Lathe - Back Gear

Jumping out of back gear (Feb 16, 2001) Back gear question (Jun 22, 2004)
Back Gear Question (Mar 19, 2001) Back gears (Sep 3, 2004)
Back Gear for Heavy 10 (Aug 23, 2001) BackGear Howl (Heavy 10) (Sep 20, 2004)
SB 10k Backgear Problem (Nov 12, 2002) Noise from area backgear pin (Oct 19, 2004)
Back gear pinion tooth repair (Dec 30, 2002) Heavy 10 popping out of back gear (Oct 20, 2004)
9B Back Gear Problems (Jan 22, 2003) Smoked back gear on 9" (Dec 4, 2004)
9" Backgear help (Apr 22, 2003) Back Gears on 10K (Jan 24, 2005)
Lathe won't run in back gear (Jan 2, 2004)  
Jumping out of back gear
I have a 50's vintage model A with quick change gear box. When I try to engage the back gear with the machine in the forward direction, it will disengage on its own by rotating the shaft back over the eccentric and then disengage completely. its as if the eccentric won't go over far enough to lock over but the gears are fully meshed. Is there any way to adjust this? some one once told me that there was a fix it kit for this, but no luck with south bend. dennis (220)
I've posted a couple pictures in the files section. The pictures are from a SB lathe book. They show the proper procedure for adjusting the back gears. Bob (226)
Dennis, You didn't mention what size lathe you have. If you have a 9" or 10K (light ten) lathe, then the following instructions might help. If you look at the headstock casting, you may have already noticed the two projections that support the backgear and its eccentric shaft. If you look (or feel) underneath these projections, you will notice a bolt (on the forward projection next to the threaded end of the spindle) and a setscrew with a locknut (on the rearward projection) Under the bolt is a spring and a brass "shoe" that provides tension for the eccentric shaft. If you tighten this bolt, you will increase the friction on the eccentric and prevent the backgear from "kicking out." South Bend states: "Tighten until tension will hold gears in mesh on heavy cuts but not so tight that eccentric shaft is hard to operate." The rear setscrew and locknut control the backgear engagement or depth of meshing of the gears. By loosening the locknut and adjusting the setscrew, the proper mesh can be obtained. Too tight a mesh will "howl" and too loose will "rattle." The way I adjust them is to: 1) Release belt tension on the cone pulley, 2) Loosen locknut and back out setscrew about one turn. 3) Engage backgear fully, 4) Screw in the setscrew to take up any clearance, 5) Place your hand on the bullgear and try "rocking" the backgear, 6) If the gears are meshed tight, screw in the setscrew a little more, 7) If there is a barely perceptible "rock" to the backgear, then the backgear is adjusted correctly. Tighten the locknut, 8) If the gears are too loose or "rock" too much, loosen the setscrew. The proper amount of clearance between gear teeth is .002". This amount is small but is perceivable using the "rock" test. Make sure the locknut is tight and double check the clearance before running your lathe. Also, NEVER engage or disengage the backgears while the lathe is running. That is the way gear teeth get stripped off. Webb (227)
Back Gear Question
About the Back Gear, Is it only designed to be engaged while in the forward direction? It kicked out when I ran in reverse. Or does it just need to be adjusted. Mike (349)
The manual describes adjusting it so it won't pop out. I'm not sure if the file area has a copy of the manual but if you don't have it, someone in the group can send it to you. Paul R. (350)
The pages from the manual are in the files section. dennis (352)
Back Gear for Heavy 10
I have a tooth missing on my heavy 10. It's the large 80 tooth back gear that's mounted on an arm with a long slot in it. I think it would be called the Idler gear. Does anyone have one that they would be willing to sell? Chris (1350)
Chris, Don't know if its the same, but I've got an extra 80T gear off a 9" SB. Have you a part number for your gear? Paul R.(1353)
Paul, I have absolutely no idea what the part number of this gear is or whether or not a SB 9" will fit on the heavy 10. I scraped off quite a bit of greasy crud off the gear in an attempt to find a part number but to no avail. Presently I do not own a manual for the Bend but will try to get one this week. I will get back to you and the as soon as I have some definitive data. Chris (1354)
Marty, As you can see below some of the text in your reply and my posting seems to have undergone some jumbling. Please confirm the name and part number as being "Quill Gear Part Number PT18". Is this correct? Chris (1356)
Chris, Here is a scan of the end gears for a South Bend Lathe "Heavy Ten" (New Model - aka: Double Tumbler Gear Box). Check out the gear number 84 on the diagram. Webb (1358)
Chris, Just for completeness, here is a scan of the end gears for a South Bend Lathe "Heavy Ten" (Old Model - aka: Single Tumbler Gear Box). Check out the gear number 83 on the diagram. Webb (1359)
Marty, This may seem like a dumb question but why is it called a "Quill" gear? When I hear quill I think of the tail stock quill. Also, I keep seeing the term "SB 10L" but I don't see that designation on my lathe. What does 10L designate? My model number says CL8187AB and Serial number 13362RKX16. I was told this was a heavy because SB also made the 10" with a smaller 1-1/2" spindle nose. Do I have this all straight? Chris (1360)
Chris, Have you checked out the South Bend Lathe web site? They have a page that will explain the catalogue number on your ID. plate. Check out: http://www.southbendlathe.com/catno.htm As to the SB 10L - the "L" stands for "Large Spindle." there were two spindle sizes for the Heavy Ten. Most are the large spindle type (1-3/8" through hole) but some were made with the smaller spindle (1" through hole). These are the SB 10R lathes. Webb (1361)
