Thread: Harrison Mill Conversion
One trick you can do with torroids is to wind about 30 to 40 turns of the same gauge wire over the top of what is already there.
Switch on and test this winding and you will get around 10 to 18 volts, depends on number of turns.
Now if you connect this to the ends of your original winding then rectify you will get either 82.5 volts plus the extra or minus depending on how you connect the extra coil up.
You then need to play around with the number of turns to get what you need, it can be worked out by voltage divided by number of turns.
Also very handy to get an extra 5 v or 12 v supply for logic circuits out of a stock transformer.
Once tested a few turns of fabric tape around the torroid will tidy it up fine.
Thats exactly what I did John, had a 0-50,0-50 10A toroidal, wound 10 turns of wire round it (keeping them spaced evenly), measured the volts given then adjusted the turns to provide a nice 8v DC for the 5v regulator.
Note: If you are using John's idea in a 'buck' (reduction) arrangement you should measure the output volts when on load to avoid it not dropping as much or more than expected. Else assume a 5% regulation. So for a 70v DC output you need a 50v AC, if you have a 55vAC toroid it may drop to 52.5vAC on load so if you buck 5v you may only have 47.5v AC (67v DC) on full load. You may only want to buck 3.5v - depends on what compromise you decide.
Guys, can you have a look at this post please:
Any progress on this Son of a Beast ?.Me
Got a 50V toroid and tested it a while back, which gave a nice 75Vdc when I tested it.
Bought a metal cabinet to house all the electrics, but it's still sitting in it's packaging.
Been too cold outside to do much, plus what time has been spent outside has been on a couple other ongoing projects.
Hopefully get back to this next month.
I presume this conversion died?
I know this is an ancient thread to drag back from the dead but I'm converting a Harrison Milling machine myself and just wondered if it got any further than the last update or if that was it?
Well and truly dead!
I realised just how much of a pain doing a good manual to CNC conversion really is, sold this machine, and bought a bigger barebones already CNC'd knee mill, although progress on that has been very slow, as other projects keep getting in the way, and I keep dithering over the tool changer.Avoiding the rubbish customer service from AluminiumWarehouse since July '13.
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