Dual 1019 - rotor RPM

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Solist
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Dual 1019 - rotor RPM

Post by Solist » 13 Dec 2018 21:05

Does anyone know the RPM of the rotor of the motor?

This week, when I was searching for a possible new platter bearing, I have read a couple of scientific articles from various bearing manufacturers and Academia.edu, about bearing lube/vs grease for the ball and sliding bearings, and it went against the use of oil on the shaft and main bearing. It looks like oil, even thick adhesive one, fails to deliver the requirements to insure proper bearing lubrication, compared to grease.

Grease just seems to be the go to lube, at least for the Dual changers.


Which made me think about the common debate about 10w30 and sewing machine oil.

DSJR
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Re: Dual 1019 - rotor RPM

Post by DSJR » 14 Dec 2018 09:17

Dual knew what the heck they were doing when they designed and built these endearing old machines and I can vouch for the use of adhesive 'sinter-safe' oils in the main bearings of these decks, as the oil does actually stay where it is over decades of use. The tolerances used to be generally too tight for grease to be used and in fact, too 'slippery' a lubricant can cause ball races to 'slide' rather than 'roll' and in gearboxes for instance, this gives rapid and uneven wear. Each lube to the particular application needed. Dual use motor oil for some mech pivots and *light smears* of grease elsewhere depending on the loading. using alternatives may well be fine, but how many people are really going to totally strip one of these decks out, remove ALL TRACES of the old lubes and sensitively re-lubricate with fresh stuff? The better Duals will be revered for many decades to come I'm sure and are climbing in price alarmingly as collectors items now. I'd suggest with the top models at least, to stick to the basic recommendations which do work reliably.

If we were talking typical lower-rent Garrard Autoslim-type decks, or the UK BSR equivalents, then maybe a suitable grease in the main bearing could take out some of the 'slop' that was almost built in in the 60's examples at least, but the Duals had tighter tolerances right from the most basic inexpensive model and since these decks were designed seemingly without the severe budget constraints that Garrard had foisted on them by Plessey (they tried damned hard though and did so well by the early 70's to redress this), I'd seriously just use the lubes recommended, as they seem to do the job perfectly for decades...

Solist
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Re: Dual 1019 - rotor RPM

Post by Solist » 14 Dec 2018 17:13

DSJR wrote:
14 Dec 2018 09:17
Dual knew what the heck they were doing when they designed and built these endearing old machines
I agree completely. But there was an advance in knowledge and lube manufacturing from the 1960s.
DSJR wrote:
14 Dec 2018 09:17
The tolerances used to be generally too tight for grease to be used and in fact, too 'slippery' a lubricant can cause ball races to 'slide' rather than 'roll' and in gearboxes for instance, this gives rapid and uneven wear. Each lube to the particular application needed.
Hmm, ok but grease comes in different viscosities, and for the most part is intended to use for low to medium rotating bearings, especially with high loads in mind.

Dual also used graphite grease for the main bearing and I do believe for the shaft also? Not sure about the last one.

Regarding the slide, that is what started this thing about lubes. I tried to use chainsaw oil 150visco at 40 degrees, and I can still hear what I believe is noise coming from the platter bearings, probably due to some parts sliding not rotating. Or maybe just metal to metal contact because the oil fails do deliver a protective film.

Also grease should do a better job when it comes to thrust loads, since we have a 4kg platter on top to put pressure on the rather small bearing balls, that is why I suspect that even with 150 viscosity the film between the metal parts just is not enough to protect the bearing. When you put 4kg on those 5 balls you get a heck of a lot of load.

And when it comes to the main platter bearing I do not think that the tolerances should cause any problems to use grease instead of oil. Addinol makes a heck of a lot of different lubes for different aplications, I am not telling you I will use a normal grease, but one specifically designed for this bearing speed and load.
DSJR wrote:
14 Dec 2018 09:17
Dual use motor oil for some mech pivots and *light smears* of grease elsewhere depending on the loading. using alternatives may well be fine, but how many people are really going to totally strip one of these decks out, remove ALL TRACES of the old lubes and sensitively re-lubricate with fresh stuff?
I did exactly that, you could probably do open heart surgery with those parts that I cleaned and still would not get an infection, although the end result might be questionable.

