# Atlas 3991 clean up



## nik (Mar 17, 2013)

I just picked this thing up yesterday, dirty and sticky, but complete and lightly used.  My goal with it is just a thorough disassemble and clean up, the paint seems to be in fine shape, and even under fairly intense scrutiny, nothing seems terribly worn.

I'm not quite sure where to look for a casting date on the bed, all I have been able to find appears to be a part number cast into the interior of the rear rail.  I believe that it is a fairly early model, based on the serial number, but that is not really founded in any actual knowledge of production numbers.

I will try to document the process as best I can, and I'm sure questions will arise, but there seems to be a great deal of knowledge floating around on this site, so the answers will likely be found as well.
N


----------



## wa5cab (Mar 18, 2013)

Nik,

The Atlas 3991 was made from either 1957 or 1958 through 1966.  Serial number data is quite sparse and Clausing has no records for whatever reason.  But I would guess that your machine dates from the first year of production.

Robert D.


----------



## nik (Mar 21, 2013)

Thanks again for the words of encouragement, progress is being made... slowly. I have gotten all of the chucks and the qcgb cleaned up, thank you school for the use of your parts washer, and finally got most of the small tooling sorted.  I think the tail stock and lead screw will be tomorrows project, at least if I can drag myself out of bed in time.

Some of the tooling it came with.


----------



## nik (Mar 22, 2013)

More time over the parts washer, everything is looking good, the only issues I have found were a little burr on the double 48 tooth change gear bushing, caused by a little steel shaving that found its way in, and the tail stock clamping shoe has been broken and welded.  That was the first time I have seen the inner workings of a qcgb, really cool, and velvety smooth for the number of bushings and gear transfers.






If time and circumstance permit, the head stock will be coming apart over the next day or so.  The mouse (or mice) who set up residence under the back gear will need to find a new home.
Would anyone happen to know the belt lengths for this thing, or where I might be able to find a manual for the under drive type, I have only been able to find the rear drive manuals.
Thanks in advance
N


----------



## nik (Mar 22, 2013)

Just a couple more pics


----------



## nik (Mar 23, 2013)

Time worked out in my favor this morning and I was able to get the spindle out, not too much trouble, the only real issue was self inflicted.  I missed one of the two set screws on the collar just inside the rear bearing and put a good scratch on the spindle for about 1/4" until I figured out what was happening.  The bearings are dated 1-56 and 1-57

I am debating removing the head stock casting from the bed, are there any reasons why I should or shouldn't attempt this? (alignment etc)

Thanks in advance, N


----------



## wa5cab (Mar 23, 2013)

Nik,

Nik,

I just uploaded an Atlas manual to the Downloads section.  It covers 3980 through 3991.  It's in the folder beginning "Atlas/Craftsman/..." as Atlas Lathe 12 3980-3991 12x24-36.pdf .  However, you have to get up to 20 posts before you have access to Downloads.  So if you want it sooner, send me an email at wa5cab@cs.com and I'll send it direct.

On removing the headstock from the bed, unless there is some good reason to do so, I wouldn't.  You said earlier that you were going to clean up the paint but not repaint it.  I can't think of any other reason why you might need to remove it.

Robert D.


----------



## nik (Mar 24, 2013)

Thanks wa5cab for the manual, it has already proven useful. I did end up removing the headstock from the ways, the thought of a fine abrasive slurry composed of mouse turds and carpet padding being flung at me was enough to convince me. I'm beginning to think that the lathe fell over at some point in its life, both headstock cover hinges have been welded, as well as the front mounting ear on the left foot. Hopefully nothing is bent, but I don't have any way to check until it is back together and making cuts, so onward with the cleaning and assembly.


----------



## wa5cab (Mar 24, 2013)

Nik,

OK.  I agree that flung slurry was adequate reason for removal.   
On the belts, I would just call Clausing and order a set.  I don't recall their prices being any worse than the industrial supply houses.  The two spindle belts will probably be a bit more expensive than the other two as they are a different belt class.  However, I may be able to find the standard belt numbers on the set I bought last year or the set I bought back in the 80's and never used.

If you think that the machine may have been tipped over, now while you have part of the weight off would be a good time to check the cabinet for squareness.

Robert D.


----------



## nik (Mar 24, 2013)

What should I be looking for, aside from the 4 mount points being on the same plane, and how would I correct if it is twisted?


----------



## wa5cab (Mar 24, 2013)

Ideally, the four lathe feet mounting points should be in the same plane and the six floor anchor points should also.  Are you going to anchor the cabinet to the floor or slab?

