springy and my wife has found that it opens and closes quite a bit depending on humidity, temperature etc.

I have started using the flip geometry idea by Brian Oltrogge seen in this video http://youtu.be/BLD4dFoXC7o. I used the flip geometry on a chopping block I cut for my mother in-law and it works really well. But I haven't yet adapted it back to this bracelet.

Better late then....
I appreciate this info & your time to post this !
Thks, it's allways interesting to read on one experiments ;)
All the best.