Still machining a part for my cement mixer. Needed to build up a 10" long
shaft back to 3/4 inch diameter. Thought I would put it in the lathe (1947±
LeBlond Regal 13"), run a few beads over the necked down area with the MIG
and then turn it down to size. I just need to build up about a two inch
length near each end. Anyway, did the above, turned on the lathe and it
doesn't work. I have real 3-phase running the lathe, and a separate 240
volt circuit for the MIG.

After a lot of sleuthing I found that one of the legs of the 3 phase had
shorted to ground. The short was in the 6 foot long flex between the lathe
and the 3-phase fused disconnect box. I figured that maybe I had crammed
too many wires (3-# 12's plus a bare ground) into the 1/2" flex and things
got too hot. It has served me for over 12 years. Replaced it all with a
3/4" flex using #10 gauge (3 each plus ground). This time, while using the
MIG, I heard popping even before turning on the lathe. The 3/4" flex was
warm and the wires melted therein.

Okay, I'm smart enough that I won't be using my lathe as a welding fixture.
BUT, what the hell is going on. Why would I create current in the lathe
feed wires. My ground clamp for the MIG was on the shaft within 2" of the
weld. BTW, both times it was the 'high' wire of the 3 phases that melted.
Two of the wires carry 120 volts to ground each, and the third wire carries
more.

All explanations appreciated. Get to make up another feed for the old
machine.

Ivan Vegvary

"Ivan Vegvary" wrote:

Okay, I'm smart enough that I won't be using my lathe as a welding fixture.
BUT, what the hell is going on. Why would I create current in the lathe
feed wires. My ground clamp for the MIG was on the shaft within 2" of the
weld. BTW, both times it was the 'high' wire of the 3 phases that melted.
Two of the wires carry 120 volts to ground each, and the third wire carries
more.


If there was a path that got into your lathes power wiring, I would be very concerned
about the head stock bearings.

I'm not up to noodling out what may have happened at this time of night.

Wes

The "ground" on some machines is not connected to earth ground
directly.

I suspect your MIG has one side of the transformer output connected to
earth ground. Then it goes thru the rectifier. Thus the "Ground"
clamp is fluctuating above and below earth ground by 15 volts or so,
with full current available. Check it with a voltmeter, "ground"
clamp to earth ground, and gun to earth ground.

I don't understand your three phase wiring.
If all three power legs were disconnected, (Assuming the lathe was
off.) I can see no way to melt a disconnected wire.

Dave J.


On Sep 9, 4:04*pm, "Ivan Vegvary" wrote:
Still machining a part for my cement mixer. *Needed to build up a 10" long
shaft back to 3/4 inch diameter. *Thought I would put it in the lathe (1947±
LeBlond Regal 13"), run a few beads over the necked down area with the MIG
and then turn it down to size. *I just need to build up about a two inch
length near each end. *Anyway, did the above, turned on the lathe and it
doesn't work. *I have real 3-phase running the lathe, and a separate 240
volt circuit for the MIG.

After a lot of sleuthing I found that one of the legs of the 3 phase had
shorted to ground. *The short was in the 6 foot long flex between the lathe
and the 3-phase fused disconnect box. *I figured that maybe I had crammed
too many wires (3-# 12's plus a bare ground) into the 1/2" flex and things
got too hot. *It has served me for over 12 years. *Replaced it all with a
3/4" flex using #10 gauge (3 each plus ground). *This time, while using the
MIG, I heard popping even before turning on the lathe. *The 3/4" flex was
warm and the wires melted therein.

Okay, I'm smart enough that I won't be using my lathe as a welding fixture.
BUT, what the *hell is going on. *Why would I create current in the lathe
feed wires. *My ground clamp for the MIG was on the shaft within 2" of the
weld. *BTW, both times it was the 'high' wire of the 3 phases that melted.
Two of the wires carry 120 volts to ground each, and the third wire carries
more.

All explanations appreciated. *Get to make up another feed for the old
machine.

