[How-To] Help with grinder

The first circuit was fine, you just had the bridge misconnected.
The motor won't run on dc, it must be fed ac from the plug, after the fuse, as shown in the first youtube circuit
The mag chuck is basically an electromagnet- you can Google it
I think a tattoo machine has a vibrating contact like a buzzer to pulse the coil on and off rapidly which makes the needle oscillate and push the ink into the skin
I'm not sure about the second to last question-? wire to wire?
Not sure if you can repair mag chuck coils- they may be potted
 
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That’s what I meant for the motor. I meant wire to wire as in how I tested the ohms.
EDIT: The mag chuck is working, I was not able to pull a 1-2-3 block of it. I hit the degauss side and it made a strange sound. Not every time just a couple. I did notice the 1-2-3 block and another small steel piece I was testing with ended up with a small amount of magnetism? Is this normal with using a mag chuck?


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Glad the chuck is working, I'm still not clear what you are asking about the meter- need more info to give a meaningful answer

I believe the residual magnetic effects you are seeing are normal. When you use the degauss, it's random chance where you happen to be on the AC waveform when the power is cut, so the amount of residual magnetism will change from degauss to degauss. The better units taper off the power automatically during degauss to reduce that effect

You might try taking the degauss power from after the 35 ohm resistor as shown: It might give a "softer" degauss with less residual.
I also added a bleeder resistor for safety- something like 68K (68,000) ohm at 1 watt. That cap will give quite a shock, the resistor would bleed it down in a few seconds- optional
-M
 

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if you can look deeper into the motor and find what looks like governor or a disc with cricular contacts it probably dosn't use a capacitor. i have a 2 speed reversable motor on a wood lathe if its loaded enough to slow down the start windings will kick in . you can hear it. you can always just wire it up and plug it in,if it starts it dosn't need a cap.
 
Glad the chuck is working, I'm still not clear what you are asking about the meter- need more info to give a meaningful answer

I believe the residual magnetic effects you are seeing are normal. When you use the degauss, it's random chance where you happen to be on the AC waveform when the power is cut, so the amount of residual magnetism will change from degauss to degauss. The better units taper off the power automatically during degauss to reduce that effect

You might try taking the degauss power from after the 35 ohm resistor like this: It might give a "softer" degauss with less residual.
I also added a bleeder resistor for safety- something like 68K ohm at 1 watt. That cap will give quite a shock, the resistor would bleed it down in a few seconds- optional
-M

I will add in the bleeder resistor after work today. Thank you mark for helping me with all of this. Not sure how far I could have gotten on my own so I really appreciate it!


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I believe your meter may have trouble measuring things like coils that have a lot of inductance. We know it measures resistors correctly, they don't have much inductance. But digital meters may get fooled.
It's good to have an old-fashioned needle type meter handy just as a backup- I use a Radio Shack cheapie all the time
Having two meters lets you sanity-check your results. Also, signals that change over time are easier to see with an analog meter.
:)
 
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Mark's schematic looks good; just remember to remove the line with the X!
The bridge rectifier converts the incoming AC to pulsed DC. The capacitor and the inductance of the chuck will combine to smooth out the current in the chuck. The resistor next to the capacitor is there to bleed off the charge in the capacitor; you need it!
In this schematic that series resistor is being used to apply AC current to the chuck. The tricky spot is figuring out how much AC current you need to reliably demagnetize it.
I think you are going to find that the switch burns up very quickly. The energy stored in the chuck's magnetic field is going to end up in a big spark inside the switch!
I suggest you look at the circuit for the Magnabend instead. http://aaybee.com.au/Magnabend/Handyman_Pages/Electrical Circuit.html
You can leave off the bending beam microswitch, start button, C3, C2,D2, thermal switch, and relay coil. Substitute a double pole double throw switch (NO CENTER POSITION) for the relay poles. Your AC power will go directly to "relay pole 1"; note that this is the common to normally open side of the switch. The other side of the switch is wired up in place of "relay pole 2". Again, note the NO vs NC positions!
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What happens is closing the switch hooks power to the bridge AND feeds from the bridge to the magnetic chuck. The chuck will power up and hold your parts. When you are done, flip the switch the other way/off. This turns off power and connects the chuck to the de-gauss capacitor. NOTE, during the transition when all the switch poles are not connected to anything, the chuck current is allowed to continue flowing either through the bridge or C1/D1. This is an important safety and durability feature! When the contacts finish switching, the energy stored in the chuck is moved into charging up C1. Once the coil current has reached zero, it reverses as the energy in C1 goes back into the chuck. There's a LOT of losses in this circuit, so the back swing generates a lot smaller magnetic field.

BTW, you can build up more of his circuit if you want to; the pre-clamping phase that uses C2 could be useful for setup.

Here's where I talk about my magnabend build and the capacitor required. Actual oscilloscope pictures too ;-) I used a bigger capacitor than Alan; about 6,000 micro Farads. Too small and you over-voltage the cap and risk it exploding.
 
Thanks, that magnabend looks wild! Thanks for all the info, it has helped me to understand it better.

Can I just throw the resistor across the switch, or should I put it down on the wires?
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Also, I wanted to see if anyone had any suggestions for these Jones plugs. So the one for the mag chuck was there, but the other side was missing. They had the wire just fed through the machine. Also, the connection on the magnet is missing the captive screw to hold it together. I can not find chassis mount Jones plugs that match. Any ideas on how to proceed? A thought I had was buying Jone’s plugs on eBay and try to fabricate my own chassis mounts, but they are around $20 each, so any other ideas I am open to.


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I would solder the bleeder resistor on to the cap legs directly.
As to the Jones plugs, I don't know of any cheap sources- you might try some of the commercial houses like Digi-Key, Mouser or Newark electronics
 
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If you've got a chassis mount series resistor (with an Aluminum housing and bolt holes, it wants to be bolted to the chassis. The higher value one that goes across the cap can go directly on the cap or via the switch lugs; whichever works and keeps it from touching any other metal ;-)
I hope that Jones plug is on the power supply and not on the chuck! Neutrik SpeakOn connectors lock in place and are rated for 40 Amps and 250 VAC. Cheap on the __zon... The panel mount one is round and might be similar size. If you really want them, it looks like McMaster has the male for $15
but they don't have the matching panel mount socket.
 
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