Re: EDM home brew units ?

> > Forced displacment is normally what they use in commercial

machines I

> > think as you are trying to force fluid through tiny gaps. I have

no

> > ideas about motorbike pumps :)
> >

> My concern is the wear on the pump.
>
> I don't know fluid, but in moving air, there are different types of
> fans. some for moving huge ammounts, but cannot generate any
> pressure. others that can create huge pressure but no volume, and
> lots inbetween.
>
> A suction would place the filter before the pump, so that may offer
> some protection.
>
> Also, automotive oil filters are spring loaded so they will allow
> bypass when filled. This may or may not be a problem.
>
> Dave
>

The KZ650 pump is a gerotor pump. Positive displacement flow control
can be by both a motor control to the DC motor that will drive it and
a blow off valve if an over pressure occurs. I'm not too worried
about wear. I have two of them and they were free. I'm a packrat
don't ya know. I have worked with an industrial size EDM and know
that the pumps deliver a fair amount of pressure in order to force
swarfe up the tiny gap between the electrode and work. Too much
pressure can have an adverse affect on the electrode if it is a thin
tube by forcing the tube to the side and causing a short.

It is all a balancing act.

It seems to me that if you were swiching power to the electrode, you
still need a cap in the system, or you would need a robust power
supply in order to drive the spark. Langlois' system had MOSFETs for
both charging the (small) cap(s) and more MOSFETs for discharging
them. (the duty cycle of charge/discharge) This system gives a nice
finish and speed (If you can think of an EDM as being speedy... )


Bill

This all started when I broke a tap and refused to toss the $20 of
aluminum away. Now I'm thinking of machining personalized forms into
punches for the custom bike market. Builders can punch their mark in
undisclosed areas in order to prove ownership in case of theft.