Gunsmithing Looking for input/help wiring up my lathe

GasLight

GasLight

That Guy
Banned !
Full Member
Minuteman
May 2, 2008
1,962
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Bozeman, MT
www.thevaultgunandloan.com
#1
Hello,

I am planning on doing a rotary phase converter, and have a static phase converter that I am going to use to start the idler motor. They provide the following schematic to use their product (Top Picture). The bottom picture is how I am planning to wire it up. I would love to hear any advice or input for my plan. Thanks! DD

a1gt3b.jpg



1znadmu.jpg
 
#2
Re: Looking for input/help wiring up my lathe

I"m about a month behind you, so any info would likewise be greatly appreciated. I've got the concept of the rotary converter, and have heard you can start the thing up manually if you want to (rope/flywheel). Crude but effective...
 
#3
Re: Looking for input/help wiring up my lathe

It is a good idea to include the 3 pole switch within reach or close.
This gives you the option of de-energizing everything, code requirement in most places as far as I know.

I don't have experiance otherwise with a phase gen./converter.
 
#4
Re: Looking for input/help wiring up my lathe

I put one in for my bil a few years ago for his lathe and it works great, sure beats adding a 3 phase service.
I sent you a pm with my phone number, I'll see if I can answer your questions.

Mike
 
#5
Re: Looking for input/help wiring up my lathe

If i was to do this i would definetly do one of these instead. Nice and small, and you get unlimited speed range

Just find one that fits your HP and your done. single phase in and three phase power out. simple as it gets and probably cheaper...

http://www.grainger.com/Grainger/items/4RA45
 
#6
Re: Looking for input/help wiring up my lathe

That item should sell over the counter at a brick and mortar Square D distributor for $280.00, so save some money, take the p/n to the counter guy along with your price.
Square D has an excellent tech line for their variable frequency line, located in Raliegh N.C. where everyone speaks english.......kinda
smile.gif

Another route is Cerus Industrial, with a good product and 5 year warranty.
 
#7
Re: Looking for input/help wiring up my lathe

I would go with a VFD, however, I got the idler motor and the static phase converter with my lathe, so my money output is nearly zero to do the rotary converter. If I had to buy all the components, I would look into the VFD harder. I can't find a VFD rated for a Hard Load 3 HP motor anywhere for what I can find a rotary converter for price wise. I also don't understand the VFD enough to set the speeds and the like on it. I am sure I could learn, but perhaps I don't understand them enough to drop the rotary plans and get one of those.

My main question on my drawing is dealing with the switches, what kind of 3-pole do I need? Where in my wiring should I put a 3-pole switch? Should I just wire it like the top drawing, and forget the 3-phase service before my lathe?

Thanks

Dave
 
#8
Re: Looking for input/help wiring up my lathe

I built my rotary converter out of an alumnium 15 hp 3 phase motor, maybe a bit overkill but it's what I had, it's really simple. There's no static converter in the system.

Mine starts with a simple braker switch, just to turn on the power to the converter, there's a set of capacitors on the convertor to start it and there's a set on the run side also to even things out, the start side switches out soon as it starts. I've got several plugs comeing out of the box to plug in the lathe, mill or other items. All said and done, I spent a couple hundred bucks on supplies and $75 for the motor.

Now if I could just rember how I did it..........just a couple dumb farm kids playing with power and a half ass diagram.

My lathe has a 7.5 hp motor in it, Clausing Clochester 15X50 Mark II
 
#9
Re: Looking for input/help wiring up my lathe

Read this
http://www.metalwebnews.com/howto/phase-converter/phase-converter.html
and this...
http://www.metalwebnews.com/howto/ph-conv/ph-conv.html

The "generated third phase" doesn't have to go back through the switch, it can go straight to the lathe motor ...

I have a magnetic starter switch (with appropriate overload elements) and then a momentary push button run through a start capacitor to start the slave motor..
The output of the slave motor has to be run through oil filled "run caps" to balance the line voltage. (preferably with the lathe under load)

I'll try to dig out my notes as well......
 
#10
Re: Looking for input/help wiring up my lathe

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: wi50</div><div class="ubbcode-body">

My lathe has a 7.5 hp motor in it, Clausing Clochester 15X50 Mark II </div></div>

Same for me, a 7 horse in my clausing,
A VFD big enough was cost prohibitive 5 years ago,
not sure about now...
 
#12
Re: Looking for input/help wiring up my lathe

chpprguy

ATV31HD11M3X would work for you wit ha single phase 240 input and 7.5 hp output at 3 phase. You should be able to tag one of these at a brick and mortar outlet for under $1100.00.
This is just 1 unit that would work and be relatively economical.

Do consider though that most manufactuers won't warranty a single phase application of their 3 phse product. Some do, like the folks I cited earlier, and offer a robust product in their Titan line.

