Fairchild Drive Unit Documentation/Tooling

[jesusfwrl]

I am looking for any documentation and adjustment tools for the drive units of Fairchild lathes. These drive units were the gearboxes used to transmit motion from the synchronous ac motor to the platter and leadscrew.

The part numbers were 824, E539-A4, E539-G4, A199-A4, depending on the lathe model and vintage.

These drive units were all quite similar in construction and operation, so any and all documentation will do. I am also after any spare parts, entire drive units, or the special tools used at the factory for assembly and adjustment.

I am having plenty of fun re-inventing the wheel with these units and I would like the opportunity to read the manufacturers opinion on the matter. If not, well, I guess I just have to keep on re-inventing...It took six month to locate and purchase the last remaining items in stock at some obscure bearing stockist for a complete set of bearings for my unit.

If you have worked for Fairchild and have experience with these units, but no written documentation, but you are willing to share your knowledge, I would really like to give you a call.

[Stevie342000]

The simplest method would be to look up the patent number, I am pretty sure that the patent numbers will be on the lathe somewhere. The manual I am pretty sure for the 539 is on the forum, I would figure under Reference Section, failing that use search on the Forum.

Search is your friend, surprising how many people ask what are fundamentally simple questions when they have the tools and the resources right in front of them as they type.

[jesusfwrl]

Stevie,
Thanks for your suggestions.
However, I am not looking for the standard lathe manuals. I have plenty of these already for plenty of lathes. I am specifically looking for the factory documentation about the drive units alone. To the best of my knowledge, such documentation had never existed in electronic form.

As for patents, all components I have here either do not mention patents at all or just mention patents pending. If you happen to have patent numbers for any of the Fairchild lathes, please feel free to share them with us.

Although I like reading through patents, I have some doubts as to whether they would contain the actual adjustment procedure used at the factory after gearbox assembly, which is all I need really.

As for the tools and spare parts that I am requesting in my original post, these unfortunately cannot be downloaded. Believe me, I have tried.

[Stevie342000]

Stevie,
Thanks for your suggestions.

You will be very lucky to find that sort of information after all this time, I would figure that that sort of thing was binned years ago. The patent numbers will be on the nameplate or somewhere on the machine.

[mossboss]

Interesting little thread here, now if it the gearbox and drive you are looking to obtain manuals for makes some sense in one way but not really required
Gear boxes are manufactured in a well established engineering criteria in so far as tolerances ratios clearances etc etc etc
It is really a case of looking at it so as to establish what is required in certain areas of its construction
Back in the days when tolerances where a little harder to achieve due to manufacturing practices as well as machines available, shims were often used to adjust them as required
If it is made from say aluminium than slightly more clearance was allowed due to higher expansion rate when temperature rises on steel or cast iron a little less
One can start with say 1-2 for steel and iron or 5-10 thou for areas in alluminium or bronze such as shouldered bushes check the clearance run it for a while see what it does adjust again until there is no obvious chatter noise or movement
In so far as ball or roller bearings i would suggest that sealed bearings be used even if open cage bearings are in there
The tolerance on these units made today, is far more accurate than similar items made back than
Any bronze bushings existing are easy to either obtain or made from phosphor bronze bar with a helix machined internally so as to allow some oil to flow in there for lubrication, assuming the box has oil in it, which is most likely
A lighter grade oif oil can certainly be used instead of the thick treacle used back than, multi grade oils today are far better adjusting to different temperatures so they are thin when cold thicker when they are hotter on comparison with single grade oils
There certainly people out there who will manufacture any seal assuming the box has oddball seals
At the end of the day manuals are very handy however in so far as gearboxes are concerned they are almost un necessary given the nature of them as in most cases they will show critical areas for adjustment in case of repairs however they tell you no more than what max speed lubrication and HP required or max allowable
Manufacturing procedures in the case of the gear box maker will definitely be a rare find, keeping in mind that they may have never been available even in the manufacturing plant
As an example There was ONE person who made just about all the SX 68 as well as the SX 74 heads (so i am told) why would a manual be available or around? I know of quite a few instances were one person been the specialist in some processes or assembly with no one else able to do it as good as fast as well as accurate
In some cases there is a "feel" for a job, there are people who just have it
Hope the above is of some help or at least a reference point
Best
C

[jesusfwrl]

Hi Chris,

All good points, but there is a few details suggesting that written documentation has existed at some point:

One of the manuals for a Fairchild lathe warned against the user attempting any adjustment of the gearbox without first acquiring the gearbox adjustment procedure documentation along with what they refer to as "special adjustment tools".