I did find some useful information about cleaning the sintered bearing on LH. We can all agree that most of these machines were serviced before so we can not be exactly sure if the technician used the correct lube when servicing.

Now what I have found and I am gonna try, is to first remove all the superficial lube, then bath the bearing multiple times, and then use a syringe.

I though it was quite a clever idea, basically you get a syringe that is big enough to put the bearing in, and then you pull so you create a vacuum. This should in theory force all the old lube from the pores out. Not sure though how to put it back in.
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DSJR wrote:
14 Dec 2018 09:17


If we were talking typical lower-rent Garrard Autoslim-type decks, or the UK BSR equivalents, then maybe a suitable grease in the main bearing could take out some of the 'slop' that was almost built in in the 60's examples at least, but the Duals had tighter tolerances right from the most basic inexpensive model and since these decks were designed seemingly without the severe budget constraints that Garrard had foisted on them by Plessey (they tried damned hard though and did so well by the early 70's to redress this), I'd seriously just use the lubes recommended, as they seem to do the job perfectly for decades...
Yep, one of the best decks for the price, and that is why I am doing all this research to figure out how to make it spin for another 100 years.

I am not going against the suggested usage of lubes mentioned, but I am the kind of person that likes words to be proven by facts, not trying to offend anyone I am sure we all did our research before putting the right lubes in, I am just trying to figure it out right now.

mrow2
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Re: Dual 1019 - rotor RPM

Post by mrow2 » 14 Dec 2018 19:54

Not over-thinking the problem might be the first step. It's not available to everyone however, but the original Klueber Isoflex synthetic PDP 40 used in Dual motors post 12xx seems about the best for newer models; a similar non-synthetic was used in the 10xx models (easiest solution = sewing machine oil). There are a lot of exchanges in various threads arguing against regular or synthetic engine motor oil only due to the addition of engine oil additives in it, which at least in theory can clog up the sintered bushing pores. Still, I believe some members have used types like Mobil One.

So the common advice has been to remove traces of the original lube during a servicing by soaking the bushing in a solvent, drying completely, and reassembling. Add as much new (small electric sew machine motor oil like Singer or similar) oil as possible (advice given me one time by Bill at FixMyDual), then trial fit the cup and bell housing to the shaft and soak away the excess 'til it stays where it should and reassemble the motor. The upper bearing isn't as critical, doesn't take the beating, and should not be taken apart because it is really invasive to do that. Just add more lube to it. I'm not sure but I think there's some Klueber synthetic for tape decks available in small quantities from online providers.

The main platter bearing solution has been endorsed by so many participants I've lost track: high quality chain(saw) oil has the right consistency. I've suggested full synthetic Mobil One EP Gear oil (think it's something like 90 wt) but no one's tried it that I know of. Thinner lubricants like engine oil can be messy if the table is inverted.

Anyone know what the best current advice is being given on the German language Dual forum?

DSJR
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Re: Dual 1019 - rotor RPM

Post by DSJR » 14 Dec 2018 22:13

I was taken to task almost aggressively once for mentioning EP gear oil (of any type) and sintered sleeves and bushes in the same sentence! At such a low rotation speed it may not be as risky, but the chainsaw oil does seem to be the safer option and it's cheap enough to buy.

Solist
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Re: Dual 1019 - rotor RPM

Post by Solist » 14 Dec 2018 22:59

I know about the sewing machine oil, dualcan suggested the same and I do believe to be an appropriate oil, was just wondering thats all. Overthinking is kind of what I tend to do so...

I think the upper bearing is as critical as the lower one (depends on how much force is the idler wheel applying to the rotor while spinning), but as you said almost impossible to take it apart, so q tips and lots of cleaning is probably the best solution.

As I mentioned chainsaw oil just does not seem to work with mine. I oiled it correctly using a 150visco adhesive chainsaw oil, and there is noise like scraping coming from what I think is the platter bearing. That is why I am gonna try to find an appropriate grease or oil which should at least from what I have read be better when used with high load axial bearing.

The oil for chainsaw is in principle not made for high load, low to medium rpm axial ball bearings, because it is not designed to be used in this application.

