Eltee pulsitron, good enough for small molds?

Would this be able to do small one off prototype plastic injection mold work. Very low production, 1 ounce max shot size, so nothing large. This was probably used as an edm drill I take it, smaller in size and amperage..?

Thanks !

Hi diyengineer:
The size of the mold and the number of parts it will shoot has no bearing whatsoever on the precision needed in the technology to make the mold cavities and related features.
While it's true that the parts of the cavity which will form the part shape sometimes don't matter very much, the parting surfaces and shutoffs matter a great deal if you need anything better than a rude and dirty hacker part.
Your ability to reliably control the machine at the 5 to 10 micron level will have a big effect on how much of a pain in the ass it is to get the shape you need in the spot you need.

The maximum machine amperage, while important if you're burning big cavities, becomes much less of a constraint when you're picking out details.
A monstrous big rough burn for me is a 24 amp burn; my usual go-to setting on my Hansvedt sinker is a 4 amp burn; so typically I'm not using a sixth of the capacity of my tiny machine.
But I can position it to within a tenth on a good day, and by golly, if I command a one tenth movement it actually moves a tenth.
Not that I can hold that tenth just because I can move a tenth, but you get picture of what's important for moldmaking.

Look at your machine critically for the level of accuracy you can realistically achieve with it and just how much farting about you're prepared to do to work to within 0.0005" (the practical upper limit if you're building molds that can not be allowed to flash)
If it cannot be coaxed into doing that, no way, no how, it's not the machine for you.
Cheers

Marcus
Implant Mechanix
Vancouver Wire EDM -- Wire EDM Machining
Clarus Microtech

diyengineer253 said:

Would this be able to do small one off prototype plastic injection mold work. Very low production, 1 ounce max shot size, so nothing large. This was probably used as an edm drill I take it, smaller in size and amperage..?

Thanks !
View attachment 156432View attachment 156433View attachment 156434View attachment 156435

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We are a mold shop, and we keep our Eltee around next to our 3 CNC sinkers. We did quite a bit of work with it before the CNCs, now it gets used once a year or so.

For $900 delivered might be worth a shot. It would be my first edm. Atleast it would be a good intro into the edm world? My plastic injector is at best industrial hobby grade for one off's or small small runs..

Here's another for $500. Easco sparkatron. At the moment it's between these Ole girls.

Hi again diyengineer:
Both brands have a long and well respected history in mold making.
If they're in good shape, either will likely do just fine.
Everything mechanical on these machines centers on the performance of the ram, because that's the part that will have seen by far the most motion and is the most critical.

I had an old beater Hansvedt SM150B sinker before I got my Hansvedt Foreman.
It had a hydraulic ram as your candidates probably have too.
The servo valve leaked and the ram was sloppy.
Because of those factors, every burn that needed any accuracy at all was extraordinarily difficult to do and was a major source of frustration.

The servo valve governs the response of the ram to the gap sensing circuitry that allow the cutting to progress, so a leaky valve means poor servo response and stalled burns.
Hydraulic servo valves are probably unobtanium by now so if yours is in bad shape it's a major problem that you may not be able to buy a solution for.
If the ram bearings are sloppy, you'll never know where the ram will end up on each downstroke, so you'll be hitting the cavity walls and shorting out, but at least you have a just a mechanical rebuild ahead of you to get the machine back into usable condition.
So check that part out very carefully before you commit to buying either machine.
The X-Y platform matters much less and is almost never worn anyway, and the rest is just electronics and plumbing.

Do be sure you have the settings chart for dialing in your burns, and preferably the operating manuals too.
Each machine brand is different from all the others, and if you're missing that information and have no EDM experience, the machine will be almost useless to you.
Cheers

Marcus
Implant Mechanix
Vancouver Wire EDM -- Wire EDM Machining
Clarus Microtech

Thank you for the honesty, and lending your experiance Marcus. I'll proceed with caution and verify.

I have a Hansvedt SM150B in the for sale section. Above your stated window from above, but capable enough and in good working condition.

Hi again diyengineer:
I suspect from the hints in your posts, that you are planning to run this new machine in a home workshop.
If that is true, please be aware of the following:

1) EDM is smelly because of the dielectric fluid (a very light oil) that is used to flood the workpiece.
There are odour free options but they are outrageously expensive.
To fill the fluid reservoir on a small machine is going to cost you well north of $1000.00 if you select an odourless synthetic like Ionoplus or Commonwealth.
Even Rustlick 250 will cost you a bundle and it stinks...enough that your wife will not be happy if you've got the machine in the basement even if she never comes down the stairs.

2) Hydraulic ram machines are noisy...the culprit is the hydraulic pump.
My beater was noisy enough that I could not understand a telephone conversation with the machine 20 feet away and I could not even hear the phone ring from across the shop!

3) Although the dielectric oil has a high flash point, there is still a significant fire hazard that is unique to these machines; even worse if you're cheap enough (or dumb enough) to use kerosene instead of EDM oil as your dielectric fluid.

4) Graphite electrodes (assuming you choose graphite for your trode material) is IMMENSELY dirty to work with unless you have a really really good (expensive) housekeeping system in place.
I run copper trodes because of this.
Most machines can burn with copper but apparently some are much better than others.
A good hint as to which category your machine falls into is to look into the burn tables...if copper is not listed as a trode material you will have big trouble learning to run it with copper (the burn settings are totally different for different trode materials) and you may never get decent results in a reasonable amount of time.

So before you leap into this purchase, keep this all in mind.
Cheers

Marcus
Implant Mechanix
Vancouver Wire EDM -- Wire EDM Machining
Clarus Microtech

Hi Marcus,

I use the Commonwealth on my Charmilles Roboform 200. If you are a hobbyist, like
I am, you won't use your machine very often, and if you don't run it often enough
the Commonwealth oil will begin to smell because it starts to grow stuff. Most
petroleum products have this problem, that's why you put a growth inhibitor in
(fuel saver) diesel fuel or gas that will sit around over the winter months.

I think if you are cutting often enough the sparking heat kills the bacteria -
just a guess.

Paul