ON TOPIC: Little Scotsman EDM

Cincinnati Little Scotsman EDM for sale on the local classifieds site. $1500 and fairly close.
I have no idea if this is a run away, walk away, or actually consider
sort of item for HSM. Don't know how little little is. Have a general idea about the sorts of work EDM can do, but not really hands-on familiar with it. Don't know if this is the more general-purpose wire type or the (old fashioned?) sort that needs a shaped electrode to make a shaped hole (sinker?).
Thought I'd see if we could veer away from the political flame-wars for a minute and discuss metalworking.
--
Cats, coffee, chocolate...vices to live by

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Ecnerwal wrote:

Appears to be a "sinker" type and not especially small:
http://www.tauberaronsinc.com/gordon/gordon4.html
http://www.tauberaronsinc.com/gordon/images/s_p1010003.jpg
Pretty limited use for the HSM I think.
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On Thu, 25 Sep 2008 02:28:42 GMT, Ecnerwal

Hey Lawrence,
Heck of a deal for 1500 bucks. The DRO is probably worth over half that much.
All EDM's are a useful addition to any shop, and while I have neither, I'd go for the sinker type like this one before a wire type.
Usually, it's easy enough to unhook the cable between the EDM and the control/power box for moving and storage. This one looks small enough, so the oil reservoir/filter is directly under the table.
Take care.
Brian Lawson, Bothwell, Ontario.
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Brian Lawson wrote:

What exactly would the typical HSMer use a sinker type EDM for? As far as I know they're mostly useful for production shops that need to make molds or dies, things not typically needed in a home shop.
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I think this machine would be a deal at $1500 if you can see it run. I have a very similar sinker. You can burn any shape into any metal part no matter how hard. Burning broken taps is my most common job. Job before that was the special spline on my power draw bar for the Excello mill. Job before that was a piece on my floor jack, another weird inside spline. "The Kid" made a little Logo and burned a mark on all his tools.
All in all it doesn't get used often. But it adds a great capability to your shop.
Karl
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If you get one, you'll be burning out broken taps for HSMs from miles around. You'll never be afraid to tap a particularly difficult material again. You can also make splines, double-dees, and square, hex, and whatever other shape holes you could imagine in any material. For $1500 in working condition, that machine is a steal.
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wrote:

First, and most important, they're really fun toys. <g>
Beyond that, they can be useful for some kinds of work. They cut hardened steel as easily as dead-soft annealed. They'll cut most metals, and carbides (the latter is extremely slow and requires multiple electrodes). They're great for eroding broken taps. They're nifty for making deep holes of small diameter. Again, this can be very slow.
But they are potentially dangerous. Dielectric fluids are flammable, although the expensive, modern ones are highly flame-retarded. The open-circuit voltage often is 300 V or more, albeit at very high impedance. Like welders, their high-amperage circuit is very low-voltage.
They stink. If your shop is in the basement and if you use the EDM a lot, your house will become all but unlivable. That is, unless your nose is not functional. <g>
They leave a remelted layer that can be really odd, either hard (common) or soft (less common, but possible with some settings). They leave microcracks in the surface that are stress-risers and that can lead to failure of highly stressed parts.
The electronic components on an older EDM like a Little Scotsman often are obsolete and difficult to obtain. And the circuits are proprietary, so you won't get much help on them from anyone.
So they're not cheap to own and operate, and they can be frustrating as hell. Unless you're interested enough to take it on as a challenge, it's unlikely to pay off in hobby work.
Still, they have their appeal.
-- Ed Huntress
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On Thu, 25 Sep 2008 09:45:53 -0400, "Ed Huntress"
BIG SNIP

MORE SNIP
Hey Ed,
Well, in industrial use with all the need for speed, you are correct. In fact, all the new ones have really GOOD flame sensing circuitry, automatic fire suppressant, and even remote view cameras!!
But you can use plain water if you wish. Just not the best thing. So the flammability range is from zero (water) to scary (Kerosene) and depends on all the usual specifics of the job, and speed speed speeeeeed.
And you did leave out dielectric fluids COST, and the cost of FILTERS, both of which are high if you do have that need for speeeeed!!
I still think this one is a good deal, and lots of fun, if it works, and if Lawrence has both the room and the correct utilities at the power panel. Of course, as you note, a separate shop is even better.
Take care.
Brian Lawson, Bothwell, Ontario.
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SNIP
SNIP
wrote:
Hey Pete,
Oh WOW!!! Lots of stuff. One of those "once you have one, you'll find a hundred uses!"
When this newsgroup is past elections and name-calling, I'll bet about 2% of the "questions" will get back to things like:
=How do I get this broken tap out? =How do I make a hole though a really hard piece of metal? =How do I make a nice "square" corner on a square hole? =How do I make a nice "no radius" corner in any hole? =How do I make a REALLY small hole? =How do I make a REALLY big hole? +How do I make a really deep really narrow slot or deep cut? =How do I make a nice tapered hole? =How do I make a "screwed" hole (helix?)    ? =How do I make "raised letters"? =How do I make a "centre" in the end of a hardened rod? =How do I machine something an leave almost no "cutter" marks? =How do I machine something that is really thin or soft? =How do I machine something to an almost mirror finish even deep down? =How do I...............????=How do I...............??? . and so on....
And the answer is: "If you are working with metal, then you can do that with a sinker EDM."
And of course, I reiterate....Once you have one, you'll find a hundred different uses! Biggest problem for the home shop type like me is....space!!! They can have a really big footprint. On the other hand, the home-made ones (a la Robert Langlois) are quite small, and have pretty good versatility..just not "fast". His second generation one is wire EDM from the same power supply, Neat!!
So, that's why I say 1500 is a good deal, if it works, if the voltage is available to you, and ....IF.... you have the room!!
Take care,
Brian Lawson, Bothwell, Ontario.
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