Bread Maker Modification

Discussion in 'The Projects Forum' started by Bames, Sep 2, 2014.

  1. Bames

    Thread Starter New Member

    Sep 2, 2014
    3
    0
    Hi all,

    I'm trying to modify my bread maker to make it completely manual. For those who don't know, they essentially consist of:
    - metal casing
    - metal bread pan
    - motor to mix and knead
    - heating element to bake
    - electrical circuitry and chips to control the programs, and the motor and element

    In stock form, it has pre-set programs that run through a particular process, eg. mix for 2 min, knead for 20 min, let rise for 60 min, bake for 40 min etc.

    What I want to is simply remove all programming circuitry, and add one switch the the motor, and another to the heating element. All I want to do is be able to switch the motor on and off, and the element on and off. I don't want any programming at all. Simply on/off switch for each.

    The motor is done, I have already done that by simply connecting the power cable's neutral and active to the motor's neutral and active and putting in a switch. Easy.

    But when I do the same for the element - as in connect neutral to one end of the element and active to the other, it heats up for about 2 minutes and then trips the circuit breaker. If I reset the breaker straight away, it will heat for a few seconds and then trip. If I leave it for a few minutes and then reset, it heats for a bit longer and then trips. It never trips straight away.

    Any ideas on why this would happen, and how to stop it from tripping?

    Thanks
     
  2. pwdixon

    Member

    Oct 11, 2012
    488
    56
    You need a thermostat, the standard electronics is performing that function to control the oven temperature and if you swap it for a switch then you need to do it yourself, you could try a suitable normally closed thermostat. Without a thermostat of any kind the heater element will just glow red hot and eventually die or burn your house down.
     
  3. Lee697

    New Member

    Aug 31, 2014
    26
    0
    It sounds like the circuitry you've bypassed limits the current to the element?
     
  4. wayneh

    Expert

    Sep 9, 2010
    12,100
    3,034
    My first boss used to drill into our heads, "Always ask WHY?"

    So I'm asking - what's the point of an automatic breadmaker that isn't automatic?

    A short-term kludge to your heater problem would be to put a lightbulb in series with it. This would limit the current while giving visual feedback.
     
  5. Bames

    Thread Starter New Member

    Sep 2, 2014
    3
    0
    Thanks Lee,

    Yes that was my hunch too. I'm going to try another element and see what happens.

    Wayneh - I'm roasting coffee in it, not baking bread. I need the paddle to spin like it does on dough cycle, and the element to heat at the same time. I also need to be able to control when they come on and when the turn off. I'd love to be able to vary the heat of the element throughout to control the roast, but one step at a time...
     
  6. wayneh

    Expert

    Sep 9, 2010
    12,100
    3,034
    A standard light dimmer could give you some control over the heating element, although it may be costly to find one that can handle the current. You need a triac controller and a thermistor for temperature sensing. The bread machine would have both, but I have no idea if you can hijack them. They're inexpensive parts, though, so it is probably easier to just get your own.
     
  7. Bames

    Thread Starter New Member

    Sep 2, 2014
    3
    0
    Yeah I just had a quick look, and the element is 500W I'd want a 700w dimmer to be safe, and they're around $80 aus.
    Ebay has some variable volt/speed etc controllers rated to higher current, but not sure what sort would actually control temp.
    I'm not worried about temp sensing, as I have a DMM probe inserted into the bread pan to graph the bean temp throughout the roast, I just need to be able to turn up and turn down the element.
     
  8. wayneh

    Expert

    Sep 9, 2010
    12,100
    3,034
    You MIGHT get away with the lightbulb trick by putting the dimmer in series with it and the element. The dimmer would only need to be rated to the lightbulb wattage, and the bulb+dimmer would limit the element's power to value below the lightbulb rating, say 100W. That might be plenty?
     
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