If you're talking about a "large gear mounted on an arm with a long slot in it" it's NOT a "Quill Gear"! I think everybody is going off on Chris's initial confused post. My understanding is that he's talking about an idler gear in the gear train from the spindle to the gearbox (like Webb indicated in his posting of the diagram). The Quill Gear (at least on the 9") is a single-piece shaft with a small gear on one end and a large gear on the other end. The small gear meshes with the bull gear and the large gear meshes with the cone gear. Paul R. (1363)
Chris, There seems to be some confusion between Marty and myself as to which gear you are inquiring about. I noticed in your first posting the this was the 80 tooth gear "that's mounted on an arm with a long slot in it. " I took that to be the idler gear on the end of the lathe. Marty, on the other hand, assumes that you are referring to the "Quill Gear" (No: 95 on the accompanying scan). If Marty is correct, then he gave you the correct part number for that part (PT18R1). But if I am correct in my assumption, then the part numbers for the "Idler Gear" are (AS33R3 for the "Two Tumbler" model; PT652R2 for the "Single Tumbler" model). Please let us know which gear you are referring to. Webb (1364)
Have you a part number for your gear? Or try measuring OD, width, bore, and keyway size. Anthony (1368)
If this actually is the large gear on the back gear quill, the number is PT18R1. Anthony (1369)
Chris, I haven't tried this yet myself, but a friend of mine is a welder, he says to drill and tap where the tooth is broken, install a couple machine screws, build up the tooth with weld, and then shape it with a die grinder. It is possible that brazing may hold instead of welding it and the brass would be easier to work with. Larry (1370)
Chris, I can't claim this as an original idea, but I had a missing tooth on my 9" SB back gear, and used JB Weld to basically mold a new tooth in place. I drilled a couple of small holes into the gear where the missing tooth was, inserted a couple of sections of cutoff nails, mixed up a little JB Weld (from auto store) and cemented the nails in place as support posts. Make the posts a little shorter than the height of a tooth. I let this set up for a day. I then mixed a little more JBW and liberally covered the posts and let this set up for a short while until it began to harden slightly, but was still workable. I then inserted a small piece of plastic baggie between the gears, and rolled the fabricated gear into the adjoining gear to mold the new tooth in place. I let this set up for a day and have been using it since with no problems. Once the tooth hardens, you can trim the tooth to make the job look neat. With a little grease, you can't even tell it's a "false" tooth! Don't think a dentist could do any better. Needless to say, I'm a real JB Weld fan now! Have found numerous uses for it around the shop. Great stuff! Jim ps: make sure the area around the tooth is cleaned with lacquer thinner prior to cementing the posts in place. (1372)
Webb, Thank you very much for the scan of the gear train. It will be very useful to me until I get my own manual. Chris (1383)
The gear I'm referring to is the large 80 tooth (in my case 79 ha) gear marked item # 84 on the Newer model diagram. As I recall it is always meshed with the gear connected to the input shaft to the threading gears. The forward and reverse tumbler gears also mesh with it when the lever is moved up and down off of the center detent position of neutral. That said, I think it might be best for me to wait until I get back home from this trip so the machine is in front of me. I would hate to drive everyone up the wall with erroneous information. You guys have been great though and I'm more excited than I've been in years. This SB is fulfilling a wish I've had since I was a kid. Can't wait to clean her up and make chips! Chris (1384)
SB 10k Backgear Problem
I recently purchased a SB 10k that was restored. When I run it in backgear the spindle cone (item 46 in the SB CE3457 Parts Manual) is getting very hot (expanding) and trying to seizing to the bull gear (item 50). When I shut the lathe down the spindle cone is very hot and when you take the lathe out of backgear you can not rotate the spindle cone independently of the bull gear with the pin still out, until it cools. It's like there is a clearance issue between the two parts. This is also causing the rpm to change as the spindle cone heats up. Does anyone have any idea what the problem could be and recommend a solution. I have never pulled a spindle out of a headstock, but do have some mechanical ability. John (7170)
Is there lube inside the cone? (7171)
First thing to do is to get some oil into the cone. There is a recessed screw in the middle pulley. Unscrew it and you'll see that it has a needle-valve-like tip. Stick the nozzle of the oiler as deep into the cone as you can and pump oil into it. There is sort of a spiral groove on the inner surface of the cone that I suppose is to distribute the oil. It may be crudded up - if that's the case you'll have to pull the spindle and clean the grooves, but try first just loading the baby up with oil, run it until it feels warm, then add more oil. While you're at it you might just check to make certain that everything else on your lathe has been lubed. I was terrified the first time I pulled my 10k spindle. But it is not that big a deal and if the above doesn't work, get back to us and I or someone else will be glad to walk you thru it. Frank (7172)
