Z-axis huge slack / beginning a conversion

[diy-john]

Think you got it spot on, Robin, crude conversion first = thanks I like that.

I am a cnc -virgin, and perhaps a big concern is, will there ever be a running machine.

My primary aim at the moment, is to get a shopping list ready.
- For that purpose, have done now two (2) things

1) Take measurements of the mill (King Midas)
- take photos too.
- Here are a couple of greasy pics, from dismantling the X/Y -table (From left to right: 1) overview; 2) X-axis dismantled; 3) X-axis leadscrew is 260mm, think it could be a bit longer; 4) x-axis one end; 5) Leadscrews are 18.34 mm thick; 6) Y-axis leadscrew at 175mm, think it could be longer)


2) Make a sketch of the Z-axis ballscrew -conversion
- think how the motor would be mounted
- how long ballscrew one might want
- how the thing would work
- This sketch is from side of the mill. (used inkscape to create the original graphics)
- Green is the body of the mill
- Blue bits are those that I'd try to buy ready made
- Red bits move up/down as "one unit", with the quill (and ballnut)




I am a bit concerned about the (horizontal) distance between the ballscrew, and the quill.
- the King Midas -milling machine is a bit difficult shape, like a mushroom.
-- Thought about using pulleys/belts, to bring ballscrew horizontally closer to the quill. But then, if possible I would like to avoid any added complexity, because of my non-existing experience with these beauties.
-- Another concern I have is the length of the Z-ballscrew (somewhere around 370mm), and no support in middle.

[Robin Hewitt]

Thought about using pulleys/belts, to bring ballscrew horizontally closer to the quill.

Close as you can, even if it means taking an angle grinder to the mill head. Nothing wrong with timing belts and pulleys, much preferable to microstepping and you don't have to align the motor to the screw. Avoid small pulleys, you want lots of teeth engaged on the belt.

Are you not using taper tooling? I don't see where you plan to release the quill from the screw when you hammer the taper out. The two point quill nut mounting looks really good.

[diy-john]

Thanks Robin, yes need "release the quill from screw". Will keep that on the list :) Need to still think ways to bring the ballscrew closer to the quill.

This has been a very useful thread, helped a lot. Thank you!

Hope to continue as a build-log here...
http://www.mycncuk.com/forums/showth...ersion?p=28322