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Spockie-Tech
Site Admin
Joined: 31 May 2004
Posts: 3160
Location: Melbourne, Australia
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I was reading about current control options a while back when I got my welder, but Ive since discovered that its not really that critical for DC-only steel welding, so I havent followed it up yet.
Since steel doesnt conduct heat that well, you just sort of hang around a bit longer if you need more heat in a spot or are just starting, and speed up your movements once the piece gradually warms all over.
But for those welding Alu and maybe Ti (I know nothing about that), more current control would probably be nice, and foot pedals would suck for anything except sitting-comfortably-at-the-bench work, so I was thinking of something like this..
http://weldingweb.com/showthread.php?79951-TIG-remote-DIY-config-ideas&p=4071881#post4071881
A problem occurs with the HF start, you have to filter out, or ignore spikes and average readings, or it goes bonkers when the HF kicks in, but it looks promising, I like the idea of fingertip pressure control, seems like it would be very intuitive. not melting fast enough ? push harder on the button !
For a hud current display, the optics for readable numerals would probably be the hard part. Since you will be focussed on the weld pool, refocussing to read numbers might be eye-straining.
Perhaps a bargraph (LED, Nixie, whatever) horizontally on the low edge of your Field of View would be better ? then you dont have to "read" digital numerals, just "be aware" of the length of the bargraph, and you can just feed a low analog voltage to an LM3914 chip. Just a thought anyway. _________________ Great minds discuss ideas. Average minds discuss events. Small minds discuss people
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Sun Dec 27, 2015 1:11 pm |
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Spockie-Tech
Site Admin
Joined: 31 May 2004
Posts: 3160
Location: Melbourne, Australia
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quote:
Originally posted by Glen:
Question though Brett - I modified a guitar pedal to replace the huge monstrosity the 200p tig came with and was thinking of making it wireless, reckon hacking the guts of a hobbyking 2.4ghz radio + reciever in both the welder and pedal might work? Been meaning to give it a go for a while now, wonder if the noise would make it useless.
As we all know, 2.4Ghz radios are fairly resistant to noise (compared to the early PPM/PCM radios), but I dont know about 200amps of pulsed welding current with HF Start as well. It might work, might not.
Good news is, its easy to test prior to making it. Plug your Tx in, put a servo on the Rx and weld away. See if the servo failsafes or jitters. Move the leads around a bit, drap them over the Tx/Rx and so on. If it holds steady, you should be right.
You could add some noise filtering code in the Rx side.
The TX side will be easy.. you just replace a Tx Stick potentiometer with the pedal pot. But on the Rx side, youre going to need something (micro probably) to convert the PPM servo output from the RX into an analog voltage or a variable resistance. Measure the PPM with a micro, PWM an output ("analogout"). Cap/resistor filter the PWM output and drive a fet to convert to resistance maybe.
Then on the Rx side, you could do some code to ignore spurious errors. I forget what the receiver/servo frame rate is.. 15-50 per second ? so if you get any values that are miles different to the present rolling average, just ignore them.. something like that should handle spike noise if the receiver *mostly works and doesnt just simply go completely deaf the moment the arc strikes _________________ Great minds discuss ideas. Average minds discuss events. Small minds discuss people
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Sun Dec 27, 2015 3:05 pm |
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