Ivan Vegvary

I don't have the answer for the wiring failures, except that the wiring
isn't properly protected (for the gage/ampacity limits) to prevent them from
heating up. Fuses should blow, or circuit breakers should trip open before
the wiring has a chance to heat up.
Some meter testing between the two machines will show that there is a
significant voltage potential difference (possibly dangerous or fatal)
between them.
Have an electrician analyze the situation, in case there is a lethal fault,
and avoid it as you would a potentially dangerous electrical circuit.

You shouldn't get yourself into a situation where you could make body
contact with any two machines where one is 3-phase, and the other is single
phase until the wiring system is checked by a qualified, experienced
electrician.

The quickest solution would be to use a separate electrically isolated motor
to drive the lathe spindle, making sure that there is no electrical path
between the drive motor and the lathe.
This method would require a belt or insulated coupler between the motor
output shaft and the lathe spindle. No power applied to the lathe, the
additional motor (slow gearhead or belt/jackshaft speed reduction) is
driving the dead lathe as if it's just a fixture.

The reason for the electrical isolation would be to prevent any current path
thru the spindle bearings or other damage.

I would be sceptical of the ground clamp slipping on the workpiece shaft to
provide an adequate ground path, but it may work.
I'm fairly certain that others have tried it, and maybe you'll hear from
them.

I've contemplated fabricating a welding fixture with a variable speed
spindle for quite some time, and I can't imagine how desperate I'd have to
be to need to use a lathe as a welding fixture, but it's your machine.

It should be very clear that the existing setup that was tried at your
location would very likely destroy a VFD or possibly other electronic
devices, including the welder electronic circuitry.

WB
..........
metalworking projects
www.kwagmire.com/metal_proj.html


"Ivan Vegvary" wrote in message
news:iiDxk.913$393.595@trnddc05...
Still machining a part for my cement mixer. Needed to build up a 10" long
shaft back to 3/4 inch diameter. Thought I would put it in the lathe
(1947± LeBlond Regal 13"), run a few beads over the necked down area with
the MIG and then turn it down to size. I just need to build up about a
two inch length near each end. Anyway, did the above, turned on the lathe
and it doesn't work. I have real 3-phase running the lathe, and a
separate 240 volt circuit for the MIG.

After a lot of sleuthing I found that one of the legs of the 3 phase had
shorted to ground. The short was in the 6 foot long flex between the
lathe and the 3-phase fused disconnect box. I figured that maybe I had
crammed too many wires (3-# 12's plus a bare ground) into the 1/2" flex
and things got too hot. It has served me for over 12 years. Replaced it
all with a 3/4" flex using #10 gauge (3 each plus ground). This time,
while using the MIG, I heard popping even before turning on the lathe.
The 3/4" flex was warm and the wires melted therein.

Okay, I'm smart enough that I won't be using my lathe as a welding
fixture. BUT, what the hell is going on. Why would I create current in
the lathe feed wires. My ground clamp for the MIG was on the shaft within
2" of the weld. BTW, both times it was the 'high' wire of the 3 phases
that melted. Two of the wires carry 120 volts to ground each, and the
third wire carries more.

All explanations appreciated. Get to make up another feed for the old
machine.

Ivan Vegvary

"Ivan Vegvary" wrote in message
news:iiDxk.913$393.595@trnddc05...
Still machining a part for my cement mixer. Needed to build up a 10" long
shaft back to 3/4 inch diameter. Thought I would put it in the lathe
(1947± LeBlond Regal 13"), run a few beads over the necked down area with
the MIG and then turn it down to size. I just need to build up about a
two inch length near each end. Anyway, did the above, turned on the lathe
and it doesn't work. I have real 3-phase running the lathe, and a
separate 240 volt circuit for the MIG.

After a lot of sleuthing I found that one of the legs of the 3 phase had
shorted to ground. The short was in the 6 foot long flex between the
lathe and the 3-phase fused disconnect box. I figured that maybe I had
crammed too many wires (3-# 12's plus a bare ground) into the 1/2" flex
and things got too hot. It has served me for over 12 years. Replaced it
all with a 3/4" flex using #10 gauge (3 each plus ground). This time,
while using the MIG, I heard popping even before turning on the lathe.
The 3/4" flex was warm and the wires melted therein.

