Drill blanks used for punching holes and discs.

Discussion in 'Tools of the Trade' started by wunwinglow, Oct 11, 2004.

  1. wunwinglow

    wunwinglow Active Member

    Quick 'tutorial'. Drill blanks are rods of tool grade steel accurately ground to a particular diameter, but not yet fluted and sharpened. You can buy them in all the same diameters that normal drill bits come in, ie 0.1mm steps for us that are metricated.


    One end is usually left unfinished, the other has a half-hearted attempt at a ground flat end, but usually not much more than de-burring. To make a clean cut, we need that end ground VERY flat, with a VERY clean edge. I used a circular sanding disc with aluminium oxide abrasive, but a bench grinder, used properly, will do as good a job.


    The paper/ card to be perforated is placed on a firm surface, with a little bit of 'give' in it. Cutting mats are perfect, hard leather might work too, or VERY hard rubber. Also, make sure your computer is on another table....


    Place the ground cutting end of the drill blank where the hole is to be, and then give the other end a sharp tap with a hammer. Bigger hammers make this easier!!


    The ground end will cut a clean hole in the paper, and underneath ( maybe driven slightly into your mat, depending on how hard you wacked it!!) will be a nice clean disc. Here I have used both paper and 1mm thick fibreboard, and the thicker material gives a slight 'burr' on the reverse side. Easy to skim off with a sharp blade, or glue and push back. The front face and the disc were clean-edged.


    This works well from 2mm diameter to at least 6mm that I have tried, smaller sizes tend to push through the paper instead of cutting, while I simply haven't tried bigger than 6mm yet.

    This technique works well with plastic sheet too, by the way.

    Hope this helps someone! Usual disclaimers. If you damage your fingers, table, model, ears, whatever, its nothing to do with me!!

    Tim P
  2. Gil

    Gil Active Member

    Bravo Tim!

    Nice technique! Another jewel for the technique file.

    Thanks, Gil
  3. Leif Oh

    Leif Oh Member

    Second that! Leif
  4. And all with out the trouble of a die.
  5. silverw

    silverw Member

    Hi Tim.

    I'm wondering if your cutting mat gets damaged, or will it still "heal"?

    I remember my dad punching holes in sheet metal this way. He would always use the end of a block of wood as the support surface, but you would have to move to a new spot for each hole.

  6. wunwinglow

    wunwinglow Active Member

    Bill, so far my mat has healed OK, but I have only done a few 'wacks'. I tend to wreck mats after a few months anyway, and a local remaindered book store has mats at very low prices, so I treat them as expendable. Certainly moreso than my tabletop!! (Or than parts of my anatomy if my wife discovered any dings in the tabletop....) I can only suggest you practice to get to know JUST how hard you need to strike, and no more, and keep moving the impact point about the mat. Repeated strikes in one place will certainly damage it beyond healing. But then so will cutting.

    Tim P
  7. While this does work I still prefer the use of sharpened lengths of tubing in either Stainless steel or brass if you only have a few holes to do. IN the States they are available in 12" lengths of varying diameters and also in square, rectangular and probably hex too. I would assume that similiar products are available in Europe and the Far East in hobby shops that cater to the scratchbuilder.
  8. SCEtoAux

    SCEtoAux Member

    Maybe this

    I have used lead sheets as a backer when punching out bolt holes in pipe flange gaskets. The circular marks left by the gasket hole punch were easily fixed because of the maleability of the lead and the harm to the cutting edge of the punch was minimal. You might find lead sheets at a home repair store in the roofing section. It is used as flashing to keep out rain, usually around chimney bases.

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