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ok, so how do I pick starting sinker "technology"

WILLEO6709

Diamond
Joined
Nov 6, 2001
Location
WAPELLO, IA USA
Many of you have followed my saga of the auction bargain Elox Model B. Its got pretty good travels at x 18 y 12, z 12 with a 20 x 40 x 14 tank, at least a 50 amp generator ( might be 100 but I don't know how to tell). I got all the books EXCEPT how to figure out where to start on the power settings. The book mentions 255 "channels" of which only 30 are set to anything past the default. I have a poco graphite book with all these graphs for various types of graphite... but what do they tell me?

I have choices of:
gap voltage
max current
elo pilot voltage
on time
off time
polarity
electrode feed

how do I pick the current and electrode feed past experience? The on time off time is kinda like my mits dwc wires... mess with them until it seems to burn good. I have read some of it has to do with surface area... right now I am playing with a 0.650 inch square with a 0.040 flush hole down centerline in an er16 holder. at first I was getting alot of burning and slag on one edge but I found another channel much lower heat and its burning better. I also added a couple "pee nozzles" outside the electrode flowing across the cut and that seemed to help. How do I read the graphs in the book?
 
To help get you started...

This is for fine grain graphite electrodes. It comes from some old Charmilles or Poco publication:
1. The recommended maximum current density is 10 amps/square cm (64.5 amps/square inch) of frontal surface area.
2. After you figure out the maximum amperage look in your technology tables and select the appropriate setting nearest to this value without exceeding it.

This has always kept me out of trouble.

For your .650 square electrode:
1. .650 x .650 = .4225 square inches
2. Disregard the missing surface area of the flush hole.
3. .4225 x 64.5 amps/square inch = 27.25 amps max
4. Round down to the nearest amp, which is 27.
5. Use the nearest roughing power setting in the table that does not exceed 27 amps.
 
Many of you have followed my saga of the auction bargain Elox Model B. Its got pretty good travels at x 18 y 12, z 12 with a 20 x 40 x 14 tank, at least a 50 amp generator ( might be 100 but I don't know how to tell). I got all the books EXCEPT how to figure out where to start on the power settings. The book mentions 255 "channels" of which only 30 are set to anything past the default. I have a poco graphite book with all these graphs for various types of graphite... but what do they tell me?

I have choices of:
gap voltage
max current
elo pilot voltage
on time
off time
polarity
electrode feed

how do I pick the current and electrode feed past experience? The on time off time is kinda like my mits dwc wires... mess with them until it seems to burn good. I have read some of it has to do with surface area... right now I am playing with a 0.650 inch square with a 0.040 flush hole down centerline in an er16 holder. at first I was getting alot of burning and slag on one edge but I found another channel much lower heat and its burning better. I also added a couple "pee nozzles" outside the electrode flowing across the cut and that seemed to help. How do I read the graphs in the book?


People actually read those graphs?? Spend some time on that controller and you will figure it out. Switch that square trode out for a thin rib, that will help you learn the settings and how they affect the burn.
 
reading the poco book a couple times has really shed some light on things. I have been successfully burning today ( although slowly ) and am figuring out what the functions in the machine do. I used the simplified automatic programming to program an orbital routine ( I think thats what it was ) but it wound up doing a z axis burn to depth and then going sideways out to the programmed number. I am running a micron I85 graphite of about 5 micron particale size so I think if I used more of a roughing graphite it would be going faster. finish does not look terrible and its making a lot more sense.I am thinking I will be better off doing z axis plunge cuts for anything I need to hold size on though. this thing has "orbital" and "rocking" routines but mostly I want to make a couple injection cavities and I need to hit size....
 
reading the poco book a couple times has really shed some light on things. I have been successfully burning today ( although slowly ) and am figuring out what the functions in the machine do. I used the simplified automatic programming to program an orbital routine ( I think thats what it was ) but it wound up doing a z axis burn to depth and then going sideways out to the programmed number. I am running a micron I85 graphite of about 5 micron particale size so I think if I used more of a roughing graphite it would be going faster. finish does not look terrible and its making a lot more sense.I am thinking I will be better off doing z axis plunge cuts for anything I need to hold size on though. this thing has "orbital" and "rocking" routines but mostly I want to make a couple injection cavities and I need to hit size....

