[sdiy] Soldering races (was something else)

David G Dixon dixon at mail.ubc.ca
Thu Jun 2 05:06:23 CEST 2022


Hey Team,
 
You may remember that I started a subthread about soldering through-hole vs
SMD.  Well, today I decided to actually time myself with a stopwatch.
 
I timed two different sets of through-hole resistors.
 
The first set was 60 of all one value (10k) that I buy in boxes of 5000 on
tape, so I can bend and cut them very quickly.  My system is as follows:
 
1) I cut 5 strips of 12 resistors each from the box.
2) I bend the strips in half so that the resistors are close packed (they
come spaced out).
3) I use long straight needle-nose pliers to bend all 12 resistors at once,
about 2 mm from the resistor body on both sides.  This gives 0.4" lead
spacing.
4) I cut all of the leads (in groups of 4) so that about 1 cm remains on
each side.
5) I stuff all of the resistors, being careful to orient them all in the
same direction.
6) I solder them all.
7) I snip them all.
8) I inspect against a strong light.
 
The entire process for those 60 resistors (on two different PCBs) took
17:40.  That's about 18 seconds per resistor.  This is a little longer than
I was expecting, but I am soldering a little slower these days.  It seems
that I'm having a little bit of a problem getting the solder to flow, so
each joint takes maybe one second longer than it should.  I think my
(Chinese) solder skimped a little on the flux.
 
The second set was 59 of all different values, from two different boxes
containing 59 different little bags in order as they go on the PCBs -- one
box of 23 bags for a 12-stage Dome filter, and one box of 36 bags for an
18-stage Dome filter (one of the resistors on the 12-stage filter is
actually 0 ohms, so that's why there are 1 fewer resistors).  My system here
is as follows:
 
1) I take the bag out of the box, tease out one resistor, put it between my
lips, reseal and replace the bag.
2) I grab the resistor body between my left thumb and forefinger and bend
the leads with my right thumb and forefinger.  This gives 0.4" lead spacing.
3) I cut the leads to 1 cm on each side and set down the resistor on my
bench in order.
Steps 1 to 3 are repeated as needed to get all the resistors needed for one
row of the PCB (there are two rows on each PCB -- rows of 12, 11, 18 and 18
resistors).
Then, steps 5 through 8 from above are done once for each PCB.
 
The entire process for those 59 resistors took 34:45.  That's about 35
seconds per resistor.
 
So, obviously, the biggest time-suck of through-hole parts is actually
retrieving the parts from their bags.  I believe that the stuffing,
soldering, snipping and inspecting only took about 13 minutes for both sets
(although I must confess that I didn't time those steps separately).
 
I'd like to conclude this post by saying that I do not enjoy "racing against
the clock" as I did today -- I didn't really work faster than I normally
would, but I was a bit more relentless than usual.  I like to take a more
leisurely time, since this is a relaxing pastime for me.  I should also
mention that I listened to one of my favorite pieces of music while doing
this challenge: Messiaen's organ cycle "Meditations sur le mystere de la
sainte trinite," and that made the time pass very quickly.  Highly
recommended listening -- I prefer the Jennifer Bate set on the Beauvais
Cathedral organ on Unicorn-Kanchana, but the Olivier Latry set on the Notre
Dame organ on Deutsche Grammaphon is also excellent, but perhaps a little
harsher, and maybe a tad too fast in places.
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