Okay, I'm smart enough that I won't be using my lathe as a welding
fixture. BUT, what the hell is going on. Why would I create current in
the lathe feed wires. My ground clamp for the MIG was on the shaft within
2" of the weld. BTW, both times it was the 'high' wire of the 3 phases
that melted. Two of the wires carry 120 volts to ground each, and the
third wire carries more.

All explanations appreciated. Get to make up another feed for the old
machine.

Ivan Vegvary


Here is a clarification to some of you who have replied.
My three phase goes from the main panel to a fused disconnect box. From the
disconnect box it went via metal flex to the drum switch on the lathe. The
drum switch has three terminals and functions as OFF, FORWARD and REVERSE.
It feeds the old GE low hp (maybe 2-3 horses) motor. The motor in turn
drives the spindle through matched belts.

I too cannot understand how a lathe, turned off at the drum switch could fry
the feed wire between the fused disconnect box and the motor. UNLESS, the
drum switch is bad and not all three legs are being shut on and off.

Ivan Vegvary

UNLESS, the
drum switch is bad and not all three legs are being shut on and off.

Ivan Vegvary



It is common here to only switch 2 of the 3 legs & leave one directly
connected.

MikeB

I suspect the armor cable.

Since it is on the floor (very likely) and might have been mashed
a little - the internal wires might be conducting through the internal
sharp edges. It might not be all of the time, just when it is pushed
back to sweep or ...

I'd take the wires from the fuse box to the lathe out of the cover
and inspect for holes or melted copper.

If the wires are good (before pulling - attach a nylon string to pull back
replacements (good idea anyway) or the original. There might be pin holes
punched through the insulation because the inductance of the motor and back
e-m-f that exceeds the insulation. e.g. using 600v wire on a 480 system
with 2or 3x emf spiking.


You might still have a faulty switch - but I bet the wire in the metal cover.

Martin

Martin H. Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
TSRA, Endowed; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal.
NRA Second Amendment Task Force Charter Founder
IHMSA and NRA Metallic Silhouette maker & member.
http://lufkinced.com/


Ivan Vegvary wrote:
"Ivan Vegvary" wrote in message
news:iiDxk.913$393.595@trnddc05...
Still machining a part for my cement mixer. Needed to build up a 10" long
shaft back to 3/4 inch diameter. Thought I would put it in the lathe
(1947± LeBlond Regal 13"), run a few beads over the necked down area with
the MIG and then turn it down to size. I just need to build up about a
two inch length near each end. Anyway, did the above, turned on the lathe
and it doesn't work. I have real 3-phase running the lathe, and a
separate 240 volt circuit for the MIG.

After a lot of sleuthing I found that one of the legs of the 3 phase had
shorted to ground. The short was in the 6 foot long flex between the
lathe and the 3-phase fused disconnect box. I figured that maybe I had
crammed too many wires (3-# 12's plus a bare ground) into the 1/2" flex
and things got too hot. It has served me for over 12 years. Replaced it
all with a 3/4" flex using #10 gauge (3 each plus ground). This time,
while using the MIG, I heard popping even before turning on the lathe.
The 3/4" flex was warm and the wires melted therein.

Okay, I'm smart enough that I won't be using my lathe as a welding
fixture. BUT, what the hell is going on. Why would I create current in
the lathe feed wires. My ground clamp for the MIG was on the shaft within
2" of the weld. BTW, both times it was the 'high' wire of the 3 phases
that melted. Two of the wires carry 120 volts to ground each, and the
third wire carries more.

All explanations appreciated. Get to make up another feed for the old
machine.

Ivan Vegvary


Here is a clarification to some of you who have replied.
My three phase goes from the main panel to a fused disconnect box. From the
disconnect box it went via metal flex to the drum switch on the lathe. The
drum switch has three terminals and functions as OFF, FORWARD and REVERSE.
It feeds the old GE low hp (maybe 2-3 horses) motor. The motor in turn
drives the spindle through matched belts.

