Note in particular the black crud.
| Here's a couple shots just after removing the spindle.
The lower one has the important parts of the bearing
lubrication
system labeled. There's an oil reservoir just beneath the
bearing
area in this photo, and a corresponding reservoir at the front bearing. Note in particular the black crud. |
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There was a problem with the front bearing, shown here.
There's a brass tube in which resides the wick, both at the
front
and rear bearing. This tube also serves to orient the bearing
shells when they're installed, as they fit into the large hole on the
bottom of each shell (look here for pictures of the bearing shells). The tube should be proud of the surface by about 0.1". As you can see here, it's sitting just slightly below the surface! There's also an oil hole in the tube that should be aligned with a corresponding oil rifle provided in the headstock casting; alignment of that hole is impossible with the tube in this position. Only the front bearing looked like this - the rear oiler tube was properly positioned proud of the surface by about 0.092" or so. It's not clear to me whether this was old damage, or if I did it when I had to set the spindle back down in the casting 3 times whilst attempting to remove it from the machine alone. It may not be critical to have it sticking up, but if it can be fixed, it should be. |
| The problem with repairing this is there's nothing to
grab on
to, and the oil tube is only ~3/8" diameter. It's pressed
into
the casting, but initially I wasn't sure just how tight the press fit
is. Turns out, the fit is not very tight at all. The top picture here is a "tool" I made to pull up the tube. It's a piece of 1/8" welding rod (6011, not that it matters) that I heated and bent a tiny (~1/8") hook into. I inserted this into the oil tube, and hooked it into the quadrant that is farthest from the operator when facing the machine - that area has a void in the casting where the hook could engage the bottom of the oiler tube. Initially I pulled up by hand, while I was experimenting with whether this was going to work. I managed to move the tube up so that it was flush with the bottom of the casting surface using my bare hands. This made it clear the press fit isn't very tight - which is good. To go the rest of the way, I clamped a pair of vise grips to the rod, hooked into the tube, and tapped upward on the pliers. The tube easily popped up, with no damage. I pulled it up farther than necessary, then gently drove it back into proper height using a piece of wood and tapping with the hammer. I set it right about at 0.1" proud. In the lower picture I'm showing the tube a little higher than it needs to be because I wanted to highlight the little hole for the oil passage. The oil passage with which that hole must be aligned is located to the right in the photo, pointing toward the operator-side of the lathe. |
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Here's the headstock cleaned up quite a bit. I used
mostly
extra-coarse steel wool and mineral spirits to remove the thick cake of
crud. I finished up with a careful scrubbing with a rag
soaked in
acetone. It's not as good as if I had removed the casting and soaked it in degreaser, but it's really not bad, as you can see. Actually it looks better in person than in the photo. I'm reluctant to pull the headstock casting because I don't want to deal with realigning it. Let me comment briefly on the paint job here. I thought the paint on this machine was factory original, but now I'm not so sure. There are clearly 2 layers of paint to be seen in the headstock casting, but the color is very similar. The top layer of paint has drips that have run down into the casting. But if it was repainted, whoever did it actually did a halfway decent job. There are no brush strokes, and only minor drips on various brackets and parts. However, the top coat hasn't adhered well to the paint beneath, as it chips off very easily. It would really be nice to completly strip this machine and repaint, but I'm reluctant to do so because, 1) the paint doesn't look too bad, and 2) I don't want to have to realign everything. Plus it's my first lathe and I want to get it up and running quickly. |
| For about $5 I got a nice little "Felt Handbook" from McMaster-Carr that came from Buffalo Felt Products Corporation. It has samples of 9 common felts with descriptions of what each is used for. Definitely worth the $5, and I recommend it to anyone working on felt-oilers. |
| With the casting cleaned up I turn my attention to the
lubrication system. South Bend used a simple, effective, and
basically foolproof method of lubricating the spindle bearings - felt
wicks. Shown here is a disassembled felt wick from the rear
bearing. We find 3 key components - the top felt, bottom felt, and spring retainer. The top and bottom felts appear to be of two different types, but it's not clear exactly what type they are. After some research, I believe the bottom felt was actually a type of yarn, bundled and stuffed into the spring. I thought the top felt was F1, but when I bought a replacement wick from LeBlond I found it's clearly not F1. It looks more like perhaps F5, which has similar applications to F1 but is less dense. See a description of different SAE felt grades here. It's difficult to tell whether the bottom felt has such low density because it's been partially dissolved by the oil, because it was designed that way (yarn), or because the acetone I used to clean it partially dissolved it. I believe it's actually felt yarn, and was intentionally loose as I found it. Felt yarn isn't readily available anymore, so I intend to replace it with some SAE felt. Read these descriptions (courtesy Buffalo Felt's website): SAE F-1 is suitable for oil retention in installations where the felt is not compressed, for feeding low viscosity or light oil, and where unusual strength and hardness are required. SAE F-5, F-6 & F-7 are recommended for dust shields, wipers, grease retainer washers, wicks, vibration mountings, and in uses where a resilient felt is required. SAE F-10, F-11 & F-12 are recommended for grease and oil retention where the felt is confined and compressed in assembly. Looking at F1 versus F10, the F10 is markedly less dense - possibly consistent with the bottom felt that I pulled out of the machine. You need a less dense felt in the bottom portion of the spring so that the entire wick can be compressed by the spindle. F1 is very resistant to compression, and probably wouldn't be "squishy" enough to provide proper spring pressure to the wick. It's possible to purchase new wicks direct from Leblondfor $15 plus $6 shipping (yikes). As I mentioned earlier, I bought one so I could examine it. I believe what they're using is a lower "felt" made from some kind of cotton-based yarn, and a top felt made from an SAE grade. |
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I've
chosen to make my own felts - I prefer to be as self-sufficient
as possible, and $15 each for LeBlond-brand felts is awfully expensive.
