Need a quick bit of Hendey info......

[George Andreasen]

I'm working on the last part of my 1920 Hendey 16" cone head rebuild......the tail stock. The screw for advancing the tail stock ram appears to be a 3/4" x 6 tpi Acme, but I'm not really sure. It should be obvious, but I'm having a hard time deciding if the threads actually have a 29* angle or not...they almost look square. I need to bore the rear of my ram to accept a left hand threaded nut to replace the botched threading already present.

Before I order a bronze Acme nut, was the Acme thread form fairly standard in the early twenties?

 

[johnoder]

Contemporary Lodge and Shipley and Greaves Klusman lathes had three square thread screws - compound, cross slide and tail stock.

J.O.

 

[George Andreasen]

Thanks John. Guess I'd better take a CLOSE look, maybe with a magnifying glass.

 

[hendeyman]

George:

I got your e-mail, but I have been out of town for a few days.

The spindle nut used in your lathe is a 29 degree, 3/4 inch diameter and 6 threads to the inch, left hand Acme. This was the standard tailstock spindle nut from August 21,
1905 until January 25, 1924. After that date, the size of the nut was increased and the
thread was changed to a 7/8 inch x 5 thread per inch, left hand Acme.

The nut is a press fit into the spindle and is installed and removed using an hydraulic
press. It is important to properly support the nut end of the spindle during the pressing
operation and use a 16 inch long, piece 7/8 inch drill rod with a pilot to fit the minor
diameter. The retaining screw is a 5/16" x 24 about 11/16" deep. If you are not able to
remove this screw, then don't attempt to press out the nut. Instead, bore out the nut,
the retaining screw (hendey screw # 276) shouldn't be hardened.

Because your chances of finding a commercial nut that will fit the spindle ( I don't have
any in stock), may I suggest that you make your own bronze nut. Once you have the
the nut pressed into the spindle, you can either drill and tap the retain screw hole in a
different location or use the original hole. If you use the original hole, it will be necessary to make a sacrificial half screw to allow the tap drill to remain centered. Also,
a simple drill jig with a boss that fits the minor bore of the nut and with a pilot hole at
the correct radius, will make redrilling the tap hole a simple job.

As I have posted before, Hendey used priority threads on many of their products and
their Acme threads are no different. A tap drill is not used for the minor diameter, but
is bored to a non-standard size. The tap produces a non-standard clearance for the
major and minor diameters. To make certain that the nut will give a good fit on the
screw, may I suggest that you send the nut to me for tapping.

Whether a tailstock spindle is reamed for a #3 M-H taper or a #4 M-H taper, all dimen-
sions are the same. It is always a much easier proposition to make and install a new nut
than make and install a new spindle screw.

Hendeyman

 

[George Andreasen]

Good morning Hendeyman and thank you for the concise information!

The existing set screw in the spindle has already defied all attempts to remove it, including heat (in fact I snapped off an Allen wrench in the bloody thing!), so my plan was indeed to bore the nut out. At that point I had intended to substitute a commercially made 3/4 x 6 LH bronze Acme cylinder nut, anchored by both a moderate push fit and secured with Loctite. I don't recall the Loctite number offhand, but it's the same type used on other parts of this lathe is capable of anchoring a battleship to a bowl of Jello.

That was the plan until you mentioned the possibility of a non standard Acme size, so yes, I will contact you later today...and thank you for your offer of help!