a mill\drill query

If its offered for £25 its probably mine, so ask away !!

no , its offered for £99 ! i reckon i need a worm and wheel , i'
struggling with the maths tho ! if i use a dial off a myford (is th feedscrew 20tpi ?) then with a 40 tooth wormwheel , would that give m movement in half thou increments
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[On a quill feed for a mill/drill]
Possibly, but it would be pure luck if it did! The quill is probably operated by a rack and pinion. You need to find out the pitch of this first before thinking about any worm and wheel.
Attach a disk of something to the quill feed, with a hole in it and a detent that falls into the hole. Set up your DTI or similar onto the nose of the quill/chuck jaw. Turn the disk one full turn so the detent pin re-engages its hole. Read off quill travel. Your worm and wheel will need to divide this into a sensible number.
Alternatively, attach a digital caliper directly between the quill and the body, use any convenient worm and wheel, with an ungraduated handwheel and read off the movement directly from the display.
HTH

thanks for that ,i fogot all about the rack and pinion
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