Lathe Rant..... and some Qs....

Could this be a variable speed DC drive?

Got a camera to take pix?

No, straight gear head.

Good idea, once I get into the 19th century..... :(

If the DC went into the motor I'd suspect a synchronous machine, but why in hell you'd need a synchronous motor on a lathe is totally beyond me.

Perhaps it was put in there specifically to confuse the hell out of _you_, because you're special.

Many applications use a shot of DC to brake an AC motor.

Paul

and again in English

Full wave bridge is most likely fo the spindle brake, might put DC to the motor, but more likely to a coil that pulls in a brake somewhere in the gear head.

Can ditties might be some kind of surge or spike suppressor.

Thank You, Randy

Remove 333 from email address to reply.

In article , snipped-for-privacy@coinet.com wrote: :On Feb 4, 1:49=A0pm, "Existential Angst" :wrote: :> Awl -- :>

:> So my buddy's fairly robust SouthBend-Nordic-15 (very accurate, 60" bed, = :I :> believe) went on the fritz, blowing fuses -- worked the the night before, :> the next morning, bzzzzt.... :>

:> When he was in Brooklyn, I was mostly off the hook for his repairs, but n= :ow :> that he is in Yonkers, not far from me.... =A0goodgawd..... :>

:> So I open the lower panel, and Holy S*it..... =A0the first thought that c= :ame :> to my mind is: :> =A0 =A0Just how many fukn wires and electro-mechanical gadgets do you g-d= : need :> to rotate a fukn spindle??????? :>

:> I said, Dude, I hope you have a fukn book/print for this thing..... :>

:> Long story short, since he couldn't find the book, I eliminated all :> supply-side problems, and then *I think* I was able to isolate the motor :> electrically, and indeed, the motor appears blown. :>

:> Which in a sense is not so bad, because having that motor re-wound will :> likely be a fraction of the cost of actually having to replace anything f= :rom :> SouthBend.... The last switch gadget he had to buy was effing $900!!!!. :>

:> BUT, it is going to be one muthafucka to get to that motor, since the lat= :he :> is in, uh, a fairly "compact" shop.... =A0goodgawd..... :>

:> But here are the Qs: :>

:> 1. =A0Is this a "motor constantly on" type lathe, with the crank switch (= :off :> the carriage) engaging a clutch? :> Or is the motor itself activated by the carriage crank switch? :>

:> Ahm no spert, but the only clutch-ditty I've seen was the newer square he= :ad :> Clausing Colchesters, with that s***ty multi-plate ditty that never worke= :d :> right on our machine. =A0Nice machine, but what a pita that clutch was. :>

:> 2. =A0 WTF =A0 *IS* =A0 alladat s*it inside the control panel? :>

:> I see a =A0transformer (about 10 lbs mebbe), with a dozen taps going to a :> terminal ditty with two bitty glass fuses; =A0a heavy duty diode *full wa= :ve :> rectifier*!! =A0DC???? =A0For what????? :>

:> A fancy-shmancy twist handle breakered switch, a semi-normal contactor, a= :nd :> some abnormal relay with some kind of timer knob?? =A0timing what???, =A0= :and :> three little can-type ditties, one in series with each phase wire, about :> 3/4" dia x 1" long. :> And another terminal block with a cupla dozen wires on it. :>

:> Goodgawd..... =A0 for a *motor*???? :>

:> I guess what I would like is mebbe an overview, and overall sense of why = :all :> this stuff is necessary. :> Heh, my crappy li'l 13x40 Enco has a bit of control box as well, but sinc= :e :> nuthin has broke yet, I don't have to be indignant about it yet. :>

:> He has the book "somewhere", altho if/when he finds it, I don't know how :> helpful it would be for the print. :>

:> None of this is critical now, since I'm 99.9% sure it is a blown motor, b= :ut :> goddamm, it would be nice to grok what alladat stuff is for. :> -- :> EA : :Many applications use a shot of DC to brake an AC motor.

That would be my guess here, explains the presence of the timer too.

BTW, DC braking is pretty hard on an AC induction motor. All the stored energy in the rotating parts gets dissipated in the armature, which isn't built to handle that.