Drill size for case for 2mm Spring bars

[Hagus]

Right, simple question I think! What size do I drill my case for 2mm Spring bars? I naively assumed it would be 2mm but of course the ends aren't 2mm are they! 

What a donut.

its on my new blue Tudor Snowflake which is my grafting watch.

Thanks all.

[jackflash]

1.2mm will do the job.

[dbane883]

1.25mm

[Hagus]

Thanks guys much appreciated

[Champagnesky]

1.25mm

+1

[highoeyazmuhudee]

i do 1.25mm its perfect. 1.20mm sometimes doesnt line up straight and the spring bar doesnt poke through properly

[ironman18]

Reviving thread.. Any suggestions on where to buy 1.25mm drill bit? The existing hole in my case is I think 1.2mm but the spring bar head doesnt stick out (i got it mod by someone and he said he used a 1.2mm mill) i want to have the spring bar kind of visible.. Is it possible to open the hole manually by hand? Any leads to where I can purchase 1.25mm bit would be appreciated.

cheers

Edited September 6, 2016 by ironman18

[lumbee]

You can open the hole a bit with a jewelers broach.

[automatico]

On vintage models (5513/1680 etc) I usually go with a #55 bit (1.32mm) because I end up with most aftmkt bracelet hoods not fitting very well.  There is very little difference between 1.25mm and 1.32mm (hard to see the difference) but I have had trouble fitting bracelets with 1.2mm and 1.25mm holes and usually end up enlarging them to 1.32mm...after all, .07mm or .12mm is not very much.  It is also a good idea to measure the tips of the spring bars to see how close to spec they are (1.2mm).  I have seen some that were a few hundredths mm too big.  You can buff them down but they usually just spin inside the tube and it does not do a lot of good.

Some of the cases I bought were already close to 1.32mm, new Yuki '5512' and '5513' were very close to 1.32mm and I ran a #55 bit through the holes with the bit in a pin vice with almost no resistance.  If you have to resort to slightly curved spring bars, the 1.32mm holes will usually allow the tips to extend all the way through the lugs without binding.

Something else about 1.32mm holes is you can use curved spring bars with a leather or nylon strap and the curved spring bars will help keep the strap from wearing away where it rubs the sharp rounded case edges.

[alligoat]

I'm with automatico on this, I use the #55 cobalt drill bit from Snap-On Tools.

[ironman18]

Thanks guys, 

Dumb question..

can i open the hole abit using jewelers smoothing broach? Existing hole is 1.2mm.. Was planning to open it abit

 

[automatico]

"Can I open the hole a bit using jewelers smoothing broach?"

Jeweler's smoothing broaches do not cut, they are made to smooth the id of a hole.  They are used mostly in soft metals and will not do much in hard metals.  Besides that, broaches are tapered, both cutting and smoothing types and are used mostly on soft movement plates etc.  Most jeweler type cutting broaches are not hard enough to remove much metal before they start getting dull when cutting stainless steel.  A precision drill bit would be better and to go from 1.2mm to 1.25mm might be done with a pin vise or battery powered slow speed mini drill/grinder.

'Precision' = made to the exact specified diameter.  Many drill bits are not made to spec, especially cheapos.

[highoeyazmuhudee]

On 9/5/2016 at 8:32 PM, ironman18 said:

Reviving thread.. Any suggestions on where to buy 1.25mm drill bit? The existing hole in my case is I think 1.2mm but the spring bar head doesnt stick out (i got it mod by someone and he said he used a 1.2mm mill) i want to have the spring bar kind of visible.. Is it possible to open the hole manually by hand? Any leads to where I can purchase 1.25mm bit would be appreciated.

cheers

i bought mine off ebay. from a chinese seller, something "tools" dont remember. came in a small plastic butterfly box with several bits inside. they were carbide bits and a fair price. could drill probably 3 cases (12 holes) before breaking. using generous amounts of 3in1 oil for lubrication.

[Hagus]

Ah I did them at 1.25 and it was a right ball ache to fit the bracelet, however it did fit! They also don't protrude, maybe I'll get some 1.32mm drills and give them a tweak.

[dbane883]

What do you mean by protrude? Gen spring bars usually stick out of a case only because the lugs have been thinned due to overpolishing.

My gen PCG 5513:

[ironman18]

Thanks for the advice..

this is what i meant..not necessarily protrude but its just that i cannot see the lugbar ends from the hole.. 

You think the holes need some opening?

 

 

 

Or just leave it as is?

Edited September 9, 2016 by ironman18

[dbane883]

If you're using gen or gen spec spring bars, and assuming the lugholes were drilled properly (opposing holes should be aligned), and assuming you've adjusted the endlinks, there should be no extraneous friction to prevent the ends from fully extending. If you are using crappy rep (non Swiss) bars with weak-ass internal springs, then you may not get the bars fully extended. Also, cartel mid cases tend to have overly thick lugs out of the box. Finally, the side flanks of most rep cases are rather straight (90 degrees). They should be closer to 87-88 degrees. As such, if your bars are gen spec and are fully extending, I would not enlarge them.