That had to be very upsetting . . . but, such is the life of a new product designer I guess. Thanks for your thoughtful explanations as you progress through these obstacles
Thank you- there is so much value in seeing each design iteration and also then to hear the reasoning after, ironically even more so for the failed attempts. Thanks again for sharing
Are you sure it’s not the gear mesh, perhaps it’s a bit rough? Or could you use direct drive? Or perhaps loop the wire so you don’t have to pinch it so hard? Sorry this isn’t working out. I would have thought it would work for sure.
That is a really interesting idea. The main difficulty in using a strain gauge however lies not in having a flexing element, but rather in having an amplifier which gives low noise sensor readings in a high EDM EMC noise environment. If I can find such an amplifier and if its affordable, then I can quickly fix this.
@@baxedm9806Should not be too difficult to design such a sensor. You even have a free EMC test generator. I always have to pay to get my designs EMC tested ;-). Groet Chris
Could a simple tension arm do the job, like how many reel-to-reel tape recorders work? You know, having the wire thread around an idler pulley at the end of a spring loaded arm to maintain even tension. As wire tension increases, the tension arm moves proportionally, and a feedback mechanism reduces the speed of the take-up pinch roller to compensate.
Tension is important, the flushing process affects the straightness of the wire. Ideally you want a ton of tension to keep the wire as straight as possible, but cutting also weakens the wire greatly and you need to avoid breaks. So its all a matter of balancing cutting power, flushing, wire tension etc.
My couple cents, if I may: -That "bodge" you made is actually how most professional wire EDM machines control the tension. AGIE uses a different one but it is less reliable and prone to maladjustment. It also requires more maintenance (as all things AGIE) -I'm afraid indirect control won't really work unless all the wire path is 100% mechanically sound. Hardly the case, even on the machines I work with. -The amount of "crushing" on the feed rollers you stated is a bit high, the rule of thumb is 0.05mm for 0.25mm wire, ie 0.20 on the exit path. I suspect you are pinching your wire too tight. Does it come out measuring the same at all running speeds? -Part of the problem could be backlash in the gears, hard to tell. All the machines I have ever seen use direct drive, usually AC/DC servos. -Also, around 3:30, looking at the top right, what is your reasoning for the wire path there? Seems you are running your wire in a loop there?
Thanks Michael! I do not have access to industrial wire EDM machines, so I cant dive in to see how they control the tension. Your comment however convinces me that the direct wire tension control method is the way to go. I'll pursue that path. At 3:30 in the top right there is a capstan drive. This provides grip on the wire without pinching/deforming it. That concept works like a charm and is definitely going to end up in the final design.
@@baxedm9806 According to en.wikipedia.org/wiki/Capstan_equation in order to decrease clip/pinch force you should increase wire-roller contact angle which is close to zero at the moment.
Hi, i am thinking abut building an EDM and follow youre progress with interest. re straingauge interference. i don't know but i assume youre box generates a spark and then has a "rest period" . if so there should be no interference in that period and a " sample and hold" type of circuit should be able to read the voltage from the sensor without the interference. If it is so bad that it is oveloading the amplifier input another option is to electronically " clip or short " the input for the duration of the pulse.
With a proper load cell, good closed loop control and sufficient shielding of the cell, I think its doable. Im working on it. Are you going to build your own arc generator, or are you thinking about the BX17?
@@baxedm9806 i intend to start with a hole driller like "applied science" and i will build my own genereator. i ultimatly intend to do a wire EDM but i will probably use a spring loaded arm with sensors to do the tension.
put the 90 degrees axial spring forced to wire-in shaft of wire bearings with manual adjusted screw for wire tension. then fix the velocity of wire-out from pull servo. but calculate your circumference of your shaft bearings than the fix your linear velocity of your pull system. ;)
How about using a Sail Wench design that wraps around the spindle a few times? ruclips.net/video/Y9BJGH8PYrM/видео.html That would give you the necessary torque. Ray
That had to be very upsetting . . . but, such is the life of a new product designer I guess. Thanks for your thoughtful explanations as you progress through these obstacles
Thank you- there is so much value in seeing each design iteration and also then to hear the reasoning after, ironically even more so for the failed attempts. Thanks again for sharing
Are you sure it’s not the gear mesh, perhaps it’s a bit rough? Or could you use direct drive? Or perhaps loop the wire so you don’t have to pinch it so hard? Sorry this isn’t working out. I would have thought it would work for sure.
Does the wire have enough force to flex the C frame. If so could you put strain gauges somewhere on the frame to feed back the tension.