I think most folks are using grease in the back gear spindle. I removed the lubrication access screw and replaced it with a grease zerk and pumped it full. Some lathes have "oil" stamped into the back gear and some have "grease". This must reflect a change in philosophy at SB over the years. There has been a lot of discussion on list about what kind of grease to use. I think the consensus is a Teflon based product. Search the archives for "lubrication" and see what you find. Glen (7173)
I've always wondered how the heck one is supposed to get the grease out of that squeeze tube SBL recommends into there. (7177)
Does a grease zerk have clearance? I've been wondering how to get grease into this thing. It is stamped "grease" but I've been told to use oil. Same with my cone pulley. It, too, is stamped "grease" but I use oil. I worry about getting lube to the ball thrust bearing. Should I worry? Frank (7178)
There is no direct path from the cone for lube to get to the thrust bearing on mine; the thrust bearing is behind the cone. I give it a splash of oil when I top up everything else. Anyone here had better or worse results using grease? Having open headstock I'm leery of using grease in the open bearing because it can trap chips. (7180)
Yes, that was the fist thing I checked. I'm almost sure the tolerances between the cone and gear are to tight for some reason. Is there suppose to be a bushing between the two parts? I don't see one in the parts manual? John (7197)
Frank, I received a lube chart with my lathe and the fist thing I did before using it was order the recommended SB oils and lube the lathe. The cone currently only has the recommended Teflon grease in it. I'm sure this has been discussed at length before, but what oil do you recommend I use in the cone. I have and use all three SB oils on other parts of the lathe. The jeweler that restored the lathe is very meticulous, so I'm positive the groves were cleaned prior to reasonably, but the Teflon grease has probably filled them. Does the tailstock need to be aligned after removing and replacing the spindle? John (7198)
If the cone is too tight against the gear it will begin to heat up there first. Try running it until it begins to warm and see if the cone is uniformly warm (suggesting lube problem) or if it is heating up more on one side. Frank (7201)
I pulled the spindle out of my 10k to find some light grind marks in the area where the cone pulley runs. It s not perfectly round at this location and I was wondering if this is normal. The cone pulley seems to spin freely when rotated by hand, but I think this could be contributing to the problem of the cone pulley sticking to the bull gear when the bull gear pin is pulled. Does anyone know how the spindle surface is manufactured where the cone pulley is located (i.e. ground and polished, hardened, etc.)? If I need to have this area of the spindle ground, what is the recommended maximum tolerance I can have between the spindle and cone pulley? The journals look great. P.S. Or is it cheaper to just by a used spindle? John (7288)
Frank, the information you provided me with was invaluable, especially the trick about using the paper clips. I removed the old grease that was caked into the cone pulley and tried using some oil, but the oil is getting thrown onto the edge of the cone pulley and I m afraid it could saturate the belt. I've ordered some of SB Teflon Grease and should have it by next week. (7291)
On a related note, anyone know why my clean, lightly oiled bullgear pin is stiff enough to require pliers to move it? it wasn't like that when I bought the lathe, and the pin and hole are very clean, just a light film of oil, and no burrs I can find. Will I hurt anything polishing .001 or so off the OD of the pin? (7294)
John: I've just this evening had a spooky, somewhat similar experience to yours. I was knurling a long piece between centers and noticed that the bull gear was rubbing against the cone when I applied a left lateral load (as in using the live tailstock center!) Would you check out your lathe and see if this is happening to you also? Essentially the cone pulley is acting like a thrust bearing and it is weird. I wonder if I didn't get the bull gear far enough to the right side when I reassembled the thing. Where do you get the SB grease? And how do you manage to get it into the pulley? Frank (7295)
Isn't there a spring-like gizmo on the inside of the bull gear that prevents the pin from coming out? That might be the culprit Frank (7296)
With it [the little spring wire clip] removed the darn thing is still tight. I can't figure how the hole in the bull gear would get smaller but it acts like it has, a few tenths. marks in the pin is the cone pulley? (7300)
John and others, The back gear Teflon Grease can be bought from Fastenal Company as Permatex P/N: 62642 Super Lube Synthetic Based Lube with Teflon, 3 oz Net Wt Tube $5.34 each. See the following URL for local outlets: http://www.fastenal.com Jim (7301)
Just a thought. On my 9" SBL, there are two holes 180 degrees apart in the cone pulley. Could it be that you always engaged the looser of the two before and now are attempting to use the tighter hole? Also are there any burrs on the pin? Paul R. (7302)
Jim, I already placed my order with LeBlond, so I'll have to wait until I need another tube. John (7320)
