Craftsman industrial not getting up to speed

Same power but the motor will run more efficiently with 220v.

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220 vs 110

I have had a 220 line run across the garage for a new G4003G lathe. I also have a 9x20 that is presently wired 110, but has the option to run on 220. Both would be using 6-15 plugs, but not running at the same time. Should I rewire the 9x20 to 220 now that it is available? What are the...
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First of all, there is no "power" difference between 240 and 120 volt motors. The difference is with how much current it draws from the line. Basically, how big a fuse would have to be. Otherwise, a 1/2 HP motor is a 1/2 HP motor. The only difference would be the cord connector type and fuse size. I happen to like 240 volt machines, but my lathes are 120 volts because that's where the cables run.

As to the size, or HP rating, I have a 101.27440. A little older than your's, but essentially the same machine on an open frame. I am underpowered with a 1/3 HP motor. But, I'm a model builder and don't push the machine hard. That small would be your call. A 1/2 HP is useable. If you had the machine in commercial service, I would suggest 3/4 HP. For that particular machine, any thing over that would be overkill. It would cut fine, but there are a lot of sleeve bearings that would wear out faster with more power.

Now, I wouldn't want to arbitrarily hook it to 240 volts without triple checking the wiring connections. As noted above, you'll have to run down the schematic for that specific motor. It will be one of many wiring types from the same source. Motor speed is based on line frequency rather than voltage. With that type of motor. There are motors where speed is a function of voltage, but that's not applicable here.

I would look more toward the starting circuit. First try the spindle floating, pull the lever out to disable the final belt reduction. Quickly start the motor and spin the large reduction pulley by hand. Watch out for your fingers. The motor should come up to speed. If it doesn't, shut it down quickly and start looking for a mechanical problem. If it does come up to speed, check the start circuit / capacitor.

You stated the reversing switch was disabled. That indicates to me that there is likely a problem with the start circuit and the PO tried to "fix" it but couldn't. It may well be why the machine came up for sale. It's easy to troubleshoot remotely... ... But that will give a starting point. Start there before spending a lot of money on parts that may not be needed.

Bill Hudson​
 
matthewsx said:
Same power but the motor will run more efficiently with 220v.

www.hobby-machinist.com

220 vs 110

I have had a 220 line run across the garage for a new G4003G lathe. I also have a 9x20 that is presently wired 110, but has the option to run on 220. Both would be using 6-15 plugs, but not running at the same time. Should I rewire the 9x20 to 220 now that it is available? What are the...
www.hobby-machinist.com www.hobby-machinist.com
Click to expand...
Sorry, but this is a persistent urban myth. Even in the linked thread, it is debunked several times.

A typical North American 120 volt line is sized to deliver 15 amps. A single phase 120 volt 1 horsepower motor usually has a maximum draw of up to 13 or 14 amps (setting aside wildly inflated marketing claims). If you want to run a bigger motor on 120 volts, you really should run a special circuit with heavy gauge wire and appropriate circuit breaker. In that case, you might as well run a 240 volt circuit and use be able to use thinner (cheaper) wire.

For any motor requiring less than 13 amps at 120 volts, there is normally no good reason to use a 240 volt circuit. There could be special cases like the motor is going to be at the end of a really long wire run but that's atypical.

Craig
 
The lathe starts up fine. And am able to cut some metal. It’s just not reaching speeds listed on the chart. Also at highest speed it struggles to keep at speed.
I can’t find any diagrams for my motor. Is there a similar motor that Ican use?
 
Ok, so maybe the motor itself won't be more efficient but the circuit is.

As for wiring diagrams you can look for a similar one or use the information provided by the PO, he's unlikely to have written it down without understanding what he was talking about. If the motor is working now it's probably wired for the service you have it connected to so I wouldn't change any wiring until you rule out other potential problems.

Often when a machine sits for a long time it will need at least a partial tear down and rebuild to make things work right.
There are many things that could effect lathe operation besides the motor itself, just because it looks clean doesn't mean everything is set-up and adjusted correctly.

How are you measuring rpm?
Have you disconnected the belt and run your motor with no load?
Have you cleaned and lubricated the spindle bearings?
Bearing preload?
Changed or at least inspected the belt and made sure it's tightened correctly?
Does the spindle get hot when running?
Does everything turn freely when the belt is disconnected?

If you're looking for a replacement motor you should be able to use anything with the correct hp and frame size. I still recommend a three phase unit with VFD for convenience of changing speeds if replacing the motor but I suspect something else is causing your problem as electric motors tend to either work or not, if the magic smoke is still in there look elsewhere for your problem.

Here is the operations manual for your machine, read it and pay close attention to any sections dealing with adjustment and lubrication.

Atlas Press Co. - Publication Reprints - Manual of Lathe Operation & Machinists Tables (MOLO) 23rd Edition | VintageMachinery.org

vintagemachinery.org


Cheers,

John
 
Roger that, now I understand. I think... I use several Baldor "Farm Duty" motors because I happen to like them. Fair price at the local motor shop and they are TEFC, totally enclosed fan cooled, so stay in good shape inside even if misused. I trust the Baldor rating for TEFC.

WWGrainger is a good source for most any motor up to several horsepower in both single phase and three phase. There are many sources for U S made motors but Grainger should be available most anywhere in the country. Their prices are a little high, but the choice is very wide. Again, Baldor is one of the first class sources, but I'm particular to them even though they are higher than Grainger.

Single phase, NEMA 56 Frame, 3/4 Horse, 5/8 shaft and you won't go wrong. I would recommend (highly) that you check out the reduction pulleys and bearings well before replacing the motor. There are other possibilities, most are covered already. Pulley size does matter too. As does back gearing. I'm sure you know enough to be sure you're not in back gear, but the thought is still there.

.

.

.
 
The various above comments are correct in that, all other things being equal, a given dual voltage motor by itself will have the same efficiency and the same temperature rise whether connected for low voltage or high voltage. The difference is that the overall system efficiency will be slightly higher when connected for high voltage than it is when connected for low voltage because the current drawn from the AC line will be double when the voltage is one-half and therefore the loss due to voltage drop in the supply lines will be double. But I doubt you would be able to see any difference in your monthly bill. However, it is my practice to favor the high voltage connection for anything over about 1/2 HP.

When talking about replacement motors the one thing that is seldom mentioned in these discussions is that the thermal breaker that is in some motors comes in two types, manual reset and automatic reset. Never under any circumstances buy a motor for use in a machine tool that has an automatic reset thermal breaker. Automatic reset means that if the thermal breaker trips because of an over-heated motor, when it cools off again it will automatically reset itself and try to restart the motor. You do not want this as you might be working on the machine trying to figure out what caused the shut-down when the breaker resets. And you could lose an irreplaceable part of your anatomy or be electrocuted when the motor tries to re-start unexpectedly.
 
I have found the issue last night. I found the old connector and found that it was a 20a 250v connector. So I hooked the lathe to 220v and it worked like a charm.
I will run this motor until it fails and go to a Vfd. Thanks everyone for their help.
 
OK. We're glad that you figured out that issue.
 
The motor itself IS actually more efficient at higher voltage. Less copper loss at lower current, for the same hp rating; less heat.
This is why high horsepower motors are always run at high voltages.
mark
 
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