Convertible Maintenance Questions

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Tape head cleaners----CAUTION!!!!WARNING!!!!DO NOT USE DENATURED ALCHOHOL to clean tape heads will cause head laminations to come apart and the head mount to the head block to come off,too.Use ISopropol alchohol for tape deck cleaning its safer for the parts.I don't think I would use denatured on motor parts,either-could damage the insulation.
 
Not true and you would be at odds with almost the entire tape community I belong to which is over 3,000 members...including EE's and past studio technicians of analog. MEK, acetone and some other strong chems, definitely not to use.


 


Denatured alcohol is fine for tape heads and I've been using it for over 40 yrs without incident. It's harder and harder to find 99% <a name="start_35654.383161"></a><strong>isopropyl alcohol....anything less and you're using too much water in the formula for tape head cleaning.   </strong>


 


Kevin
 
UPDATE

I have taken some of your suggestions and done some work.

I sanded the commutator w/ 1500 grit wet/dry, seated the brushes with a drill on low speed, and lubed the motor bearings.

The motor runs smooth, but it does sound a bit noisier than before. I did also lubricate the brushroll bearings, replace the belt and bag.

Is this extra noise something I should be concerned with?
 
Most tape head manufacturers recommend AGAINST using denatured alcohol for cleaning.Use Isopropol instead.Being doing this for 40 yrs,too.I have had to order replacement heads that get worn out during the older days when RR machines were used all the time in broadcast work.Save the denatured stuff for cleaning insulators in the transmitter-and transmitter tube envelopes,vacuum cap envelops.Works good for these.
 
Well, I couldn't disagree more on the denatured alcohol for tape heads and I have almost an entire tape communnity to back me up, plus over 40 yrs using it.....do as you wish. I guess we agree to disagree.


 


@hoover4089<span style="font-family: Arial;"><span style="font-size: small;">   </span></span>As far as the noise, you're going to have to be more specific? New brushes will be a bit noisier than old ones for awhile. The spark is what's important here....it should be even, low and not shooting out one side unevenly from the two brushes.


 


Kevin

[this post was last edited: 12/31/2017-07:49]
 
@real1shep:

What I'm hearing now is not dried bearing noises and the previous scraping noise is now gone. The motor itself just sounds a little noisier. Perhaps I could keep using it for a while to see if it will run quieter after the brushes fully seat.

I did take the motor apart a couple of times after running with the new brushes to clean the commutator with isopropyl.

The motor turned perfectly smooth by hand after I lubricated the bearings. However, it took at least 12 hours for the top sleeve bearing to completely soak the few drops of 3-in-1 oil I applied to it. I had seen some videos on lubricating these bearings and was informed that they should drink the oil immediately.

The top bearing also seemed more difficult to slide back on the shaft. I did sand the bearing surface on the shaft, first with 220 and then with 1500.

Thanks again for all of your suggestions. If this information still leaves you with questions, I could post a video or audio clip of the cleaner running.
 
My old ears aren't the greatest....so videos don't usually work for me....in person is still the only way I can hear trouble.


 


The noise could just be increased rpm from a cleaned motor.....hence the motor is louder. I rebuilt/cleaned a truck starter once and it was quite noisy afterward. Like a motor on steroids.....but it worked great and lasted.


 


Kevin
 
@real1shep: The motor is running at the same rpm as before, just sounds a little more raspy. I think you could be right about the brushes needing to break in a little.

As for the bearing, do the symptoms I have described in my last post suggest that it would be good to replace. The first user to reply to this thread recommended against it but I've heard numerous suggestions in other threads to replace if lubrication is unsuccessful.

I will try to clean it thoroughly again and see if it takes oil.
 
If you're dealing with a sintered bushing that won't take oil from a wick after being thoroughly cleaned, then yes, replace the bushing.  I've actually seen this happen....my guess is that the porousity of the sintered bushing is ruined.


 


New brushes often do make a lot of noise when first used. Watch the sparks though when the motor is running to determine if they are seating properly. If you've got more spark shooting out one side of the brush than the other at the commutator, they're not seated well.


 


Kevin
 
I have done an extra thorough cleaning of the bearing with rubbing alcohol and it subsequently took about 12 drops of oil. I then put a drop on the bearing itself after sanding both the inside of the bearing and the shaft with 1500 grit.

The bearing went on a little smoother and the motor, little by little, is starting to quiet down.
 
Hate to say it.

I would not have sanded the upper bearing surface on the shaft. Not only will the diameter be smaller now (more play), but the shaft surface will likely never be as true or as smooth as it was before. If the surface is not as smooth as it was before, any bearing, new or used, lubricated or not, has the potential to wear out the bearing more quickly now.

But do not panic. Although it may be less than ideal, I'm sure it will last just fine. Replace the upper bearing if you want, but If you have already lubricated the original one and it doesn't sound or look terrible, the original should work just fine too.

The honest truth is, it's a pretty robust vacuum motor that is likely never going to see enough use to wear out any of its components ever again. Use it to your heart's content, let the motor break in after all the work you have performed on it, and enjoy your Hoover. I would be surprised if it ever failed you.
 
You need to burnish a shaft, rather than sand it, I agree.  But putting a blackened shaft end back in from long use is not ideal either. It's easy enough to mic a shaft too, to tell if you've taken off material residue or actual shaft material. The real wear is most likely in the sintered bushing....considered sacrificial by design.


 


I doubt however if the tolerances in this case are that critical.


 


Kevin


 


 
 
The reason an upper bearing will be stiff is it has not been seated. The original bearings wear down from Round to an Egg shape. You don't want to give an armature spinning at 7000rpm the opportunity to shift back and forth.
Install the new upper bearing, and then rotate the fan by hand. Then, while spinning the fan as fast as you can, give the upper bearing some decent smacks with a rubber mallet. This will seat it, and allow the motor to freely spin with no resistance. Make sure the felt pads around the bearing were soaked with the proper oil (i use 3-in-1 MOTOR oil) so it will continue to self lubricate.
 
I take it that I need to lubricate the new bearing before installing. Is that correct?

Once again, thanks for all your help.
 
Agreed...always 'prime' a sintered bearing like that....then the wick oil will take over. Just make sure the new sintered bushing you use isn't the 'dry' lubricated type.


 


Kevin


 


 
 
Here's another update:

I replaced the top motor bearing temporarily with a known good used one and lubricated it. The motor is even noisier now. It sounds like a sick cow.

While running, I turned the lights off in the room to look at the sparks on the brushes. One brush is shooting sparks like an angle grinder on metal while I can't quite see anything from the other brush.
 
I thought you replaced the sintered bushing with a new one? Or are you talking about greased bearing? Sintered bushings wear in relation to their shaft.....you can't usually pop one out of another motor and put on a different shaft....or at least it's not good practice. 


 


I think most of the noise sounds like it's might be coming from your brushes....they're not seated correctly if you have sparks coming out one side more than another. You can buy a commutator stone online for about $5. I just bought two from a dealer who sells Kirby stuff online. But you have to use it with the motor running for best results and depending on the motor access, that can be a bit twitchy...plus, you have to be mindful not to touch any part of the motor with your hand near the brushes because of the shock potential.


 


You really need an Elmer in this to show you the ropes....keyboards don't get it. That's probably why some here said to leave things alone.


 


Kevin


 


 
 
Commutator stones would indeed be tricky. It looks like the only way to do this would be to run the motor with only 1 brush. My only other option would be to connect a drill to the armature and run that, as I had done seating the brushes.
 

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