Homebrew PCBs

Richard Mcfarlane wrote:

>Hi Curtis,
>>From Homebrew PCBs-Groups, I came to know about your
>interest regarding EDM.
>I am also an EDM diy hobbyist like you. I built
>several EDMs from the following plans :-
>
>1. Build This Space-Age EDM -( Popular Science,Mar-68)
>2. A Light-Bulb EDM Project--(Meadre Hanks)
>3. A Spark-Erosion Machine--(C.Roy Amsbury)
>4. An Workshop EDM--(Peter Rawlinson)
>5. Build This Shop EDM--(Robert Langlois)
> I observed these machines have poor mechanical
>constructions and moreover the EDM power supply are
>RC-Types.These are very slow and crude metal removal
>process and presently obseleted.
>  
>

I agree!  My prototype machine uses Thomsom linear slides mounted on 
ground plate.  I use 1/2 inch - 10 acme rod for lead screws.  I used a 
lead lap to remove any "drunkenness"  and a double bronze nut to take up 
backlash.  I prefer the acme thread since speed of traverse is not an 
issue and the "stick-tion" is an asset while EDM head makes a cutting 
pass across the PCB.

> My friend Mr. Graham Stabler advised me to use PWM
>EDM Pulse Generator--to control Gap-Voltage and also 
>cutting rate-Fine/Rough cuts.The "Garden Of EDM" uses
>this principle.I modified PWM power Supplies from
>various EDM  Patents.
>
I've had good luck with the Garden of EDM supply, but I'm now working on 
a Mosfet version controlled by a PIC that will be cheaper to build and 
more flexible

>Camtronics EDM plans are also
>based on PWM technique.The mechanical construction is
>also very rigid.
>Regarding the Up-Down  servo  electrode quill 
>movement I prefer to use a ball-screw instead of a
>lead screw to eliminate back-lash error.
>  
>

My prototype uses a stainless 1/4-20 rod with a double nut.  Although I 
lapped the rod and used Teflon nuts I think you are right -- a ballscrew 
would it's higher cost

>I will look forward to know more about your comments
>or advce to help me for building a CNC - Sinker/Wire
>EDM.
>If you need any help from me also I will be glad to
>co-operate with you.
>  
>

I've started a thread on Yahoo's Homebrew_PCBs and will publish my 
results there.  They are a very helpful and innovative group.  I'll be 
glad of any comments you might care to add and will happily answer any 
questions.  My postings will be limited  for a week or two as I am 
looking for the "right" digital camera to document my prototype and I am 
tied up on the circuit redesign.

>Regards.
>Richard.
>******************************************************
>  
>
I'll post a copy of this e-mail and very likely Stefan or Dan will have 
something useful to add.

-- 
Curtis W Richards

--

"The natural progress of things is for liberty 
 to yield and government to gain ground."
 --Thomas Jefferson

Does anyone have more information on this light bulb EDM mentioned in
the list. Could not find any references using google.


--- In Homebrew_PCBs@yahoogroups.com, Curtis Richards <cwrxr@e...>
wrote:

> Richard Mcfarlane wrote:
> 
> >Hi Curtis,
> >>From Homebrew PCBs-Groups, I came to know about your
> >interest regarding EDM.
> >I am also an EDM diy hobbyist like you. I built
> >several EDMs from the following plans :-
> >
> >1. Build This Space-Age EDM -( Popular Science,Mar-68)
> >2. A Light-Bulb EDM Project--(Meadre Hanks)
> >3. A Spark-Erosion Machine--(C.Roy Amsbury)
> >4. An Workshop EDM--(Peter Rawlinson)
> >5. Build This Shop EDM--(Robert Langlois)
> > I observed these machines have poor mechanical
> >constructions and moreover the EDM power supply are
> >RC-Types.These are very slow and crude metal removal
> >process and presently obseleted.

>I've had good luck with the Garden of EDM supply, but I'm now working on
>a Mosfet version controlled by a PIC that will be cheaper to build and
>more flexible
> >Regards.
>
>Curtis W Richards

News here?

Starting to seriously study the Garden of EDM power supply I found 
(theoretically, for the moment, because the
ordered components will arrive in 5 weeks) that IR2108 (double driver with 
cross-conduction prevention) now used
to fire CHARGE and BOOST is better to fire CHARGE and DISCHARGE, because 
those have not to cross-conduct.
Am I wrong?
Cristian