Micro Drilling

Discussion in 'Watch Repair' started by Jerry Kieffer, Nov 8, 2018.

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  1. Jerry Kieffer

    Jerry Kieffer Registered User
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    May 31, 2005
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    I thought this may be of interest some.

    I recently had a request for assistance from a partially handicapped student of many years ago. (Long story)
    His request was if there was a way to set up his common standard WW watchmakers lathe for Micro drilling.
    His interests were that it require little to no skill development (Another long story) and have the ability to drill holes about .3mm (.012") down to about .07mm (.0028") for watch repivoting. In addition, he wanted a system that would have the least chance of drill breakage on a consilient basis. To make it even more interesting, He was apparently given a life time supply of circuit board drills and wanted to use those for financial reasons. And of course the cost of doing this was also a legitimate concern for this individual

    Personally I do not use a watchmakers Lathe lathe especially for micro work because of their limited capabilities compared to other options. My first suggestion would normally be a different type Lathe or at least a watchmakers lathe with a drilling/collet holding tailstock but not financially feasible in this case.

    However, in the early years, I had successfully setup a Paulson watchmakers Lathe for Micro drilling that met the requested concerns and still have it yet today. I have even used it as recently as a couple of years ago. The photos and setup items are actually of that Lathe since making a duplicate attachment and shipping it to the student free of charge. The very simple Setup was as follows.

    (1) The setup consists of four simple parts shown in the first photo and assembled and installed on the lathe in the second photo. They consist of a standard non drilling tailstock runner of either 5/16" or 8mm diameter the most common sizes utilized and readily available from any metal supplier. They may require slight sanding for a desired slip fit. For both sizes, the spindle and spindle nut were threaded 5/16" x 40 thread. A standard fine 5/16X 24 could also be used with a little less sensitivity. In addition, a plastic threaded ball from a hardware store and 3-3/4" disk of whatever to be friction fitted to the threaded nut.

    (2) Once installed, a reference punch mark was installed on the front of the runner per the third photo. Almost all micro drills in the sizes to be utilized come with a single shank size per Mft. making collets or chucks unnecessary. A spotting drill is used to spot the runner and then it is drilled to except the arbors of the drills used, using the lathes spindle with the runner punch mark held straight up. Done with quality tooling, this eliminates all runout with the exception of the spindle bearings. The drills should be a slip fit with no locking method required or desired. The rear of the drill shank should be ground to a chisel point per fourth photo. This will easily supply several times more resistance than required by micro drills when making contact with the bottom of the hole. Lubrication of the shank with fine oil will further increase accuracy by centering the drill shank in the already tight slip fitting hole.

    (3) In operation, the tailstock runner or spindle is pushed forward with the punch mark held straight up while slowly rotating the disc with your middle finger allowing the runner to move forward. Per fifth Photo One can also push the runner forward and rotate the disc with your other hand if more comfortable.
    In this case, about 1/2 inch of movement of the OD of the disc will allow the drill to advance no more than .025mm or (001"). This type of mechanical control will allow drilling without fear of breakage providing quality tooling is used for what it is designed for. In addition, one area of concern is re -engaging the workpiece and breaking a Micro drill when clearing chips. This is eliminated with this system by retracting the runner and returning to position that will not allow cutting to take place until the disc is turned.

    Additional runners or spindles can be made for additional sizes if required. Personally, I have never had the need for more than two sizes.

    This attachment was first constructed many tears ago because hand controlled and factory drilling options were not practical for consistent micro drilling at least by my hand.

    Jerry Kieffer

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  2. DeweyC

    DeweyC Registered User
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    Feb 5, 2007
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    Jerry,

    If one can cut a true female cone, it is not much further to learn how to drill a hole down to 20/100 mm with a pinvise. I even taught this via the internet back in 2000 when I was trying to prove to AWI that distance learning courses were practical and possible.

    I had to develop this skill because you and I know that most WW lathes are sold with mixed head and tailstocks. It took me 15 years to find a Levin that was as original.

    What has to be stressed is that the speed has to be very slow with a light touch and saliva. No matter which approach you use. While MSC now sells micro twist drills in carbide, I also found that those high twist ckt. board drills will work if you break the drill off the shank and chuck it up short.

    Of course, the student should start with brass then mild steel and then hardened steel. Once you master it and bite the bullet for carbide, you can drill pinions without tempering. But everything starts with being able to consistently cut a true female center.

    FWIW, I tried the drilling attachment that came with my Horia. The one that fits in the TS, has bell mouthed holes and a mounting for the drill. No joy. In Switzerland, the Senior instructor told me he knew of no one who could make that setup work. He was one of the ones who smiled when I showed him your method for making fly cutters.

    Happy Thanksgiving.

    Regards,

    Dewey

    P.S. Had a conversation with a WOSTEP student asking about your approach to turning. I told him it was a valid approach and may make more sense to master given the paucity of good WW lathes. He was still going to buy turns for reasons I believe to be correct. But the Sherline can be used as I use my Levin, for roughing out staffs before going to turns and he also can use it to make movt holders and jigs as I do on the 102. That combination may well serve all his needs.

    Also told him that I use the Sherline mill even to mill out chronometer detents. I just still have reservations about how easy it is to modify an existing staff or rectify old work. But then, I am a very old dog. I know my world and am comfortable with it.
     
