Extra holes in some Western Electric 500 bases - what were they for??

[RotarDad]

Can anyone explain why some 500 bases have a set of 3 extra holes in the lower left corner (looking from the bottom) of the base?   I've seen these more often on 60s 500 sets, but here is a '57 base with the 3 extra holes.   I've never see a variant of the 5XX series that used these holes.    Paul F?  Anyone?   What was WE planning for, and why did only a small percentage of the bases get these extra holes??

[Jack Ryan]

I don't see that many 500s but they don't look like company holes to me.

Jack

[RotarDad]

Jack - They are definitely factory.  Here's a '63 base with the extra holes - much better pic and easy to see the factory paint runs around the holes.

[Jack Ryan]

Jack - They are definitely factory.  Here's a '63 base with the extra holes - much better pic and easy to see the factory paint runs around the holes.

In that case I have no idea why a 500 C/D would need extra holes and I look forward to finding out.

Jack

[Ktownphoneco]

Paul   ....   The normal 500 series base is used for several different models within that series.     For example the 510 set has an push / turn switch that utilizes the 2 holes I've put a red square around.  (I'm using your picture Paul).   The switch can be used for a number of things, including operating 2 C.O. lines, excluding an extension telephone, turning a ringer on and off or transferring the incoming C.O. line from the internal ringer to an external ringer, and so on and so forth.    Without going through my catalogs, I'm sure there a number of other model types within the 500 series telephones that probably use the other holes for one thing or another.  Here's a link to a 510 set posted here on CRPF back in 2010 :  http://www.classicrotaryphones.com/forum/index.php?topic=3355.15

Jeff Lamb

[Jack Ryan]

I dug up some pictures and it seems early 500s had one set of spare holes and later ones had two sets.

Here is one used set.

Jack

[RotarDad]

Thanks for the input.  The holes I'm referring to are the 3 holes near the other foot.  Those 3 I've never seen used on any set.  Jack, the 500 U set in pink you posted is an example without these other 3 holes, which is much more common.  You guys are right about all the holes in the base having multiple uses.  These 3 have stumped me for years, even after reviewing all the models on Paul-f.com.  After finding that one from '57 on EBay recently, I thought I would ask the forum....

[Jack Ryan]

Yes, that was just an example of the earlier base with one set of holes - used in this case.

Later bases - 1960ish - have two sets of holes and I haven't seen the second set used either. However after Jeff's post and finding the example I did one would expect that the second set of holes would be used for a similar purpose.

Perhaps there is a two line set with a dial light. In that case both sets of holes would be used.

No doubt someone will post an example of the second set being used.

Regards
Jack

[andre_janew]

Some of the phones from the early 1950s still have mounting holes for a separate equilizer even though they have a 425B network.  Also, some 425B networks are secured with 3 rivets and some with only 2, yet the base has 3 holes for the network.

[RotarDad]

Andre - Good points.  The two holes near the handset entrance point were used for the 311A equalizer (or terminal block in the T/J/K sets).  However, those two holes remained throughout 500 production as far as I know.  They were used for other later models such as the 532 hearing-impaired set to hold the amplifier, etc.

The network mounting holes are also interesting.  You are correct that early networks (through sometime in '55 I believe) used 3 rivets.  Then a transition occurred where only two of the holes were used, but the third hole remained.  Then sometime in '56, the third hole was removed from the base.  The  "open third hole" is almost always found with the early sets after refurb in my experience.  A 425A net was removed and a 425B was installed using only 2 rivets, leaving the third hole empty.

[paul-f]

Other than the three mystery holes in Paul's original post, the one we haven't discussed yet was used by the 501-type sets for mounting the 426-type tube.

It was held in by a hex head machine screw. Often, when 501-type sets were converted to 500-types, the screw was removed, leaving a circular wear mark around the hole. That provides a quick way to determine whether the tube is (still) in a set.

As an example, here's the bottom of a relatively scarce 501T set. It has just about as many of the holes filled as we're likely to find. It's interesting that the open holes planned for line keys, switches or volume controls were present beginning in 1949. However, by the time sets that used those features were offered, the 500D sets, using the 425B network were the standard, so the holes previously used by the 500, 500T and 500K-type sets for the equalizer or terminal strip were vacant.

[RotarDad]

Thanks Paul F for adding to this thread.  Sounds like you haven't seen where the 3 "mystery holes" were used either.....  I was hoping you'd know..... .  Nice 501T, by the way.  Great to find party line sets still equipped with their tube!

Do you think it is possible that the 3 "mystery holes" were used to hold the base in some type of jig, perhaps during part of the phone assembly process?  If so, the other end of the base could have been held by existing ringer sound holes without creating interference with other parts.  WE wouldn't have added the holes unless they had some purpose.  Could some type of automated assembly being phased in during the early 60s when these holes became standardized(?) explain their existence???

If I could go back in time, one stop in the Tardis (Dr. Who reference), would be WE Indianapolis Works during the 50s.  It would be very cool to see the manufacturing process live.

[paul-f]

...  Sounds like you haven't seen where the 3 "mystery holes" were used either...

Still looking!  I'm aware of related conversations held elsewhere several times over the last few decades, with no resolution to date.

Several of us have looked through our collections of 500-type set variations and photos, and not found anything requiring the holes.

I'd be surprised if they'd put in extra holes for some manufacturing process. There was more likely some optional equipment to be mounted there, and we just haven't found an example - yet. Hopefully something will eventually turn up. It's good to have a few things like this to remind us that there's still more to learn.

[HarrySmith]

I recalled a field trial 500 with a tone ringer in it. I thought that might fit those holes but I finally found a picture and that is a totally different base. There are other field trials that I could not find a picture of the bottom but I am thinking those holes might be there.

[RotarDad]

OK, to add a bit more about the use of the holes in the base, here is a pic of my 532 (hearing impaired) set from 1956.  You'll notice several things:

1) The two holes on the handset entry side that were used on early sets for the 311A equalizer or junction block (T/J/K sets) are now used to hold the amplifier unit.

2) The volume control for the amp uses the two hex-head screws for mounting, filling those holes.

3)  This set was made in 6-56, after the third network attachment rivet hole was eliminated from the base.

4) The only unused hole on this base is the one on the left which, as pointed out by Paul F., was for the hex-head screw holding the 426A party-line tube.  If this set had been a 533 (hearing impaired, party-line), all the base holes would have been utilized.