Meek screwcutting clutch – Fortis/Clausing

[colinbParticipant @colinb]

A bit of a hail Mary here I’m afraid. In continuing to populate my long list of projects, I came across this 10 year old discussion at Home-Machinist.

I wonder if Gray @grahammeek88282 you can shed some light into whether that collaboration with COMachinist got any further than the “preliminary mockup with the measurements” posted on that other thread?

The reason for asking – I’ve a Fortis lathe, which is essentially a Clausing 100 MK3, so naturally would prefer to get hands on the most developed drawings possible to ensure the inevitable errors are my machining (in)ability rather than my design inability!

[Graham MeekParticipant @grahammeek88282]

Hello Colin,

I must admit you did catch me out there for a moment. I was uncertain as to whether I had actually done a Design of Screwcutting Clutch for this lathe.

Luckily the drawings are still on the computer file, despite two computer and one drawing package change.

As regards to whether this design was ever finished I cannot say. Some of those who start out wanting to fit a clutch to their machines fall by the wayside and lose interest. You will realise that this then stops any feedback from the participant(s) and I no longer know if it worked. My memory problems also do not help on this front.

That said, without seeming to be Big Headed, the high number of clutches that I have designed to date, have all worked as intended. The last and final one being for my Emco Compact 5.

I have all the drawings in DWG format, can you handle this Format? If not I could convert them to PDF but this will take a while.

Regards

Gray,

[colinbParticipant @colinb]

Thank you Gray. No intention at all of catching you out, and I am very impressed the drawing have survived those changes. Most of my files barely make it through a single change of computer, never mind two and a package change!

DWG format is absolutely fine – if I can’t open it already, I can definitely work out how to do so.

One question – what is the licensing on your drawings/designs? Just so I am aware in case anyone else in possession of the same/similar lathe wishes to follow the same path.

[Graham MeekParticipant @grahammeek88282]

Hello Colin

I have sent you a PM with my email details.

Regards

Gray,

[Howard LewisParticipant @howardlewis46836]

As I see it, Graham’s clutch satisfies the need to disengage the Leadscrew, but so that it can only re-engage with the geartrain in one position.

Even if you can’t fit Graham’s clutch, as drawn, could you amend the dimensions, but retain the operating principle?

FWIW, made for my mini lathe, a sleeve to engage the key on the Leadscrew, but with a separate, extended key to engage the gear on the Leadscrew, (And to pass through any spacer).

In this way, the gear can only engage to drive the Leadscrew in one postion.

Howard

 

[Graham MeekParticipant @grahammeek88282]

Hi Howard,

Just to say I have seen your leadscrew disengagement device and I am aware of how it works.

Any Screwcutting clutch in order to operate correctly needs to be higher up the screwcutting train. That is directly coupled to the mandrel gear. However even with the screwcutting clutch in neutral. The leadscrew will still have to turn all the gears in the gear train on the Banjo Quadrant plus any gears in a screwcutting gearbox if one is fitted.

Thus as a leadscrew disengagement facility it would be a non-starter. As the load applied by all these gears would make sensitive adjustment of the leadscrew very difficult. Depending on the thread being cut it might be said that this task would be impossible, due to the high reduction necessary on very fine threads.

The Emco Compact 5 version of the screwcutting clutch does have a separate leadscrew disengagement facility. It is something that comes with the Emco Fine Feed attachment. However as this engagement facility has six different positions in which it can be engaged. It is imperative that once screwcutting has commenced this facility has to remain engaged until the job in hand is completed.

Regards

Gray,

 

 

[Howard Lewis]

On Howard Lewis Said:

…
FWIW, made for my mini lathe, a sleeve to engage the key on the Leadscrew, but with a separate, extended key to engage the gear on the Leadscrew, (And to pass through any spacer).

In this way, the gear can only engage to drive the Leadscrew in one postion.

 

But you cannot use it for screwcutting, except on threads where the TPI is a multiple of the leadscrew TPI. EG a 24 or 40tpi thread with an 8tpi leadscrew.

 

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