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Registered Member #599
Joined: Thu Mar 22 2007, 07:40PM
Location: Northern Finland, Rovaniemi
Posts: 624
I finally got together SRSG for my 8" coil. I use quite large AC motor, 1/3hp (i think bigger is better, more torque and rotating mass -> steadier RPM)
So few questions if i may:
1) 100bps or 200bps (synchronous operation @ 50Hz) I heard somewhere that 100bps is better but it might cause troubles with safety gaps??
..and if 100bps is the way to go
2) What is easiest way to determine correct motor alignment to make gap to fire only once at the peak of each half cycle? Is there better ways than trial and error?
Registered Member #135
Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735
#1 proper safety gap setting. I have some issues with 120 BPS here, but proper safety gap setting catches the misfires.
#2 try to get as close to sync. as possible. I have a lot of issues with this because the rotor mass overwhelms the sewing machine motor's rotor mass. The velocity of the rotor isn't terribly stable but I don't have any method to tach. it yet so I can't implement a control system.
Just do the best you can with what you have.
The difference between 100 BPS and 200 BPS is going to affect your spark length by 20-30%. You can see this graphically if you plot a sine and compare peak firing times with two firing times per half cycle. It is a noticable difference if you're counting every inch but in my case that translates to maybe 8", so its hard to tell overall.
Registered Member #599
Joined: Thu Mar 22 2007, 07:40PM
Location: Northern Finland, Rovaniemi
Posts: 624
I use 1/3hp AC motor from magneto tester rig. There is a buttload of torque! Motor was 1475rpm and i milled 4 'flats' to armature to make it do 1500rpm synchronous
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Yet another SRSG question
