Quick Change Tool Post T-Nut For The South Bend Lathe

I finally got sick and tired enough of the sloppy feel of the T-nut on my Aloris tool post and decided to make a “corrective” base to bridge the wallowed out compound on my South Bend Lathe. Any of you guys out there with a lathe that came from a High School shop class probably know the situation I was up against. The tool holder locked down alright MOST of the time, but I was never REALLY sure. Here’s a shot of the compound, and the damaged area:

The project was to build a T-slot nut with a tighter fit, and long enough to bridge the damaged area of the compound, so that it supported the nut and allowed for a good solid lock-down. I made it the full width of the tool post.

The machine work was pretty straight forward on the Bridgeport, due to a good Kurt vise, and some set-up fixtures. I had planned on whipping up a few extra for sale in the store, and took the time to make a couple of jigs to speed things up. I whipped up about a dozen, and plan on making some for the 9 Inch size lathes shortly.

I left the load bearing surface on the lower step of the nut ROUGH to add traction to the grab on the compound. I thought it might look like hack machine work, but it just looks like it means business. I tried a couple of “blueing” methods, with mixed results, and finally just decided on the old blacksmith’s oil quench blackening. I heated the nuts to cherry red, and quenched it in used motor oil. This has the added benifit of hardening the metal and blackening it too. I can’t tell you the Rockwell hardness, but the finish looks pretty darn good for something I’m never gonna see, anyway. It should protect it against corrosion too.
I have to do some research on heating temperature to make sure I’m getting hard enough, without getting it brittle, but I’ve tested them, and they seem perfect to me. I will fine tune the heating on the next batch, as these seem to have areas where the “black” is light in the areas where the rosebud got too close to the nut. Live and learn; I’m not a blacksmith.

The hardened studs are about a half inch long for the Aloris tool post and the Phase II I tried. I plan on trimming mine, but will probably ship the others out long for the final user to trim to fit. The 5/8″ studs are stout, like the hardened flange nuts. Lots better than the old setup I was using. It has a solid feel that you know is locked down every time.

These are in the store section, and will ship in a Priority Mail Small Flat Rate Box @ $4.95  regardless of quantity. This version is for the Aloris BXA size (Phase II 250-200 size), and should fit any offshore clone sold as BXA compatible.  The 9 inch (AXA size) is in the work and will be available shortly.

All in all, a good project, and gave me some good experience for a future post on heat treating / blueing metal. More on that at a later date.

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4 replies
  1. John Young
    John Young says:

    “….plan on making some for the 9 Inch size lathes shortly”
    I’d like to buy one if “shortly” has come around yet.
    Thank You

  2. admin
    admin says:

    John,

    This one of those projects in the “roundtuit” file that fell between the cracks, and you are not the first guy to ask about them. I guess its time to get back to work on them again. I got side-tracked putting together a line of lubricants for South Bend owners (just about done), and overhauled my horizontal mill specifically for this job, so maybe I ought to put the old mill back to work.

    Mick

  3. John Seal
    John Seal says:

    This is a great help, but I want to attach a milling adaptor so I need to remove the slider that the tool post attaches to. I thoughtit was just a round piece held in by the set screw but it seems to have a cener screw or something in it. Thanks John

  4. admin
    admin says:

    John,

    The only thing holding my compound on my cross slide is the two allen bolts you see at 10 and 2 O’clock in the post. I have seen lathes that have brass grubs installed, so that the bolts don’t scar up the compound. That may be whats holding you up, the grubs are stuck in the compound by dried grease. Try removing bolt hold-down bolts, and spray some penetrating oil or choke cleaner into the bolt holes, and try to rock the compound off. I’ll bet thats all it will take to lift the compound off.

    Regards,
    Mick

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