Frank, I was knurling a long piece between centers and when I applied a left lateral load (as in using the live tailstock I was turning a slender piece between centers. I m not convinced that it is interference between the cone pulley and the bull gear though, because there does not appear to be any wear at this location and the cone pulley gets uniformly hot. This might be contributing to the issue of the cone pulley binding with the spindle though. to you also? Essentially the cone pulley is acting like a thrust gear far enough to the right side when I reassembled the thing. The bull gear is a taper fit on the spindle and appears to be all the way on. I pulled the keyway out and reinstalled it to make sure there was no interference. get it into the pulley? I ordered the CE1625 Teflon Grease from LeBlond (888) 532-5663 for $18.00. I m going to disassemble the spindle and apply a thin coat to the spindle and the inside of the cone pulley. I m also going to apply some inside of the groves of the cone pulley. My thought on this issue is more is not necessarily better, because it could start to hydraulic if too much is used. Periodically I m going to add a pinch to the cone pulley and let the centrifugal force distribute it along the spindle. I don t recommend pumping it full of grease because the additional grease and pressure could defeat the purpose. Just my $0.02. I m open to other suggestions though. John (7321)
My distributor today told me it was discontinued. He showed me some specs tables and there are many greases with the same specs. Frank (7322)
Back gear pinion tooth repair
I have a 1960'S Hercus (SB clone) in pieces. I'm in Australia. The smaller gear (pinion) on the back gear assembly has a partially broken tooth. There has been discussion recently (here?, rec.crafts.metalworking?) on repair methods. It seems that my options are 1. Do nothing, and suffer noise and wear. 2. Build up by welding and re-hog the tooth. (I don't have a mill, and the lathe is not operational) so that would have to be commercial. 3. File or grind a flat where the tooth was, silver-solder a small section in place, and file to shape. 4. As for 3, but use pins instead of silver solder (to avoid having to heat the back gear assembly to silver-solder temperatures). There doesn't seem to much of a market in Hercus spares these days. I suppose I could try Ebay assuming the SB part is identical, but US prices, plus shipping costs and delays, make that rather unattractive. Anyone got an opinion? :-) Any Australian members know of a local source? Rob (8371)
1 or 3 would be the best bet. Probably 3, solder vs. weld. brazing might by the best way to go. wrt shaping the tooth, don't discount filing. filing can be a very powerful and accurate way of removing metal. I think another way that you could do this in the lathe as long as the carriage was operational and use it like a shaper. I have never seen anything written up on it anywhere. maybe there is geometer article floating out there somewhere....? I have done this to cut a couple of keyways and to clean up splines on a shaft a few times. Just done by trail and error. basically fix the gear on an arbor and chuck the arbor in your lathe and use the tailstock to keep the arbor centered. Get the bit in the right place using a good tooth as a guide. Rotate the spindle to index the gear to the right place. I think you said it was an idler gear, then maybe use the backgear to index with. Shave off a bit at a time by traversing the carriage and bit across the gear. dennis (8373)
Our group member from the Netherlands has recently made a tooth repair by drilling a couple of holes into the gear and tapping with an appropriate size tap. After inserting a couple of screws, he filed the replacement to approximate the shape and used some "kneadable epoxy" to fill out the tooth. Glen (8374)
I made a couple of pictures of the repair I have put it in the photo album off this very nice group this is the name off the map -First time repair off a Gear- Good luck I have no experience how long it will hold. Maybe steel pins are better or welding. Who knows may tell it. Bert (8382)
9B Back Gear Problems
First the Taper Pins wouldn't come out. Ended up drilling one out and the other is still stuck, but know its got a broken punch stuck about half way through it. The set-screw bolt that holds the spindle in position also was rusted. Had to drill it out. Hopefully I'll be able to re-tap it. Since there is one taper pin out, I think I should be able to still get the spindle out. I can get it to move about 3/8", but then it just stops. I'm assuming the spindle presses on the handle, correct. I'm afraid to use my press in this type of scenario since I'm not really sure how it goes together. Anybody have some suggestions. What about getting the taper pin out. There's a punch stuck through one side which is what I was using to push the broken drill bit out the other side. Or should I just chop it of with a bandsaw and try to find a replacement? (8839)
You don't say if the taper pin that did come out is at the headstock end or the tailstock end of the back-gear shaft. According to my parts book, one taper pin holds the tailstock-end eccentric, the other holds the handle-which-is-also-the-headstock-end-eccentric. There's supposed to be a 'stop screw' [a setscrew with a locknut] under the headstock-end of the headstock casting which limits eccentric travel, and on some lathes there's a regular setscrew with a spring and shoe under the tailstock-end which sets eccentric holding tension, although my ca. 1936 9-inch lacks this latter setscrew-spring-and-shoe. Also the grease screw in the middle of the backgear--there's gotta be some sort of a narrow spot in the shaft to give a place to get some grease in there. Could something be hanging on the end of the grease screw? (8841)
