Sunday, February 26, 2017

Arrow Stapler Model ETF50 -- Microswitch Failure

I was part way through installing some baseboard footing molding when my Arrow stapler started acting up.

Sometimes it would fire a brad, and sometimes it wouldn't. Finally, it wouldn't work at all.

I took it apart in hopes of finding a bad solder joint or some such, but a thorough visual inspection of the tool's innards revealed nothing that looked amiss. One item caught my eye, though, as a possible culprit -- the tiny microswitch that's operated by the trigger. Here's a view of the stapler's printed circuit board that has the microswitch on it.

The stapler is many years old, and has had very little use. In my experience, microswitches can and will develop high contact resistance with age. A little investigation with an ohmmeter was in order.

The switch has the usual terminal arrangement of common (C), normally closed (NC) and normally open (NO). The NC contact was ok; the NO contact wouldn't close. I did what I always do with flaky switches -- I hosed the switch down with WD-40 so the WD-40 could wick its way inside, and gave the switch many actuations. That did it. The NO contact came back to life. I reassembled the stapler and tried it out; sure enough, it worked. The stapler got me through my baseboard footing molding job without further trouble.

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Needless to say, I'm a big fan of WD-40. The stuff is my go-to solvent/lubricant for all kinds of things. Switches love it. It improves their operation and lengthens their life.

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The Arrow ETF50 stapler is a nicely constructed tool that's readily openable for maintenance such as that described above. To open one up, you'll need:
  • No. 2 Phillips screwdriver.
  • 5/16" wrench or nutdriver.
  • 3/8" nutdriver.
Proceed as follows:
  • Remove the magazine -- one special screw and a 5/16" A/F nyloc hex nut at the rear of the magazine.
  • Remove three 3/8" A/F nyloc hex nuts from inside the magazine chamber. Remove the magazine chamber.
  • Remove three No. 8 x 11/16" pan head thread-rolling screws from the side of the plastic casing. The casing opens up like a hinge.
WATCH OUT for the little coil spring under the trigger, that it doesn't go flying on you.

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1 comment:

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