[Klox]

On my Hitachi 203f2 edm i had the problem of keeping the waterpressure constant. Sometimes the upper surface of the workpiece is not 100% parrallel with the bottom part and with a fixed upper nozzle it spells PROBLEMS. I made my self a floating upper nozzle. The water pressure is now constant, better flushing and i can cut FASTER. According to the manual i'm suppose to get a max feed rate of 12.3 to 13.1 mm/min (0.48 - 0.51 inch/min) on 10mm thick alluminium i equaled it on medium settings!!!
I know that the guys with Charmilles, Agies and the new Fanucs don't have this problem.
A more expensive solution would be to buy a submersible edm.

Klox

[Wjman]

We are currently cutting a job on one of our Hitachis, that is 400mm high, and as such have a problem with the flushing on the skim cuts. We cannot keep the flushing on the job to ensure 24Hr machining. If you have any suggestions I would appreciate input. By the way I am interested in your floating upper nozzle idea, could you elaborate?
Thanks Mark...

[Klox]

Mark,
I'll take pics and post it so that you can see with your own eyes what i did. I'll even make you drawings with specs (if you want)!

Regarding your flushing problem: You can either enlarge the hole in the upper nozzle so to up water supply without increasing water pressure (but that means butchering to me!!!). Or you can "help" the upper and lower nozzles with an additional water supply from the side to keep the middle part "wet" if space allows it.
Keep in mind that if the upper nozzle is flush with the workpiece it deflects the waterjet. I always leave about 5mm clearance between upper nozzle and workpiece to counter the deflection.

What model Hitachis do you have?

Klox

[Wjman]

Klox,
We have 5 machines in total, 4 6Qs and 1 5Q. By the way I think I have sorted the flushing problem, I have taken a piece of nylon about 10mm thick 50mm wide and the length of the job, fixed it to the top head, and drilled a row of holes down it, then I have used four extra flushing pipes just poked through the holes, it looks a bit dodgy, but I've managed to fully cover the wire and have a speed increase of about 0.4mm/min. If you could do me some drawings of your nozzle mod, e-mail me @ [email protected] (DXF, DWG, BMP or whatever)
Thanks Mark...

[Klox]

I'll do it. Expect within a day or two as i have to clean my edm today and it will keep me a bit busy.

Klox

[Klox]

Mark,
I've sent you some images. Hopefully we can share it with the rest of the guys right here.
Let me know what you think.....
There's some other money saving mods i did on my machine.
I'm getting the info together....coming soon!

Klox

[Wjman]

Klox,
I got the pictures, thanks! I can see what you mean, If I'm correct the "insert" floats up and down when necessary? Good idea.
We have also made some money saving mods, we made our own wire guides, lower arm front and rear spindles on the wire drive.
The ceramic insulating plate between the upper head and the rest of the machine.
What is the difference between the high and the low pressure nozzles? (apart from the hole size) surely you could make a low pressure nozzle with an interchangeable insert (and turn up the flushing?) the gnurling on your mod is a good idea, failing that you could drill some blind holes, and use a pin to remove it.
It is interesting talking to another Hitachi user, (By the way if I'm going on a bit, I have just come back from the pub(friends birthday!)) Sorry everyoner.
Catch you later
Mark...

[Klox]

Yes, the low pressure nozzle's hole is bigger. It is to get a thicker jet of water. I seldom have use for it. It helps on jobs where you have to start from the edge of the component or when skimcuts are on a taper.
The interchangeble insert is much the same as the (lower nozzle)standerd one on the mod i've made.

Please enlighten me on the wire guides you have made yourself as they are very expensive to buy.

Do you also find the need for a dividinghead from time to time?
That's next on my list to make myself one from stainless steel.

Klox

[Wjman]

Klox,
What can I say about our wire guides other than we made them by digitizing all the measurements, angles etc, turned the shape on a CNC lathe, then we wired the slot through them to create the moving "jaw" drilled and tapped all the relevant holes, used the spare parts off other "scrap" guides, and we managed to find where to buy the replacement sapphires or Diamonds also the glue used to fix them. Also we made a slight mod to the width of the top of the guide, (you know how vulnerable they are to damage) to make them a bit stronger and bored out the lower flushing caps to suit. We set up the guide heights as the book says, and touch wood have had few problems. We have done this with 6Q AWF guides and lately our 5Q.
Mark...

[Klox]

Mark,

You said that you can buy the gems for the guides. Is it expensive, do they make them to order or is it a stock item.

Do you have photos by chance to show me....
Did you already start making your floating nozzles or must i still send you drawings?

Keep well...

Klox

[Wjman]

Klox,
I'll find out about the gems for you and send you some pictures soon. I haven't had chance to start making the floating nozzles yet.
Catch you later Mark...