The Shop > Tools

Setover Topslide Screw Cutting

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lordedmond:
Use the method Eric describes

It's in GHT books it works fine no maths involved when both dials read zero it done


Stuart

Will_D:

--- Quote from: BillTodd on September 26, 2014, 08:38:36 PM ---er collet chucks are usually metric so thread angle is 60° ( bsf, bsw and some odd microscope threads use 55° . BA is 47.5°)

--- End quote ---
Agreed but the body screws onto the lathe mandrel's nose (ML-7 Imperial like Johns Boxford). The Collet Closer is the metric bit!

Will_D:
Cheers Eric for this but I think something is missing?

Set Top slide to Zero.
Touch the work with the tool using Cross slide and set dial to Zero.
Back out tool using Top slide.
Move carriage to right to clear work.
Advance Cross slide to the root diameter of thread.

Something for the top slide here?

Back out Cross slide move carriage to work area

Touch tool on work and set Cross slide dial to Zero.
Advance Top slide to touch the work.
Start cutting thread
Back out using the Cross slide
Reverse
Advance depth with top slide
Cross side back to Zero
Repeat until Top slide reads Zero

BillTodd:

--- Quote from: Will_D on September 27, 2014, 01:54:58 PM ---
--- Quote from: BillTodd on September 26, 2014, 08:38:36 PM ---er collet chucks are usually metric so thread angle is 60° ( bsf, bsw and some odd microscope threads use 55° . BA is 47.5°)

--- End quote ---
Agreed but the body screws onto the lathe mandrel's nose (ML-7 Imperial like Johns Boxford). The Collet Closer is the metric bit!

--- End quote ---

Ah yes. must learn to read these before replying ;-)

So, you're  cutting an internal thread.  The topslide needs to be angled like this  /   and you should realy make a male thread measured with wires or mic to ensure you get it right (infeed is +0.0597 @ 26.5° but ...)



bill

Fergus OMore:
As  follow up to Eric's dissertation, I would also add reading up Martin Cleeves Screwcutting in the Lathe.

Two reasons really! The first is that George Thomas and Martin Cleeve( actually Kenneth Cleeve Hart) both had Myford ML7 at one time and the words and the music  require no re-design to achieve these results.

Actually 'Cleeve' was made redundant many years ago and used his highly modified ML7 to make 'special' nuts and bolts( and a very good living) from his machine.

Over the years, I made a lot of GHT and Cleeves additions to their designs which appeared in Model Engineer and some of Cleeve's in Engineering in Miniature.

Regards

Norman

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