Help please before I blow up another old motor..

[Beanwood]

Befoe I start - everything I mention in here has been stood, untouched, for 12 years in what appears to have been a dry garage, before I got my hands on them in case that's relevant to the story.

As part of my freebie haul a couple of weeks ago, I picked up an Atlas floor standing pillar drill. The wiring was very much from the 1950's, maybe 60's - certainly not the 70's... but I thought before I try and work out how to deal with this particular new toy, I'd remove the 5a unfused plug, and put a 3 pin standard on to see if it even worked.

Well - it did work briefly - before letting out blue smoke.

No problem - there was also another spare motor - which I wired and tried for 5 seconds - worked fine before I turned it off.

There was MORE - another motor which had been cobbled into a frame as a 12" sander (Sanding disc).
I tried this one tonight - it's a 2.0 Amp 1/4Hp motor according to the data plate, so I started with rewiring with a 3A fuse - which blew immediately. I replaced with a 5A and t ran for several seconds before stopping - I'm guessing blown a fuse.
Now - before I put a larger fuse in, and risk blowing the thing altogether, and before I start to try and attach the other motor (That I tried for 5 seconds) to the pillar drill - am I doing something wrong.

Is there anything I should do to recommission these motors to give me best chance of them surviving, other than just plugging them in?

 

[Beanwood]

This is the one attached to the sanding station.

 

[gaz1]

i think your issue is down to the motors and there coverings inside of the motor more precise the windings protective covering

with age they do go faulty and the windings start to fail rather well

it looks like your following what is rated so other than fitting a plug on the end and plugging it in and hope that the windings are fine and that is all you can do

but wait for other responses though

 

[Nomad]

Do the motors turn ok by hand?
On smaller motors that have been standing for years I've sometimes found dried grease or rust that makes it difficult to turn the shaft ...

Maybe remove the drive belt to give the motor an easier time? if that works ok then reconnect the belt and try the complete unit.

 

[Brad93]

Insulation resistance test

 

[8ob]

Shot caps

Bob

 

[GRW]

Damp possibly due to idle a long time. Drying a motor for a week or more in (say) an an airing cupboard (or better a fan oven on a low setting) can cheer a motor up.
If a brushed motor, stuck brush holders, broken/rusty brush springs & glazed/stuck/dirty brushes and slip rings giving poor contact to the rotor.

 

[Brad93]

Damp possibly due to idle a long time. Drying a motor for a week or more in (say) an an airing cupboard (or better a fan oven on a low setting) can cheer a motor up.
If a brushed motor, stuck brush holders, broken/rusty brush springs & glazed/stuck/dirty brushes and slip rings giving poor contact to the rotor.

i'd just stick it in the oven at 120-150 for 2 hours

 

[Beanwood]

i'd just stick it in the oven at 120-150 for 2 hours

Is this serious? Would it be that sort of temperature - I genuinely don't know.

 

[Brad93]

Is this serious? Would it be that sort of temperature - I genuinely don't know.

Yep 100%

Exactly how my rewinder does it and how i have done it since being shown. Albeit they have a much bigger oven

 

[Beanwood]

Damp possibly due to idle a long time. Drying a motor for a week or more in (say) an an airing cupboard (or better a fan oven on a low setting) can cheer a motor up.
If a brushed motor, stuck brush holders, broken/rusty brush springs & glazed/stuck/dirty brushes and slip rings giving poor contact to the rotor.

Dirty is likely -everything is very grubby.

 

[Brad93]

But you need an insulation test to be sure that if you have low readings before they have increased after baking *and cooling*.

Elevated temperatures affect insulation resistance readings.

 

[Beanwood]

Yep 100%

Exactly how my rewinder does it and how i have done it since being shown. Albeit they have a much bigger oven

Thanks Brad - just need SWMBO out of the house for a couple of hours

 

[Beanwood]

But you need an insulation test to be sure that if you have low readings before they have increased after baking *and cooling*.

Elevated temperatures affect insulation resistance readings.

So just measure winding resistance pre and post heat.
Can I work out what they should be?

 

[Memmeddu]

So just measure winding resistance pre and post heat.
Can I work out what they should be?

It's no winding resistance.
But insulation resistance, you need a specific instrument which does a resistance testing, ok it looks familiar nothing special right?
No .
Usually a tester in ohms mode send a 3V roughly signal through the probes, an insulation tester has various options but generally speaking starts at 50V, 250V, 500V, 1000V, 2.5kV, 5kV .
Smaller ones usually reach 1kV but the usually do 250, 500, and 1kV .
I don't even think mine does 50V...
Anyways it measures the wires/ winding insulation resistance , and the breakdown voltage.
Cause 20Mega ohms means one thing on 3V and a completely different one on 250V .

 

[eddie49]

So just measure winding resistance pre and post heat.

No, you measure resistance from either end of the winding(s) to Earth - i.e. the motor frame.
The copper wire winding may be about 20 Ohms end-to-end
- see Post #7 here:

Sealey 180 supermig v3

My uncle has asked me to look at his Sealey 180 V3 but it looks like someone has been in there playing as some of the wiring looks (from the supplied schematic from sealey) to have been messed around with. One quick question, there is a sort of ferrite ring bolted through the base with red and...

www.mig-welding.co.uk

but as Memmeddu said, you need to measure the resistance of the insulation, not the wire, and this should be millions of Ohms. This has to be done at a high voltage, at least comparable to AC mains voltage, rather than the 3v to 9v of a multimeter, and for that you need a "Megger".

 

[Agroshield]

Start winding switch could be corroded contacts or simply falling apart.

If it is a mechanical/centrifugal switch, the long period of inactivity could mean it is seized or gummed up. An older motor is more likely to be split phase than capacitor start, so it is a good thing to check.

 

[6ply]

Is this serious? Would it be that sort of temperature - I genuinely don't know.

That motor has an insulation temperature rating of class B, which is a maximum 130 C above ambient temperature. Personally, if I thought damp were an issue I'd just stick it somewhere warm and dry for a couple of weeks, assuming I were in no rush. Actually, I'd use my Megger to test it first, and then periodically test until it passed.

I have serviced a lot of old motors and in my experience the windings are most often ok but the "tails" attached to the windings frequently fail with the insulation cracking up. If that's the case, the tails can be sleeved or new tails soldered on.

1/4 HP is a bit small for a 12" diameter woodworking disc sander, unless you use it very lightly.

 

[Beanwood]

Hmm - so looks as if I need to find someone nearby with a Megger that can work for beer tokens!

@angellonewolf - got a Megger in your armoury ?

 

[angellonewolf]

Hmm - so looks as if I need to find someone nearby with a Megger that can work for beer tokens!

@angellonewolf - got a Megger in your armoury ?

i might have acquired one


pm me