I too cannot understand how a lathe, turned off at the drum switch could fry
the feed wire between the fused disconnect box and the motor. UNLESS, the
drum switch is bad and not all three legs are being shut on and off.

Ivan Vegvary




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---= - Total Privacy via Encryption =---

Ivan Vegvary wrote:

Here is a clarification to some of you who have replied.
My three phase goes from the main panel to a fused disconnect box. From the
disconnect box it went via metal flex to the drum switch on the lathe. The
drum switch has three terminals and functions as OFF, FORWARD and REVERSE.
It feeds the old GE low hp (maybe 2-3 horses) motor. The motor in turn
drives the spindle through matched belts.

I too cannot understand how a lathe, turned off at the drum switch could fry
the feed wire between the fused disconnect box and the motor. UNLESS, the
drum switch is bad and not all three legs are being shut on and off.
Your flex-conduit has a spiral metal sheath that acts as the
safety ground, or at least a back-up safety ground. If that is
your only safety ground, it probably is high resistance. Your
"hot" wires likely were not "in circuit", but the safety ground
is always connected. My guess is welding current ran through
the flex-conduit to the panel and back to the welder, something
that REALLY shouldn't happen! It sounds like the current ran
through your spindle bearings, too, which is really bad news.
I'd check the quality of the entire welder ground cable, it may
be worn out or loose anywhere from the ground clip to where it
attaches to the welder. I can't imagine any other way this
could have happened if the ground cable on the welder was OK.

Jon

Okay, I'm smart enough that I won't be using my lathe as a welding fixture.
BUT, what the �hell is going on. �Why would I create current in the lathe
feed wires. �My ground clamp for the MIG was on the shaft within 2" of the
weld. �BTW, both times it was the 'high' wire of the 3 phases that melted.
Two of the wires carry 120 volts to ground each, and the third wire carries
more.

All explanations appreciated. �Get to make up another feed for the old
machine.

Ivan Vegvary

Ivan

I think you mentioned your problem in the part of your query about
"creating" a current in your lathe feed wires. Check your grounding
paths. Don't use or rely upon any ground circuits using any part of
the flex. Period. And from your explanation of your "220" you don't
have a conventional 3 phase source. What you have is sometimes called
a wild phase or wild ground. This is OK under some circumstances but
certainly not with mixed use as you have with a welder and a lathe.
GFI protection would be prudent here also.

A solution is to have your power company or source upgrade your 3
phase so that each leg is the same voltage from ground. A separate
ground from the transformer is also provided to the user that the is
used as a source or safety connection for the neutral and the ground
rod you have installed. As it is two of your legs are 110 from the
center tap of one of the windings in the transfromer. This used to be
done to provide both 110 and 220, single and 3 phase, to the customer,
you, to keep costs low. For both the consumer and power company. Now
days true 3 phase is provided and a transformer is used to provide 110
and 220 single phase from 2 phases of the transformer. There are also
several other schemes to do this.

Another important thing to do is to upgrade your wiring so there is no
chance of the wiring in the flex giving problems. Don't under any
circumstances allow any possibilty of the flex to be part of your
grounding. Use a fitting to isolate the flex from becoming a part of a
ground loop. Remember flex is a mechanical item used to isolate
vibration and provide some mechanical protection from among other
things foot traffic. There are non-metal flex conduits available for
many circumstances.

Hope I said all this correctly at the middle of the night.

Bob AZ

"Ivan Vegvary" wrote in message
news:iiDxk.913$393.595@trnddc05...
Still machining a part for my cement mixer. Needed to build up a 10" long
shaft back to 3/4 inch diameter. Thought I would put it in the lathe
(1947± LeBlond Regal 13"), run a few beads over the necked down area with
the MIG and then turn it down to size. I just need to build up about a
two inch length near each end. Anyway, did the above, turned on the lathe
and it doesn't work. I have real 3-phase running the lathe, and a
separate 240 volt circuit for the MIG.

