Dean Hedin wrote: > This is a revisit of this topic. Some time ago we were discussing the tiny > bit problem > and what type of motor would be best for this. > > Yesterday I picked up what I believe will be my new emc machine. > Some time ago, where my brother worked. they disposed of some old printed > circuit board routing machines. > He was able to save two of them from the dumpster, and gave me one. > > It's a Seebach LPKF (West Germany), 20x26" table, gantry style. > I went to thier website and the closest thing they offer today is something > like this: > http://www.lpkf.com/products/rapid-pcb-prototyping/circuit-board-plotter/protomat-m60.htm > > My unit is a little different. The gantry does not have a sheetmetal cover > like the one above. > All major items are made 1/2" thick aluminum. The rails are about 7/8" > precision rods with linear bearings. > > The X,Y axis have two steppers. The Z axis is a solenoid that moves about > 1/4 inch. > I intend to construct a new stepper driven Z axis. I will probably use a > xylotex controller. > > The steppers have 10 wires, so there may be encoders on them. > No electronics or documentation was included. So I will have to figure > everything out. > > There are a few circuit boards that serve as wire junctions and for mounting > the limit switches. > I think from this (and an ohm meter) I can figure out the wiring to the > steppers. > > The power head is what I'm getting to. The motor is a cylinder about 1 1/2 > inch diameter and 5 inches long. > It has ball bearings. > > I hooked up my bench DC supply and powered the motor up. > Even at 24 volts (the limit of my bench supply) I don't think this motor was > even close to 10,000 rpm. > It definitely needs more voltage. At 24v it was drawing very little > current, about 160ma. > > Unfortunately I don't what the motor rating is, but given the thin guage of > wire, I suspect that it is a > high voltage, low current type of DC motor. This is something I have never > encountered before. > > The spec sheet for their current model states 60,000 rpm spindle speed. > I don't know how I am going to come up with a power supply for this. It > might take 80-100 volts > before it hits this speed. > > I have access to tachometer. So that's a start I guess. > > Anybody know where I can get a 100 volt 1 amp DC supply? >
For test purposes, a variac with a fuse, followed by an ISOLATION transformer (120V to 120V) followed by a bridge rectifier and cap, would work. Start with the variac on zero and slowly increase. Doing it without the isolation transformer is EXTREMELY unwise, we'd like you to stick around for a while. Even with the isolation transformer, it is very dangerous if you get sloppy. You need to establish the required voltage first though, so you don't wind up over-speeding the motor and wrecking it. If you can spin the motor at a known speed using something else (I've used my drill press for small motors), you can measure the terminal voltage while it spins. Then you can figure out the volts per 1000 RPM. Multiply that by 60 to get the volts at 60,000RPM. Then at least you'll know what voltage you need. Example: spin it at 450 RPM, measure 2.35 volts. Then volts/1000RPM is 2.35/0.450 = 5.22, and volts at 60,000 RPM = 60 * 5.22 = 313V. I doubt your motor will be that high, I just pulled those numbers out of the air without working the math first. For the test, you want to spin it as fast as you reasonably can - 1500 rpm would give a more accurate answer than 450 rpm. The above assumes that this is a simple brush type DC motor. If it is some brushless thing (which I'd expect at those speeds) then I have no clue. Regards, John Kasunich ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
