[bjay]

I am thinking about starting this project as i have a spare edm machine and would like to convert it to a wirecut machine , I have disconnected the servo belt and the machine happily runs a electrode sideways ,The machine in question has already got ballscrews on x and y so all good there,I am thinking of running a stepper motor for the pinch roller so i can control wire speed from within the program or mach 3 ie; spindle speed,I have converted a mill to cnc before so familiar with that part ,Would be just x and y at this stage u and v maybe later

So can you clever people see any major pitfalls
Thanks in advance

1~ edm 50 amp with ball screws
2~ mach 3 full version
3~ cadx11 drawing package
4~ cambam g code
5~ Stepper motors for x and y
6~ Roll of .25m/m wire for starters

[jetski]

I made a wire head attachment to fit a Deckle 20 years ago. For about $1500.00 total. My wire was pulled through with a variable speed motor, I did not program the speed of the wire. I ran the wire horizontaly and use old carbide inserts for wire guides. So we programed it in Y and Z. Kind of ran like a big cheese slicer. You will need on and off times that are very fast or the wire will burn through. P.M. me and I will dig up what I have for paperwork and fax or copy and mail it to you.

[bjay]

Jetski

The reason i am using a stepper for the wire is i have one allready and the added bonus of speed control through mach3 , When it gets closer i may just go with a dc motor and variable speed ,, Carbide guides sounds interesting did you spark a wire hole in them ? ,, Thanks for your reply i will PM my email address ,fax number if you could find any info on your conversion would be appreciated

regards
Bernie

[mdynac]

i agree with jetski.
your going to have to examine the output pulses of that sinker genrator.

a wire machine's generator output is not quite the same as
a sinker generator.
the "ON" times may be too long.

the pulse generator may need to be modified as it may not produce
short enough ON times as is.

just some thoughts

what brand and model generator????

[bjay]

The edm i will be converting is a Hostek SH310p 50 amp machine , I will examine the settings for on and off times when i get back to the workshop,, Do you know roughly what on/off times i should be looking for

Bernie

[mdynac]

PULSE RATE (frequency) adjustment may be a problem with the sinker gen.
usually there is no provision for that as they adjust OFF time instead.
the pulse rates should be variable from approx. 5Khz to 55Khz

ON time variable from like 1 uS to 3 uS
use 250 nS increments.
so you will have like 12 ON time selections.

OFF times would be all the rest of the time in relation to 1 second minus
the rate and width of the ON time.

so you would really, really, really like to have the following in you wire machine generator:

variable PULSE RATE

variable ON TIME


don't get me wrong, the sinker may generator work as is, kinda..........
or it may just break wire all day.

you also need to generate consistent tension on the wire
and also smooth consistent wire feed system.

good luck.

[bjay]

Okay just been looking at the manual for this machine and it has variable on times of 1us to 999us and it looks like the off time is a percentage of the on time from 1 to 9 ,So i will just have to try it and see how it goes i will get back ,I am building the head at the moment then i will try it cutting steel in a manual feed as the cnc part is the easy bit

Bernie

[jetski]

I had thought of an idea many years ago if you did not have a pulse generator. Could you take and make a 10 lobe cam and put a set of points on it like the way a motor use to work and run the power through the points and the cam on a variable speed motor geard up or down as needed. The points would open and close and send the voltage to the wire. Or in todays world you could use a solid state relay to pick up and send the voltage picking up on the high spots on the cam or set screw sticking out of the pully. The motor could be variable speed AC or DC and not have to have much torque. You could have several pullys with several different screw configurations (2, 4, 8, 10, 12, ect). To make more pulses per revolution. Just an idea. Take it for what it is worth.

[mdynac]

that would work
but it would be a crude spark.

AT&T also offers Rotary Phone service.......


mac

[jetski]

Hey are you making fun of my cell phone? I am out of Northern Indiana and well my phone carrier is Amish Bell, And I don't get good signal till I pull the string tight and can actually see Yoder. I have the only Cell phone with a party line, (you'll have to be old to get that joke Graber). Sometimes I have these wild dreams...Like I am going 2 times the speed of horse! Hey I got to go and shut down the generator the Parson is headed toward our lane. Talk to all of you later. Be radical wear your Amish hat backwards, and make them call you Jeb Daddy.

