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  1. #16
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    Oct 2007
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    Quote Originally Posted by DSEL74 View Post
    Pete what is the angle on a prick punch?


    My issue is getting a good fit between all the optical punch parts, facing them square and centred. I’m no good with a 4 jaw chuck and an indicator, there is definitely some black magic involved that I’m not privy too. My lathe have a lot of slop & back lash in all parts.
    I've never had to sharpen mine, so couldn't say what the angle should be. I'd say the Elora is less than 60 degrees however, more like 30-40. I'll try to measure it when I can. Unlike a centre punch, there's no hard and fast figure for this as far as I'm aware.

    There's no black magic involved in any of this, merely the ability to drill and ream a hole in "something" and have a punch and clear perspex rod of the same diameter slide within it. Turning a centre is a complete no-brainer and I'd suggest the most difficult part is to scribe two lines on the perspex that are precisely in the centre, approximately at right angles, and has a magnifying shape polished at the opposite end. It should all be quite straight forward lathe work with a tool set to accurate centre.

  2. #17
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    Oct 2008
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    N.W.Tasmania
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    Quote Originally Posted by Pete F View Post
    I've never had to sharpen mine, so couldn't say what the angle should be. I'd say the Elora is less than 60 degrees however, more like 30-40.
    A prick punch has a point ground to 30 to 60º, while a centre punch is ground to an angle of 90º usually according to my copy of "Shop Theory" which originated from The Henry Ford Trade School.
    Rob

  3. #18
    Join Date
    Dec 2007
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    Melbourne
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    Default Layout & bending Jig Tables -Optical Centre Punch

    Quote Originally Posted by Piers037 View Post
    Have you seen this video?


    when are you planning on drilling the holes? I am just about to make a 16mm annular cutter jig to drill my new table

    Cheers

    Piers
    Cool video.

    I’m doing two tables one with angular radial patterns and one with the 50x50mm grid. The plans is to start drilling the radial one at the end of next week (fingers crossed). The other can be delayed a bit I guess if need be. What is your time frame?

    I’m wondering how tight and accurate the jig holes are after drilling all those holes or if they start to open up. He seems to be just aligning by feel. I’d think a thicker jig would be more accurate than the thin edge of the angle iron in that regard. Are you going to do a box section with bushes again?

    …..Live a Quiet Life & Work with your Hands

  4. #19
    Join Date
    Aug 2010
    Location
    Near Bendigo, Victoria, AUS
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    72
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    3,102

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    Once the holes in the angle iron are drilled with the same core drill, the alignment of all subsequent holes will be spot on, Aligning the core drill with the magnet off is the 'trick'. Once you turn the magnet on, the drill won't move. I guess you have to be reasonably careful not to bump the magnet drill once its in the hole....
    Seems to me that you won't even have to layout the whole table, just the drill jig (the angle iron and the tabs).
    This is the easiest way I can see or thnk off to get the holes right.... The only thing I would do is use accurately fitting pins (or the shanks of suitable bolts), rather than the threaded part of bolts - which is invariably a smidgeon undersize.
    Cheers, Joe
    retired - less energy, more time to contemplate projects and more shed time....

  5. #20
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    May 2011
    Location
    Castlemaine
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    244

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    Quote Originally Posted by DSEL74 View Post
    I’m wondering how tight and accurate the jig holes are after drilling all those holes or if they start to open up. He seems to be just aligning by feel. I’d think a thicker jig would be more accurate than the thin edge of the angle iron in that regard. Are you going to do a box section with bushes again?
    Not sure if the holes will open up with the annular cutter. They certainly did with my mild steel bushes and the hand drill with standard twist drills.

    the plan is to make a jig with removable bushes. Not sure of the material yet. I will use the Retro Welders idea on indexing one set of holes off the previous set which I did not do. I will be drilling on 100mm centres 1800x900 table top but could pop additional holes in if you want to use the jig.

    I am a little way off having the time to get started on this project. Got to finish off some others first.

