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Blanchard 18 Chuck Wiring

gtermini

Cast Iron
Joined
Dec 20, 2008
Location
Amity, OR
I screwed up and cooked something on the chuck power supply of my Blanchard 18. I was surfacing a weldment to become a machine base and had a low spot. I made the poor decision to weld up the low spot with the part on the machine (I know...). I used a Miller XMT 350 and suitcase feeder to make the weld. I had the ground sitting directly on the part. It was done with the main chuck power contactor off. After I went back to grinding and found the magnet wasn't holding. The magnet ON light is illuminating and the Neutrol is working as before, but there's no magnetic force.

The machine has a motorgenerator feeding to a variable resistor, then to the Neutrol. I have 172V coming from the vari-resistor and cannot turn it up any further. The chuck has a tag that states 220V rated, so I am outside of the ±10% voltage window. I do not know if the voltage was full 200+ prior to this. I believe the genset and control are operating correctly.

The issue I have found is across the "CHUCK" poles in the Neutrol box, I have 2.7 K-ohms resistance. The manual says my 30" chuck should have 86 ohms. I lifted the chuck to inspect the brushes and slip rings. With the chuck lifted, I have the same high resistance across the poles. I am in the process of cribbing the chuck so I can get underneath and check continuity from the brushes to the control box.

My main question is, where is the 2-wire supply cord to the chuck carriage from the Neutrol located? I see the leads go into the side of the base, but have no access to track them further. There is nothing going from the chuck control switches by the operator in toward the chuck ways.

EDIT: I confirmed a broken or burned wire between one chuck brush and the Neutrol

Any other ideas or jabs at my stupidity are welcome.

Thanks.
 
Did you remove and check the spider in Neutrol? Is it still cycling back and forth ok? The contacts need attention once in a while.
Since it checks ok when lifted I think you have somehow blown the selenium rectifier in the Neutrol or something got hit and is not connected well.
Easily replaced with a more modern full wave bridge but a 30 inch chuck needs a rather serious puck here.
You need to own a Blanchard with vacuum tubes in it on the chuck, so nice and glowy with that blue light... :)

Maybe with the edit your problems are already solved .....:confused:
The weird thing is that what you did should not have screwed stuff up. Not a good ground when welding and found a new way home?
On a cnc this weld on machine is a problem but on a old school Blanchard it should not.
Bob
 
I'm not sure what exactly caused the wire to let go, but I'd guess something about a grounding issue. These new inverter welders are picky about good grounds and will hammer the OCV to find ground. I didn't expect the welder to screw anything up, but the wire may have not been long for the world anyway. By my documentation, the last time anybody was in here was 1964.

I found where the wire goes though the coolant sump near the chuck control switches. I was surprised it just kind of flops around in the coolant. I can't get to the cable clamp under the chuck, so I'm just going to cut the old wire off below the brush holder and run a new one without the clamp and restrain it somewhere else on the carriage. Unless there's a secret way to get to that spot under the carriage?

The brushes and slip rings looked good in my opinion. Should the oil level be above the bearing surfaces?

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Found the bad spot in the cord when I pulled the old one out. It had been rubbing on the carriage drive pinion. Probably had a frayed spot for 50 years prior to it letting go on me the other day.

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Your saddle ways look in pretty good shape, the table has some wear. Maybe have the table ways broken up/spotted while you have it all apart.
 








 
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