Having just run into this same problem recently, I think I know what has happened. The setscrew bolt on the headstock side has a reduced dia. that rides in the slot in the eccentric shaft. Someone at some point had evidently gave the shaft a shot to move it, and the reduced diameter had broken off and was still in the slot, even though the setscrew had been removed. On yours, if you drilled out the setscrew, you probably got the threaded portion, but the reduced diameter portion is still there, holding the shaft from moving. Enlarge the dia of the hole where you drilled out the setscrew, get the piece out (it may fall out one the hole is enlarged, then just make a similar larger size screw when you go back together. Okey (8843)
I know what you're saying, but do you think would he get a full 3/8 of movement before it hangs if that were the case? (8847)
Yep, the shaft will slide 1/4 to 3/8 with the broken piece in there. Okey (8854)
Forget about it for a few weeks and then go back to it and it will probably fall apart. I'm not kidding. I have been thru the same thing hundreds of times. Patience. Mike (8857)
Welcome to the oddball techniques machine repair world. There are often unusual methods needed to recover otherwise unusable and unrecoverable parts on these critters, and many here have used them. In the past, have used a carbide burr or carbide drill in a Dremel or similar rotary hand tool to remove the broken punch, setscrew, drill bit, and then continue with drilling the hole thru using a drill press or such. I have seen folks take a carbide masonry bit and grind a proper metal cutting edge on it by hand with a diamond hone, then use it to gently drill out a stuck or broken-off hardened steel item such as a setscrew. A carbide drill or end mill can be used similarly either in a drill press or a hand grinder with careful method and very carefully controlled pressure. EDM and other electric cutting methods can work also on some of these situations but are usually a lot messier and more expensive. This is a wonderful opportunity to exercise your imagination and ingenuity. My first inclination is usually to find the most economical way to get the offending item removed using careful work in increments so you can see how you are doing. This takes volumes of patience and often means you will sharpen that bit a few times before the job is done, but it usually gets there. It also recovers items that otherwise would go into the scrap bin, with mucho $ handed out for replacement parts. if you need the machine working right now - the better method would be to get another part and save the one you have for later rework when you have the time to go at it carefully. (8882)
9" Backgear help
Isn't there a friction screw/spring/shoe assembly installed on the underside of the right headstock boss? (10379)
According to an assembly drawing I downloaded there is just such an arrangement. I have just installed a new Head stock on my 405Y. I fabricated this assembly with a 5/16 fine thread screw, a spring from Sears Hardware, (and this is the week point) and a shoe turned from a 3/8 rod. It holds the back gears in OK but I think I could use more spring pressure. I have no idea what the spring really looks like. I also fabricated the backgear stop from a piece of 5/16 fine thread all- thread by turning it to 1/4 inch for about 3/8 of an inch. (10380)
Lathe won't run in back gear
It will engage the spindle but then the motor won't turn it. I must be doing something wrong Did you disengage the bull gear from the spindle? (16183)
That sounds interesting. I just don't know what the "bull" gear is. I did mention I was very new to this lathe or for that matter any metal lathe. I sure wish that book would show up soon. Could you explain what you mean a little better please? What I am doing is putting the small lever that runs the drive screw in the neutral position (middle) putting the backgear into the spindle and applying the clutch. The motor slows a bit and the belt slips. I then stop the operation and scratch my head.:-). I know this is a simple thing but I'm not about to mess around too much and hurt something. Tom (16189)
Tom, go back from your chuck, spindle bearing. Right behind the spindle bearing is the face of your bull gear, roll spindle around and you will see a pin on the face of the bull gear this is what locks the bull gear to the pulley stack. Some pins a spring loaded pull out and quarter turn. Will unlock bullgear from pulley stack and your back gear will work. Mine has a block with a bolt in it. Loosen bolt slide block down tighten bolt and back gear works. Duane (16190)
On the spindle, near the collets side of the head stock, just behind the front journal is a large gear. This is the "Bull Gear" It is keyed to the spindle. The Belt pulleys are not keyed. They would be free to turn except there is a pin. It goes through the Bull gear and into the Pulley. On the back end of the pulley is a smaller gear. If the pin is in place when you engage the "back Bears" then to whole system will be locked. Nothing will turn and the belts will either slip or the motor will stall. If the pin is pulled out, (There should be a detent, it may be tight and you may need a pair of needle-nosers ) then the small gear on the pulley will engage the large back gear. This gives a reduction. The pulleys and the small gear are now free to turn on the spindle. (Be sure that you oil the pulleys, there should be a small screw covering a hole with the word oil.) The small gear turns the large back gear, the large back gear turns the spindle and you have a double reduction. I have described the operation on a SB-9. The 10K is identical. The Heavy 10 may differ slightly but should be similar. Jim B. (16191)
Correction The small gear turns the large back gear, the large back gear turns the BULL GEAR and you have a double reduction. Jim B. (16192)
