Hamilton Beach 40DM restoration (and enamel badge repair)

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#1: Post by Sw1ssdude »

I have another completed restoration i'd like to share, with a lot of fantasy, it is even remotely related to the topic of coffee, so I try to make it worth your time.

I recently found a reasonable priced HAMILTON BEACH 40DM, the go-to-machine when it comes to milk shakes. Its jadeite green, was built in the USA sometimes in the early 40's, weighs a ton (probably because it's made from the same iron as Sherman tanks) and has three independent operating mixer shafts.

The holy trinity of fast food, hamburger, french fries and milk shake, sound in my european ears as american as 'Mickey Mouse', 'automatic transmission' and 'Pop! Goes the weasel', although 'french fries' originate, as the name implies, somewhere in Belgium, and 'Hamburgers' seem to be of german descent, probably named after a city from the north, maybe Rostock...?

This leaves milk shakes as the true American treat. And it seems to be true that the combination of milk and ice cream never caught on in europe as it did across the atlantic ocean. In the heyday of american drug store counter milkshakes, europe was busy with succumbing to looney dictators, waging wars and recombobulate society and economy from ruins. Twice.
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Sw1ssdude (original poster)

#2: Post by Sw1ssdude (original poster) »

Switzerland, the birthplace of me and Ovaltine (or OVOmaltine, as it is named here), was mostly spared from the commotions during that time, and came up with the OVO-mixer, a device that still can be seen in countryside restaurants. While being a bold copy of a single headed Hamilton Beach blender, its purpose was the production of an absolutely clot-free, fine frothed malted milk. My guess is that coming by some decent ice cream at the time was difficult, as people had other stakes at hand. Adding a scoop of ice cream to an Ovomaltine is, to this day, an outrageous proposal here in Switzerland.

While milkshakes in Europe are occasionally served in cardboard cups in the restaurant with golden arches, the demand of milk shakes in the USA must have skyrocketed soon after its invention, and a variety of multi-spindle mixers entered the scene, which brings this history class back to the Hamilton Beach 40dm, which spent the last couple of weeks on my work bench.
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Sw1ssdude (original poster)

#3: Post by Sw1ssdude (original poster) »

I got it from the USA, with all the cup holders missing, one cup missing, one switch missing, a hack job of a wiring loom, and in desperate need of 'a yeomans cleaning' as the seller described it.

I quickly disassembled it, and found the three motors covered in layers of carbon brush dust and rancid bearing grease. And some pine needles for some reasons. First things first, I took the motors out and cleaned the cast iron foot and the cast aluminum head of the machine.

You cannot imagine the putrid smell that developed as soon the soapy water liquefied the crusty stains and released the spirits of countless prepared milkshakes of the past. It was really bad, but it cleaned up nice.
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#4: Post by Sw1ssdude (original poster) »

Next up were the three motors. Those came apart fairly easy, they were just really dirty, with the brushes all run down and dry bearings.

Interestingly, they are very well spring-suspended, both axially and radially, and all the rubber mountings are still soft and pliable. A bit concerning was the electrical safety standard of the machine with missing insulations and bare contacts everywhere, but being from a time where cigarettes were prescribed to asthmatics and cough syrup was mere opium, this seems to be pretty decent. All those small mounting parts got glass bead blasted, and turned out as shiny as new. Unfortunately, the chrome plated bottom halves of the motors are a bit pitted, but I decided to leave all the battle scars and just make sure it is mechanically sound.

The motor armatures were badly grooved, the brushes and armature wore out severely. After pulling off the bearings and cleaning the rotors, I turned down the armatures on a lathe. I took off almost one millimeter of copper, but they turned out perfect. I also quickly brushed the stainless steel shafts.

New bearings of the closed type (which were completely metric for some reason) were fitted, and the motors went back together with the cleaned stators, which after lots of cleaning revealed different cable colors for different speeds under all the grime.

New brushes of 6x11x15mm were ordered and installed, completing the motors and preparing them for another 50+ years of operating. I had to file them down a little bit, but now they fit well again.

The different speeds can be selected individually for each of the motor using the according three speed switch on top of the machine. Those humble switches required only a drop of heavy duty oil and continued their job like it was 1943.
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Sw1ssdude (original poster)

#5: Post by Sw1ssdude (original poster) »

The cup-operated on-off switches on the other hand were in bad shape. H-B themselves had to admit that they were way too complicated and sensitive for a rough gastronomical environment, so they came up with a replacement micro switch, which can be found often in those machines, as did I. One of my switches was already jerry-rigged with a micro switch assembly (and lots of duct tape), the other one was still original and working, and the third one was missing completely.

