RWG Technical Posted November 22, 2006 Report Share Posted November 22, 2006 Just to clarify the calculations... HSS Twist Drill Recommended Speeds and Point Angles Type of Steel.............Point Angle.........SFM Steel < 180 HB..........118....................80-110 Steel 180-280 HB.......118....................45-70 Steel 280-380 HB.......135-140.............30-45 Steel >380 HB...........135-140..............15-25 Stainless Steels..........................Point Angle...........SFM Stainless steel 200-300 series......135-140...............20-40 Stainless steel 400 series and PH..118.....................30-60 RPM = SFM x (12/pi) Diameter of drill bit In my example I chose this, Stainless 300 series, and I chose the high end value of 40 SFM Drill bit #55 is 0.0520" diameter Plugging the variables into the formula 40 X (12/3.14) 0.052 40 X 3.82 0.052 152.8 0.052 = 2938 RPM Me thinks were onto something now, and will get good results... Bill shamed me into going to get myself a small drill press and start offering this service, although I have been doing some research for a few weeks with that idea in mind, he gave me the push I needed to do it. I dont' believe in half jobs, or guessing at this stuff, with this data it should be easy to do... RG Link to comment Share on other sites More sharing options...
HauteHippie Posted November 22, 2006 Report Share Posted November 22, 2006 Me thinks were onto something now, and will get good results... Bill shamed me into going to get myself a small drill press and start offering this service, although I have been doing some research for a few weeks with that idea in mind, he gave me the push I needed to do it. I dont' believe in half jobs, or guessing at this stuff, with this data it should be easy to do... RG Awesome Rob!! I'd be proud to send you a guinea pig. Link to comment Share on other sites More sharing options...
vaccum Posted November 26, 2006 Report Share Posted November 26, 2006 I have been doing some reading as well... Here is the formula for calculating drill bit speed... For Stainless Steel, 200-300 series, drill bit point angle is 135-140 degrees, and speed is 20-40 SFM (Surface Feet per Minute) For 400 series Stainless, point angle is 118 degrees, and SFM is 30-60 To convert SFM into something useful like RPM RPM = SFM x (12/pi) _________________ Diameter of drill bit So for a #55 drill, 0.0520 inches, we get 2900 RPM for the drill bit speed... If you used a 0.50 (1/2 inch drill) in the same formula, you get a speed of 300 RPM... The smaller the bit, the faster the speed to achieve the same SFM. The other interesting point, is that Stainless tends to "Case Harden" if drilled too SLOWLY...firm and steady cutting avoids this problem... RG You are correct. The smaller the bit size the higher the RPM's. I was thinking on my current 110 TON Chilled Water Air Conditioning project. We use bigger size drill bits every day not this tiny ones. I need to separate my job from my hobby, two completely different fields. Now you know why my username is vaccum....NO it is not misspelled....vaccum is the rep for vacuum. Cheers, vaccum Link to comment Share on other sites More sharing options...
haveblue Posted December 1, 2006 Report Share Posted December 1, 2006 wow!!!! i'm speechless. i decided to do some last minute reading on lug hole drilling before tackling my wm 1680 and cam across this thread. bill, chief, and rob.....you guys are an amazing wealth of information. i think i will put my lug drilling on hold for now. i'm especially glad i didn't attempt to try the lughole re-bias project first. the craft has come along way from just punching through the lug holes with a dremel or a hand-held drill. my hats off to you guys. Link to comment Share on other sites More sharing options...
musicale Posted March 24, 2008 Report Share Posted March 24, 2008 Great thread. What is the correct method for drilling lug holes from the inside, on watches which aren't drilled right through? Link to comment Share on other sites More sharing options...
Toadtorrent Posted December 10, 2008 Report Share Posted December 10, 2008 Great thread. Nicely documented. Link to comment Share on other sites More sharing options...
toi Posted March 24, 2010 Report Share Posted March 24, 2010 Omg I need something like this done to my genuine watch. Is this drilling doable just from the inside?? I kinda need extra lugholes from within the lugs. Got my fingers crossed Link to comment Share on other sites More sharing options...
cjjoyce1 Posted April 1, 2011 Report Share Posted April 1, 2011 To add to an old thread (because I just finished up mine on my 5512) - I don't have a proper drill press so I was a bit nervous about chamfering the holes afterward. One thing I tried on my practice case before "going live" was an old hand crank drill. Yep, straight from my grandfathers toolbox. I just rested the bit on the case at the proper angle and cranked the handle letting just the minute weight of the drill put the pressure. About 6 or 7 cranks did the trick perfectly! It really let me control the process too! So if you don't have the proper set-up - or are afraid of going too far, this is just the trick! Link to comment Share on other sites More sharing options...
Niqlndym Posted April 1, 2011 Report Share Posted April 1, 2011 Found this on youtube. For Panerai lugs, but I guess the technique would be the same for Rolex. It looks easy enough. Maybe I'll give it a try. Link to comment Share on other sites More sharing options...
Guest Gotohavearolexnow Posted June 30, 2012 Report Share Posted June 30, 2012 That's how I did my seadweller and. Submariner no problem at all very simple to do , now getting strap to fit pins ( SEL ) end links was another matter then getting it to fit watch was a night mare all sorted in the end though . Link to comment Share on other sites More sharing options...
SSTEEL Posted August 26, 2013 Report Share Posted August 26, 2013 (edited) I know this is an old thread, but I was wondering if anyone knows the answer to these questions below, as I have the same question. What is the correct method for drilling lug holes from the inside, on watches which aren't drilled right through? Is this drilling doable just from the inside?? Anyone know please? Is it done with a tiny angled drill such as a dentist type drill? Edited August 26, 2013 by SSTEEL Link to comment Share on other sites More sharing options...
SSTEEL Posted August 26, 2013 Report Share Posted August 26, 2013 I wonder if there's a drilling tool that drills the two inner lug holes at the same time, ensuring they are accurate for the spring bar, and SEL's? Link to comment Share on other sites More sharing options...
SSTEEL Posted August 27, 2013 Report Share Posted August 27, 2013 Nobody? Link to comment Share on other sites More sharing options...
B3nj4min3 Posted August 28, 2013 Report Share Posted August 28, 2013 I know this is an old thread, but I was wondering if anyone knows the answer to these questions below, as I have the same question. Anyone know please? Is it done with a tiny angled drill such as a dentist type drill? +1 to this question. I've been wondering the same thing myself. Any ideas would be great. SSteel, I'm hoping to get a drill press within the next few weeks and will try a few things to see if I can drill the lug holes on these types of "half-drilled" lugs. I'll report back back with any progress I make. Link to comment Share on other sites More sharing options...
SSTEEL Posted August 28, 2013 Report Share Posted August 28, 2013 Thanks, look forward to seeing how you get on mate. Link to comment Share on other sites More sharing options...
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