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547 Fan lubrication

 

Hi all,

The fan in my 547 was running slow and taking a long time to run up to speed. I took it apart to find the bearings all gummed up with sticky greasy old oil. I've washed it all out with an appropriate solvent and now need to relube it. Is there a recommended oil to use? I have various grades available ranging from 3-in-1 to heavy EP90. I'm leaning in towards 3-in-1 or maybe Mobil-1 motor oil. There's no recommendtion in Stan Griffiths' book.

Any ideas or advice?

Thanks, Morris
 

What kind of bearings are they?

I¡¯d consider using a Teflon-based lubricant.

DaveD

Sent from a small flat thingy

On Aug 13, 2019, at 06:43, Morris Odell <vilgotch1@...> wrote:

Hi all,

The fan in my 547 was running slow and taking a long time to run up to speed. I took it apart to find the bearings all gummed up with sticky greasy old oil. I've washed it all out with an appropriate solvent and now need to relube it. Is there a recommended oil to use? I have various grades available ranging from 3-in-1 to heavy EP90. I'm leaning in towards 3-in-1 or maybe Mobil-1 motor oil. There's no recommendtion in Stan Griffiths' book.

Any ideas or advice?

Thanks, Morris
tom jobe
 

Sewing machine oil...

On 8/13/2019 3:43 AM, Morris Odell wrote:
Hi all,

The fan in my 547 was running slow and taking a long time to run up to speed. I took it apart to find the bearings all gummed up with sticky greasy old oil. I've washed it all out with an appropriate solvent and now need to relube it. Is there a recommended oil to use? I have various grades available ranging from 3-in-1 to heavy EP90. I'm leaning in towards 3-in-1 or maybe Mobil-1 motor oil. There's no recommendtion in Stan Griffiths' book.

Any ideas or advice?

Thanks, Morris
 

On Tue, Aug 13, 2019 at 05:43 AM, Morris Odell wrote:


Hi all,

The fan in my 547 was running slow and taking a long time to run up to speed.
I took it apart to find the bearings all gummed up with sticky greasy old oil.
I've washed it all out with an appropriate solvent and now need to relube it.
Is there a recommended oil to use? I have various grades available ranging
from 3-in-1 to heavy EP90. I'm leaning in towards 3-in-1 or maybe Mobil-1
motor oil. There's no recommendtion in Stan Griffiths' book.

Any ideas or advice?

Thanks, Morris
As you well know, the problem with these bearings is that the ideal lube is a light bodied grease that stays put. Simple to apply such grease when the motor is being assembled, unfortunately, it is impossible to get such a product into the bearings because of the close tolerances and other design characteristics. One must revert to a less viscous product that will penetrate the slim gaps, but still lubricate and stay in place. Definitely use a synthetic product that will not gum up. I use synthetic motor oil on many of these type applications.

--
Michael Lynch
Dardanelle, AR
 

I have used Mobil One 0W-15 for decades to lube small electric motors and always had great results. Sleeve bearings are made of sintered bronze and are porous, so care needs to be taken to be sure the old residue is flushed out and plenty new oil is absorbed.

Bruce Gentry, KA2IVY

On 8/13/19 6:43 AM, Morris Odell wrote:
Hi all,

The fan in my 547 was running slow and taking a long time to run up to speed. I took it apart to find the bearings all gummed up with sticky greasy old oil. I've washed it all out with an appropriate solvent and now need to relube it. Is there a recommended oil to use? I have various grades available ranging from 3-in-1 to heavy EP90. I'm leaning in towards 3-in-1 or maybe Mobil-1 motor oil. There's no recommendtion in Stan Griffiths' book.

Any ideas or advice?

Thanks, Morris
 

Bruce,

EXCELLENT advice. Getting the gummed up residue out is 75% of the battle.

--
Michael Lynch
Dardanelle, AR
Chuck Harris
 

The bearings are oilite, which is a sintered bronze
sponge like material.

You definitely do not want to use any lube with fine
particles in it, like teflon, as it will clog the pores
of the oilite.

To clean the old bearings, a fine brush, and a long soak
in naptha works about as well as you can do.

Heat causes the oil to leave the bearing, and cooling
causes the oil to be sucked into the bearing, so warm them
up good and hot in a puddle of light synthetic motor oil,
and allow them to cool. They will be as good to go as
they are going to get.

The felt that is held against the bearing is there as an
oil reservoir. The oil basically flows from the felt into
the oilite, and forms a very thin film between the shaft
and the bearing. This is why it is important that the
clearance between the oilite and the shaft be only a
a couple of thousandths of an inch, or so.

Oilite tends to be a little abrasive when it wears, and
usually the hard steel shaft will wear out before the
oillite. So, if your bearing rumbles, it generally means
you need a new shaft.

Over oiling the bearing will just work for a few days,
then the oil will go away, and the rumble will return.

-Chuck Harris

Dave Daniel wrote:

What kind of bearings are they?

I¡¯d consider using a Teflon-based lubricant.

DaveD

Sent from a small flat thingy

On Aug 13, 2019, at 06:43, Morris Odell <vilgotch1@...> wrote:

Hi all,

The fan in my 547 was running slow and taking a long time to run up to speed. I took it apart to find the bearings all gummed up with sticky greasy old oil. I've washed it all out with an appropriate solvent and now need to relube it. Is there a recommended oil to use? I have various grades available ranging from 3-in-1 to heavy EP90. I'm leaning in towards 3-in-1 or maybe Mobil-1 motor oil. There's no recommendtion in Stan Griffiths' book.

Any ideas or advice?

Thanks, Morris
Chuck Harris
 

I use mobil 1 5W30... because my car uses it, and I collect the
drips from "empty" bottles.

-Chuck Harris

Morris Odell wrote:

Hi all,

The fan in my 547 was running slow and taking a long time to run up to speed. I took it apart to find the bearings all gummed up with sticky greasy old oil. I've washed it all out with an appropriate solvent and now need to relube it. Is there a recommended oil to use? I have various grades available ranging from 3-in-1 to heavy EP90. I'm leaning in towards 3-in-1 or maybe Mobil-1 motor oil. There's no recommendtion in Stan Griffiths' book.

Any ideas or advice?

Thanks, Morris
 

Thanks to everyone who responded to my question, it has turned into quite a large and interesting discussion!

I have had the bearings soaking in a naphtha type solvent for the last couple of days and will let them dry out later today. Successive solvent changes now look pretty clear. The rotor shaft journals look fine. The oilite bearings are located in diecast end bells with some sort of fabric around them to retain the lubricant. I'm reluctant to disassemble them further or remove the bearing shells from their housings for fear of damaging them.

I've decided to use Mobil-1 oil but not to bake the whole end bell assembly because of lack of facilities and the potential effect on the absorbent fabric. I'll just dribble the oil into the holes in the bearing housings and run the motor for while to let it warm up and soak through. Maybe a blast with the hot air gun will help.

The rotor was located axially with a mixture of nylon and fibre washers together with wavy spring washers that look like phosphor bronze. Some of these are quite worn. In his book Stan Griffiths mentions that Tek used to supply replacement teflon washers but I'm sure they would not be available now. However I have found a source of teflon washers of the right size intended for the radio controlled model industry and they should arrive next week. In the meantime the scope is sleeping on its side on my workbench and I'm taking the opportunity to clean the filter and a few more areas.

Incidentally the stator of the motor has a date stamp of January 16, 1964. Electronically the scope works perfectly and is a pleasure to use. It's only needed minor maintenance in the 15 years or so since I paid $100 for it. Not bad for a 55 year old classic!

Morris

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