I'm slightly confused by what you wrote. The basic orbital function is supposed to Z-burn down to depth (less your OB) and then begin to orbit laterally to size. It will obviously do this in stages as it reduce power settings to bring the finish up. If you need to "hit sizes" then this is how you would control your sizes.
 
I'm slightly confused by what you wrote. The basic orbital function is supposed to Z-burn down to depth (less your OB) and then begin to orbit laterally to size. It will obviously do this in stages as it reduce power settings to bring the finish up. If you need to "hit sizes" then this is how you would control your sizes.

in a simple electrode shape I could see doing this but once electrode shape becomes more complex.... for example one of the parts is a multi ribbed rectangular "pusher" about 3/8 thick 2.25 wide and 6 inches long...flange on one end and multiple ribs each side coring down thickness. Draft everywhere...a couple little fine features. I don't see how I would size the electrode for orbit and still get what I need end up with. I don't need a mirror finish... a "medium aluminum oxide blast texture" is acceptable. But as a side not I did get probably a 16-32 rms finish in the test burn where it was orbiting..... I was surprised for a 1986 cnc elox....

I see where orbit is way cool but for instance, if I am cutting a hemisphere I likely can't orbit on a 1986 Elox correct?
 
in a simple electrode shape I could see doing this but once electrode shape becomes more complex.... for example one of the parts is a multi ribbed rectangular "pusher" about 3/8 thick 2.25 wide and 6 inches long...flange on one end and multiple ribs each side coring down thickness. Draft everywhere...a couple little fine features. I don't see how I would size the electrode for orbit and still get what I need end up with. I don't need a mirror finish... a "medium aluminum oxide blast texture" is acceptable. But as a side not I did get probably a 16-32 rms finish in the test burn where it was orbiting..... I was surprised for a 1986 cnc elox....

I see where orbit is way cool but for instance, if I am cutting a hemisphere I likely can't orbit on a 1986 Elox correct?

Regardless of how complex an electrode is, machining the electrode to - (negative) stock and orbiting the detail to size is the way to go. Don't discount that 1986 Elox, which I assume has a Fanuc control? We follow this method regardless if the work is going on my newer Mitsubishi Edm or on the older 80s Deckel Edm.

Anyhow good luck with your machine.
 
http://img.photobucket.com/albums/v185/willeo6709/pusher4_zps01384add.jpg

this is part one of 2 of a plastic assembly I want to make. the flange is about 1 x 3 x 3/16 inches, overall width of the "square part" 2.250, length about 4 inches. The oval depressions are for a detent feature and there is a sleeve with matching "tits" to detent this party in the sleeve. I would assume that I would have to notch out around the recessed ovals for material safe and then offset all side surfaces to make an orbiting electrode.....

http://img.photobucket.com/albums/v185/willeo6709/sleeve_r4_zps34460d8a.jpg

the second link is what the pusher goes in. 1 core from each end of the sleeve, plus a 1/2 cavity burn in the a and b plates respectively. doing a simple overburn offset I can figure out the electrode shapes but orbiting and all of a sudden it sucks drawing the electrode... but I could see making an orbit roughing electrode to get it close. I am undecided about roughing on the mill and doing a finish burn....

anybody heard of "rocking cycles"? or is this a fanuc/ elox only term? I have rocking cycles, rocking cycles with taper, orbit cycles, orbit cycles with taper, and normal g code to work with on this machine. also are edge finding and center finding macros and another page I have not taken time to understand yet.

the orbiting thing could be cool but I want to understand the electrode design before I scrap a mold base....

a pic of the test burn:
 
and another question - would there be any advantage of mounting the electrode to the table and the part to the ram so that gravity makes stuff fall out of the cavity????
 








 
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