my new SB lathe and an "interesting" relay box

noobie · Jan 10, 2013

Hi all, I'm trying not to be the typical noob and make my first post scream to all that I didn't do my homework. But after talking by phone to a forum member who has oodles of experience, and asked me what it was, I thought it might be ok to look for your help. I'm a total neophyte, and with many other hobbies I've found a small investment, even if I get snookered, helps me get down the path of learning how to do something.

This South Bend Lathe was purchased at random, and has all sorts High School vocational tags. Any guess what this relay box is for? Should I just bypass it, remove it and put it in the "treasures for another day barn?
Thanks for a great site.

"

Grey Rider · Jan 10, 2013

Looks like the motor starter to me, although I don't know why there are two of them.

You can either wire it into service or design and build your own. No big deal. But you can't not have a motor starter of some kind. (Well, ok , yes you could in theory not have a starter, but I would imagine the arrangement would rather hazardous and ill-advised from an electrical standpoint.)

Here's a link that explains how it works and how to build your own. Electrical

-Ryan

packrat2 · Jan 10, 2013

I see two stop-start buttons also.??

rowbare · Jan 10, 2013

Perhaps the second set was for a coolant setup?

bob

BobRenz · Jan 10, 2013

It looks like a reversing starter setup, but two complete setups. Its possible that it had a coolant pump, or pumps?

Since you will probably be using this in a home shop, and you probably don't need three phase power for anyhting else, you can always convert to a single phase motor, with a standard drum-type switch for on/off--forward / reverse control.

SBLatheman · Jan 10, 2013

I'm sure it has a 2 speed, 3-phase, single voltage motor
Ted

noobie · Jan 10, 2013

SBLatheman said:
I'm sure it has a 2 speed, 3-phase, single voltage motor
Ted

Sure does have 3ph, here are some other photos. I'm going to research the motor to see whether it can be wired single phase, it seems to have two hp ratings, I would hope that lower rating is single phase, but that could also be part of the "two speed" motor.

Thanks for the replies!, I hope it is at least a head scratcher.

atomarc · Jan 10, 2013

noobie said:
I'm going to research the motor to see whether it can be wired single phase

Nope!

Stuart

jkopel · Jan 10, 2013

No, you cannot re-wire a 3-phase motor for single phase and you don't want to!
That motor has two speed/HP ratings, but they are both 3-phase.
Get yourself a VFD and hook it up.
May well be the best money you will spend on your machine.
Well, maybe second best, after a tailstock.

doug8cat · Jan 10, 2013

From the picture the contactors etc. don't look all that bad, I have seen some bad boxes, and this one looks salvageable.

Ohio Mike · Jan 10, 2013

Yep, two speed three phase motor with twin forward/reverse motor starters, one for each speed. This would have been the most expensive setup you could have purchased.

packardbill · Jan 10, 2013

That's going to be a great set-up with a compound, a tailstock, and a vfd! I'm envious.

k3vyl · Jan 10, 2013

What you have there will not run on single phase power,unless you provide a so called phase converter.If the controllers/starters look to be in good condition you can get a wide range of speeds on the machine with a converter.Those old contactors are very rugged,and will run for years if they are in good condition now.
The VFD option will give you infinitely variable speeds with some sacrifice of torque at certain speeds.The vfd will also reverse easily.
Another approach would be to get a VFD,and use it as a converter ie set it for full speed 60HZ and just feed the existing setup from it.That way if your electro mechanical setup goes west at some point,you can just put the 1800 rpm side of the motor on the VFD and controll it that way.
Other issues may also come into play ie is it a threaded spindle lathe.If so you may not really want reversing capability.Another is do you want outboard "stuff"ie the converter or VFD.Check what speeds the machine has,and look at turning speed tables to determine if you even need the wide range.Those buttons are a "reach over" setup not considered safe in this day and age (im still using the reach over on my 13).Dont jump at a solution there is much to consider

noobie · Jan 10, 2013

I'd like to go with a static converter for starters from a local vendor at $40. Get a sense of this machine, yet with this speed control system am I advantaged to work with a static converter or limited to a VFD. A no name VFD at $120 seems risky, sense my experience with inverters is that there is no life expectancy at discount.

If anyone can share a sense of the safety of the stop start buttons being across the work area and above. My instinct is that in an emergency this would slow my ability to react and I couldn't use my foot or knee to bang a stop switch. Please take this from a beginner thinking of what my shop teacher taught us first and last, practice hitting the stop switch so that your body knows where it is before your brain has to think about it. I would think adding a kill foot switch into the base of the cabinet would be basic, but am I thinking about this wrong?

k3vyl · Jan 11, 2013

An emergency stop on the front of the cabinet would give you the ability to stop it without reaching over the moving parts.You could even make a habbit of stopping the machine with it,using what your shop teacher suggests.Most emergency stops use maintained push button operators which you have to pull back out in order to start back up.You can use a momentary operator that will re-close the stop contacts so you can re-start or reverse without having to pull the mushroom out.
Looks like the cabinet even has knockouts where you need them.

noobie · May 5, 2013

I finally got it spun up with a rotary phase converter. Wow...the high low fwd rev controls are nice. It seems a bit decadent
n abstract, but in practice this is a very nice feature. I kept cycling it in awe of how smooth it made the lathe. The response is instant. I tried running it with a static converter but was my screen name apt, I kept trying a single button, until it dawned on me you need to use a combination of a speed and direction. The switches are a bit buzzy some settings more than others. This could be the RPC and or the solenoids are dirty and need attention.

Avrgjoe · May 7, 2013

noobie said:
I'd like to go with a static converter for starters from a local vendor at $40. Get a sense of this machine, yet with this speed control system am I advantaged to work with a static converter or limited to a VFD. A no name VFD at $120 seems risky, sense my experience with inverters is that there is no life expectancy at discount.QUOTE]

I used a static converter that I built myself to start with, comparatively speaking, there is no comparison. I surely would not spend $120 on a no name anything, you can get a TECO VFD 1HP 115 Volt -- USE AS A PHASE CONVERTER PLUS GET VARIABLE SPEED, Model JNEV-101-H1, Single Phase Input ONLY, Three Phase Output, variable frequency drive, variable frequency drives, ac drive, vfd, afd, frequency drive, drive, inverter, adjustable sp here that will run that thing beautifully, also it will give you a lot more versatility with anything belt driven. I am running 2 of these, 1 on my SBL and 1 on my Bridgeport Mill. Dealers Elect is a fast dependable place to buy from and TECOs customer service is great.

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my new SB lathe and an "interesting" relay box

noobie

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rowbare

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BobRenz

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SBLatheman

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noobie

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atomarc

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jkopel

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Ohio Mike

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k3vyl

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noobie

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k3vyl

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noobie

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