Mars Lathe DC motor conversion.
Hi All,
Rather than this getting lost in the Wow huge price difference thread i am starting a new thread.
I have a 1.5 hp, 180v DC treadmill motor that i will be using for the conversion. The controller will be a KBIC240 DC (thanks Rob"nearnexus"), with a simple tacho running off a hall effect sensor.
The one undecided fact is still switching. To reverse the motor a switch needs to be put between the controller and motor, but the AC supply to the controller must be cut first. Currently i have a rotary on off switch and a toggle for forward and reverse. Basically, i don't like it! At the moment i have 2 ideas in the pipeline (i may use both yet) I am basing my thoughts around threading as this is really the only time i have ever needed to reverse the lathe.
Thought 1, use a 2 position 3 phase switch(which is basically 3 separate switches) I can wire the AC to one switch, then the DC to the other two switches to give me forwards and reverse. I am very slightly concerned about switching both the AC and DC simultaneously, but it stands to reason there will be no DC load until the AC contacts have touched, in which case arcing of the DC contacts should not be a problem. I like this idea BUT it means when threading, you can come up to a shoulder fast, turn the speed down and then you have to MOVE YOUR HAND TO THE ON OFF SWITCH.........
Thought 2 is to replace the 5k speed pot with a twin 5k pot. Then a can use the second pot as a voltage divider and use it to switch a relay on the AC line (after a master on off switch) This way i should be able to cut threads fast, slow the machine down and then stop it without taking my hand of the speed pot. The lathe can them be reversed, turned back on with the pot, repeat.
Sorry if that got a little long winded.....anyone got any thoughts as to which sounds better?
Now for some pics of the motor and fan. I am going to trial with only one. I tried to but found very little difference in a smoke test (not being a smoker i finally found a good use for incense......) A small ally frame to hold and seal the fan to the motor and it all went together a little too easily (gulp...)
http://i1151.photobucket.com/albums/...ps46ef97ec.jpg
http://i1151.photobucket.com/albums/...ps1f596941.jpg
http://i1151.photobucket.com/albums/...ps277ae1ec.jpg