Pittler spiral cutting test

[vic neweyParticipant @vicnewey60017]

My Pittler lathe is capable of many different types of turning and milling. Here I am trying out milling a spiral using the lathe being driven by the leadscrew itself via an overhead drive to the tailstock mechanism.

The power then passes up through the reversing box and onto the headstock mandrel. The chuck and saddle will turn very slowly, dependent on the worm and wheel used. It’s most important that the headstock pulley is free to turn so the flat drive belt for this must be slackened off or temporarily removed. My video on Youtube can be seen here

https://youtu.be/wOrPeptvLJ4?si=oRUHl6WAOwA0KK6i

In total there are 4 belts running and 7 pulleys are used!  The cutter is a 1/2″ ball nosed endmill

[John HaineParticipant @johnhaine32865]

Neat.  Actually it’s a helix – not sure how you would mill a spiral on a lathe.

[BazyleParticipant @bazyle]

Very interesting but needed to be stopped every few seconds as it was flying around too fast to take in the details. Alos liked the other videos you have on this lathe.

Now I’m curious about the thing with a big hole in it under the lathe in the above picture.

[John Haine]

on John Haine Said:

Neat.  Actually it’s a helix – not sure how you would mill a spiral on a lathe.

Fusee making involves cutting spirals. Fusee engines are a specialised form of lathe for doing so. Jerry Kieffer has shown a setup on a sherline lathe for doing so which uses a curved template.

[Bazyle]

On Bazyle Said:

 

Now I’m curious about the thing with a big hole in it under the lathe in the above picture.

It’s a rare Pittler radial compound slide, it has 3 handles compared to normal compounds with 2, the 3rd handle rotates the top slide. See:  https://sites.google.com/view/pittler-lathes/c3-lathe-menu/radial-compound-slide

You can always pause the Youtube video

[Clive Brown 1Participant @clivebrown1]

For cutting the helix on the “Quorn” vertical column, Prof. Chaddock illustrated his set up for driving the lathe via the leadscrew whilst milling a 3/32″ wide slot. Each pass along the column took nearly an hour. I think that his lathe was a Drummond.

Fortunately, the MES materials kit at the time offered this operation pre-made.

[John Haine]

On John Haine Said:

Neat.  Actually it’s a helix – not sure how you would mill a spiral on a lathe.

Maybe it’s a helix but mister Pittler would not agree as he has sections and tables in the catalogue under spiral cutting. Examples are shown of spirals cut on a round ball, all produced on this lathes standard equipment.

 

[Peter Cook 6]

On Peter Cook 6 Said:

on John Haine Said:

Neat.  Actually it’s a helix – not sure how you would mill a spiral on a lathe.

Fusee making involves cutting spirals. Fusee engines are a specialised form of lathe for doing so. Jerry Kieffer has shown a setup on a sherline lathe for doing so which uses a curved template.

You got me thinking when you mentioned milling a flat spiral and this would be no problem on this lathe using the similar set up. I have in the video. This lathe has a power cross feed activated by the leadscrew but using a universal joint to connect to the cross slide.

Mounting a flat workpiece on a faceplate, or in a chuck, the milling cutter would slowly move across as the workpiece turned at the set slow speed. Using back gear and worm/ wheel combination you could get 1/2 revolution per minute or more/less Tailstock belt speed would need to be on it’s slowest pulley but would need trial and error to work out the settings for everything.

I might have a go at setting it up as another project

[John HaineParticipant @johnhaine32865]

Fusees are a complicated hybrid of spiral and helix. – a helix which reduces in diameter as you go along it.  Illustrates why exact terminology is important.

[John Haine]

On John Haine Said:

Fusees are a complicated hybrid of spiral and helix. – a helix which reduces in diameter as you go along it.  Illustrates why exact terminology is important.

I’m not trying to try to make a Fusee though, just the correct definition of a spiral instead of a helix.

[Howard LewisParticipant @howardlewis46836]

Did something similar, but was really cutting a coarse screw thread.

Theoretically, my lathe cannot cut coarser than 3 mm pitch, but by replacing the 40T drive gear by a 30T, and making up a sort of tangential turning tool, with a 1/8″ round toolbit, it was possible to cut a 4mm pitch, half round thread.

Slow using minimum speed and back gear.

But it did what was required.

Not so easy if the thread has to be wide and deep

Howard

[vic newey]

On vic newey Said:

On John Haine Said:

Fusees are a complicated hybrid of spiral and helix. – a helix which reduces in diameter as you go along it.  Illustrates why exact terminology is important.

I’m not trying to try to make a Fusee though, just the correct definition of a spiral instead of a helix.

Try Wikipedia.

[John Haine]

On John Haine Said:

Fusees are a complicated hybrid of spiral and helix. – a helix which reduces in diameter as you go along it.  Illustrates why exact terminology is important.

I’m not trying to try to make a Fusee though, just the correct definition of a spiral instead of a helix.

Try Wikipedia.

Hello john,

The Wikipedia description of a fusee is a cone shaped pulley with a helical groove around it,

Pittlers obviously outdated description of a spiral is: when travel is obtained via the lead-screw, it’s a spiral. When the pitch is greater than that of the lead-screw, it is a spiral. when less it’s a screw-pitch. 

Amongst the many descriptions of the lathes abilities is- “scrolls or spirals on internal and external cones”

that sounds similar to a fusee to me so I will have a go at making one as an experiment.

 

[Alan JacksonParticipant @alanjackson47790]

The Stepperhead lathe can cut spirals to any pitch and taper if desired. This is cutting wood but most metals can be used.

Alan

[Alan Jackson]

On Alan Jackson Said:

The Stepperhead lathe can cut spirals to any pitch and taper if desired. This is cutting wood but most metals can be used.

Alan

That’s interestingly different that it’s cutting sideways from overhead, the Pittler lathe is used by ornamental turners for wood but I only cut metal with mine.

Using it’s standard accessory of a power circular feed it’s capable of cutting a ball and then cutting a thread on it, and then you can make a 1/2 hollow threaded ball and screw them together. von Pittler used that as one of his demonstrations at 19th century trade shows, this video just a quick glimpse of the power feed https://youtu.be/VhNWJGQzAZc?si=-I80t_h3fRfuAwGz

[John HinkleyParticipant @johnhinkley26699]

All this confusion between fusee, spiral and helix makes me inclined to write a dissertation defining DNA as a fusee spiral, not, as Watson and Crick proposed, a helix.  Do you think I might qualify for a Nobel prize?

John

 

[vic newey]

On vic newey Said:

On John Haine Said:

Fusees are a complicated hybrid of spiral and helix. – a helix which reduces in diameter as you go along it.  Illustrates why exact terminology is important.

I’m not trying to try to make a Fusee though, just the correct definition of a spiral instead of a helix.

Try Wikipedia.

Hello john,

The Wikipedia description of a fusee is a cone shaped pulley with a helical groove around it,

Pittlers obviously outdated description of a spiral is: when travel is obtained via the lead-screw, it’s a spiral. When the pitch is greater than that of the lead-screw, it is a spiral. when less it’s a screw-pitch. 

Amongst the many descriptions of the lathes abilities is- “scrolls or spirals on internal and external cones”

that sounds similar to a fusee to me so I will have a go at making one as an experiment.

 

[ pedant alert ]

Despite what you might read on Wikipedia … a useful fusee is rarely, if ever, simply conical: the curvature is there to compensate for the non-linearity of the spring.

MichaelG.

.

https://www.model-engineer.co.uk/forums/topic/fusee-turning-and-groove-cutting-on-my-myford/

and also:

https://youtu.be/ohgc4ykm6go?feature=shared

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