    Cheers

    Piers

  6. #21
    Join Date
    Jul 2014
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    Alphen aan den Rijn, Netherlands
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    208

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    Quote Originally Posted by Piers037 View Post
    I will use the Retro Welders idea on indexing one set of holes off the previous set which I did not do.
    It might be a good idea to mark the hole locations anyway. By indexing the holes off the previous set you may likely introduce compound error and by having all holes marked you will at least be aware of it happening.

    Peter

  7. #22
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    May 2011
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    Castlemaine
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    Quote Originally Posted by WoodBee2 View Post
    It might be a good idea to mark the hole locations anyway. By indexing the holes off the previous set you may likely introduce compound error and by having all holes marked you will at least be aware of it happening.

    Peter
    Good point. When I did the first table I scribed a datum and measured off that. I will do the same to check for any compounding errors.

    Cheers

    Piers

  8. #23
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    Aug 2010
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    Near Bendigo, Victoria, AUS
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    Just thinking aloud here, Piers and Dale:
    If Piers makes a 100mm jig that you can use, I suggest you use that in the first instance.
    You can then drill a couple of accurate holes in between and then use the 100mm jig registered to those two holes and off you go again with the next lot of holes. Do that in both directions for a 500 centreline pattern.
    Cheers, Joe
    retired - less energy, more time to contemplate projects and more shed time....

  9. #24
    Join Date
    Dec 2007
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    Melbourne
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    Default Layout & bending Jig Tables -Optical Centre Punch



    I spent 6hrs on the table today and only got this far.

    The black dots are done the two X I couldn’t do due to existing holes. Long long way to go yet.

    I switched to water soluble cutting fluid and that quickly takes off the blue.

    I was surprised at the amount of swarf generated.
    …..Live a Quiet Life & Work with your Hands

  10. #25
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
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    6,444

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    Dwarf's, are they hiding ?
    Best Regards:
    Baron J.

  11. #26
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    Jul 2014
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    Alphen aan den Rijn, Netherlands
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    Quote Originally Posted by BaronJ View Post
    Dwarf's, are they hiding ?
    Don't know, but Thorin's will know what to do with them. Heard they are prone to compound error thoughLayout & bending Jig Tables -Optical Centre Punch

  12. #27
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    Dec 2007
    Location
    Melbourne
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    Default Layout & bending Jig Tables -Optical Centre Punch

    About 50 Holes left to drill in the first table....My lord the time it takes to manually align the centre pin in each punch mark takes ages. I watch for the pin to deflect in the hole then adjust until it is dropping in deadcentre from all sides. This also involves turning the magnet on and off repeatedly. Once the magnet is off there is a certain amount of time where there is still a residual magnetic pull where you can get some fine adjusting in before the thing comes loose and moves too freely.

    I also have to spin the chuck to make sure it is the same all around and the with the drill running slightly score the surface and eyeball to see if the ring looks centred to the scribed marks and punch mark. The pin still is pretty loose so no matter how much I try I'm always fighting an uphill battle for accuracy.

    Piers037 when did you say you would be making your jig??????



    The apprentice sooking cos she wasn’t allowed to operate the drillLayout & bending Jig Tables -Optical Centre Punch
    …..Live a Quiet Life & Work with your Hands

  13. #28
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    May 2011
    Location
    Castlemaine
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    Quote Originally Posted by DSEL74 View Post
    Piers037 when did you say you would be making your jig??????
    I have found my old jig. I will be in the shed tonight so I will see what work it needs to modify it to suit a rota broach.

    Cheers

    Piers

  14. #29
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    Dec 2007
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    Melbourne
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    Piers how did you go with the jig?


    Sent from my iPhone using Tapatalk
    …..Live a Quiet Life & Work with your Hands

  15. #30
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    Dec 2007
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    Melbourne
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    First one down fully drilled and counter sunk.





    I quickly relaid my line with marker to double check and lucky I did cos I missed one. Quickly did that one and done.


    I had intended to be able to mount my ub100 bender and I measured the holes and all are equally spaced around the perimeter and should have dropped right in. Nope Chinese quality the diagonals are miles off the thing is ♦️ diamond.
    …..Live a Quiet Life & Work with your Hands

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