It is my hope that what I've done here will inspire you to make
your own rather than giving in to Leblond's price. I decided to make the bottom felt out of F10. It's not possible to buy F10 in cord form, so I bought a 12"x12"x1/8" sheet from McMaster-Carr. Some experiment had to be made to determine the proper dimensions and method for getting a bit of F10 inserted in the spring. I settled on cutting a piece 5/8" wide by ~1.5" long. Such a piece, folded in half lengthwise, twists itself rather nicely into the lower part of the spring. To do this, I first folded the felt in half lengthwise, then "threaded" it into the spring from the top. For the top felt, I decided to use F5, which is significantly less dense and less firm than F1. F1 is too hard and incompressible to use here, and F5 will flow more oil than F1 in general. Unfortunately, I couldn't locate F5 in cord-form, so I had to buy a strip of it 1" x 3/4" in cross section (again from McMaster-Carr). I cut myself a small block from the F5 strip, then used a razor blade to trim it until it was mostly round and small enough to fit inside the spring. F5 is much more consistent with the felt at the top of the new wick I bought from Leblond, although it appears the Leblond stuff is very low-grade, low-density, low-firmness felt. F5 is rather high quality stuff. The resulting wick is shown at left. Indeed, the spring does compress as desired, although the force required to do so is considerably higher than the old felts. That may be because the old felts were quite worn, or it might be that this wick design packs too much felt into the spring. The nice thing about using the big F5 strip to make my top felts is I was able to customize the shape a bit. The felt I made is slightly larger diameter at the top, so that slightly more of it is in contact with the spindle. That should provide a little more lubricant to the spindle. |
| I wanted to do an experiment to determine whether my
wicks
would perform properly. So I set them in oil and watched how
long
it took for oil to saturate the top felt. The experimental setup is
shown at right. I carried out 2 experiments: compressed and uncompressed. In each case the wick was submerged as shown in ~1" of Mobil Velocite 10 spindle oil, as specified in the South Bend lubrication literature. The uncompressed case is shown in the photo; the compressed case was carried out on a wick that was compressed as though in the headstock with the spindle installed. Uncompressed Time to completely saturate the bottom felt: <60 seconds Time to completely saturate the top felt: 8 minutes Compressed Time to completely saturate the bottom felt: <20 seconds Time to completely saturate the top felt: 6 minutes These experiments are worst-case, since in service the oil level is actually within 1/2" of the tip of the wick. That means the wick only needs to pull oil up a very short distance. They show that this arrangement is acceptable. Furthermore, we find that the F10 felt acts to quickly move oil from the reservoir up to the top felt, where it is retained until transferred to the spindle. After putting the whole spindle back together I ran it at top speed for about 10 minutes. The bearings reached a temperature somewhere between 105°F and 110°F. Spindle movement is extremely smooth, and I can tell from the "feel" of it that a lot of oil is being fed to the bearings. |
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| The shims I found beneath the rear bearing cap were
badly
mangled. They are obviously not the original equipment - or,
if
they are, someone really did a number on them. I measured
each and found them to be between
0.015" and 0.017" thick. So I bought a small sheet of brass shim stock 0.015" thick. I used some blue layout fluid to transfer an impression of each bearing cap onto a sheet of paper. The impression was then scanned, and a CAD model was created as a template for making new shims. The rear shims are shown at right (there are two drawings because my rear bearing is slightly different on each side). If you print the photos at 1:1 scale they are the correct size for the real thing. The small hole is 5/16" diameter, and the large hole is 9/16" diameter. If you'd like a copy of the drawings, please drop me an email! After quite a bit of work I ended up with the replacement shims you see in the last picture. It was a lot of work because: 1) 0.015" brass sheet is harder to cut than you think. Use a good pair of metal snips. 2) These were the first shims I've ever made 3) The CAD templates are imprecise. They're close, but not quite - you have to do some filing and trimming to get things lined up perfectly. 4) It takes awhile to drill through 0.015" brass sheet, since you must use very light feed pressure to avoid destroying the sheet. The second shim went a lot faster than the first. Notice the new bit of F10 felt I've installed in the expander. F10 is the right grade to use here because you need something very compressible so as to avoid binding the spindle. I tried initially with F1 and found the spindle bound up badly when the bearing cap was installed. |
