Haighton Cadet - enhanced threading modifications

[BillTodd]

A while ago I picked up a little Haighton Cadet 2.5" centre height modeller's lathe.

I have been fiddling about fixing up the machine, replacing the motor and generally renovating it and felt I could improve on the rather simple change-gear arrangement. In particular I wanted to add metric threading.

The Cadet has a chain of five or six gears that are driven from a permanent 24T on the spindle to a fixed spindle (carrying a 60T gear),  one adjustable gear spindle which slides in a radial slot a fixed distance from the fixed-spindle (allowing only two sets of second-gears as standard, 50:40 and 30:60)  that enables a range of lead-screw gears  to be used.  While the arrangement works OK, it requires a different lead-screw gear for each thread.

My simple mod it to fit an eccentric spindle in place of the sliding spindle to allow a greater range of second-gears, in particular a 37:47 metric translations pair.

The Cadet uses  30dp 14.5 PA gears with a 1/4" spindle hole . Bizarrely, the gears are coupled with a pair of holes & pins (fixed in the 60T)  or, in the case of the 60:20 feed rate pair, permanently riveted together. Each lead-screw gear has an unusual boss just to add to the complexity!

I chose to stick with the holes and couple my gears with removable pins (the downside of this, is it limits the gear to a minimum 30T ) .

After some juggling with a spread-sheet I finally settled on eight additional gears (61, 60, 47, 45, 43, 37, 35 and a 20 with hub) that allow me to cut M2 - M16 and 0BA - 10BA  at  good accuracy , with a passable 30dp & 32dp as a bonus.

By good fortune the 61T gear will fit on the fixed spindle in place of the standard 60T (the 24:61 ration provides an alternative metric translation for some threads that require additional divisions/multipliers ( M12 x 1.75  and some BA sizes)

I'd like to thank Peter Colman, for making a superb job of hobbing my blanks in to gears.

[BillTodd]

When I bought the Cadet, the original Brook Gryphon motor had been removed, but luckily I was able to find a 3 phase gryphon 'cub' motor which uses the same frame as the original Cadet motor.

I converted the 'cub' from 415vac to 240vac by extracting the star point wires and wiring the motor in a delta configuration. I used a spare 200w Omron VFD left over from my HLV-H conversion and made a rather avant-garde box for it from some 2U frame extrusion.

The use of a VFD then allowed me to add a motor reverse and electrical threading  stop.

The stop-switch slides along a rectangular guide mounted to the rear of the bed. The switch commands the variable frequency drive (inverter) to stop in 100mS (less than 1/4 turn of the chuck ), allowing fast threading upto a shoulder. A reversing button on the VFD control box will quickly return the carriage to the beginning of the thread ready for the next pass.

A relief groove at the end of the thread is required to prevent tool damage. A threading-stop enable switch on the VFD control box allows the stop to be disabled, allowing the threading stop to remain in place during normal turning operations.


A flip-up or quick retract threading tool is an obvious addition

You tube video of the threading stop in motion.

[DavidA]

Bill, 

Great reading about other members modifications to old lathes.

One point.  You're not doing your dial gauge any favours by letting it rest on the probe.

Dave.

(cadet lathe.jpg)

[BillTodd]

Bill, 


One point.  You're not doing your dial gauge any favours by letting it rest on the probe.

Dave.

(cadet lathe.jpg)

Bloody cat! 

[Meldonmech]

Hi Bill,

        A nice solid looking lathe you have there, like the mods you've made, have you tried the screw cutting yet? The lathe has some similar features to my Myford M L10. I have two larger lathes but tend to use the ML10 the most, evertything is so simple and handy.
                                            Cheers David

[BillTodd]

Hi Bill,

        A nice solid looking lathe you have there, like the mods you've made, have you tried the screw cutting yet? The lathe has some similar features to my Myford M L10. I have two larger lathes but tend to use the ML10 the most, evertything is so simple and handy.
                                            Cheers David

Yes, i cut a few threads to check pitches etc.  M8, M12 and M16 in stainless (just to see how it cut)

Your ML 10 is a bit bigger :-)  the cadet is only 2 1/2"  centre height with 8" between centres. I can just about lift the whole machine , although it is bloody heavy and awkward.

Bill

[BillTodd]

Left-hand threading bracket.

I finally found time to make a new banjo to allow the lathe to cut left hand threads. There is no room on the gear plate to fit the usual toggle reversing gears so the reversing gear has to be fitted on a new banjo between the last pair of gears.

The result, albeit a fiddle to fit, seems to work well

And, in another moment of madness, I've started organising the accessories into a box (I'm particularly pleased with the  art work which was cobbled together from Haighton's original 'Major' brochure)

Bill