After a lot of sleuthing I found that one of the legs of the 3 phase had
shorted to ground. The short was in the 6 foot long flex between the
lathe and the 3-phase fused disconnect box. I figured that maybe I had
crammed too many wires (3-# 12's plus a bare ground) into the 1/2" flex
and things got too hot. It has served me for over 12 years. Replaced it
all with a 3/4" flex using #10 gauge (3 each plus ground). This time,
while using the MIG, I heard popping even before turning on the lathe.
The 3/4" flex was warm and the wires melted therein.

Okay, I'm smart enough that I won't be using my lathe as a welding
fixture. BUT, what the hell is going on. Why would I create current in
the lathe feed wires. My ground clamp for the MIG was on the shaft within
2" of the weld. BTW, both times it was the 'high' wire of the 3 phases
that melted. Two of the wires carry 120 volts to ground each, and the
third wire carries more.

All explanations appreciated. Get to make up another feed for the old
machine.

Ivan Vegvary

I think I diagnosed the problem. (Partially)

The wires running through the flex conduit (3-#10's and one bare copper
ground) are always hot. One of the three wires (white in my case) carries
the higher voltage of the three phase. The lathe is well grounded through
the bare copper wire. When I am welding (stupid thing I will never do
again) I must be inducing a high current which returns through the bare
ground wire. This bare wire heats up and melts the insulation on the
adjacent high leg (white). The two melt together, and yes, I do blow the
cartridge fuse on that leg only.

This scenario happened identically both times (ground and hot leg melted
together within the flex). The thing that I cannot figure out is why the
current from the welding wire (MIG) would choose to go to ground (from part
being welded, to chuck, to spindle bearings OUCH, to lathe frame, to
electrical bare ground wire) instead of the welding clamp a mere 2 inches
away. Only somebody familiar with MIG circuitry could explain that to me.

Thanks,

Ivan Vegvary

Ivan Vegvary wrote:

I think I diagnosed the problem. (Partially)

The wires running through the flex conduit (3-#10's and one bare copper
ground) are always hot. One of the three wires (white in my case) carries
the higher voltage of the three phase. The lathe is well grounded through
the bare copper wire. When I am welding (stupid thing I will never do
again) I must be inducing a high current which returns through the bare
ground wire. This bare wire heats up and melts the insulation on the
adjacent high leg (white). The two melt together, and yes, I do blow the
cartridge fuse on that leg only.

OK, this is exactly as I had thought. But, there has to be
something about your welder making that "ground" cable not be
ground. It doesn't make much sense, but if the ground cable is
truly grounded to the welding machine, and is in good condition,
then there should be only small leakage to other grounded stuff
such as the lathe. Maybe, however, even "small" leakage,
relative to the full welding current, is enough to really heat
up some #10 wire.
This scenario happened identically both times (ground and hot leg melted
together within the flex). The thing that I cannot figure out is why the
current from the welding wire (MIG) would choose to go to ground (from part
being welded, to chuck, to spindle bearings OUCH, to lathe frame, to
electrical bare ground wire) instead of the welding clamp a mere 2 inches
away. Only somebody familiar with MIG circuitry could explain that to me.
Well, only three possibilities. One, the "ground" terminal on
the welder is NOT connected to frame ground, but has some kind
of circuits between the cable and ground. Seems really odd, all
welders I've used really had the ground terminal grounded. For
safely reasons, it really needs to be so.

Two, the welder itself is wired improperly, and the welder frame
is not grounded. I'd think you (or your next of kin) would know
about this one by now. But, since this has come up, it really
seems like something that should be checked.

Three, the ground cable is shot, or maybe just loose. If
there's no other path, it works well enough to weld. If there
IS another path, the welding current divides.

Jon

had wiring smoke on my 9x20 lathe a few years back....

motor smoked ...switch went....

$175 later for the parts/repair

i feel your pain

xman

Current flows in the least resistive path. It might have been your belt buckle
to your sweaty body... caution!

The chuck had a hard grip on the metal...roller bearings have wide surface...

The clamp might not have the surface contact that you think. Perhaps only
points contacted and the chuck was lower than the points.

Your return on the MIG is likely not a number 10 or better. If so, perhaps
the wires in the clamp are broken or just points on the clamp.