The heavy 10 is the same. There is a cast recess for your fingers on the side of the bull gear. There is a wire spring inside and a notch on the side of the pin. Just pull the pin out about 3/8" and you will feel the spring restrict any more movement. This keeps the pin from going back into the pulley. The pin is about 1/2" in diameter with some knurling on its small head. JP(16193)
JP, Jim and Duane, I have it running now. I bet you don't have to explain that one too often. So I just have to pull out the pin and just leave it? I tried to turn it but it doesn't seem to make any difference. I hope it doesn't try to pop back in while it's turning. It does seem to stay put though. It is a rather awkward thing to get at isn't it?. I know not to change gears with the lathe turning but is it ok to go from forward motion to reverse with the little lever on the far left while turning? What is that lever called properly? I'm sure glade you guys are around to give me a hand. I suppose the book will tell me the spindle speeds? That oil hole you spoke of, is it the one on the pulley itself? I did see it. I see a lot of oil holes in fact. There are a few on the compound and cross slide as well. Do they need oiling very often? Mine seem to be painted in place in some cases, I may be mistaken on this. The previous owner is a well known machinist and he really looked after this lathe. When you change the belt to another speed (slide to a different step) should the motor be off and do I need to open the door in the base and move the pulley down there as well? One more thing, should the compound slide be easy to turn? Mine turns but it isn't all that free, you really have to crank on it. I sure hope I'm not being a pest here but like I've said I really want to do well by this machine. Tom (16195)
Tom, it is not a good idea to change gears or directions with the spindle turning. RichD (16196)
Tom, That's the reversing lever, for the lead screw. Spindle stopped when changing gears or reversing with the lever. Motor off when changing belt on pulley sheaves, if you value your fingers. Oil all of the oil holes every day that you use the lathe and top up all oil cups. Under the back cover there are holes in the gear hubs near the center, these are oil holes as well but not marked. Spindle oil in the spindle and apron cups and way oil everywhere else. Oil is cheap, worn parts are not. Oil everything except the leather belt. Put a couple of drops of way oil on the backgear faces as well. On the cross slide and compound there is a large head Allen bolt to the left side of the handwheel. This is the gib adjusting screw. There is a locking screw along the side of the cross slide and compound in line with the gib screw. Loosen the locking screw and then you can adjust the gib for tightness. The slide should travel freely but have no slop with everything well oiled. After you adjust the gib screw tighten the locking screw. You may find that the cross slide will be tighter at the ends rather than the middle, this is due to wear in the area most commonly used but is generally no problem unless it is excessive. JP (16197)
I think the "lever on the left" you are referring to is the "forward/out of gear/reverse" lever. You should not reverse the lathe with the lever while it is running. Bring the lathe to a complete stop before engaging this liver. You could mess up the spindle gear. You may need to turn the spindle by hand to fully engage this lever. Again I am speaking from the stand point of a 9" or 10K lathe but the "Heavy 10" should be similar. there is an in between position where the feed gears are not engaged. The oil hole on the 9" and 10K is on the middle pulley. You need to lubricate the pulleys when running in back gear. If you don't run in back gear this is not a concern. Do not change belts with the motor running. I guess this is an under drive and if so yes you need to open the door to change the belt position on the spindle. If the compound is tight first be sure that it is well oiled. You can adjust the gibs with the series of set screws on the side. They will need to be tight enough to remove any play but loose enough to allow relatively free movement. If the lathe has not been run is some time it would not hurt to loosen the compound and remove and clean and oil it and reinstall it. Duane (16198)
When you release the belt tension and move the belt on the upper sheave it usually moves on the lower one as well but it is a good idea to check it. You will feel a difference in the belt tension arm if it is not aligned. Release the belt tension when you are done using the lathe. Don't engage the belt tension with the motor running either, some people do this but it can shorten the life of the $60 belt. On the compound, if adjusting the gib screw doesn't fix the problem it may mean that the leadscrew nut had been misaligned when the compound was taken apart and put back together. Holler if that's the case, its an easy fix. JP(16199)
Mistake, the gib adjuster screws are on your right when facing them. JP (16200)
Back gear question
When I engage the backgear, it runs fine but slowly starts to disengage itself. I have to hold the engagement lever down to keep things in gear. Is there technique or adjustment to keep the backgear firmly engaged, or am I missing something here? Dave (19761)
Dave, I'd suggest not running it in BG until we figure out how to adjust the engagement properly. Suggest you check al the gears and clean each tooth of ant crud. If I recall the BG engagement lever rotates on an eccentric shaft. I'll look in my SB book tonight and see if there is an adjustment procedure. The heavy 10 is a nice, versatile lathe, Given good care it will last several life times. Eric (19763)
