DMM probe sharpening?

Discussion in 'General Electronics Chat' started by smilem, May 19, 2015.

  1. smilem

    Thread Starter Active Member

    Jul 23, 2008
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    Hello, I wonder did anyone tried to sharpen their DMM probes, I have Agilent u1168a type of kit probes.
    The tips are not like new, so I though a rubber wheel and dremel is good start, but how thick is the plating? Perhaps they are solid stainless etc?
     
  2. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    I'd guess nickel plated brass.. Sharpening will expose the base metal quickly but really shouldn't cause any real problems IMO.. Plating is only maybe 50-100 microns thick max..
     
  3. smilem

    Thread Starter Active Member

    Jul 23, 2008
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  4. nsaspook

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    Aug 27, 2009
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  5. KJ6EAD

    Senior Member

    Apr 30, 2011
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    I also have a set of those. The probes are stainless steel and have very sharp tips which are excellent for SMD PCBs and when extended can reach down between larger components. The same ones are also sold branded for Fluke.
     
  6. ErnieM

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    Apr 24, 2011
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    Another vote for Pomona. They have several styles, some with sopring loaded tips, some firm, some gold plated too I believe.

    I prefer a thin fixed probe myself, though they also make a thicker probe with various tip adaptors such as a clip end (handy for grabbing and holding some wire end).
     
  7. nsaspook

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  8. ian field

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    Oct 27, 2012
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    IME: the plating is usually pretty thin to start with and doesn't last long anyway, sharpening the brass underneath works for a while but ultimately accelerates wear.

    In my first ever job after leaving school, I was fault finding on very early desk calculators that had about 200 DTL chips in them. The boss showed me how to make a sharp pointed probe that doesn't slip off the DIL pin shoulders.

    Take a disposable (non-retractable) ball point pen and take apart the end with the ball in it - at least some of it will be brass, although the whole ball holder that the refill pushes into used to be all brass. Separate the brass bit from the plastic bit it pushes into (you'll need to solder it soon). Get a box of sewing pins (not sewing needles) find something you can use as a die/anvil that you can rest the brass bit in and use a pin to punch the ball out. Now take a new pin that you haven't just blunted and solder it into the brass bit, the lead/wire/cable is soldered to the head end of the pin shaft and its all assembled back to the pen barrel.
     
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  9. Externet

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    Nov 29, 2005
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    Very correct, Ian.
    That has been my oscilloscope probe for 10 years. On a red Papermate disposable pen, with RG174. But I used a sewing needle instead of a pin, force fitted. Is much sharper and durable. Protudes about 3mm from where the ball was. And what a pleasant difference to probe without any slipping.!!!
    Made a few for co-workers and enjoyed them. It pierces surfaces so well, ensures firm contact.
     
  10. dl324

    Distinguished Member

    Mar 30, 2015
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    Thanks for that tip. I'm going to make some before resuming troubleshooting a power supply. My probe slipped off a lead and shorted a regulator. Fried a couple diodes, blew the fuse, and may have killed the regulator...
     
  11. DickCappels

    Moderator

    Aug 21, 2008
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    I sharpen the tips of some DVM probes, but as per mcgyvr sharpening the tips is like smoking. Since the protective coating is soon gone, once you start things get bad if you stop.
     
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