Old rotator

[G4YVM David]

I was recently given an old Ham 2 or Ham M series 5 rotator from the 38th week in 1976!!

I have stripped it and cleaned it and everything works, its ready for new bearings...alas, the motor is seized solid. Very sad. Its now covered in wd40 and sat in a dish of coke. Much frequent waggling of the shaft, I am.told, works wonders.
Frankly, I doubt it...but having got thus far I ought to try a few weeks.

A replacement motor will cost me 70 USD. I bet for a hundred quid I could get it going...but it'll still be a rotator from the 38th week of the year of the heatwave.

David

[Refugee]

Have you got a photo of the seized bearing?

[Bazz4CQJ]

The problem there is that WD40 is a hydrocarbon water repellent and will therefore tend to keep the cola from getting where it needs to be.

Is the whole motor immersed or have you got the bearings out?

As a means of breaking loose corrosion products, I'd definitely go for citric acid solution or even vinegar in preference to cola.

Worth persevering with!

B

[Scimitar]

A Water Dispersant will hinder, not help. Try a penetrating oil, something like a 50:50 Acetone/ATF mixture. Even a drop of diesel would do at a pinch.

[Terry_VK5TM]

If the cola or any acid gets onto the enamel of the motor windings, it's a new motor you'll be needing regardless.

Yes, been there, done that. Not a pretty sight.

[emeritus]

Lighter fluid, such as Ronsonol, can work miracles on severely seized moving parts. You can use ordinary petrol at a pinch, but lighter fluid does not have the nasty additives that you get in motor spirit.

[Bazz4CQJ]

Originally Posted by Terry_VK5TM

If the cola or any acid gets onto the enamel of the motor windings, it's a new motor you'll be needing regardless..

The constituents of cola that come in to play are carbonic acid (from the CO2) and phosphoric acid. Having been tasked in the past with trying to find substances to remove traditional enamel from wire at ambient temperature, and failing miserably, I'm surprised that cola would effect the enamel.

Citric and vinegar (acetic) are both dilute and weak acids (note the distinction) and I'd be even more amazed if they attacked traditional enamel.

Of course, any of these substances would attack un-protected copper.

All that said, if you get the stage where you're putting aqueous solutions of any kind in to the windings, I'd say that you'd need to be sure that you got it all out before applying any power.

B

[Terry_VK5TM]

Agreed, but the problem arose where the enamel had been removed from the copper to make the connections to the armature/commutator.

stuff ate through the copper at that point, rendering the motor useless (I didn't bother fixing it as it really needed a new gear as well).

Like Davids, it had seized and was sat immersed in cola for quite a while, which did clean it all up nicely by the way.

This would have been 30-35 years ago, reason it sticks in the brain is because I actually paid for the rotator as part of a tower/antenna deal. Oh well, live and learn.

[G4YVM David]

I'll get a photo of the bearing but a rotator repair specialist reckons the stator and rotor laminations will have rusted together.

I might be persuaded to buy a new motor. At 60 USD it's not cheap for a motor, but it is for a braked rotator.

[G6Tanuki]

Ill get a photo of the bearing but a rotator repair specialist reckons the stator and rotor laminations will have rusted together.

That's usually terminal: the rust gets in between the lams and makes them swell. The expansion-forces generated when ferrous metal rusts can be *enormous*!

[I once tried to separate the stator and rotor of an old 'Smiths' car heater-motor that had filled up with water: it defeated an 8-ton hydraulic press]

[G4YVM David]

Ouch.

Yes, it sounds final IF that's what it is

[G4YVM David]

Here are some pics of the unit. I note that the circumferencial laminations are buckled in the vertical plane...I can't imagine they were made like this so this could be a sign of great rust induced stress!

[G6Tanuki]

That does not look good. I'd be inclined to subject it to the Royal Navy flotation test //[1]\\ and if it fails, buy a new one.

"Oxide jacking" as it's known has in the last few decades been a big issue in things like motorway flyovers, where rusting of the steel reinforcing-rods in concrete bursts the concrete asunder and led to hundreds of millions of pounds in repair-bills. It's also been a nightmare for residents of 1940s/50s-build reinforced-concrete council-houses.

//[1]\\ Hurl the part-under-test into the nearest body of deep water. If it floats, recover it and use it.

[G4YVM David]

Thanks. Rather as I feared.

Looking at the Hygain / MFJ catalogue, the motor is 69 dollars and the potentiometer at the top a further 39, but that works so shouldn't be needed. The bolts that fasten the two together will though.

d

[Refugee]

That motor looks like the rust has gone rusty.
Rust contains oxygen that has been absorbed during the rusting process so steel gets bigger as it rusts.
Concrete does fail due to the steel rusting inside the columns. Rust claimed junction 19 on the M1 so that they had to fully rebuild all of the elevated parts.

[G4YVM David]

That motor looks like the rust has gone rusty.
Rust contains oxygen that has been absorbed during the rusting process so steel gets bigger as it rusts.

I think you're saying it's a gonner!

[Refugee]

No it is a duffer

[AndyWright]

Hi David I have a scrap hygain ham 4 rotator, as I’ve upgraded to heavier duty rotators here. It’s yours if you want it. I also have a new rotation pot. Drop me a line.

Cheers andy

[G4YVM David]

Done.

[G4YVM David]

A case for not screwing amateur pa transistors up to 150pc of their stated output I think. 20w ft 817 anyone?

D