Martin

Martin H. Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
TSRA, Endowed; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal.
NRA Second Amendment Task Force Charter Founder
IHMSA and NRA Metallic Silhouette maker & member.
http://lufkinced.com/


Ivan Vegvary wrote:
"Ivan Vegvary" wrote in message
news:iiDxk.913$393.595@trnddc05...
Still machining a part for my cement mixer. Needed to build up a 10" long
shaft back to 3/4 inch diameter. Thought I would put it in the lathe
(1947± LeBlond Regal 13"), run a few beads over the necked down area with
the MIG and then turn it down to size. I just need to build up about a
two inch length near each end. Anyway, did the above, turned on the lathe
and it doesn't work. I have real 3-phase running the lathe, and a
separate 240 volt circuit for the MIG.

After a lot of sleuthing I found that one of the legs of the 3 phase had
shorted to ground. The short was in the 6 foot long flex between the
lathe and the 3-phase fused disconnect box. I figured that maybe I had
crammed too many wires (3-# 12's plus a bare ground) into the 1/2" flex
and things got too hot. It has served me for over 12 years. Replaced it
all with a 3/4" flex using #10 gauge (3 each plus ground). This time,
while using the MIG, I heard popping even before turning on the lathe.
The 3/4" flex was warm and the wires melted therein.

Okay, I'm smart enough that I won't be using my lathe as a welding
fixture. BUT, what the hell is going on. Why would I create current in
the lathe feed wires. My ground clamp for the MIG was on the shaft within
2" of the weld. BTW, both times it was the 'high' wire of the 3 phases
that melted. Two of the wires carry 120 volts to ground each, and the
third wire carries more.

All explanations appreciated. Get to make up another feed for the old
machine.

Ivan Vegvary

I think I diagnosed the problem. (Partially)

The wires running through the flex conduit (3-#10's and one bare copper
ground) are always hot. One of the three wires (white in my case) carries
the higher voltage of the three phase. The lathe is well grounded through
the bare copper wire. When I am welding (stupid thing I will never do
again) I must be inducing a high current which returns through the bare
ground wire. This bare wire heats up and melts the insulation on the
adjacent high leg (white). The two melt together, and yes, I do blow the
cartridge fuse on that leg only.

This scenario happened identically both times (ground and hot leg melted
together within the flex). The thing that I cannot figure out is why the
current from the welding wire (MIG) would choose to go to ground (from part
being welded, to chuck, to spindle bearings OUCH, to lathe frame, to
electrical bare ground wire) instead of the welding clamp a mere 2 inches
away. Only somebody familiar with MIG circuitry could explain that to me.

Thanks,

Ivan Vegvary




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See my response, #3.

Dave J.

I think I diagnosed the problem. *(Partially)

The wires running through the flex conduit (3-#10's and one bare copper
ground) are always hot. *One of the three wires (white in my case) carries
the higher voltage of the three phase. *The lathe is well grounded through
the bare copper wire. *When I am welding (stupid thing I will never do
again) I must be inducing a high current which returns through the bare
ground wire. *This bare wire heats up and melts the insulation on the
adjacent high leg (white). *The two melt together, and yes, I do blow the
cartridge fuse on that leg only.

This scenario happened identically both times (ground and hot leg melted
together within the flex). *The thing that I cannot figure out is why the
current from the welding wire (MIG) would choose to go to ground (from part
being welded, to chuck, to spindle bearings OUCH, to lathe frame, to
electrical bare ground wire) instead of the welding clamp a mere 2 inches
away. *Only somebody familiar with MIG circuitry could explain that to me.

Thanks,

Ivan Vegvary

A) How did you clamp the MIG ground to a rotating shaft?

B) CYA #1: Connect all the metal frames in your shop with a separate ground
strap to a known ground. If fuses blow, you just saved your life.

C) How can you have a white whire as a hot? That's evil, at least. [This is in the US?]

D) CYA #2: Can you clamp the piece so it's insulated from the chuck? That will
solve the issue, but when the MIG won't work, you'll need to fix its ground cable.

E) I too fear for your lathe's bearing...



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A host is a host from coast to
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is busy, hung or dead....................................20915-1433