Recently I was able to acquire the clock that I consider to be the most beautiful art deco wall clock ever made, the Hammond model 341. From what I have been able to gather, the 341 was a dealer clock, so they are fairly rare. The clock has wonderful art deco chrome fins on the sides, and a beautiful lighted dial.
Sometimes you’ll see a “Postal Telegraph” dial with the chrome fin housing, but that just means someone had to replace the dial at some point. The correct 341 has the “Hammond” dial. Here is my restored 341:
I thought I would make mention of two issues I encountered in repairing my 341, since I couldn’t find very much information on the internet. Hopefully it will be of help to you if you are in the process of restoring one.
First, the light bulbs. When you see pictures of these clocks on eBay, you will often see a very red glow, and they are very dim:
The lights in the 341 were wired in series, not parallel. This causes the voltage to be drastically reduced. Additionally there is a resistor, which further reduces the voltage. When people replaced the bulbs over the years, they probably just used a modern 120 volt bulb. The 341 however was designed to use 34 volt bulbs (I found that information here). The red glow from using a 120 volt bulb comes from the voltage being so low that the full light spectrum cannot be produced. Depending on the wattage of the bulbs, you may find that putting all five lights in series reduces the voltage so much that they barely glow at all. The previous owner of the clock I acquired had replaced two of the five bulbs with screw-in fuses in order to provide enough light. However it was very uneven since there were only three bulbs in use (see photo above). I also noticed that the ceramic resistor was melting…. this does not seem particularly safe.
I wrote to a friend of mine who is a physics teacher, and he explained that matching the voltage of the bulbs, wattage, and resistor as designed was important. For those of you who are solid in math, here is his response:
Power = voltage x current. But since current = voltage / resistance, Power = voltage^2 / resistance (34 volt bulb, 15 watts). So given the ratings the resistance per lamp is nominally 77 ohms.
In a series circuit the current is constant throughout the circuit. In this configuration the current is determined by taking the available voltage divided by the total system resistance, or 5 x 77 ohms = 385 ohms. So the current draw is 120 V / 385 ohms = 0.31 A.
The voltage will distribute itself across each component in proportion to its resistance. Since they are all identical each lamp will see a voltage “drop” of 120V / 5 or 24 V each. So the power consumed by each bulb (brightness) will be 24V x 0.31 A = 7.2 W.
OK so each bulb should be producing about 7 watts, without considering the resistor, which I didn’t have the tools to measure, so I am estimating that the resistor would provide similar resistance to one additional bulb. Recalculating with that in mind I arrive at 5 watts per bulb. That’s dim, but probably perfect for the purpose. If we recalculate based on using modern 120 volt bulbs however, we can see why someone replaced two of the bulbs in my clock with fuses:
120^2/60 (there were three 60 watt bulbs in the clock when I got it)=240. 240 ohms times five bulbs means 1,200 ohms of total resistance. 120 volts divided by 1200 is a current draw of .1 amps… and that means that each bulb will only produce (24 volts x .1 amps) 2.4 watts! And that is without considering the resistor, which further reduces the voltage (my estimate) to less than 2 watts. Sure enough, when I inserted a 60 watt bulb into each socket, they were so dim that I wasn’t even sure they were on at all at first. So clearly I needed to find 34 volt bulbs.
Fortunately you can still get 34 volt bulbs from boating suppliers! I ordered these 34 volt A15 bulbs from iboats.com. They worked great. As you see from my picture at the top of the article, the light is more of a golden tone. In the photo you can still see“hot spots” from the bulbs, but fortunately in person the light is nice and even. Best of all, by using the proper bulbs, the lights run extremely cool. Safety!
I also decided to rewire all the connections with modern stranded copper #12 wire. The old wire just looked too fragile to me. If you do this, just make sure you replicate the connections so you stay in series!
Next, the clock motor. Mine was broken. I believe some of the gears had just worn down over the years. You purists out there may not like this, but between the difficultly in trying to find an original 341 motor, and the safety concerns in running a 1930s motor 24/7, I elected to retrofit with a modern battery operated movement. But I definitely wanted a continuous movement second hand, not a quartz movement which would not be at all authentic. For those who are interested in trying to make their original motors safer, check out this article.
Fortunately I found a movement that had a long enough shaft to fit and provided the continuous second hand. Here is the link.
As you can see, it works great and I have no safety concerns. NOTE: I did not attach the motor to the glass clock face as you see in the diagram below. I attached it to the metal housing beneath the glass and the spindle just sticks up through the glass face. I did not want any undue pressure on that glass.
There is work required to get the old hands to fit. I wish I had taken pictures during the process, but I wasn’t thinking of it. Basically you must drill out the holes of the hands slightly so they will fit the new spindle. Be careful! If you go too large you’ll have a new set of challenges. Fortunately this went fine for me and I was able to friction-fit the hour hand, and hold the minute had in place with the newly included brass “open nut.”
The red second hand is the trickiest part. It is threaded and simply tightened onto the second hand spindle which sticks out beyond the minute hand spindle. But the modern battery operated second hand spindles are recessed and friction-fit, not threaded (see diagram above). The second hands for these types of motors have a post on the back of the hand and you just push it onto the second hand spindle. This presented a problem since the Hammond crescent second hand has no post.
What I decided to do was to trim the ends of a modern push-on second hand and attach it to the back of the Hammond crescent second hand. This would provide me with the needed friction-fit post. To marry the two pieces, I sanded the back of the crescent second hand so it was perfectly flat.
I then attached the modern second hand to the crescent second hand with crazy glue gel. Then I simply pushed the second hand on the modern friction-fit spindle. You can see from the video above that it still looks perfectly authentic and works great.
I hope this information will be helpful to someone. Feel free to leave questions in the comments.
