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Thread: Centering Parts In A Drillpress

  1. #1
    Supporting Member rgsparber's Avatar
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    rgsparber's Tools

    Centering Parts In A Drillpress

    I often need to drill on the center line of standard sized stock, both flat and round. Here is a set of tools that make the job easy and accurate.

    If you are interested, please see

    https://rick.sparber.org/CenteringPartsDrillpress.pdf

    Your comments are welcome. All of us are smarter than any one of us.

    Thanks,

    Rick
    Rick

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    Altair (06-04-2019), ranald (06-06-2019), Seedtick (06-04-2019)

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    Thanks rgsparber! We've added your Drill Press Centering Tools to our Drilling and Drill Presses category,
    as well as to your builder page: rgsparber's Homemade Tools. Your receipt:




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    Quote Originally Posted by rgsparber View Post
    I often need to drill on the center line of standard sized stock, both flat and round. Here is a set of tools that make the job easy and accurate.

    If you are interested, please see

    https://rick.sparber.org/CenteringPartsDrillpress.pdf

    Your comments are welcome. All of us are smarter than any one of us.

    Thanks,

    Rick
    Rick

    That is a good hint. If one is lucky you don't even have to make a special part to do the centering. Just put a step drill bit in the chuck.

    Centering Parts In A Drillpress-step_drill_bit.jpg

  5. The Following User Says Thank You to Dorn For This Useful Post:

    rgsparber (06-05-2019)

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    Supporting Member Crusty's Avatar
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    Crusty's Tools
    If I need to cross drill a cylinder I often use a small metal rule to find the center. I balance the rule across the clamped flat cylinder then bring my bit down until it touches, which generally will make the rule tilt to one side, and then I move the table until the rule comes to level. At that point my bit is centered on the cylinder.

    I use the DRO and a wiggler to find the exact center if more precision is required but that's a pointless exercise using a drill bit.
    If you can't make it precise make it adjustable.

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    Supporting Member rgsparber's Avatar
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    rgsparber's Tools
    Quote Originally Posted by Dorn View Post
    Rick

    That is a good hint. If one is lucky you don't even have to make a special part to do the centering. Just put a step drill bit in the chuck.

    Click image for larger version. 

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    I just tried your idea and it works great! A limitation that is easily overcome is that for larger diameters, the drill bottoms out in the vise. It would be easy to make a stepped diameter tool with less rise per diameter. The one you show has a 0.1" rise followed by a 0.1" transition. The custom tool could have a 0.05" rise and no transition. This would let you go from 3/8" up to 1" in 0.3" of rise. Alternately, go with a 0.1" rise and make one tool that goes from 3/8" to 5/8" and the second tool going from 3/4" to 1".

    Rick
    Rick

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    Supporting Member rgsparber's Avatar
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    rgsparber's Tools
    Quote Originally Posted by Crusty View Post
    If I need to cross drill a cylinder I often use a small metal rule to find the center. I balance the rule across the clamped flat cylinder then bring my bit down until it touches, which generally will make the rule tilt to one side, and then I move the table until the rule comes to level. At that point my bit is centered on the cylinder.

    I use the DRO and a wiggler to find the exact center if more precision is required but that's a pointless exercise using a drill bit.
    Yes, I often use that trick too. I don't think it is faster than using the stepped drill because you just lower the tool until it enters the gap and lock the vise down. Fine adjustment is done automatically.

    You have a DRO on your drill press?

    Rick
    Rick

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    Supporting Member rgsparber's Avatar
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    rgsparber's Tools
    As I thought about Dorn's great observation of using a step drill, my mind wandered into other ways to find center over a range of gaps. This brought me to thinking about ways to find center over a range of widths. A VERY old technique is to drill 3 equally spaced holes in a bar. Put pins in the outer holes. To use, straddle the tool over a rectangle and rotate the bar until the pins touch the flanks. That center hole will be on the centerline of the rectangle.

    OK, now turn this idea up-side-down. Mount a rod in that center hole and put that in the chuck. Here is a video of how it works:



    Rick
    Rick

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    Crusty (06-05-2019), Dorn (06-05-2019)

  11. #8
    Supporting Member Crusty's Avatar
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    Crusty's Tools
    Yes, if you consider how often I use my mill for drilling.

    It's usually quicker to punch a hole or two with the mill than it is to get the drilling station ready to go, so it frequently gets deployed for just a few holes but if I have more than a few holes to make then I'll get out the collets, tools and other stuff to use the drill press.

    ETA: If you center punch before drilling (recommended - but bite the bullet and buy a Starrett automatic punch) then it's cheap and easy to use a wiggler to get your spindle aligned with your punch mark. Bonus - How to punch at the intersection of two scribed lines. Tilt your punch towards horizontal with the tip in one of the scribed lines and then using a light touch push the punch tip in that line towards the crossing line. You'll be able to feel it when you get there and then without moving just stand the punch upright and make a dimple right at the intersection.
    Last edited by Crusty; 06-05-2019 at 09:27 AM.
    If you can't make it precise make it adjustable.

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    rgsparber (06-05-2019)

  13. #9
    Supporting Member rgsparber's Avatar
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    rgsparber's Tools
    Quote Originally Posted by Crusty View Post
    Yes, if you consider how often I use my mill for drilling.

    It's usually quicker to punch a hole or two with the mill than it is to get the drilling station ready to go, so it frequently gets deployed for just a few holes but if I have more than a few holes to make then I'll get out the collets, tools and other stuff to use the drill press.

    ETA: If you center punch before drilling (recommended - but bite the bullet and buy a Starrett automatic punch) then it's cheap and easy to use a wiggler to get your spindle aligned with your punch mark. Bonus - How to punch at the intersection of two scribed lines. Tilt your punch towards horizontal with the tip in one of the scribed lines and then using a light touch push the punch tip in that line towards the crossing line. You'll be able to feel it when you get there and then without moving just stand the punch upright and make a dimple right at the intersection.
    When my mill was manual, I too used it a lot as a drill press. But now it runs CNC so not as easy to just walk up to it and turn the motor on. My drill press is just sitting there like your mill so is my first stop when I need to knock a hole. I don't expect the precision of my CNC mill, but often don't need it.

    I really like your technique of finding the intersection of two scribed lines. It is worth the time to learn to have the right touch.

    Thanks,

    Rick
    Rick

  14. #10
    Supporting Member Crusty's Avatar
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    Crusty's Tools
    Not my technique - I got it from Tubalcain (Mr Pete) who got it from his brother years ago, but it worked better the first time than anything I had ever tried before and continues to do so. It's one of those ah-ha! moments. Just tracing the scribed line with the tip will give you the right, light touch and you'll feel the intersection. It might work a little better if you follow the first line that you scribed with the tip so that it runs into the ridge thrown up by the second.


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