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Not much more to tell here, except that the front shims
were
in much better condition than the rears. I replaced them
anyway. Here, both sides of the bearing cap were pretty much identical, so I only had to make one shim template. It took me about 1 hour per side to make these shims, which seems like quite a long time just for shims. Here again, notice the new bit of F10 felt for the expander. F10 is the right grade to use here because you need something very compressible so as to avoid binding the spindle. I tried initially with F1 and found the spindle bound up badly when the bearing cap was installed. |
| It was difficult to decide whether this section should be here or on the gearbox page. Anyway, it's here for now. The reversing geartrain is used to control whether the gearbox (and hence the leadscrew) rotate in the same direction or opposite direction of the headstock spindle. As shown in the first photo, if the selector level is moved up to the upper detent, gear "A" engages the gear on the headstock spindle, which causes the gearbox and leadscrew to rotate in the same direction as the headstock. On the other hand, if the selector lever is moved down to the lower detent, gear "B" engages the gear on the headstock spindle, which causes the gearbox and leadscrew to rotate in the opposite direction as the headstock. In the photo the selector is positioned at the center detent, which is neutral. Neither "A" nor "B" are engaging the spindle gear. As I note in the photo, the nut on the bottom gear (aka the stud gear) is threaded onto the gear shaft, and rotates with the gear. The nut shouldn't be very tight. To remove it you'll need to lock the spindle using the back gear. To do this, simply engage the back gear with the lever and don't pull the bull gear lock pin out. If, like me, your back gear isn't installed when you get around to working with the reversing gear train, you'll need to find a way to hold the bottom gear fixed whilst loosening the nut. I clamped a pair of Vise Grips to the gear on the front and rear faces (back away from the teeth) to wedge against the central casting. This held the gear while I loosened the nut. I did this with the reversing gear assembly removed from the headstock. |
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To remove the reversing geartrain, simply remove the two
slotted screws that retain the reverse assembly retention bracket
(bottom of photo above). The whole assembly then slides right out
of the headstock casting. You must remove the takeup nut on the spindle (if installed) to clear the reverse gears! This is what it looks like removed from the headstock. The nuts that retain gears "A" and "B" don't rotated with the gear, so they're easily removed. Dismantling this is straightforward. Remove the stud gear nut (as discussed above), and the two nuts that retain "A" and "B". Drive out the small pin that retains the selector lever to remove it and the pin. There's a strong spring around the pin, which will shoot the pin across the room when the selector lever is removed! The second photo shows gears "A" and "B" removed and sitting in the background on their shafts. It's a good idea to mark which side each gear and shaft goes. If the lathe is old the gears will have worn according to their position, and it's probably worth putting them back where they were. Don't panic if you don't, it'll probably be alright. I removed the smaller of the 2 stud gears using a gear puller, because there's plenty of clearance between them to get the puller jaws in there. Piece of cake. To remove the larger stud gear you'll need to drive the shaft out by pounding with a hammer into the picture. But there is great danger in this. I slightly damaged the key in the shaft and the reverse casting because the key was in just the right position relative to a felt wick groove in the casting. The third photo here shows how I damaged it. There was no way to see what was going on with the stud gear in place, so I had no way of knowing what I was doing. Thank God the key is made of soft steel and the damage to the casting is almost undetectable. To avoid doing this, I suggest: 1. If possible, pull the key out before driving the shaft off. This wasn't an option for me, because the key fit too tight with the stud gear. 2. Rotate the shaft so that the key is in front of a section of the casting away from the felt wick groove. This should cause the casting surface to push the key out as you drive the shaft. The key cleaned up nicely with a file, and the damage won't harm the operation of this assembly. |
| The reverse gear casting has a series of oil rifles drilled
through it, which form a
sort of oil reservoir for feeding oil (via wicks) to the reverse gears.
