What are these spindles from?

[jaCK HobsonParticipant @jackhobson50760]

Two pulley driven spindles.

The straight one is full length bronze with little oil holes all they way down. I guess quite a fancy high speed spindle?

The other is 90 deg drive with a thrust bearing on the short stub shaft.

Same diameters so my guess is they are off some clever, configurable machine tool.

Now that I have fettled them, I really don’t have a use for them…

 

[jaCK HobsonParticipant @jackhobson50760]

Thinking about it… the thrust bearing is in the ‘pull’ direction and at the stub shaft end. There is no radial bearing at this end. There is radial bearing at other end.

[Nigel Graham 2Participant @nigelgraham2]

They are driven from the pulley? Not the rest driving the pulley?

Tool-post mounted, milling or grinding spindles?

[duncan webster 1Participant @duncanwebster1]

<p style=”text-align: left;”>The one on the left in the first picture appears to have a worm and wheel. What happens if you twiddle the smaller shaft?</p>

[duncan webster 1]

On duncan webster 1 Said:

<p style=”text-align: left;”>The one on the left in the first picture appears to have a worm and wheel. What happens if you twiddle the smaller shaft?</p>

It is a right angle drive. It was very gritty/lumpy/sticky but now I’ve taken it apart/cleaned/grease it is smooth. I guess it is pulley driven – its the only thing that makes sense. I going to dismantle again in case I missed something, but I think the small shaft is designed to take an axial pull. Low speed. The bar of metal with set screws suggests tramming adjustment.

 

And the straight one does seem like an external tool post grinding spindle. Maybe half inch shaft. And I guess the fancy bearing is for very high speed. What make?

[Nigel Graham 2Participant @nigelgraham2]

If the gear is a worm and wheel, the smaller shaft will subject to an axial load anyway: that given by the action of the worm itself. Hence the thrust-bearing, and if there is only one the gear is intended to be driven only always the direction that loads the bearing.

Also, the smaller is the input shaft so it drives the pulley, with a fairly large reduction in speed.

Normally it is impossible to drive a worm from its wheel. It can be done with a very long worm lead giving a very high helix angle on the wheel, but at low efficiency. There are some applications for this, such as the speed-limiting “fly” in a musical-box movement, but little else.

Alternatively the drive is a helical-gear pair, but there does not seem room for that in this mechanism.

——–

Just looked again…..

Photo 1 gives just enough view of the larger gear to suggest it is not a worm-wheel.

Photo 2 gives a glimpse of the smaller gear. It is hard to tell but it does not look like a worm: the two diagonal lines suggest a high helix-angle more akin to a helical pinion; and teeth not a single “tooth”. (Worms can have 1, 2, 3 or 4 “teeth” (threads) but the angle on this one does not suggest even a single-start thread.)

So this may well be a helical-gear pair, which may drive in either direction. I think it will still give some axial load hence the thrust-bearing.

If so you should be able to rotate it by hand from either shaft. A worm drive would lock if you try to turn it from the pulley.

——–

I note too, that the pulleys appear to be for round-section belts.

The flat on the smaller shaft has a grub-screw bruise so perhaps from another pulley.

The small block on the top seems to give a small degree of rotary and/or adjustment, but not much.

.

Is the shaft on its own, actually a “spare” for the assembly? Or do you have there the bulk of a tool-post accessory set designed for use both axially and radially to the lathe, assuming a plain top-slide not a QCTP with its two sets of slides? In that case the adjuster, which looks like an add-on, may have set the centre-height.

[jaCK HobsonParticipant @jackhobson50760]

The straight spindle has A5074 marked on it.

Packed with grease, it takes a bit of effort to turn but I think the 90 degree works equally in both directions and can be driven from both ends. Looked like a helical gear to me. The trust bearing probably is as you describe – to account for helix angle gear pressure – I don’t think it is there to take any loads like cutting forces.

[jaCK HobsonParticipant @jackhobson50760]

With my newly refurbished 1″-2″ micrometer, I measure 1.3779″. So 1 3/8″ in colder weather.

 

I also fettled my 6-12″ micrometer this w/e – looking nice but now I need something to measure (only down to 1/100″ though 🙁 )

[duncan webster 1Participant @duncanwebster1]

Low ratio worm/wheel back drive readily, early motor vehicles had worm/wheel back axles, and I know of several narrow gauge diesel locos with 5:1 worm reduction an axles, they over run readily. Question, when does a worm/wheel become a pair of skew gears.

[Howard LewisParticipant @howardlewis46836]

A single start worm cannot be driven, it can only drive. The low helix angle provides a gear ratio equal to the number of teeth on the wormwheel. (Meccano worm and 57 tooth wheel = 57:1 ratio, 19:1 with a 19T pinion)

Multi start worms can, which is why they were used in vehicle axles,  (Otherwise with a single start worm, the wheels would lock on the over run). especially commercial vehicles where a compact single stage high ratio reduction is required.

Howard

[jaCK Hobson]

On jaCK Hobson Said:

I measure 1.3779″. So 1 3/8″ in colder weather.

 

Or 35mm in new-money doh!

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