INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Jobs

Small motor repair assistance

Small motor repair assistance

(OP)
Hello, thanks for having this forum. I have a 1/2 hp electrical motor on a Toledo pipe threader. I would like to repair the motor and I will need some advice on how to do it. When I push the on switch it kind of growls and dims the lights a bit but won't start. I removed the end bell on the shaft end but cannot remove the armature. The frame is molded and the other end bell does not come off by design. I removed the brushes and they are quite healthy, even though one brush cap cracked in the removal process. I can see the commutator through the brush holders and it looks great. It is a nice coffee colored brown and looks as smooth as a baby's butt. But the problem is that the armature will not come out. It turns very smoothly, but I don't want to force it for fear of breaking it. I'll attach a photo to show how it looks.



Thanks for your help. Regards, Jim

RE: Small motor repair assistance

The problem is most likely not in the motor. The reversing switch may be bad.
Many of those machines have a large multi-connection plug between the switch and the motor.
That is another possible failure point.
It may be that the male plug is not fully inserted in the female plug. (Sort of an electrical coitus interruptus.)

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Small motor repair assistance

(OP)
Hi Bill, that's a great idea. The unit came without the trigger, just a bunch of wires coming from where the trigger used to be installed. I knew where the input was since it came from the power cord. (Duh...) But the motor wires weren't so obvious. I'll attach a photo so maybe you can figure it out. Maybe I guessed wrong when I tried to hook it up. I bought a DPDT momentary rocker switch and fabricated a mounting plate but naturally I'm no where ready to install that.

RE: Small motor repair assistance

(OP)
I think I found a relevant forum link, but it has confused me more than helped. Bill, can you help me see how this link pertains to my situation?
Link

RE: Small motor repair assistance

The power cord will have a white, black and green.
Green is the ground.
White is the neutral.
Black is the hot.
The motor will have two wires from the brushes and two wires from the field.
1> Connect the white to a field wire.
2> Connect the black to the foot switch.
3> Connect the other wire from the field to a centre terminal on the switch.
4> Connect the foot switch to the other centre terminal on the switch.
5> Connect the two field wires to either of the two end terminals of the switch.

The current flow should be into the foot switch.
From the foot switch to the reversing switch centre terminal.
From the switch end terminal to the field.
From the other field lead back to the switch on the other end terminal.
From the other centre terminal of the switch to a brush.
From the other brush back to the white wire.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Small motor repair assistance

(OP)
Thank you Bill, I think I can do that. I'm afraid I misled you with that link however. I'm not using a foot switch. I'm using the switch in the picture. It's DPDT momentary rocker. Hopefully it will allow me to use forward and reverse. Do you think that will be possible? I will be mounting that into the hole where the wires are coming out. The wires as-is are very fragile and crumbly so I'll probably have to open the motor so I can replace them. That will give me an opportunity to see which are field and brush wires. Do you have any ideas about how to get into the motor? I have already replaced the power cord with a nice sturdy one with 12-3 wire. Thanks again. I'm overwhelmed by the complete and detailed instructions in your post. I went to the Milwaukee School of Engineering in the 60's, but I dropped out after two years to have a better relationship with my friends Schlitz, Pabst and Millers. (Things are better now, I just celebrated 30 years of recovery.)

RE: Small motor repair assistance

The DPDT switch cannot be used for starting and stopping the motor, only for selecting the direction. You will need a separate switch (Footswitch) to start and stop it. The reversing switch should be a 2 position, maintained, DPDT switch.

RE: Small motor repair assistance

Quote (OP)

I'm not using a foot switch.
Instead of the black wire in the cord running to the foot switch, run it direct to the reversing switch. (Instead of the white wire from the foot switch.)
The reversing switch should have a centre off position. It is also more convenient if the switch is maintained contact rather than momentary contact.
These machines worked fine without a foot switch for years until the foot switch was introduced as a safety measure.
The hand held power threaders used a momentary switch.
The tripod and leg mounted threaders used a maintained switch.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Small motor repair assistance

The DPDT switch in the photo probably doesn't have a horsepower rating and is therefore unsuitable for motor applications.

RE: Small motor repair assistance

(OP)
Hi davidbeach, thanks for catching that. Here is a link to the switch that I bought,

http://www.ebay.com/itm/181599274899

Does it have the specs that I need? Thanks, Jim

RE: Small motor repair assistance

Well the current rating is almost 3 times the probable current rating of the motor.
The switch has a 230 Volt rating so we may assume good breaking clearances.
The question is how long to failure?
The switch may last indefinitely.
The switch may fail in a matter of weeks or months.
You may see an "HP" rating somewhere on the switch.
I am guessing that you will not be submitting this to the local inspector for an inspection. grin
You will be assuming all liability.
We sure won't accept any liability if you use an unrated switch.
If you go ahead, let us know how long it lasts.
The price is attractive.
Stay in touch.
Good luck.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Small motor repair assistance

If what I saw is what you posted, you have delightfully developed senses of humour and irony.
A quote from Bill Murray;
"I wanna party with you!"

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Small motor repair assistance

(OP)
conehead

At least something has developed in my 75 years.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close