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  3. Karl Burghart

    Karl Burghart Registered User
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    Thanks for sharing your knowledge Jerry. I made one of these setups for a chapter meeting demo on repivioting. Works like a charm. I ended up making a few for friends. I still use the Sherline for most everything, but it shows how easy it is to do with a WW lathe.
     
  4. glenhead

    glenhead Registered User
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    This question may be going a bit overboard...

    When dealing at these scales, with super-slow speeds and fingertip control, does it make any sort of sense to have a set of dubbed drill bits for non-ferrous metals? Or is that sort of a belt-suspenders-duct-tape-bubblegum-and-staples solution to hold your pants up? I have dubbed sets (with the indexes marked "brass") for all sizes from 80 to "why do I have one that huge?"

    Thanks for all the cool solutions you bring to the forums, Jerry, and thanks to everyone else for chiming in with experience.

    Glen
     
  5. Jerry Kieffer

    Jerry Kieffer Registered User
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    May 31, 2005
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    Dewey
    Thank you for the kind comments as usual.

    As with yourself, my personal methods are developed based on my personal god given capabilities that I can not alter and a strong desire to achieve. Experience has taught me that the path of least resistance has always produced a superior result in a timely fashion.

    Again in the early years it was suggested that I use a pin vise. By my hand, results and success rates were not what I was looking for especially the quality of the hole in regard to being round and straight. However, what can be demonstrated by any one individual such as yourself , can not be disputed. On the other hand, I have found methods of drilling quality holes on a consistent basis down to .0001" on the Sherline Lathe, as demonstrated at the school in Columbia that requires the least amount of developed skill of any method I have experienced so far. We each have to use what works for use as individuals. In my personal case, methods that will work for a students requiring the least amount of developed skill so one can move on and accomplish as much as possible.

    A Very happy Thanksgiving to you also

    Jerry Kieffer
     
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  6. Jerry Kieffer

    Jerry Kieffer Registered User
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    Karl
    I am happy it has worked out for you.

    Glen
    Actually a good question.

    For critical work, I use drills that are specifically designed for the work and material that I am working on. For all other work, what ever will do the job.

    Jerry Kieffer
     
  7. praezis

    praezis Registered User

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    I read this thread with much interest.
    However I wonder, if a deep 1/8" hole can be made with the needed accuracy (<<0.01mm for microdrilling <0.2mm) by just drilling (also after spotting).
    Frank
     
  8. Jerry Kieffer

    Jerry Kieffer Registered User
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    Frank
    Its a very good question.

    However, this is proven probably millions of times daily in industry if certain precautions are utilized and understood. They are as follows.

    (1) The quality of your drills/tooling will determine what can be achieved.

    (2) Very critical is the spotting process that MUST be done with a DESIGNED SPOTTING DRILL that has the SAME TIP ANGLE as the drill to be used. Spot drilling is not drilling , but a boring process that assures that the spot is dead center to spindle rotation. The same angle pocket for the drill assures that the drill will start its drilling process dead center to spindle rotation without deflection. For example, when using other methods including catching center with a graver, one will often see the tip of the drill bounce when making contact with a non conforming spot sometimes causing the drill to start off center. The result is a drill that wobbles to various degrees as it drills. The hole then will then be tapered and not straight to some degree.

    (3) The accuracy of the hole will be directly proportional to the quality of the Drill. Most critical is the grinding of the tip of the drill so the point is dead center to the OD of the drill itself.
    Under these conditions, if centered to start, the hole will also be straight to center of rotation. On lesser quality less expensive drills, the tip may or may not be centered and the cutting process less than desired.

    (4) The RPM should be slow enough to allow for continuous cutting of the drill. To fast will work harden the work piece and damage the drills cutting edges.

    Jerry Kieffer
     
  9. praezis

    praezis Registered User

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    Jerry,
    thank you very much for clarification.
    You did not mention drilling first with smaller diameter. Do you use a drill with full diameter only?
    Fran
     
  10. Jerry Kieffer

    Jerry Kieffer Registered User
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    Frank
    Another great question.

    As mentioned earlier, one must understand your tooling and equipment to be consistently successful. For the highest level of accuracy one must use the highest quality tooling. A high quality drill will have a cutting tip ground center to the OD. The forward part of the tip will establish center while drilling and drill the hole straight at the OD of the Drill. So yes, in this case where a high degree of accuracy and hole quality is concerned, I only use full diameter of the highest quality designed for the work at hand.

    With lesser quality drills, the tip is seldom ground perfectly centered to the OD of the drill. Thus when the center tip of the drill establishes a center, it swings the long side out wider than the short side enlarging the hole larger than the designed OD. In return, the off center point is forced in several directions by the long side often causing the drill not to drill perfectly straight.

    One can attempt to to get a more accurate OD hole by using a smaller then a larger desired OD drill, but the results will often be far from a highly accurate quality hole. When using the larger drill, the cutting tip is no longer in control or utilized. In this case, the quality of the work piece will control the outcome. If one side of the hole is harder than the other, then that hard spot will push the drill into the softer area driving the drill off center producing a taper in a non straight hole to some degree.

    However, a high degree of quality and accuracy is generally not required in general construction where the above discussion would be of no concern. Under these conditions, a smaller hole followed by a larger drill is a common way of getting greater OD accuracy when using lesser quality tooling. But it can really make a mess when a high degree go quality and accuracy is required.

    Jerry Kieffer
     
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