[bjay]

Okay ive been snapping wire all week , Can anyone give me a starting point for the settings iam cutting a piece of p20 tool steel 15m/m thick ,It works but i have to have the settings very low otherwise the wire breaks, These settings are as high as i can get , It is very slow like .5m/m in 10min

Current 2 amps
on time 200us
off time around 50% of on time

PS : I remember party lines you would pick the phone up and hear a voice then would have to wait untill they finished to make a call,, ahhh good old days

Bernie

[mdynac]

you should read the info supplied above and you will see that the your ON time is WAY too long and your OFF time is WAY too short.

what about your wirefeed system and wire tension BOTH must be smooth and consistant or you break wire?

what about the flushing????? how are you doing it????

pictures please!!!!!

[bjay]

I tried it at the settings see below and it was no better ,I must be missing something here
any higher and the wire snaps , Flushing is normal edm fluid i know its not perfect but if the wire will not cut it doesnt matter what the flushing is at this stage, Same with the wire tension ,,once i can get the power supply working correctly then i will sort out these items , The voltage on the guage is 100v then drops to around 30v when sparking i have no control over this ,I will post up some pics later , I have been working on edm sinkers for 20 years and the sound it makes is close but very slow material removal


2 amps
1us to 10 us on time
off time 90% of the on time

Bernie

[bjay]

Here is a few pics from the machine also the wire is standard wire cutting wire .25m/m dia brass

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[packrat]

How fast is the wire speed? If the wire moves too slow,it will melt/break.

[bjay]

I can have the wire speed from about 10 rpm to 140 rpm thats at the drum and i have tried fast and slow ,Same with all the settings high and low and everything in between , I called in on a friend who owns a fanuc machine and looks like the current and on and off times are close to his settings ,So what am i missing it does seem to work better with the on times at around 100 so maybe that is 1 us but still very slow ,, The noise that my wire makes compared to my friends fanuc is very quite his sound is more high frequency , I will keep trying but dont know what to try next

Regards
Bernie

[jetski]

On the one we made we had the on, off times as fast as the machine would go. Here is the thought behind this, you only have a wire .012 thick if you put an arc across it for a millisecond it is .009 thick. The next piece of wire behind it is .012 and ready to arc because it is now close to the steel. So we used as big of dia. wire as we could and as quick of on, off times as possible. I will look though my notes to see if we wrote down a fpm on the wire.

[bjay]

One of my thoughts was to get thicker wire but the supplier only had .3 m/m on a 8 kg roll so still thinkin about that one,,Just read a paper about pulse rates on wirecut machines and they were messing around at .5us on times so ?? , Anybody found any plans for power supplies for wirecuts as i can and would build my own but dont want to build one the same as what i have allready ,,I havent spent a fortune yet so it can get shoved under the bench ,And i could buy one already going ,But then i wouldnt have learnt anything

Thanks all for your input

Bernie

[bjay]

I was mulling this beast over the other night and i thought i will have a look at the wave form with my oscilloscope ,As all along i just assumed it was nice and square ,And i found it to be all over the place didnt resemble a square wave at all ,And i put this down to you can only take the measurement while it is running (sparking) and thinking this would be the cause,, I should be able to get it better than it was with a capacitor so i wired a 1 uf 100v in parallel with the head supply and it sharpened up the wave form a lot , And increased the cutting speed 3 fold ,So i am going to try a slightly larger cap and go from there its still slow but usable,, Now i need to look at flushing and wire tension ect ,But i didnt want to go to all that trouble then find i couldnt improve the speed ,,I will even change the dialectric to dionized water ,, Still basking in the glory couldnt believe it is a totaly different machine for a 30 cent part , I will be converting the tables now to cnc for sure, And working on guides,and tension rollers, ect

Regards
Bernie