The first photo here shows the position of the oil rifles and the
wicks that I found installed. The semi-transparent green lines in
the photo are indicating the oil galleys drilled into the casting.
This is a fairly complex felt scheme. The top felt carries
oil across each of the two holes behind gears "A" and "B", as shown.
At each of those holes, oil is transferred to another felt that
carries it out to yet a third felt embedded in a groove in each shaft
for "A" and "B". There are a total of 7 felt wicks in this
assembly! In order to remove the wicks you'll need to remove the plug in the casting as shown in the second photo. To do this, drill a hole and tap it for a small screw which is then threaded into the plug to pull it out. I used a #10-24 machine screw to do this, but anything between a #6 and a #12 should work fine. The third photo here shows my setup on the drill press to bore a small hole (for a #10-24 screw) in the plug. Notice I'm nowhere near center, which didn't have any effect on my ability to pull the plug out. Truth is, I thought the plug was thinner than it turned out to be, and started drilling it with a hand drill. When I realized it's a little thicker than you might expect, i moved to the drill press to do it right. The fourth photo in this series shows my crude method for pulling the plug. I threaded a machine screw into the drilled/tapped plug, then held the head of the screw in a vise. I then struck the casting as shown with a hammer until the plug was freed. Conveniently, the hole size here is compatible with 1/8-27 NPT threads. Actually, it's a little oversized for 1/8" NPT, but since we're only trying to seal against an extremely light pressure it doesn't matter that the threads are exactly the right dimensions. All you have to do is run a 1/8-27 NPT pipe tap in the hole 3/8" or so and you can insert a 1/8 NPT pipe plug. This will permit easier maintenance in the future. With the big plug removed you can fish all the felt out of the cavity with a small pick and pliers. However, there is another plug that you may consider removing as well - one that is substantially more difficult. The fifth photo here shows the location of the plug, with the location of gear "B" noted to help the reader understand the orientation of the casting in the photo. This plug is closing off the upper oil rifle, and has been cut flush with the casting. It's not a plug in the same sense as the larger one - it's merely a piece of 3/16" steel rod pressed into the end of the top oil rifle (which is 3/16" diameter). The sixth photo here shows the setup to drill out the flush-cut plug. Actually, it shows the operation finished, with a 1/16" NPT pipe plug installed. To begin the process, I used a 3/16" drill bit, which is the same size as the top oil rifle shown in the first photo. There is danger in doing this! I failed to properly orient the casting with the drill bit by assuming the plug was perpendicular to the casting surface. In reality, it moves at an angle as shown in the first photo in this group. This caused me to bore my hole offset from the oil rifle, and nearly penetrate the hole for the gear "B" shaft! If you decide to drill out this plug, may I suggest the following: 1. A better way might be to drill a small hole in the plug, say for a #6 machine screw. Tap the hole and try to pull the plug using a similar method what I've shown for the large plug. 2. Or, if you decide to drill out the plug with a 3/16" bit, carefully orient the bit so that you're drilling concentric with the oil rifle! It's okay to be off a little, but too much will result in penetrating the hole for the gear "B" shaft. After drilling the plug out it's easier to install felt in the top oil rifle, since you have direct access to it. I attempted to install the wick before removing the plug, and found it too difficult. But I believe with a little patience it might be possible to stuff new wick in the top oil rifle without drilling out the plug. For example, it's probably possible to thread a wick in there via the main (vertical) oil rifle. I was left with a rather large non-round hole when I got done drilling (since I drilled at the wrong angle, as mentioned). I tried a few different ideas for plugs and finally settled on a 1/16" NPT plug. To do this, I had to drill a 15/64" shallow hole in the casting centered at the top oil rifle. If you do this, you can only drill to a depth of around 3/8" at most, since any deeper would risk penetrating the hole in the casting for the gear "B" shaft. Simply tap the new hole and insert the plug, as shown in the last photo. I used 1/8" F1 cord for the felt in the upper oil rifle and the little holes that feed the upper gear shafts. For the bottom where the stud gear shaft runs, I used 3/16" F1 cord at the oil rifle. The felt grooves in this assembly call for either F10 or F5, since it must be compressed. I decided to use F10. |
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