Week 16 Nov. 8-13, 2010

Well it was a big week this week for me. We got the German silver for my mainplate and all the specific drills I needed to get it done. So I was ready to get started. Making a mainplate is no easy task (for a human). The first step was to drill all the holes in the plate. There are a lot of holes to drill and tap, and a lot of recessed areas in the plate that need specific depths to make the parts functional. I had to check, re-check, then check again with someone else if all my holes were in the correct locations and that I had them written down correctly. After this I printed out the list of the 49 holes to drill, with specific co-ordinates from the X: 0.000 and Y: 0.000 point I was headed to the M1 to get busy.

Here is the plate after flattening it in the M1. Nice finish hey! But it won't last...

After flattening I had to use a center drill for all the holes I was drilling to make sure they didn't go off center. Obviously this adds to the time because I can't just go with the bit, drill the hole and move on. Here is the plate after the center spotting.

Then I went and drilled all the holes. There were 49 holes in total, ranging from size 2.80mm to 0.50mm. Some of the holes have to be tapped to accept screws. and some holes have to be very accurate because they are the locations for the jewels. Those holes must be exactly 0.01mm less than the jewel that fits in them. I had special reamers for those holes to be precise. After all the drilling here is the plate again.

The barrel bridge fits!

The next step was to tap all the necessary holes for the screw locations. These holes are drilled to 80% the size of the tap so that the teeth take up the other 20%. To make sure all the holes would be tapped straight I used the M1 attachment to center the hole, then put it on the lathe, and then used the tailstock with a pin vise centered on a brass rod to tap by hand. Didn't take too lang and was more accurate than tapping freehand. I didn't tap the 0.60mm threads yet because my mainplate is quite thick and the tap will not pass through the plate so I will wait until the recess has been made in the specific area.

All of the drilling and tapping took 8 hours. A long process for sure, and that was the easy part. If you are wondering why is my mainplate not round, well there are a few reasons. I had to leave spots to screw the mainplate onto another brass plate to hold it while milling the recesses. And I also milled the sides 90 degrees to the winding stem and the dial feet. I have to drill holes into the side of the mainplate so this will help in aligning perfectly 90 degrees and straight. A good idea I thought!

So I had to make a holder for my mainplate so I can remove it from the M1 without gluing it all the time. I flattened a piece of brass and made the tapped holes for the screws. Then I fitted 2 pins where the dial feet holes are so it will align in the same spot in case I need to take it out in the middle of milling to check the depth of the mill. To the left is me flattening the brass on the lathe.

After all that I started to mill the recesses for the gear train and balance. I figured this would be the easier part so I would do it first.

It went quite smoothly until I was milling the recess for the barrel. It was the last step but I somehow miscalculated my starting zero point and milled too deep! I was extremely angry with myself after being almost finished. Luckily there was enough spare material on the dial side that I could save it, but this meant going back to all the previous spots to mill deeper. So 2 hours later I was done the bridge side. It looks pretty damn good, actually starting to look like a mainplate!

The last thing I was able to do was mill the recess for the barrel bridge on the other side. I almost had a problem when the holder moved but I noticed it before I started milling and fixed it. But now the barrel bridge fits and all is good. Here is a pic of the barrel bridge recess. That little extra part sticking out is for the rack that will hold the hand for the power reserve indication. I had to put it in this location because of the shape of my dial.

Now I just have to mill out the complicated setting mechanism recesses and I'm done, riiiiight. Not going to be easy or fun.... wish me luck!