Look in the "files" section under Techinfo and you will see a file for back gear adjustment. It shows a picture gives you the SBL directions on how to do the work. Chris (19764)
First thing I would for sure find how to run a lathe put out by South Bend years ago. They are very easy to find , Ebay is just an example. Your back gear lever sounds as if it is pretty loose? there are two adjustment cap screws on the back gear shaft. The left side just keeps the lever from rotating too far. the right end closest to the chuck goes into a eccentric, and will snug things up for you. just tighten it enough to take out some of the slop and see if that is not better. Also there is a lot of info on this site in the faq section also a section for fellas and gals with there first lathe. Dee (19765)
Chris: The techinfo on backgear adjustment you directed me to seems right to the point. Dave (19766)
The adjustment procedure is in the parts manual. There are 2 set screws with nuts on them under the eccentrics at the back of the lathe. The one nearest the chuck pushes a spring against a brass plug that tightens the shaft, it should be adjusted for a firm (not hard) movement of the lever. If the gears begin to disengage when running in backgear then tighten it a little. The other setscrew should be loosened until the gears just bottom and then tightened about 30 to 45 degrees. The gears will just be off the bottom. Lock the nuts, grease the shaft and make some chips or threads. JP (19770)
There are two screws. One sq. head underneath on the chuck end and one on the back side that is slotted with a lock nut. Snug them up a bit. (19773)
Back gears
I just bought a 10" South bend that has a missing tooth on the larger of the back gears (Quill Gear?). I think the part number is PT18R1. Any recommendations would be appreciated. I've run the back gears and everything seems fine but I'm afraid to put a load on them by turning anything. (20758)
Howard, I had the same thing on mine. I sent the gear to Miller Fabrication in the links and they did a fine job of repairing it. The cost was very reasonable. I also see back gear sets on Ebay all the time. Paul (20759)
BackGear Howl (Heavy 10)
When running my lathe in backgear, I get a lot of howling (especially at high speed) I have made the necessary adjustments to the backgear as suggested by the SB Parts manual. The brass gear (small one) on the spindle does show some wear. I used some way oil on the gears which didn't help, and then some Teflon grease on them. (The same grease that you use inside the backgear shaft) I have never heard another SB running before, and I don't know what is acceptable for noise. (20993)
The SB 10" Heavy does make a characteristic hum in back gear but it is a pleasant running noise. "Howling" in my experience would be indicative of a bearing that is lacking oil (lube). Does your lather have a small access screw on the BG shaft? Mine does and you squirt oil in it. Eric (20994)
Yes I keep the backgear shaft lubed with the "superlube" as described in the FAQ. The entire lathe has undergone a restoration, and the backgear shaft assy has been rebuilt, and the gears have been cleaned/inspected. Everything looked normal with the exception of the wear on the brass gear on the spindle. Maybe I should take a close-up picture of it and post it so you can give me an opinion. "Howling" may not be the best way to describe the noise. It pretty much sounds like gears meshing together, just really loud. (20995)
I don't know if it is the same set-up as on a 9" lathe, but on my 9's there is an adjustment for the gear mesh. I seem to remember that it was a screw that bumped against the eccentric that pulls the back gears in. Glen (20996)
Noise from area backgear pin
I have a South Bend Lathe that I think is a Junior from about 1927. I am almost ready to be able to use it, just got it wired up last Saturday. I was test running it and noticed a noise that seemed to come from the pin that must be pulled before engaging backgears. I wonder if anyone is familiar with any kind of noises from that area, and if this is normal or bad? I can put up with it if it is normal, but I don't want to do any damage if it is not. Jim (21397)
Could be a worn pin and hole. With the pin engaged how much play is there between the bull gear and pulley? In other words hold one and try and rotate the other. There should be almost no play. Ed P (21402)
I don't think the noise you described is normal but it maybe due to wear on the pulley/spindle assembly. I suggest that you investigate the cause of the noise. If you find something then you can choose whether to fix it or not. If you don't find anything then you will probably have to live with the noise. Just watch in case it gets more noticeable. Either way you will get some piece of mind. I'd check the fit of the pulleys on the spindle, the thrust bearing and whether it is noticeable when you turn it by hand. If the pulley bore is worn then it will wobble on the spindle as it rotates. It's also possible the pulley is moving laterally on the spindle and bumps up against the bull gear. Either of these movements will cause wear on the engagement pin and the hole it fits in. This will only get worse with time. When I changed the belt on my 1963 9A (last month), I started getting a clunking sound that appeared to be coming from the same area of the headstock. This only occurred when running the belt on the two larger headstock pulleys. When rotated by hand there was a barely perceptible tight spot that occurred once per revolution. I took the headstock apart, carefully cleaned everything and checked for any looseness. I never found what caused the noise but after I put it back together it was gone. Because everything seemed to fit quite well, I suspect I had a piece some grit in the thrust bearing. John (21403)
