No announcement yet.

Center punch help...

  • Filter
  • Time
  • Show
Clear All
new posts

  • Center punch help...

    I hope someone can help me out, I use a tungsten scribe to put a small indent in 1/2" by .018" shim stock using hand pressure only....then I use one of the many center punches to enlarge the indent enough for my hand punch to orient itself where I need it.

    Problem is, I'm hitting the center punches into a hardened material and they go dull relatively quick (that's why I said "one of the many"...cause it's a bother to re-sharpen all the time)
    I admit that I don't know much about hardening, tempering, or metallurgy in general to the degree of most on I ask: what should I do......I'm using regular old punches, Craftsman, proto, etc. and I sharpen them on the grinder then heat them red-hot, quench in water....and I have tried to temper them by bringing them back up to yellowish or thereabouts, but it's kinda hard with a torch and no knowledge.

    Any help would be great,

    Johnny "blunt punch"

  • #2
    Stop with the re-heat treating. With a good center punch, the heat treating will go well up the body of the punch and survive many regrindings.
    When sharpening, hold the punch oriented 90* to the wheel, tilted up at the angle desired for the point. Twirl the punch to sharpen. Grind very lightly and cool frequently.
    It might help the tip life to back up thin work with brass or other softer material. The resulting dimple on the backside will have to be dealt with though.
    By the way, when tempering, or drawing back, the part should be heated to the desired color, straw say, and then quenched. Sounds like you may be missing this step.

    [This message has been edited by JCHannum (edited 12-08-2003).]
    Jim H.


    • #3
      Useful trick when drawing temper on tools is to put the heat NOT on the place you want to make softer. On punch (for example) hold with vise grips and heat evenly well up on the well polished punch. you will see "colors" appear and start traveling down the punch to the cold end. Heat slowly so the punch is hot all the way through- (slow don't mean Bar-B-Que for minutes though). As the colors travel, the hardest color will be at the lead (say straw is what you want) the softer colors follow. When the straw reaches the tip of the punch' quench immediately by pushing it vertically into the quench material of your choice. If the softer colors get to the tip (you are too slow to quench) you have to make it hard again, and there are just so many heat treat cycles you can expect to perform.

      When properly done in this manner, the tip remains hard, the place where you applied the heat is softer. LESS chance of flying shrapnel with the softer body.

      The magnet test is very good way the determine the "critical temp" for the hardening before tempering. when it hits the critical temp, quench. The heating should avoid excess oxygen- you can burn the carbon right out of the metal.


      • #4
        Use an spring loaded so called "automatic center punch". Seems this would do the whole job in one step. Very hard points that don't dull easily.


        • #5
          Call round your local diesel equipment repairer and scrounge some needles out of fuel injectors.
          These things are unbelievable, glass hard but not brittle and can be used for umpteen uses in the shop. Punches are a good use. Use two together as points to line collet chucks up with centres of dividing heads or rotary tables.
          Take one and grind half the side away at the point to make a 'D' bit engraving cutter.
          Loadsa uses for these. Can't advise on types are there are many, my local guys save these up for me as they no longer regrind and lap these as it's cheaper to replace with new.

          John S.

          Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.


          • #6
            Tattoo springs?

            I made some from some high quality stainless shim once.

            Using a blunt rod in a drill press will soften a spot to drill. (spring steel)

            Also, use a brass block to punch over.


            (ps) one of my mentors used to use CuKoo clocks to make his springs in the 30's 40's.

            He'd build a frame to match the coils he salvaged from doorbells.

            I miss him, he tattooed over 75 years. Died in a VA hospital.

            Sailor Russel, He is in many tattoo history journals. He worked with Stony up north for a while. Was a orginal carnie tattoo artist.

            [This message has been edited by ibewgypsie (edited 12-09-2003).]


            • #7
              Thanks guys.....backing it up with brass, auto punch, drill press indent....all will be tried and I'll see what works best for it!!

              David, you must've heard plenty of colorful stories....I'm jealous, just reading the book about Stoney was pretty cool....getting a look at the rough and tumble way of life it USED to it's pretty different haha.



              • #8
                An old pulley tap w/the threads ground off and ground to a point makes a nice prick punch. Good for hard materials and also for trying to spin broken bolts out.

                Disclaimer: Only light blows. You could shatter the whole thing.

                If you know anyone who works on molds try to get some old ejector pins. They are hard as hell. Again only light blows.

                Zinom I told my wife to buy her springs since they are relativily cheap. I didn't want to mess with that blue spring steel and there are only so many garage hours.

                Jon Bohlander
                Jon Bohlander
                My PM Blog


                • #9
                  Pick up one of those cheapie carbide pc board drill bit sets. They usually have more than one of a few sizes. Pick a small tipped one, drill an hole in something with it, then after it breaks, grind a point on it. Insert it into a hole you drill in an old softened punch, and maybe wick some crazy glue in with it. Leave enough sticking out for resharpening. An easy half hour tool making project.
                  I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-


                  • #10
                    <font face="Verdana, Arial" size="2">Originally posted by Cass:
                    Use an spring loaded so called "automatic center punch". Seems this would do the whole job in one step. Very hard points that don't dull easily.</font>
                    Hmmmmm, well don't buy "General" brand, they dull to round bumps in short order on soft steel. At least mine does.

                    And the (&^%*&^$ replaceable points are not stocked locally....might go in somewhere mail order with other stuff.


                    • #11
                      Starrett points fit the General brand. They used to have carbide and diamond available


                      • #12
                        If you can't mark it with a center punch, how will you drill it??? There are a couple other tricks with center punches worth having in your hat, up your sleeve, etc. The sharp point on the smaller punches is good for starters. It makes a nice crisp hole that is easy to see the location with a loupe. If it's not on the required mark (mine rarely are) lean the tip toward the proper spot and tap again. You can 'walk' the punch mark over to the required location, where you will once again tap the punch, this time perpendicular to the work. It was a few years before I learned this; I thought you had to take what you got on the first whack... The other trick is the center mark then needs to be whacked once more with a blunt punch, the tip angle more closely matching the angle of the drill point. Otherwise the drill will skate before it locates the spot. All of this 'whacking' by the way is with an 8 oz. peen and a light touch. Wish I could say I was good at it, but I really suck at this eyeball layout stuff. But these are the tricks I use to help get my holes to line up. As others have said, if you don't let the punch get too hot when you grind it, it doesn't need to be retempered.
                        I'm here hoping to advancify my smartitude.


                        • #13
                          Gizmo, I don't drill it, I punch it with a hand punch....and the method you described is totally useful....I always THINK I'm on mark only to see how far off I am afterward.

                          Jon, yeah, buying them is a lot easier....cutting them into tapered points is an exercise in hand-slicery....thin, hardened stuff holds a sharp edge hahaha.

                          Jen caught me off guard one time on the other board about being on was funny, like I got busted.

                          Thanks again all,



                          • #14
                            An old trick I learned somewhere back in the mists of time. Use a punch ground round at the point to make the first mark. Finish the mark with a punch ground as the point of a tetrahedron, a three sided pyramid. It stops the drill from walking out of the punch mark.

                            Same principle as a three legged stool, it can't rock.

                            [This message has been edited by Evan (edited 12-10-2003).]
                            Free software for calculating bolt circles and similar: Click Here


                            • #15

                              Is that why sometimes I drill triangular holes with MY home sharpened bits?

                              I had a punch with a fence made on it too, just located it and pulled.

                              Is it springs you are making?

                              (things really are different now, too many people are tattooing)