Gallery, Projects and General > Project Logs
Mill Power feed
Darren:
Can I ask if anyone is finding this interesting as i seem to be rambling on a bit here....as usual... :ddb:
If you want me to carry on I'll knock something up and do a "how to" post to clean the thread up a bit.. :thumbup:
telstar:
please carry on , I am waiting to see the end result
dave
Darren:
OK, I found a CB transformer power supply and an ATX supply.
I decided to start with the CB unit as this is about the simplest "proper" way to do this that I can think of for those that are not proficient with electronics. This is mainly because most of it is already done and you only have to make a small change to the circuit.
By proper I'm referring to a regulated supply, that is one that will not fluctuate in voltage even if the mains does. It will also keep the electricity supply company happy by not introducing noise into the mains supply.
The power unit
Oops, I seem to have lost a picture, you know what they look like I'm sure. If not have a look on Ebay. You will need one that is rated for 5A or more. That way we know the circuit will be the right sort.
Here it is opened up, nothing much inside. Just a small transformer and a circuit board.
The bit you need to look for is the voltage setting device. This will be a resistor or a zenier diode (auburn coloured glass)
You can see it here pointing vertically.
Closer view
We need to disconnect this and take it out. Replace with a variable resistor of about 5 - 10K value. I used a 10K as it is what I had to hand.
You can see two wires soldered to the board, these are connected to the variable resistor (pot). Doesn't matter which way round the wires go. On the pot connect these two wires to the middle and one outer connection. Again doesn't matter which outer connection you use. One connector on the pot will have nothing connected to it. we don't need to use this.
The clip leads are connected to the original power output of the unit and connected to the motor.
That's it...all we need now is a reversing switch, I'll do this later and fit it back into the case.
Here is a video, not very clear, sorry, but you will get the idea. Notice when I unclip one cable and the motor speeds up, we could add a push switch here for quick transverse of the mill bed. Hold your finger on to power, let go to revert back to the pot setting speed.
The digital meter is showing the Amperage, not voltage. I found that on the motor the high speed used much lest current (amperage) than the slow speed. I really don't think we need to be bothered with the slow speed.
Hope you enjoy the video, it's rough...... :ddb:
I will fit it all in the case later....
Darren:
Now time to put it all back in the case,
This is the reverse switch, it's a DPDT center off. ( Double Pole, Double Throw, Center OFF ) Meaning it switches both positive and negative with three lever positions. on-off-on.
Note the black and yellow wires and how they are connected. The center is the feed from the power supply and the two outer positions both go to the output terminals/motor. Only one side works at a time.
Drilling the hole for the direction switch, another was drilled for the speed control pot.
From above, the whole internals where moved back and extended wires made up for the LED on/off light.
And finally here it is with it's lid on.
The only thing I would like to add is a momentary switch for the rapid tram control. That way the desired speed setting can be left alone.
Hopefully this vid will demonstrate it working....
There, a simple but very versatile power supply from very inexpensive parts, or the junk pile in my case...... :)
Now then, fitting the motor to the mill.....or lathe or rumbler.....now there's a thought......!!!
ja2on:
Great job and a very informative write up :thumbup:
Cant wait to see it working on your mill.
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