When you size a 3 phase vfd to run one 1 phase line, be sure to take the motor FLA at 240 volts and divide by 0.62, then buy the vfd by the continuous output amp rating, not hp rating.
 
#13
Re: Looking for input/help wiring up my lathe

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Michael</div><div class="ubbcode-body">chpprguy

ATV31HD11M3X would work for you wit ha single phase 240 input and 7.5 hp output at 3 phase. You should be able to tag one of these at a brick and mortar outlet for under $1100.00.
This is just 1 unit that would work and be relatively economical.

Do consider though that most manufactuers won't warranty a single phase application of their 3 phse product. Some do, like the folks I cited earlier, and offer a robust product in their Titan line.

When you size a 3 phase vfd to run one 1 phase line, be sure to take the motor FLA at 240 volts and divide by 0.62, then buy the vfd by the continuous output amp rating, not hp rating. </div></div>

Thank you for the info,
my home built rotary is still chugging along after almost 5 years and it was under $200 in parts for me.... of course I am a scrounge...
wink.gif
 
#14
Re: Looking for input/help wiring up my lathe

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Michael</div><div class="ubbcode-body">ATV31HD11M3X would work for you wit ha single phase 240 input and 7.5 hp output at 3 phase. You should be able to tag one of these at a brick and mortar outlet for under $1100.00.
</div></div>

I have less than that in my entire lathe with the phase converter parts. I think I will rock with my rotary for now, but I would be interested in learning more about balancing the thing with oil filled caps.

Thanks!

Dave
 
#15
Re: Looking for input/help wiring up my lathe

I converted my 3 phase lathe (Logan) using a VFD or variable frequency drive. You can find them cheap on ebay. If your only using one 3 phase motor a VFD works great. A VFD is used one per application or motor so if you have multiple machine a roto phase would be a cheaper move. A VFD is matched to your motor HP and if it's small they are inexpensive. If you need a big HP rating the cost goes up.
 
#16
Re: Looking for input/help wiring up my lathe

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cal50</div><div class="ubbcode-body">I converted my 3 phase lathe (Logan) using a VFD or variable frequency drive. You can find them cheap on ebay. If your only using one 3 phase motor a VFD works great. A VFD is used one per application or motor so if you have multiple machine a roto phase would be a cheaper move. A VFD is matched to your motor HP and if it's small they are inexpensive. If you need a big HP rating the cost goes up.
</div></div>

I have looked into a VFD, for a lathe, it is considered Hard start. Therefore, for my 3 HP lathe, they recommend a 7.5 HP rated VFD. Those are not cheap. I already have the stuff to build my rotary phase converter. Other than balancing the lines, I really can't see any reason why I would spend the money on a VFD instead of just building the rotary that I already have the motor and static phase converter for?

Sorry to get frustrated, but I am really interested in help with the wiring plan I put up in my original post, and am really not interested in spending more money to get a VFD which while it may be easier, won't do anything that my rotary won't. Not to mention, if you look into them, they are cost prohibitive when you start looking at what I actually need VFD wise.

Thanks,

Dave
 
#18
Re: Looking for input/help wiring up my lathe

Just curious, but what does three-phase power actually enable for a gunsmith? I could see if you were turning ten-ton rated axles from 48" x 12" billets of high tensile steel, but...

How much more efficiency and full/immediate power is beneficial if your biggest job is turning a barrel that might go 1.5" x 34" max, or turning a billet 3" x 12" max into a receiver?

Production line is one thing, because presumably CNC is doing several rough-outs per length of bar stock, for producing actions, rings, bases; but for normal gunsmithing capacity?

Are these converters providing pure sine-wave frequency clean power? Aside from more rapid actuation of the motor, and ability to flow more current to the motor, what is the benefit of 3-phase in a non-manufacturing environment where the tool or bit is removed from the work for each new cut?

Are you using pure sine-wave current to drive your stepper motors? Seems to me that is more critical than 3-phase to the headstock motor?
 
#19
Re: Looking for input/help wiring up my lathe

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Swamper</div><div class="ubbcode-body">Just curious, but what does three-phase power actually enable for a gunsmith? I could see if you were turning ten-ton rated axles from 48" x 12" billets of high tensile steel, but...

</div></div>

You usually find better deals on used industrial equipment...
industrial equipment is typically three phase...
 
#20
Re: Looking for input/help wiring up my lathe

So not a matter of "needing" the benefits of 3-phase current flow; just having to adapt from 240vac to use the gear.

Thanks!
 
#21
Re: Looking for input/help wiring up my lathe

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Swamper</div><div class="ubbcode-body">So not a matter of "needing" the benefits of 3-phase current flow; just having to adapt from 240vac to use the gear.

Thanks! </div></div>


Exactly, I got a nice,large lathe on the cheap because it was 3 phase....
 
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