Thank you for your feedback. The LM358 opamp is used as a comparator and it is set to detect the very low voltage pulses at the electrode, which can damage to your work, and then trigger the NE555 timer which in turn stops the pulse frequency to the power generator by effectively grounding or turning off the pulse. A short delay time cycle has to be used because the pulse has to be restarted in order for the EDM to work again until another very low voltage at the electrode is detected when the cycle starts again. If the output frequency pulse is not restarted then the power generator will remain in an off state which is no good as this will just cause the Z axis to retract fully up. This is basically how an EDM works, by sensing the output voltage at the electrode via a voltage divider and comparing it to a reference voltage, above the reference voltage the Z axis goes down, below the reference voltage the Z axis will go up. I hope this helps.
So in previous videos post you have made on RUclips do I understand that you had NO control circuit? The movement of the electrode was just a timed cycle. If a short occurred it remained shorted until that timed cycle was completed the electrode retracted thus breaking the short?
@@Uflyppc Thank you for your feedback. No there is a control circuit to maintain the correct positioning of the Z axis to maintain the burn. The Anti-Arc board is a separate add on feature designed to prevent the very low voltage pulses which could lead to an arc which would damage your work and the timed cycle that the Anti-arc board uses is there to allow the 555 timer to reset otherwise the output will remain in a low or off state. Originally the control and the Anti-Arc circuits were combined into one which made it more difficult to regulate as making any voltage adjustments to one circuit altered the other circuits performance, so now they operate independent to each other.
OK thanks for the clarification on the comparator vs op amp. I read up a little on op amps.and I want to make sure I understand, but I am still confused. So that I understand correctly you use a pot or resistor network to establish a Z high voltage You also use a pot or resistor network to establish a Z low voltage both of these voltages are sent to the Op Amp The signal from the gap is also fed to the op amp. I will assign a few voltage numbers here just to illustrate my confusion. Let make Z high 5 volts Lets make Z low 3 volts. We do a resistor network or pot so that when the EDM is working correctly the op amp sees 4 volts it is exactly in the middle of the Zhi and Zlo. I am guessing that the stepper/or dcmotor is not doing anything it is turn off. If a short occurs this 4 volts is going to go to near zero I would suspect. his would cause the motor to move the electrode up to break the short. but from your description the timer turns off right so No more pulses/voltage are being sent to the gap. this means no more power (voltge) is present at the gap. if this is what happens how does the op amp know to tell the motor to pull up. How would it know when it gets above the 5 volt signal and tell the electrode to move down ?
When the output from the timer turns off, transistor 2 is no longer turned fully on and returns to normal operation. This sends the square wave pulses to the power generator which in turn outputs the high voltage pulses to the electrode until a low signal is detected and sent again to the op amp, and then the cycle starts again.
This is a little bit difficult to understand but If I understand correctly when the voltage across gap gets to low you are shutting off the frequency generator ?? Is this right
Thank you for your feedback. Yes you’re right, the aim is to stop all the very low and potentially arc forming pulses before they can damage both the electrode and the work piece
That is good because the arcing can cause big problems. I see you have a comparator LM358 on the board so I am assuming you are using that in some way as a control the z axis motor circuit (with and upper V-hi and lower V-lo voltage) window. If you turn the power off to the gap how does the comparator get an input signal to tell the motor to move up or down ??
The LM358 is an op amp not a comparator, it can be used as one but a comparator can’t be used as an op amp and the reason I used one here is that they’re more stable than comparators (but not as fast). The output from any design of feedback control to a stepper motor or dc motor is set so that a high voltage signal = Z axis down and low voltage signal = Z axis up so if you’re using a stepper motor to drive the Z axis then this feedback signal would go to the direction terminal on the stepper motor controller which changes the stepper motor direction on a high or low voltage signal. Also don't forget that the pulse off time is very small and that it self resets back to on until the next bad or very low voltage pulse which starts the cycle again.
Thank you for your feedback. My idea was to stop all the very low voltage pulses to the electrode before they can cause an arc and damage the work piece or electrode. It can be done by using a 555 timers output to stop the pulse at the frequency generator output stage before it switches the 100V power output generator on. This seems to work ok but I was just asking if this is the right way to do it, and does anyone have a better way to do it? As you may know arcing at the fine finishing stage on an EDM can damage your finished product and if you can stop it, it will save you having to do a lot of rework or possibly start again from new. I don’t normally get any arcs on my EDM even when at the fine finishing stage but some people have a problem with it but it’s usually just down to bad flushing of the electrode.
Your machine can achieve best surface quality among DIY. Mine has been concentrated only on how the electrode wear. On my electronic board the output from a comparator(pulled up) is fed into a push-pull common emitter output stage then to ON Mosfets. You can interrupt(off) the MOSFETs by grounding input of the push-pull(output of the comparator)
Ok thank you. I’ve just designed a simple new mosfet power generator and quickly rebuilt with “rats nest” wiring and no RF shielding to make it difficult, the original EASY-PEASY machine to test it on. The results surprised me so if you’re interested keep a look out for it when I post it online tomorrow.
great way to cut those pulleys. And love the teaser at the end.
hi, super work
can you explain more about how it is taking the signals and what role is playing to control the mosfet switching.
