3646 How to build stage 1
Let’s assume you have purchased a 3646 Case kit like the one featured here. This type of kit will arrive as machine finished parts, your job is to shape them a little and make the surface a smooth finish. The authentic Panerai 3646 Cases were made in the same way. First they were machined and then the sharp edges were removed by hand.
Where to Start: Start by using a small round file (fine grade) and shape the area around the Stem Tube (center hole). Try and follow the images you see in this post and make your 3646 case look similar.
3646 How to build stage 2
Your 3646 Case should start to look like the image above.
3646 How to build stage 3
The next stage is to file the edges of the case smooth as shown
3646 How to build stage 4
Finish the case with wet and dry paper I recommend using P400 (medium grit) and then finishing with P800 (fine grit). Later we will use P1200 (super fine) to shine.
3646 How to build stage 5
Its important to get the areas around the lugs smooth and shiny. Do this before fitting the Lug Bars because once the Lug Bars are fitted this area is difficult to polish.
3646 How to build stage 6
Cut the Lug Bars to the correct length. They want to be close to the case but not too close that you cannot fit your strap. If you haven’t done this before then I advise cutting the bars long and then adjusting until you have the length shown in the image.
3646 How to build stage 7
Its very important that you use a good flux and fine solder (available online). The difference is huge, good flux will make soldering easy, cheap flux will be difficult. For Stainless Steel soldering I recommend using “Stay Bright Flux”. I have tried many and this is by far the best. Also fine solder is much more easy to use than thick.
3646 How to build stage 8
Start by adding Flux the the area
3646 How to build stage 9
Apply heat, you should see the Flux bubble and then turn black, this is a good indicator that the area is hot enough. As soon as the solder touches the case it should flow. If it doesn’t and stays in a “blob” (ball) then your case is TOO HOT. Cool with flux and you should see the solder flow. Keep using the Flux it helps “Sweat the solder into the Case“
Look at the image above, the solder has been “sucked into the case” this is know as “SWEATING”.
3646 How to build stage 10
The first set of Lug Bars are now attached. Repeat this process on the other side of the case.