Heavy 10 popping out of back gear
In running some test cuts I noticed that with a heavy cut 0.100 in steel in the slowest back gear speed with very slow feed, the back gear lever starts moving backwards until it disengages. The chips were coming off nicely with no sign of excess heat or strain on the motor, and the lever started moving backwards very slowly. I first cleaned all the hardened grease out of the gears and re-greased. It still pops out under a heavy load. 2 questions. Will back gear levers generally pop out under too heavy a cut? There is an adjustment screw on the housing behind the back gear lever, I tried a couple adjustments but it doesn't seem to tighten anything. I don't know the exact adjustment procedure for this situation. (21409)
What exactly is your feed rate? How sharp is your bit? that may be too much for your lathe. These machines are not THAT rigid. No, but they can. This is a common problem with many lathes, they need proper adjustment. Look in the the files section and maybe the FAQ for info on how to do it. dennis (21411)
A few things I would do differently. I would not have grease on the gears, oil yes, grease no, it holds swarf. Second a 0.10" cut on steel may be a bit high. Back to your original question. The screw under the backgear eccentric nearest the chuck is a spring-loaded and applies a friction to this eccentric and helps hold the gears in engagement. To begin the adjustment, this screw should be loosened so the backgear moves easily. The screw under the other eccentric away from the chuck is a stop. Loosen it (out) and engage the backgear so the gears bottom into each other, then adjust this screw so the gears just come off the bottom. Lock the stop nut. Now go back to the spring loaded screw and tighten it so the lever shows a some resistance. This one holds the gears in engagement under normal cutting conditions. You can also hold a finger on the backgear lever while cutting and if you feel any random pulsing on it you might want to check your spindle bearings. JP (21415)
South Bend will give the clearance on the gear mesh. They are not supposed to bottom. It puts added stress on the gears and wears the bore or shaft. They are also less noisy if you allow the clearance. Paul (21420)
JP and Paul, The adjustment went well. Lever spindle snugged up nicely, then the lock screw backed the gears off bottom. I used the earball clearance method. Too much bottom causes a characteristic whining noise. I set the screw in just enough to quiet the back gears down and allow them to be hand turned. (21424)
I checked the files for a back gear spindle adjustment. None to be found. Anyone know how to make that adjustment? There's a flat set screw with a locking hex nut. When turning it inward the back gear lever appears to deflect further backwards and doesn't seem to tighten up. Bear in mind, I know not what I'm doing. (21426)
The instruction ARE there- http://groups.yahoo.com/group/southbendlathe/files/Techinfo/Backgear%20Adjustment/ (21429)
That's the stop, on the back. The spring loaded one is on the other eccentric on the bottom. JP (21439)
Smoked back gear on 9"
I recently purchased a 9" Model C lathe. The only problem that I can see is that the previous owner brazed some teeth on the small gear of the back gear. Anyway, where can I get a new back gear or do a much better repair? or, is there a way that I can create a mechanism where If it ever happens again, I can just get a replacement from a place like McMaster-Carr? Also, what is the correct gear pitch and pressure angle. I am thinking 16 diametral pitch and 14.5 degree pressure angle? (22568)
I'm not sure, but I THINK 16 and 14.5 is right. Those assemblies turn up all the time on eBay. You could also bore a replacement gear and press it onto the turned-down hub of the old one maybe. (22572)
You can count the number of teeth and add 2. Then divide this number by the outside diameter of the gear in inches to get the pitch. Pressure angle is 14.5 deg. You should be able to get a steel gear relatively easy to make this up if that is the route you take. JP (22573)
Back Gears on 10K
I recently joined the group after purchasing a SB 10K lathe, and I read over the entire FAQ. I know it tells you where to find the file on Back Gear Adjustment, and in that folder it only has instructions on adjusting a 13 or 16 inch lathe, not a 9 or 10 inch. My Back gears pop out immediately upon startup, and they seem to be meshed to tight against their mating gears too. I can hold them in place while the lathe runs, and it works just fine, but there is a lot of force pushing them backwards. The only things I saw to adjust this was two set-type screws underneath the eccentrics, and they didn't help. I can't figure this one out. Shawn (24239)
Shawn, You are on the right track. My 10K jumped out also. I tightened up the 2 setscrews then the locknuts and that cured the problem. Mine also stayed in if I held the handle. Try the setscrews again it should work. Bob (24240)
Shawn, I have the South Bend procedure for adjusting the back gears in a 10k. The set screw at the front sets the drag and the one at the rear is the stop which controls the depth of mesh. The front set screw should be tighten just enough to keep the gears in mesh, no more. The back gear lever should not be hard to operate. The rear set screw should be adjusted with back gear running and set to provide minimum noise. A howling noise indicates too little clearance, a rattling noise too much. Ed P (24249)

Index       Home Page