One thing that you should do while the bed is unloaded is to replace the rubber grommets between the drip pan and the foot mounting points on top of the cabinet and right leg.

Also, when you start putting the thing back together, start with the headstock and make sure that the grooves in the spindle pulley and countershaft pulley line up.  And that the belts have as much clearance as possible between them and the cutout in the pan.  My 3996 came from the factory with the bed too far towards the tailstock end.  It shreaded the right-hand belt within a month or two.  And I discovered that the pulleys were not lined up.  When they were lined up, the set screw in the countershaft pulley was clear of the end of the shaft.  I've been running the machine for years with one belt in the left spindle pulley groove and right countershaft pulley groove.  Sometime this Spring (I hope) I am going to pull the spindle to replace the belts and try to put everything together properly. 

Robert D.


----------



## nik (Mar 29, 2013)

Rather a hectic week, but still a bit of progress.  Everything aside from the cabinet is clean and waiting to go back together, I'm almost completely convinced it did fall over at some point, the right front mount point on the bench was bent pretty badly, this correlates with the broken cover hinges, front left mounting ear, and dented tray.  I really hope the bed is not twisted.  Aside from that everything looks good, only missing parts have been the carriage lock and the half nut lever detent spring.
View attachment 50886

View attachment 50887

View attachment 50888


----------



## george wilson (Mar 30, 2013)

That model lathe,in the bench top model,was my first lathe.


----------



## nik (Mar 31, 2013)

Happy easter to everyone.  Through the coercive powers of beer and bacon, I was able to convince my friend to help me move the lathe cabinet onto its new platform, a 3"x22"x7' slab of sugar maple, which in turn is bolted down to the 3" old growth hemlock barn floor.  And through the coercive powers of a 3lb cross peen hammer and some acetylene, the ripple in the cabinet mount point is back to being flat.  It really feels like progress is being made, seeing it where it will live, and nearing the end of the cleaning.  

Thanks again to everyone for the help and support, I will put up another round of photos once I round the horn, and start putting it back together.
N


----------



## nik (Apr 2, 2013)

Hi again from the land of never ending winter, I have the bench pretty close to leveled and on the same plane, the flattened mount point is not exactly even with the other three, but it is nothing that a few thou of shim won't solve.  I cut new rubber grommets (washers?) last night, and was thinking that with all of the trouble that I am going through to make the table and bed level, why would it be soft mounted?  Is the isolation mounting just to prevent vibration transmission from the drive system, and if so, wouldn't it make more sense to soft mount the motor, and perhaps pulleys? 
Perhaps there is something I am missing, I have been wrong before...
Any help would be great.
N

This is the current state of the lathe, the old level was in a pile of scrap wood that I moved to set up the shop in this corner of the barn, straighter and more accurate than the modern stanley I already had, adjustable too.


----------



## wa5cab (Apr 3, 2013)

Nic,

The grommets are seals, not vibration isolators.  You can get new ones pretty cheap from Clausing.  Level the cabinet first with the carpenter's level.  Then mount the bed and level it with a precision level.  Shims go under the cabinet feet and under the bed feet, not the grommets or tray.  The requirement isn't actually that the bed be level, but that both ways be straight and in the same plane.  And the easiest way to do this is with the level.

Robert D.



nik said:


> Hi again from the land of never ending winter, I have the bench pretty close to leveled and on the same plane, the flattened mount point is not exactly even with the other three, but it is nothing that a few thou of shim won't solve. I cut new rubber grommets (washers?) last night, and was thinking that with all of the trouble that I am going through to make the table and bed level, why would it be soft mounted? Is the isolation mounting just to prevent vibration transmission from the drive system, and if so, wouldn't it make more sense to soft mount the motor, and perhaps pulleys?
> Perhaps there is something I am missing, I have been wrong before...
> Any help would be great.
> N


----------



## nik (Apr 16, 2013)

Hi again, I have been busy with some other projects recently, but finally managed to wring enough time out of this past weekend to get the lathe mostly put back together.  It went pretty smooth aside from the woodruf key under the spindle gear not wanting to clear the outboard spacer and having one of my beard hairs getting wedged between the bed and carriage gib.  I spent about an hour trying to figure out why it just wouldn't adjust right, only to find out that I am shedding, and that was causing the problem.  I still need to clean and set up all the drive pulleys and associated bits, but progress is being made.  With luck, I should be setting up to do the two collar tests and fine leveling this weekend, so long as no new insanity springs up.

Thanks again for all the help.
N


----------

