L00 Spindle Nose Adapter -- The Impossible Dream?

My 13" SB has a 1-3/4 x 8 spindle thread and I've got a bunch of nice L00 tooling.

Does anyone know of or have an opinion about the practicality of making an L00 adapter? Looks to me like it could be done w/o a lot of overhang or loss of rigidity. The 1-3/4 spindle thread would more or less nest inside the long L00 nose. With the right finnagling the exisiting MT3 taper might remain useable with the adapter in place. (I believe I've attached a drawing of the L00 nose, but if it didn't make the trip one can be found on lathes.co.uk.)

Also looks possible that this adapter could be made w/ reasonable accuracy since the final grinding on the L00 taper could be done w/ a toolpost grinder while the semi-finished piece was installed on the spindle.

I've got a little heat treat furnace, so I could harden the adapter--or maybe there'd be less chance of warping if it were case hardened. The one thing I'm not setup to do is grind the internal 1-3/4 x 8 thread--that'd have to work as cut.

Anyway, I'd very much appreciate any opinions or the benefit of your experience in this area.

It might make sense to think about making a new spindle with an L00 nose. You'd have maximum rigidity that way, and probably less trouble with repeatability when installing/removing/reinstalling the adapter.

I would glue the adapter in place with locktite, and do the final grinding insitu.

allan

kitno455 said:

I would glue the adapter in place with locktite, and do the final grinding insitu.

allan

Click to expand...

Good idea. The only drawback would be removing the adapter, but if he has a pile of L00 tooling, it would probably be a 1-time installation anyway.

Go for it!

I feel it's a great plan!

But to try it out, Skip the "hardened and ground? part . Just make the adaptor from "machinery steel". (That is, something better than old chewing gum)
It is amazing how well tooling can hold up if the mating surfaces are clean.

That way you can refine the design without difficulty. Accuracy is up to the machinist;-)

One thing that may complicate a "removable adaptor" is the threads on top of threads". Tightening one will loosen the other. Which set will come undone when a chuck or face plate is exchanged? You may want to put a "holder" in the chuck jaws to lock up the spindle from that end. Or some other locking device (like loc tite)

Thanks very much for the helpful comments.

There's a piece of 8620 lying around somewhere that'd be big enough. And, yes, for garage use unhardened would be good enough. The locking ring could be made from any scrap of 1-1/2" steel plate.

Looking at the L00 drawing, there's enough room to bury the entire 1-3/4 x 8 SB spindle thread including its shoulder within the adapter. That'd leave just a short chamfer about 1/4" long leading to the original MT3 spindle bore. I assume the fixture should be sized to tighten against the original spindle shoulder and not its nose.

Not a bad idea to prevent the thing from spinning off. Maybe a couple pins or screws thru the adapter and into the buried shoulder. If you wanted to make things complicated, maybe an axial slit along the adapter about half as long as the 1-3/4 x 8 threads and a counterbored SHCS with nylon patch to cinch things up. The real world solution: Loctite.

For removal, I believe the joint ANSI and ASME standard calls for Kroil, back gear, a 3-jaw and that nice length of pipe over there in the corner.

The threads-on-threads problem shouldn't be too bad due to the L00 drive key. You could hold onto or lever down the chuck, drive plate, etc being installed while tightening the lock ring; the key would keep the thing being held from turning.

The thing that will drive me to the bookshelf is setting the compound to cut the L00 taper of 8 deg 17' 50". It's not like I can mount an L00 piece in the spindle and use it as a reference--I'll be making the L00 piece. Only idea that comes to mind is piece of drill rod held in a good collet plus a sine bar and blocks--gotta give this a little thought.

jackw19 said:

The thing that will drive me to the bookshelf is setting the compound to cut the L00 taper of 8 deg 17' 50". It's not like I can mount an L00 piece in the spindle and use it as a reference--I'll be making the L00 piece. Only idea that comes to mind is piece of drill rod held in a good collet plus a sine bar and blocks--gotta give this a little thought.

Click to expand...

Mount an L00 backplate turned backwards on one of your sb backplates, and dial it in. Then indicate the compound off the back side of the tapered hole. Make sure you are indicating on center height. When you then cut on the front side of your spindle adapter, you should have the same angle.

allan

There have been times when cutting tapers of any sort that I have used the "cut and measure" method.

That is, when using the compound, the first couple of tapered passes produces a surface useful for either "blue and rub", or passing an indicator on.

Armed with the knowledge gained from the test surface, bumping the compound angle setting is not too difficult. A mag base DTI makes the bumping a "known process".

A thou. too much on a taper is way too much;-) But the time you get to the finished taper configuration, The angle is well zeroed in, and you can concentrate on getting the diameters correct.

Just my way, certainly it's not fast. The methode has worked well for me however. The A1-3 spindle nose adaptor for the Wade 94 didn't leave a lot of room for calculations, but even that one worked out.

And if you screw up, just cut off the length and start over ;-)

The draw back nut detail is here.

http://img.photobucket.com/albums/v337/johnoder/LTypeNuts.jpg

When I rebuilt my heavy 10, South Bend had some of the nuts in stock. I like the L00 chuck there is a hook to put behind the nut makes it easy to release and then the hook swings out or the way.

John