I do remember that post DSJR :D

I guess what I am gonna do is try to find a lube which is specifically designed for these kind of bearings, they do exist as I mentioned addinol has a wide variety to choose from.

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Re: Dual 1019 - rotor RPM

Post by samba » 15 Dec 2018 00:33

Solist wrote:
14 Dec 2018 17:13
Now what I have found and I am gonna try, is to first remove all the superficial lube, then bath the bearing multiple times, and then use a syringe.

I though it was quite a clever idea, basically you get a syringe that is big enough to put the bearing in, and then you pull so you create a vacuum. This should in theory force all the old lube from the pores out. Not sure though how to put it back in.
You are referring to Die Unterdruckmethode :-)

I have used this method after reading about it on the German language Dual-Board.de: https://www.dual-board.de/index.php?thr ... post607582.
The way it is explained there is more or less as follows (after cleaning and bathing):
  • Take a syringe, put the bearing in there and fill it with a solvent (acetone, lacquer thinner or any other poison of choice, be careful and take the right protective measures!)
  • Make sure there is only air and solvent in the syringe. Close the tip and pull a vacuum. If the vacuum is deep enough, you will see bubbles escaping from the bearing surface and probably some dirt. The air trapped in the bearing is replaced by the solvent. Keep the vacuum on for at least one minute or as long as you can. Repeat a few times. I found that with the syringe I use, no air comes out after the first vacuum, so I tend to keep the vacuum on for as long as I can.
  • After filling the bearing, I usually leave it overnight in the solvent (the German site does not mention this) and then dry it to remove the solvent. This can be done by drying it in the sun in the open air, on the radiator of you central heating system or baking it a few hours in an oven at 100°C if you are in a hurry. (Again, be careful, especially when applying heat when using a solvent!)
  • When the bearing is dry, repeat the same procedure, but now with the appropriate lubricant. At least 2-3 minutes under vacuum are recommended, until no more bubbles escape.
Some remarks:
  • Do use a good quality syringe with a good rubber seal on the plunger. The better it seals, the lower your vacuum.
    A so-called "Luer lock tip" syringe with a cap works very well. Below is a picture of the one I use.
  • Use the smallest syringe you can, a large one only requires more force to draw a vacuum. I found that a 10 ml syringe works well. Below is a picture of mine.
  • One word of caution: pay attention not to pull the syringe out too far. You risk pulling the plunger out of the barrel and making a big mess. (My keyboard still has traces of sewing machine oil :( )
  • Some people have made more elaborate vacuum devices, e.g. using a Mityvac hand vacuum pump for automotive brake air bleeding and a (Nutella) jar https://www.dual-board.de/index.php?thr ... post586902. The advantage of this set-up is that you can put the jar in a hot bath of say 70 °C and make the oil thinner, improving the chances of full impregnation of the bearing. When I have time, I think I will make me one of these.
  • Did I already mention to be careful when playing around with aggressive, volatile and flammable solvents? Make sure you understand what you are doing and take the right safety precautions. If you are not sure, don't try this at home ;-).
syringe with luer lock tip and cap.jpg
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I use this method because I think it does a decent job in cleaning the bearings and it looks like you can get more oil into the bearing. The guy with the Mityvac actually did measure this using a scale, see https://www.dual-board.de/index.php?thr ... post588243.

In any case, if this method does not work, I guess it will also do no harm.
DSJR wrote:
14 Dec 2018 09:17
using alternatives may well be fine, but how many people are really going to totally strip one of these decks out, remove ALL TRACES of the old lubes and sensitively re-lubricate with fresh stuff?
I do O:). I figure that if you are overhauling a deck, you might as well go all the way, you either do it properly or you don't do it at all.

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Re: Dual 1019 - rotor RPM

Post by Spinner45 » 15 Dec 2018 01:15

All that fussing around with syringes.....
I simply take a clean, hot soldering iron tip and stick the bearing on it for a "moment" until the old gunk bubbles out, and use solvent on it.
Repeat again, till no more gunk bubbles out, then cool and saturate it by dropping it in Zoom Spout Turbine Oil.
And call it a day.
Been doing it this way for decades on gummed up bearings, and never had an issue afterwards.

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