Tall part in sinker EDM

We have some parts to burn that are too tall to get submerged in the tank, so are burning above the oil in air and flushing with hoses and babysitting so things don't get out of hand (sparks igniting a fire), but it's concerning to say the least. Any hints at how to do this safely? Its a very shallow burn (basically "engraving" a print die), so we don't put a lot of energy into the electrode.

Good morning RJT:
Is it possible on your part to make a dam so you can have a little pool to put the trode into?
I've used stainless foil wrap for heat treating and a big hose clamp to make a 1 inch tall dam on the top of a tall part so I have a nice puddle to dip into.
I point a flushing wand into the dam and I don't care how much it leaks provided it's less than the fill rate of a flushing wand.
Excess pours out the leaks and over the top of the dam...since it's all contained in the work tank I don't care.

Resist the urge to use something like Plasticene for the dam...the dielectric oil will dissolve it and make a big mess as well as contaminating the dielectric.
I've never experimented with hot glue...I don't know enough about its chemistry to predict anything, but a test is simple and cheap.
The dam doesn't need to be an inch tall either...even a quarter inch is already way better than nothing.
You probably could get away with just hot glueing a bunch of scrap blocks onto the top of the job and butt them up together so the leaks aren't too big.

Or you could get fancy and mill a frame if you have a lot of parts to burn.
If the frame is heavy enough and the part is flat on top you can just lay it there and let its weight hold it in place.
If the job is ferrous (and magnetic) you can make the frame from steel and hold it in place with magnets.
Just don't let the trode ever touch it or you'll arc it to the job and trash the workpiece.

As a completely different alternative, I assume the part is too big to just lay over and burn sideways?

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining

Yes, burning sideways is not an option, I like the idea of making a "pool" , we have some stainless heat treat foil that would work. I'll post a picture if it's successful. Thanks for the tip.

Just gonna throw this out there, can you reverse the polarity and mount the work piece on the head and electrode on the table?

Hi Luke.kerbey:
Yes you can, but you have to be careful...the weight capacity of the ram is important, so you can't just bolt some honkin' monstrosity onto it and still hope for the Z axis servo to remain as responsive as it needs to be.

As an example, I had an old beater hydraulic ram Hansvedt SM 150B with a 300 pound ram capacity.
The servomotor driven successor (MS4) could safely lift a 25 pound lump by contrast.

Most servo rams are better than that, but not THAT much better, so safer to check before you bolt!

Making a temporary dam is just so much easier, and it works very well too.
A lot of burns have been done in this world with just a couple of flushing wands pissing onto the burn...you don't NEED all that much so a puddle is already pretty damned good.
Probably the biggest benefit of flooding the tank is that the volume of oil keeps the workpiece cool, so you;re not fighting thermal growth so badly.

So you can flood it as much as convenient and leave the top sticking out a bit...it'll still be better than no oil at all.
Besides RJT is doing just a small burn and it doesn't sound like he needs to split tenths on it either.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining

Success, we just put the whole thing in a big piece of tubing and made a taller "tank". Pictures, .005" end mill in a 50k air turbine to cut the electrode. the electrode, burning,inspecting, drawing art, finished rotary print die. Pictures don't do the detail justice,it's too small to get a clear image. Thunderbird and a previous rotary print die.

only 5 pics per post allowed 4 pads per die, prints at about 1500rpm. What made it so tall , is the whole part and fixture is on a sine plate to set the angles and that is on the magnetic chuck.

Nicely done

Thanks for sharing. Hopefully will help others in the future. I'm stashing this away in the memory bank. One could also weld up a odd shaped piece out of sheet stock for bigger blocks.

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