Spindle spider for South Bend SB1001 lathe

A spindle spider is used to add another support for long shafts that extend through the bore of a lathe. Without a spindle spider, the there is no support left of the chuck and the work piece can flop around inside of the bore, and this motion may transmit and impact the machining.

Not all lathes come with spindle spiders. The South Bend SB1001 does not, but here we will make one. The spindle spider we’ll make is shown to the left of the original SB1001 spindle nut. The stock for the work piece was 1215 2-1/2″ steel rod from McMaster.

The first operations are to face, turn outside, spot drill, drill 1″ through the center, bore to under minor diameter of the spindle, and bore thread relief. The outside turning is partially for looks, but mainly to reduce the diameter so it’ll be possible to access a set screw that locks the spindle spider in place, given it recesses a bit into the spindle pulley. Spot drill and then immediately drill to a diameter suitable for boring, e.g. 1″. Drill bits are meant to have pressure at the center of the bit, and step drilling, e.g., starting with 1/4, then 1/2, etc. messes this up, and the chatter can create problems and the bit can jam.

After flipping the work piece over in the chuck the next operations are remove extra length of material used to previously hold it, bore to minor diameter, thread 40mm-1.5 thread. After the extra material is removed, the spindle spider is now to the its final length. Because it’s going to be difficult, especially with a three jaw chuck, to get the previously bored hole centered with the spindle after flipping the work piece, finish boring to the minimum diameter after flipping, which also trues up the bore. To perform the threading, the compound is going to be rotated around to 60deg, or slightly under, instead of 30deg as would be used for external threads. Watch a YouTube video on this to make sure the particular set up is clear. Calculating the depth of cut can be done with some trig. The SB1001 can’t use the thread dial for metric threads, so at the end of a thread pass, leave the half-nut in place, advance the cross slide, and put the spindle in reverse to back the threading tool out of the bore.

I don’t have a rotary table, so to get decent layouts on a circumference, I create and print a template for layout, e.g., in a CAD program, hold in place, verify first and last marks line up, whose distance matches the circumference, and mark positions with a scribing tool. The layout can aligned against the work piece edge or a line offset from the edge. If careful, this method seemed to work fine.

To line up the drill press spindle, a center finder can be used. This center finder can be used to get the correct offset, as well as hit the top, i.e., drill through the center.

Spot drill, drill, tap now or later, rotate, repeat. Use parallels as additional vice fences to help positioning. As long as the vice is not moved, it will not necessary to re-indicate work piece center. Line up spot drill with scribed lines. Drill two shallow holes on outside face to receive a spanner wrench.

To create non-marring screws for the spider, drill screws to receive round head aluminum rivets, e.g. AN470AD-4-4. After inserted, turn the rivet heads down to avoid interference when screwing into nut. The head of the screw may need to be turned down to avoid interference with the spindle pulley.

Create a simple spanner wrench using a piece of stock and a couple screws. Grind the screws to a length that allows the wrench to correct seat on the spindle spider. Tighten spindle spider onto spindle and tighten set screw.

Enjoy. Unless the pulley cover is modified, when using the spindle spider the cover will probably need to be opened. As always, be very careful to avoid the gears and pulleys when operating the lathe.

This Post Has 11 Comments

  1. Anonymous

    Looks great. I have the same lathe and was contemplating the same setup. Do you remember the bearing preload torque when you switched out the but? South bend is proving difficult to contact. Thanks, Pete

  2. Kent A. Vander Velden

    Thank you for the kind words Pete. I did not know what preload to use, so simply tightened the nut till it "felt right." When the lathe arrived, the original nut was so loose I spun the nut off with my fingers. There is a rattle in the bearings, and someday I'll replace them, hopefully with bearings with a bit more information, such as from a local bearing shop, instead of SouthBend or Grizzly. Regarding contacting SouthBend, for what it is worth, I tried to contact SouthBend about documentation on their four jaw chuck, which has no instructions included, and received zero response.

  3. Anonymous

    Thanks for the reply. I finally got a hold of Southbend today. I faxed, called an obscene amount of times and contacted Grizzly who in turn also pestered them. Guess the squeaky wheel gets the grease. Anyway, the South bend and Grizzly techs both called me back. What they said was to " snug up until the play is out of the assembly, kinda like a wheel bearing". Fortunately I have no bearing noises after the break in. I did get a fair amount of heat during break in, however it subsided as far as I can tell with normal use.