I have no idea what these tools look like, but I have the feeling that they were probably designed to make the adjustment process less tedious.
The gearbox on most Fairchild lathes is a 2 speed unit, which could be shifted into low speed, high speed, and neutral. The low speed is a fairly straight forward worm and gear affair with an engaging mechanism. The weirdness starts with the high speed. This is derived by disengaging the crown wheel from the output shaft, and engaging it to a conical ball race step up, with a high speed race coupled to the output shaft. For a ball race step up to operate without slip, significant pre-loading is required.

This is achieved through 4 independently adjustable springs pressing against the stationary part of the ball race. This adjustment can be pretty tedious, since it interferes with the normal pre-loading of the centre spindle bearings (essentially a thrust bearing at the top and a single ball at the bottom), so the adjustment must be completed in a complementary fashion. The stationary part of the ball race step up assembly is actually centred by the springs, not only pre-loaded.

I have been doing this procedure successfully without any original documentation and without any special tools, aside from standard engineering tools. It is quite likely that the special tools mentioned by Fairchild included some sort of "adjuster block", which could be temporarily inserted into the assembly to speed up the process.
While not strictly necessary, such a thing would make it a lot easier to rebuild and adjust these gearboxes.

Alternatively, the entire 78rpm ball race step up affair could be removed and the gearbox internal workings could be slightly modified to derive a single speed of 33 1/3 rpm, which would dramatically reduce the number of moving parts and quite possibly make the whole thing quieter.

Incidentally, the helical oil groove is machined directly onto the centre spindle which transports oil into the bushings and other parts of the mechanism. The driving shaft and auxiliary shaft have oil galleries and drilled bushings.

The most interesting feature of the assembly is that the platter is located directly on the output shaft, which also acts as the centre bearing. Despite the number of moving parts and complexity of the gearbox, and the fact that it is driven by an 85 year old synchronous AC motor, it is a surprisingly quiet assembly, offering exceptional speed stability when correctly adjusted. The performance of this assembly is quite respectable even by modern standards, and it must have been considered stunning when it was new.
I have often considered just using a modern motor to drive the platter on the Fairchild, but anything that would outperform the original drive unit would be seriously expensive by comparison. We went that way with the AM44.

I will post some pictures of the internal workings, it is definitely an interesting assembly to look at.

[mossboss]

Thanks for the deataiked reply. At the end of the day it sounds like you got it sorted.
It sounds to me the box was made by a third party as a general purpose unit rather than specific for the lathe. It sounds like it since no one would have such an intricate setup to achieve two speeds
Why would you need to adjust the speed after initial setup. They don't do that much work
Perhaps after a repair I can understand
That's a guess of course, best of luck with your search I would expand it in other areas assuming my guess is right.
Best

[jesusfwrl]

Chris, Fairchild had the benefit of manufacturing a variety of different equipment, including airplanes and cameras, so I would guess it is very likely to have been one of the Fairchild companies with an advanced engineering department that would be responsible for this unit.

My lathe, the Fairchild model 199, appears to be the first one of a range of lathes by Fairchild using a very similar gearbox. The castings (aluminum) of the housing have Fairchild model numbers cast and/or stamped all over them. It is very likely that the unit was developed specifically for Fairchild lathes, given all the various low noise /low vibration design features, which would probably not be necessary in other applications.

My lathe was manufactured and sold by the Fairchild Aerial Camera Corp., pre-dating Fairchild Recording Equipment Corp. by a significant number of years.
No patents had been issued yet at the time.
Later on, audio related equipment was manufactured by the separate Fairchild Recording Equipment Corp., still making use of the same gearbox. The model 199, became model 539, being almost identical. The later models were all refinements, with the 523 moving the gearbox and motor to the floor, and using a separate centre bearing to hold the platter and a shaft. Then they discovered vacuum platters, and they were still at it up until the 60's, when Scully and Neumann eventually dominated the market.

The extensive use of stainless steel parts and general tendency towards over engineering is probably what keeps these machines in a usable state to this day.

By the way, would you happen to know what the correct engineering term is for what Fairchild describes as "the ball race step-up"? It is essentially a epicyclic ball race, operating on a similar principle as an epicyclic gearbox, but relying on a preloaded conical ball bearing rather than gears.

[mossboss]

Ball race step up sounds good. Infinitely variable conical drive?
No idea really. The method has been used from industrial machinery, dough mixers, drilling presses etc, to motor cars, dutch small Car, lots of examples out there.
You almost qualify for a Fairchild historian.
Best

[jesusfwrl]

Yap, I have always been fascinated by the history of early recording technology and relevant engineers/manufacturers and so on.

Here is a link to my other thread with detailed photographic documentation of the gearbox.

http://www.lathetrolls.com/viewtopic.php?f=15&t=6142&p=44554#p44554