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Hacking Small Electric Motors

Discussion in 'Hacking' started by Gizmo, Jan 28, 2024.

  1. Gizmo

    Gizmo Chief Site Administrator Staff Member

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    So, this isn't hacking in the computer sense, but it's still IMO hacking, because it is taking something and repurposing it.

    I bought my wife a Samsung Gas Oven Range a few years ago (model NX58K9850SG/AA if you're curious) It's about 8 years old now. In general, it's a nice stove. The main reasons I got it are:
    1. Because it has a nice cast iron griddle on top for cooking things like bacon or pancakes
    2. It has a split oven, so I can cook two different things at two different temperatures at once. At the same time, I can remove the oven splitter panel and use it as one large oven for when I need to cook something big (like the Thanksgiving turkey).
    3. Because it has a split oven, I can use the top oven when I only need to cook something small but don't want to nuke it in the microwave, which allows it to heat faster and use less energy overall.
    Yes, I know the talk about electric stoves/ovens, how they are more energy efficient, etc., etc. I've had the electricity go out often enough because of ice/snow storms that I want a gas stove, so that when the electricity goes out I have SOMETHING to provide at least a LITTLE heat.

    Anyway, the split oven feature is the issue here. It uses a pair of electric fans (one in the upper and one in the lower oven) to help circulate the heat. I have to replace the top motor about once every couple of years (the top oven gets the lion's share of the use) because the motor bushings are shot. The motor is pricey (between $100 and $150, depending on who has it in stock). To make matters worse, there are two motors, the only difference between them being the direction of rotation; they are otherwise identical, but the lower one won't work in the upper slot, and vice/versa. The upper one is part number dg31-0014f, and the lower one is part number dg31-0022a.

    Anyway, it appears that what happens is that the lubrication pad built in to the motor bushing dries out because of the oven heat that is conducted up the motor shaft. Once the lube is gone, the bushing dies. There is a small hole for introducing oil to the lubrication pad, but this is not mentioned as a required service item in the owner's manual.

    It galls the hell out of me to throw away $100 motor over 10 cents in bushings.

    So, I started doing some investigating. The bushings have a 5 mm bore, 10 mm diameter, and 7mm length, and are spherical about the major axis. Basically a ball bearing with two opposite faces shaved off to make flat surfaces, and a hole drilled through the middle from face to face. I can find bushings that match one, or even two of these dimensions, but I've yet to find one that matches all three. I can get them made to my specification, but I have to buy like 10,000 of them at a time. Even at 4 cents each, that's still $400 to fix my fan motor.

    Well, it turns out there is another motor, dg31-0005a, which is also used in these Samsung Oven Ranges, uses the exact same bushings, and can be had for between $15 and $25, depending on where you get it.

    Taking the motors apart to get the bushings out and then putting the motors back together again can be a bit challenging, but it can be done with a little care and determination.

    So now I'm throwing away a $15 motor instead of $100 one. Still galls me, but it's an improvement.

    Oh, BTW, as I said above, the only difference between the upper and lower motors is the direction of rotation. So it is perfectly possible to take an upper motor and convert it to work in the lower slot by simply removing the motor mounts and swapping them around and then remounting the motor in the new orientation.

    Also, since there is a lubrication window, I'm going to make it a point to freshen the lube once every 6 months or so. I figure 3-in-1 oil should probably do the trick. Hopefully that will keep me from having to replace any more bushings, but if I do have to replace them, I know where I can scavenge some from now.
  2. ThunderRd

    ThunderRd Irreverent Query Chairman Staff Member

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    Can you not simply remove the blades and turn them over to make the fan blow air the other direction?
  3. Gizmo

    Gizmo Chief Site Administrator Staff Member

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    Oh, if only! That would be too easy. The fan hub is asymmetrical, so you can only mount the fan one way and still have it clear the housing properly.
  4. booman

    booman Grand High Exalted Mystic Emperor of Linux Gaming Staff Member

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    Wow, you are a true engineer!
    I'm always worried about breaking something proprietary and having to replace the entire appliance.

    I'm also not very good with electronics, as in voltage, wattage, ground. Some things I just won't touch, like a power supply.
    I've opened one to paint the outside, but didn't touch anything inside.

    I can soldier electronics, but its because no voltage is going through the components, but I am worried about damaging other components connected.

    You really have the patience to research, trial-n-error and figure out what is wrong and repair it.
  5. Gizmo

    Gizmo Chief Site Administrator Staff Member

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    Dude, I have been hit by everything in the frequency spectrum, from DC to Light, and from 12 volts to 120,000 volts. Some of it tingled, some of it knocked me on my butt, and frankly I'm amazed I don't glow at night, LOL.
  6. booman

    booman Grand High Exalted Mystic Emperor of Linux Gaming Staff Member

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    Ha ha, wow! You are braver than I am.

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