Since replacement is easy, I had no restraints and glass-blasted the original switch. It turned out really clean, works perfectly and looks really good again. The jerry-rigged one needs a resoldering, but works as well.

In the meantime I also found a used stepdown transformator which allows me to operate this 110volt mixer on Switzerlands 230volt power grid. The NEMA power cable was ordered new, as the old one was cracked and dirty and disgusting. The wiring was redone completely, I didn't trust those twisty nuts that connected the cables and replaced those with proper connectors for lamps, and after a thorough cleaning the ground contact is no longer isolated with layers of milkshake, so this thing should be safe to operate.
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Sw1ssdude (original poster)

#6: Post by Sw1ssdude (original poster) »

Unfortunately, this machine spent the last couple of years in an attic or a basement, and tipped over or was bumped into. The front badge lost a big portion of its enamel, and is beyond repair. I'll try to fix that, and honestly, this is the reason I posted this to the Homebarista forum (also because there is no milkshake forum):

The repair was astonishingly easy, since the badge was already FUBAR (f*cked up, but apparently repairable :). I chiseled all of the remaining enamel off with a variety of small tools. Wear goggles if you attempt this, it sends small glass shards flying in all directions. After that, I cleaned the copper badge with acetone and citric acid, to get rid of all the gunk which was embedded in the cracks of the enamel. After having a squeaky clean badge, I went shopping for nail polish.

Nail polish is lacquer paint, comes in all colors, and is fairly cheap. I drew white nail polish in a small syringe and mounted a soldering tip needle, those are short and have no pointy tip, its just a small barrel. Electronic engineers use those to apply soldering flux. With a needle like this, it was easy to distribute and guide the flowing lacquer through the letters, and small hickups were cleaned with acetone after drying. Like this, I applied a couple of coats, and got a good enough result for this machine. With a final clear coat the paint would be as glossy as the enamel, but I like the contrast between shiny chrome letters and matte background. Now, the background is no longer flush with the letters, but single headed Hamilton Beaches have the same style of recessed badges, so nevermind...

This might be useful for someone who wants to refresh his old La Pavoni badge, or similar lettering. I am quite satisfied with the result. I bet it works even better with flat badges. And if it ever turns ugly again, I'll wash it off with acetone and do it again...
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#7: Post by Sw1ssdude (original poster) »

There. All that I could do with what I had to begin with. The only things missing (besides a few imperial screws) are the cup holders, which can be found by Gerald aka 'The Malt Mixer Man', a really cool guy who knows a lot about these machines. He has a webshop and provides everything you need to keep your mixer happy. His site has also a lot of useful informations and How-To's.

He was able to send me some used cup holders, new rubber feet and some other missing small parts to complete this mixer all the way to Zurich. He even sold me three original H-B 30oz cups. With all missing parts in my workshop, I reassembled the whole machine, and after fiddling with the electrics, and shaving all the brushes, I made myself a decent first vanilla milkshake.

I really like the jadeite green with all the hicks and dents, the painted top part is a bit dull by now, and the brass shines through the chrome on the cup stands. The new brushes send out an aroma of ozone which mimicks the smell of a toy train set perfectly. All in all a really cool machine.

Since the quality of ice cream in Switzerland really picked up (or waved over from Italy) over the past few years I hope I can interest a certain ice cream parlor from Zurich into selling milk shakes. I have neither the room nor the appetite for a three headed milk shake mixer at home, and this machine really needs to be ridden. And seen.
Maybe even producing iced coffee or a frappucino, which ties this machine very loosely to the home barista forum and concludes this rebuild thread.

I hope you enjoyed the read.
Greetings from Zurich,
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#8: Post by OldNuc »

Nice job and you will really enjoy the home made malts come summer. Try making a milk shake (no malt powder) with coffee.

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#9: Post by HB »

Sw1ssdude wrote:I hope you enjoyed the read.
Loved it!

In the USA, some shops use them for mixing in candies, fruits, crushed cookies, etc with ice cream (so-called "mix-ins" or "concretes"). They use an insert that looks like a malt cup with the bottom cut off so the blades don't cut the side of the (paper) takeaway cup. I'm a fan of chocolate ice cream with Reese's peanut butter cups and Oreo cookies. Not sure if they're a thing overseas (?).
Dan Kehn

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#10: Post by sweaner »

Why do they call it Ovaltine?
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