[AT] OT EDM (Electrical Discharge Machining) Drilling on old tractor steel and iron.

[Stephen Offiler]

Thanks Jack.  Your comments are spot-on.  Since the original comment on EDM
was aimed at me, I'll elaborate.  I conducted an experiment of cobalt drill
bits versus a more modern alternative made from high-Vanadium
powder-metallurgy steel.  I concluded the cobalt drill bits are far more
cost-effective.  I was questioned about the EDM portion of my experiment,
which I never mentioned, was never a consideration, and did not happen.  My
total cost-per-hole, including the cobalt drill bit as a consumable, plus
labor and overheads, comes to roughly $0.30/hole and there are roughly 2000
holes per year so grand total $600 annually to make those holes. That kind
of money will never pay for an EDM machine.

Steve O.


On Tue, Oct 29, 2019 at 1:40 AM Jack <jacktractor at live.com> wrote:

> What got me started was thinking about whether EDM, now defined in this
> group, would be cost effective in drilling Vise Grips to mount tooling to.
> Reading this definition suggest EDM hole drilling is likely not cost
> effective in any case where a twist drill will do the job. And yes, I did
> not stop to think whether others commonly use the term. Stephen was getting
> 50 holes per bit so the Vise Grips are pretty drillable.
>
>
> https://en.wikipedia.org/wiki/Electrical_discharge_machining#Fast_hole_drilling_EDM
>
> The magazine in which the tap was EDMed out of an aluminum casting got
> jettisoned in a move 20 years ago. I widh I still had it.
>
> If it is the case that EDM would not be cost effective when a twist drill
> could be used, then a portable EDM device for drilling out broken bolts
> would not work either.
>
> I have long been fascinated with the portable machine tools offered by
> climax.
>
> https://www.climaxportable.com/products/drills/
>
> [Phil Auten] Thank you, Farmer! I was wondering just what the **** EDM
> was. Your advice is spot on.
>
> [Indiana Robinson] EDM – Electro Discharge Machining
> There is an old writing rule that says that you shouldn't use an acronym
> or an initialism in an article without first giving a definition of the
> letters involved. After doing that you are then allowed to use the letters
> abbreviation  constantly even to the point of silliness if you want and all
> is fine...  :-)  Most of us (myself included) break this rule constantly.
> One example is "PTO" = Power Take Off. That is pretty safe on an old
> tractor group. If you were writing for a group of pie repair shop owners
> you should probably pre-define it first.
> I'm not really questioning James use of EDM here, we as a group define the
> word casual, but I took that link... I hunted all over their site and could
> not find the initialism defined there. I Googled it and had to look at
> several returns to find it there. Obviously it is only a household word
> among a fairly limited group of engineers and machinist. Why would they not
> define it up front on their site? I suppose some of it is that most sites
> are created by computer geeks who are not always journalist.
> Back in my data processing days we discovered that the systems analyst
> guys were horrible at writing instruction manuals for clients to use when
> preparing data input. They knew their end of it but just couldn't connect
> with the customers. I became the interface between them and the customers.
> While I'm here I'll insert one of my favorite gripes. "Nothing should go
> on the internet that is not dated up front. I hate it when I'm researching
> and can't find a date on an article then find that the article is 25 years
> old and the information badly out of date... Especially so on medical
> information that keeps evolving.
> And now back to old tractors.  :-)
>
> [James] Probably 25 years or so ago, an article discussed a homebrew low
> tech EDM a man had built to EDM a broken tap out of the aluminum block or
> head of a small engine. The article may have appeared in “Home Shop
> Machinist”.
>
> The downside is that the setup may have only worked in the down direction.
>
>
>
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