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Wanted: Tips for Accurately Marking Holes

Discussion in '40- & 55-Series Tech' started by Coolerman, Aug 28, 2006.

  1. Coolerman

    Coolerman SILVER Star

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    I have been working on the Cruiser again and noticed I am drilling a lot of holes that are not quit lined up. Example: Spare tire mount bracket. Sounds easy just hold the bracket up against the panel, mark holes with marker, center punch, and then drill. Then you find that each hole is just a bit off cause of your old eyes and now you have trouble lining up the carrier. So you enlarge the holes... We've all done it and it gets old quick.

    I know some of you folks are engineers and machinists or are just blessed with good common sense and great skills so post up some tips on transferring marks that are accurate. Here are a couple that I have used.

    Tip 1: I use this IF I have the specs on hole spacing. Draw the center points in a cad program then print them out, tape to panel and use a punch to mark the holes. This works great if you have the specs....

    Tip 2: Clamp the piece in the correct position and use a drill bit that is almost exactly the same size as the hole and drill just enough to mark the holes. Remove and drill with the proper size bit.
     
  2. Mr. Green

    Mr. Green

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    Some tips:
    Step up sizes after drilling a pilot hole first. Large bits have a tendency to walk.
    Use sharp bits (and quality ones to boot, not the sweet bargain bin $10 - 50 piece set at the local retail center.
    Drill with a drill press if possible, not hand held, even if it means removing said part to obtain access.

    My only experience with this so far has been building a winch mount plate for the front. I had it plasma cut to my print for the low price of $35. Fit perfect. No holes to drill.:grinpimp:
     
  3. Coolerman

    Coolerman SILVER Star

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    Those are all good tips for drilling. I would add get a Drill Doctor it's a great tool. Any suggestions on how to get the holes marked accurately in the first place? :)
     
  4. my64fj40

    my64fj40

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    Ahhh

    Went through this myself last week

    I only got around to doing the holes for the tailgate hinges. First off there is quite a bit of slop in those hinges themselves. What I did was first make sure everything is lined up properly.

    Put up both tailgates, put the latch together and such, use some clamps. It doesn't really require any engineering skills to do it, but more patience. Measure 1500 times then drill



    The main thing is to put it completely together being it is tire carrier, tailgates, etc. and clamp it up. Then I even tested it, opened it played with the tailgates and such. Then take a pencil stick it through the holes in the hinges make your little circle. Remove the assembly and center the bit in the center of the circle. and drill.
     
  5. Walton

    Walton

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    I'm a Journeyman Sheet Metal Worker. They make a set of tools for this type of work. They are centering punches, and fit into the hole you are transposing to center punch. I have a set, and they come in handy at times.
     
  6. Degnol

    Degnol

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    Although I don't own a set, I have borrowed a set several times. They are very accurate when used with some of the above steps.

    Ed
     
  7. emtee

    emtee HAHA...Wait, Wut?

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    Centering punches are awesome for this type of stuff; if you're eyeballing things, an automatic (variable-pressure spring-loaded) punch is a nice tool to have. Not as expensive as it sounds, either :)

    Chisel-point bits won't walk as much as a standard tip; a Drill Doctor will allow you to chisel-point a bit if you wish.
     
  8. 65CRUISER

    65CRUISER

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    The centering punches you are speaking of are called transfer punches, McMaster Carr has them in sets or sold individually. We use them dailey in our shop, they work great.
     
  9. Walton

    Walton

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  10. Coolerman

    Coolerman SILVER Star

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    That's the answer I was looking for! I knew there had to be a way to do it.

    Searched and found this http://tinyurl.com/mjjvg
     
  11. ar2stp48

    ar2stp48

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    Pick up a set of the transfer punches and get a couple of center punches also. Keep your drill bits sharp---either get something like a Drill doctor or learn how to sharpen them. Drill pilot hole and enlarge to required size. On clean metal, a layout dye is useful; pencil and pen marks dont work if you want accurate layouts.
     
  12. Coolerman

    Coolerman SILVER Star

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  13. honk

    honk

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    Split points do work pretty good.

    Don't use HF transfer punches on hard steel - they'll dull. OK in sheet and mild steel.

    Automatic center punches are nice to have. The Starrett ones sometimes take work to get them to fire, especially the middle sized one - maybe mine's just ornery.
     
    Last edited: Aug 31, 2006
  14. too tall

    too tall

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    centering punches are awesome .I also use a metal scribe instead of soapstone or marker or what have you .I find it's way more accurate for holes as well as cuts .
     
  15. fjwagon

    fjwagon

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    I agree, A centering punch works great. I usually use masking tape and drill the hole on top. For me it's easier to mark and remove and start over if you have to. Also clamping it down when to trying to center the holes but sometime that part is impossble.
     
  16. cheap 40

    cheap 40

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    x3 on the split point bits. Even if you use a centering punch, if you hand drill with a regular bit, many times it will still walk if you are not perpendicular with the part. Split points help (but not totally) eliminate this.

    Tony
     
  17. kulangot

    kulangot

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    I use a fast drying lauquer spray paint. Spray into the hole and marks it perfectly, just need a dust coat. This is the same type of paint that I keep around as a guide coat when doing bodywork. Dust on and then sand in one direction, the overspay stays in the low spots...

    Wipe off right afterwards with laquer thinner.

    Ideally do this before paint work is done. It's amazing how well this technigue works, you can see irregular holes very clearly. This also works great for making patch panels when doing rust repair.

    It's also very easy to clean off the thin layer of laquer overspray if you are carefull.
     
    Last edited: Aug 28, 2006
  18. honk

    honk

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    I wasn't going to mention the machinist way of marking holes because of the ridiculous cost of many machining tools but I just got a new sale catalog from Enco and lo and behold, they have a new product that is the cheapest optical center punch I've ever seen. Here's a link to the item - I can't speak to how well, or even if it works but they claim accuracy within .002" :
    http://www.use-enco.com/CGI/INSRIT?PMAKA=DY632-5260

    If the link doesn't go to the page it's their item no. DY632-5260 in http://www.enco.com
    They sell Chinese and european made tools mostly.
     
  19. Coolerman

    Coolerman SILVER Star

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    I had to plead ignorance on what an 'optical punch' was so I Googled it and came up with this: http://www.nucleus.com/~harlan/punch.html

    Neat tool! Excellent for transfering drawing marks to metal.

    I did get a set of the Harbor Freight Transfer Punches yesterday. They were $9.99 and work perfectly! I was able to quickly get my tail gate latch holes lined up.
     
  20. Colorado Boy-74-FJ40

    Colorado Boy-74-FJ40 I may grow older but I refuse to grow up!

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