Thank you for your feedback. The LM358 opamp is used as a comparator and it is set to detect the very low voltage pulses at the electrode, which can damage to your work, and then trigger the NE555 timer which in turn stops the pulse frequency to the power generator by effectively grounding or turning off the pulse. A short delay time cycle has to be used because the pulse has to be restarted in order for the EDM to work again until another very low voltage at the electrode is detected when the cycle starts again. If the output frequency pulse is not restarted then the power generator will remain in an off state which is no good as this will just cause the Z axis to retract fully up. This is basically how an EDM works, by sensing the output voltage at the electrode via a voltage divider and comparing it to a reference voltage, above the reference voltage the Z axis goes down, below the reference voltage the Z axis will go up. I hope this helps.
So in previous videos post you have made on RUclips do I understand that you had NO control circuit? The movement of the electrode was just a timed cycle. If a short occurred it remained shorted until that timed cycle was completed the electrode retracted thus breaking the short?
@@Uflyppc Thank you for your feedback. No there is a control circuit to maintain the correct positioning of the Z axis to maintain the burn. The Anti-Arc board is a separate add on feature designed to prevent the very low voltage pulses which could lead to an arc which would damage your work and the timed cycle that the Anti-arc board uses is there to allow the 555 timer to reset otherwise the output will remain in a low or off state. Originally the control and the Anti-Arc circuits were combined into one which made it more difficult to regulate as making any voltage adjustments to one circuit altered the other circuits performance, so now they operate independent to each other.
OK thanks for the clarification on the comparator vs op amp. I read up a little on op amps.and I want to make sure I understand, but I am still confused.
So that I understand correctly you use a pot or resistor network to establish a Z high voltage
You also use a pot or resistor network to establish a Z low voltage both of these voltages are sent to the Op Amp
The signal from the gap is also fed to the op amp.
I will assign a few voltage numbers here just to illustrate my confusion.
Let make Z high 5 volts
Lets make Z low 3 volts.
We do a resistor network or pot so that when the EDM is working correctly the op amp sees 4 volts it is exactly in the middle of the Zhi and Zlo.
I am guessing that the stepper/or dcmotor is not doing anything it is turn off.
If a short occurs this 4 volts is going to go to near zero I would suspect.
his would cause the motor to move the electrode up to break the short.
but from your description the timer turns off right so No more pulses/voltage are being sent to the gap.
this means no more power (voltge) is present at the gap.
if this is what happens how does the op amp know to tell the motor to pull up.
How would it know when it gets above the 5 volt signal and tell the electrode to move down ?
When the output from the timer turns off, transistor 2 is no longer turned fully on and returns to normal operation. This sends the square wave pulses to the power generator which in turn outputs the high voltage pulses to the electrode until a low signal is detected and sent again to the op amp, and then the cycle starts again.
This is a little bit difficult to understand but If I understand correctly when the voltage across gap gets to low you are shutting off the frequency generator ?? Is this right
Thank you for your feedback.
Yes you’re right, the aim is to stop all the very low and potentially arc forming pulses before they can damage both the electrode and the work piece
That is good because the arcing can cause big problems. I see you have a comparator LM358 on the board so I am assuming you are using that in some way as a control the z axis motor circuit (with and upper V-hi and lower V-lo voltage) window.
If you turn the power off to the gap how does the comparator get an input signal to tell the motor to move up or down ??
The LM358 is an op amp not a comparator, it can be used as one but a comparator can’t be used as an op amp and the reason I used one here is that they’re more stable than comparators (but not as fast). The output from any design of feedback control to a stepper motor or dc motor is set so that a high voltage signal = Z axis down and low voltage signal = Z axis up so if you’re using a stepper motor to drive the Z axis then this feedback signal would go to the direction terminal on the stepper motor controller which changes the stepper motor direction on a high or low voltage signal. Also don't forget that the pulse off time is very small and that it self resets back to on until the next bad or very low voltage pulse which starts the cycle again.
If you have an arc generator If you have the total diagram, please share it so that I can also make EDM. Thanks
Good but I have no idea what are you trying to do. May be I use higher voltage than your then arcing is not a problem but rather electrode wear.
Thank you for your feedback. My idea was to stop all the very low voltage pulses to the electrode before they can cause an arc and damage the work piece or electrode. It can be done by using a 555 timers output to stop the pulse at the frequency generator output stage before it switches the 100V power output generator on. This seems to work ok but I was just asking if this is the right way to do it, and does anyone have a better way to do it? As you may know arcing at the fine finishing stage on an EDM can damage your finished product and if you can stop it, it will save you having to do a lot of rework or possibly start again from new. I don’t normally get any arcs on my EDM even when at the fine finishing stage but some people have a problem with it but it’s usually just down to bad flushing of the electrode.
Your machine can achieve best surface quality among DIY. Mine has been concentrated only on how the electrode wear.
On my electronic board the output from a comparator(pulled up) is fed into a push-pull common emitter output stage then to ON Mosfets.
You can interrupt(off) the MOSFETs by grounding input of the push-pull(output of the comparator)
Ok thank you. I’ve just designed a simple new mosfet power generator and quickly rebuilt with “rats nest” wiring and no RF shielding to make it difficult, the original EASY-PEASY machine to test it on. The results surprised me so if you’re interested keep a look out for it when I post it online tomorrow.