[inov8r]

I recently purchased a used manual sinker (Pacific Controls 30.) The manual is a little on the chinglish side and minimal on information. I did manage to get the thing to work but am a bit clueless on settings and such. I had a pressing job that needed completed and after a few test burns and messing around I luckily got the job done and am pleased with the results (see pic below.) However, I had a soot buildup that I had to clean out about every .0005 of depth. The burn is about .005 deep. I am using graphite as the electrode. I would like to hear what some of you would use as settings for this piece and hear what I might adjust to stop the soot buildup. The control panel pic is just to show the settings I have available, It does not show my settings. The burn time was about 30 to 40 min. not including soot cleaning time.
My settings:
SERVO CONTRL
Ram Vibrtr: 1
Gap Volt: 3
Servo Gain: 8

PULSER
Top Knob: 7 inside knob (in work time) 8 outside knob (out work time)
Frequency: Hi
Pulser Amplitude: 7
Flush: Bypass (always flushing)

ARK DETECTOR
Sensitivity: 5
Slow In: 5.5

HEAD POLARITY: +

PULSE GENERATOR
On Time: 14
Off Time 42

POWER LEVEL
Transistors 2,3,4: On, set at 1 amp each (2 and 3 have an ionization enhance feature)

Thanks, Steve

[C-DubTate]

Hi inov8r

Let me start off by saying thats a sweet looking burn. Now about your soot buildup issue...The key is flushing. A 0.005" deep burn wont bee too much of an issue, but a deeper burn can literally stop making progress if the soot collects in your cavity without being flushed away. You probably know this. I have ran into deeper burns that had poor flushing conditions and literally welded a gob of this metallic soot to the end of the electrode. This violated the cavity because my electrode was now larger. Now, I dont know anything about the machine you are running. I've only ever ran my Makino and its CNC. It has a tank and submerges the work piece in dielectric oil and has a "Jumping" function. This function will jump in and out of the burn with whatever jumping pattern I specify. Being submerged, this jumping in and out of the cavity creates pressure differences within the cavity, pulling oil into it when its on its way out and pushing oil out on its way back into the burn. This effectively pulls and pushes the soot out of the cavity. Because a tighter fit means more pressure, the less orbiting you can get by with, the more effective your jumping will be at removing the silt. Your machine might not have this jumping function built in. I dont know. My Makino also has positive and negative flushing nozzles for when jumping isn't enough. I can use tubing to plumb over to my work piece and either pump oil into the cavity or pull it out also effectively removing silt during the burn. I very rarely have to do this, but the option is there if I need it. Again, I dont know if your machine has either of these features. If so, utilize them. I hope this helps.

[inov8r]

C-DubTate, Thank you for the response.

[C-DubTate]

No thanks necessary
I forgot to mention something. In regards to pumping negative or positive flushing, keep in mind that flowing fluid WILL erode your graphite electrodes. How much depends on a few factors. My machine has pressure regulators on it so I can control how much fluid is passing through. I keep it as low as I can but still high enough to keep the fluid (and bubbles) flowing. Also, when flushing through your electrode, reduction or orbit distance factor in. If you are burning with a small reduction, very little pump pressure will force the fluid out of the very small gap between the trode and part. If you turn up your pump pressure the fluid will be forced out faster and erode your electrode more. If you are using a larger reduction creating a larger gap for the fluid to flow through, erosion will be less but flushing will be less effective at removing soot. This is true for both positive and negative flushing. I very rarely have to use this method of flushing and mostly use jumping. I also haven't really done a job where I attributed much of my electrode wear to erosion because I use such low pressure when I do. Therefore, I don't know how much it factors in. I just know its something to think about when having to use this method of flushing.