That is a really interesting idea. The main difficulty in using a strain gauge however lies not in having a flexing element, but rather in having an amplifier which gives low noise sensor readings in a high EDM EMC noise environment. If I can find such an amplifier and if its affordable, then I can quickly fix this.
@@baxedm9806Should not be too difficult to design such a sensor. You even have a free EMC test generator. I always have to pay to get my designs EMC tested ;-). Groet Chris
Wawwwhhh Mike, thank you for the nice design, and explanation!
At 7:29 it is clearly David Bowie - Ashes To Ashes first note
Could a simple tension arm do the job, like how many reel-to-reel tape recorders work? You know, having the wire thread around an idler pulley at the end of a spring loaded arm to maintain even tension. As wire tension increases, the tension arm moves proportionally, and a feedback mechanism reduces the speed of the take-up pinch roller to compensate.
I just found your videos a couple days ago and watching intently. Can’t the clear path motors offer you a force feedback which is usable?
No, unfortunately not. But Im working on a nice solution. Stay tuned!
Does wire tension even matter so long as the wire remains linear in the cut? I thought that EDM is a contactless maching method....
Tension is important, the flushing process affects the straightness of the wire. Ideally you want a ton of tension to keep the wire as straight as possible, but cutting also weakens the wire greatly and you need to avoid breaks. So its all a matter of balancing cutting power, flushing, wire tension etc.
My couple cents, if I may:
-That "bodge" you made is actually how most professional wire EDM machines control the tension. AGIE uses a different one but it is less reliable and prone to maladjustment. It also requires more maintenance (as all things AGIE)
-I'm afraid indirect control won't really work unless all the wire path is 100% mechanically sound. Hardly the case, even on the machines I work with.
-The amount of "crushing" on the feed rollers you stated is a bit high, the rule of thumb is 0.05mm for 0.25mm wire, ie 0.20 on the exit path. I suspect you are pinching your wire too tight. Does it come out measuring the same at all running speeds?
-Part of the problem could be backlash in the gears, hard to tell. All the machines I have ever seen use direct drive, usually AC/DC servos.
-Also, around 3:30, looking at the top right, what is your reasoning for the wire path there? Seems you are running your wire in a loop there?
Thanks Michael! I do not have access to industrial wire EDM machines, so I cant dive in to see how they control the tension. Your comment however convinces me that the direct wire tension control method is the way to go. I'll pursue that path.
At 3:30 in the top right there is a capstan drive. This provides grip on the wire without pinching/deforming it. That concept works like a charm and is definitely going to end up in the final design.
@@baxedm9806 According to en.wikipedia.org/wiki/Capstan_equation in order to decrease clip/pinch force you should increase wire-roller contact angle which is close to zero at the moment.
@@AlexanderYastrebov In other words, increase the wheel diameter, in this case. FANUC wheels are about 180mm dia.
@@baxedm9806 If you need any more info about Wire EDM don't hesitate to ask me, I know these things inside and out.
Michael Silveira Rather wrap a wire around the roller (e.g. half a turn) and then pinch it with the other
Well damn, I too was hoping these would solve the issue by having an easy way to use them :/
Hi, i am thinking abut building an EDM and follow youre progress with interest.
re straingauge interference.
i don't know but i assume youre box generates a spark and then has a "rest period" . if so there should be no interference in that period and a " sample and hold" type of circuit should be able to read the voltage from the sensor without the interference. If it is so bad that it is oveloading the amplifier input another option is to electronically " clip or short " the input for the duration of the pulse.
With a proper load cell, good closed loop control and sufficient shielding of the cell, I think its doable. Im working on it. Are you going to build your own arc generator, or are you thinking about the BX17?
@@baxedm9806 i intend to start with a hole driller like "applied science" and i will build my own genereator. i ultimatly intend to do a wire EDM but i will probably use a spring loaded arm with sensors to do the tension.
You might need some PID tuning of the servos?
Just finished that, its working great with an additional sensor and tuned PID. Ill cover this in the soon to be released next video.
This is a sample of how complicated it is to build a machine of this type, encourage, i'm sure you to solve it
put the 90 degrees axial spring forced to wire-in shaft of wire bearings with manual adjusted screw for wire tension. then fix the velocity of wire-out from pull servo. but calculate your circumference of your shaft bearings than the fix your linear velocity of your pull system. ;)
5:30 you better write some Gcode to play a tune!!
That crossed my mind indeed 😁
How about using a Sail Wench design that wraps around the spindle a few times? ruclips.net/video/Y9BJGH8PYrM/видео.html
That would give you the necessary torque.
Ray
I actually tried that, did not work out well. Which is why I settled with 2 grooved wheels instead.