Lug hole drilling...

[automatico]

I have drilled out a lot of lug holes to 1.3mm for different projects and always use HSS 'cobalt' drill bits.

Why?

Here is some info:

https://bestdrillbit.com/cobalt-vs-hss-drill-bit-comparison/

 

Btw, many drill the holes out to 1.25mm but I go with 1.3mm because it makes it easier to install bracelets/straps as the spring bar tips have a slightly bigger target.  It is not much but it makes it little bit easier.

I have also drilled quite a few holes in the sides of clasp caps and use a .9 or 1.0 cobalt drill bit.  If a six hole DJ cap has enough room for a seventh hole (like most genuine caps), I usually drill one.  I use an old clasp cap (clamped to the new one) for a guide and drill through the existing holes into the new cap so the bit will not walk away.  I clamp the two clasp caps together using vise grips with the jaws padded with plastic electrical tape.

 

The drill bit needs to be long enough to go through both holes on the guide clasp (16mm+/- on a DJ) and through one side of the new clasp.  A .9mm or 1.0mm drill bit long enough to pass through both clasp caps and drill two new holes in one shot would have to be about 40 or 45mm long.  The last bits I got were 38mm long, they might work but there would not be much of the bit in the chuck or collet.

 

 

[Tribal]

I've done it 1,2mm on my watches in the past, and yes use Cobalt drills.Use some Oil or Drillfluid to do it.

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[automatico]

I use ST spring bars on my projects and just now measured 10 of them and all the end plugs are 1.18mm in diameter.  I tried 1.25 holes on a few projects and some spring bars did not want to go through because of misalignment of the hoods and bracelets.  I settled on 1.3mm because with it all being replica parts it was a little easier to put it all together.

Sometimes I had to curve the spring bars a little to make them work and the larger hole diameter helped quite a bit.

 

I have worn an MBK '5512' quite a bit lately with WSO hoods/'Mary foldoyster' and with everything having some slack, it went together Ok.  I ended up removing the soldered tubes from the hoods because the lug hole location did not agree with the hoods even after quite a bit of filing on the hoods.

I usually wear a quartz watch but I felt sorry for the MBK. 

Besides, with the sloppy fit of the hoods and bracelet it reminds me of the high mileage genuine rolex watches from my past.   

Since the old genuines are now unaffordable, I'M going to Be oK with this one.  Ha!