    As far as the 4 jaw chucks go, I received the 5" D1-3 Grizzly branded back plate from Grizzly today and it run out at under .001 on the face. Tomorrow the Little Machine shop 5" 4 jaw chuck should arrive. There needs to be one hole drilled and 3 counter bored, plus a bit turned down on the registration boss to fit the chuck. I think the SB system looks a bit nicer, but this method shaves off a few bucks.

    Thanks again, Pete

  4. Kent A. Vander Velden

    The SB model requires some machining as well, but I'm not sure what all is involved yet. Saving a few bucks is important. Easiest complaint about the SB1001 is so little is included, and the official SB accessories are pricey. In case you are interested, I have a short article on adding a Aloris quick change tool post to the SB1001, which was a nice alteration.


    BTW: I had to replace the nuts and t-bolts on the compound. I over tightened them and stripped the thread on the t-bolt. Grizzly delivered them in only a couple of days, which was really nice. I only lightly tighten them now.

    Thank you for the messages. It's nice to hear from another SB1001 owner.

  5. Anonymous

    Yup, seen your tool post, looks good. I used the Tormach OXA being I had extra tool holders from last lathe I sold. It bolts on without modification and has enough stud sticking out to use the handle from the 4 way toolpost to lock it down.

    Regards, Pete
    Got the 4 jaw chuck mounted tonight and seems to work great. Only issue was that the Grizzly cam lock plate seemed a bit unrefined in the cast iron used. Ended up mounting a import carbide boring bar to cut it, as this is the only carbide tooling I have on hand.

  6. fgaryamy

    I'm going to copy your design.

  7. Anonymous

    This is just what my SB1001 needs also… and just started making one. For the 1215 steel, what rpm and tool did you use for facing and turning the outside? It was a 1.75 years ago so don't expect you to remember, but am not getting good surface finish and looking for suggestions. Thanks!

  8. Kent A. Vander Velden

    Thank you for the comment. Sorry, I don't recall the exact details. You can see some of the tools in the pictures. They are all HSS insert tools including the internal threading tool, except the boring bar which is a carbide insert tool. The HSS insert tools came from Little Machine Shop (PN 3570 and 1619) and the boring bar from Enco (TMX SCLCR, does not look like it's currently available), both are nice tools. The speed was probably 450rpm or so. Getting technical, cutting 2.5" stock at 270fpm, 2.5"x3.14=0.65ft, 270/0.65 = 415rpm. Finally, be sure the bore is centered so the nut is as close to balanced as possible.

  9. Anonymous

    Thank you, I was running it too slow. Just ran it faster per your suggestion and the surface finish was perfect. I am running carbide tooling and needed to bring it up to (a scary) 1500 rpm (1000 fpm/0.65). Thanks also for the pointer to Little Machine Shop. I had bought their '3048 Quick Change Tool Post Set, 0XA' and it fit perfectly on the SB1001 and when I went back to look on your suggestion, I found they have this handy cutting speed page 'http://littlemachineshop.com/reference/cuttingspeeds.php' which has 1215 carbon steel right there at the top of the table… 270 for HSS and 1000 for carbide. Thanks again!

  10. Glad to help, makes writing these posts worthwhile, and I need to get back to it. The hit rate is down a lot. I think more people are going to YouTube to watch than read.

    I used to have a much larger lathe, and when I moved to town, and got the SB1001, I made the decision to stick with HSS for new tools. I just can't think and react at carbide speeds anymore. 🙂

    You probably realize this, but as the diameter changes the speed changes, some people use rpm = spfm * 3.8 / d where d is the diameter in inches and 12 / pi ~= 3.8, or round up to 4. 270 * 4 / 2.5 = 432… close enough 🙂

    Oh, a problem I had with the SB1001 that you may find interesting is the compound support has a very narrow diameter and the support will flex under load. The resulting finish looked like a phonograph groove. Perhaps there is an engineering reason not to, but I've always meant to enlarge the support. Eventually one of the t-bolts with jam nuts attaching the compound broke.

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