King Midas mill conversion

[diy-john]

WOW it runs now

- connected PUL- and DIR- to pin 25 on parallel port, like you say Jonathan.

The cables are so loose one does not dare to breath near the machine.

Going to try to buy some electrical connectors or something for the parallel port, tomorrow.
- I have tried to use an old printer cable, which I cut in half. But the wires are so small it is difficult to handle them.

Thanks so much, very happy now.

[diy-john]

Status is now that all three (3) Nema 23 -motors turn. Driving them with EMC2 (linuxcnc)

To get here, what I have done yesterday and today is:

1) Bought some sundries from a local Electrical store:


2) Parallel printer cable - test each of the small 25 different wires with a multimeter.
- try to understand which colour cable links to which PIN on the parallel port
- here is the printer cable cut, from the "printer end" of the cable
- measured with "continuity mode" in multimeter, each of these 25 small wires.
- for all of you these are probably really elementary steps. But for me it was a bit of a surprise, that one would have
to get into this level of detail.
-- Had relied on some charts I had found from internet, on colour schemes of the parallel cable wires. But they did not seem to match my cable, so had to manually check each of the wires,
to which PIN they connect in parallel port.
- Found these "alligator jaws" handy


3) Here are the parallel port PIN's, cable colours, and where I have connected them on the Leadshine M752 drivers.





4) A picture of how they are on the table now
- had bought 30 LED's for troubleshooting.
- found them helpful, though 30 is too many. I ended up using just one single


5) Now, what do you think?
- Could one now solder cables neatly in place?
- Have been thinking of using this kind of 9 PIN -cables for each stepper-driver


-- So that the cables could be quickly attached / detached.
-- Would use these for the low-voltage, parallel cable wires.
--- Parallel cable (25 wires) ---> divide to 3 smaller cables (9 PIN) ---> each stepper driver

Motors seem to work okay, though they don't "home" itself on the EMC2. Not sure why that is. Haven't got a stop-switch, limit switches yet.

Please comment on whether one can now solder things, or should one wait until have limit switches and emergency stop-button?
- actually, any and all comments welcome

Thanks!

[Jonathan]

- for all of you these are probably really elementary steps. But for me it was a bit of a surprise, that one would have
to get into this level of detail.

Most people buy a breakout board and connect the drivers to that which simplifies things as the pins are labelled. Breakout boards also add isolation, but since the drivers you are using are already optically isolated there's no point having additional isolation on the breakout board, so connecting it directly is fine. However if you connect the switches directly (with just one pullup resistor on each) clearly there is no opto-isolation, unless you DIY.

[diy-john]

Just a brief update;
- decided not to solder cabling yet, as one might still want to make changes
- today have been thinking what kind of functionalities one might want from the mill, in terms of
-- homing
-- limit switches
-- zeroing

Fiddled with EMC2 (linuxcnc), added a similar function, as here
http://www.youtube.com/watch?v=DOBxt9MIbFo

...to auto measure workpiece surface level.

Of course haven't got the mill converted yet. Just simulated the real thing, with Z-axis motor running on table, and two wires in my hands (one cable attached to parallel port PIN 13, the other ground, think it was PIN 21).

[diy-john]

Hello!

Well, it has been some 6 months since this project has been on hold.

Not much has happened since. Got screws machined - thanks to Jonathan. Then got tied up with work, had to put all hobbies aside, and let's leave it at that. Really quite embarrassed and sorry for being away for this long.

1) Plan now is to pick up the pieces, try to remember which planet we are on, and get the mill running. Not pretty. Not good, but get it running.
1.1) For that need some bearing mounts made. A local machining workshop will make some simple mounts, hope to get them in a couple of weeks
1.2) Need attach the ballscrews
1.3) Need attach the ballnuts

For 1.2) attaching the ballscrew on Z-axis, I have today started removing the Z-axis existing pinion / spring.
- For reference, discussed this Z-axis matter earlier here: http://www.mycncuk.com/forums/diy-ma...onversion.html

What I have done today is:
A) Started removing these levers


B) So far quite easy, just use a HEX -key to open screws


C) After about 5-minutes, got already most things away from right-hand-side of the mill



D) Spring mechanism was on the left-hand-side


E) Now the spring-mechanism was easy to remove, but this is as far as we got today


F) On the other (right) hand side it looks now like this:



Now, would appreciate some tips:
- please should one remove the rest of the gears?
-- Reason I would like to remove the gears,is that I am hoping to use the hole(s) for attaching a rigid structure, on either side of the quill, to mount Z-axis bearings + motor
-- Or do you think one would be happier having the hand-lever to lower the quill?
- If gear should be removed, how does it come out? Attached is a technical drawing of the mill components, if someone would take a care to give an opinion (on how to remove the stuck gear/shaft)?



Thanks for reading

[Jonathan]

Have you tried tightening the two nuts in picture C against each other, so that they lock on to the thread, then use the inside one to unscrew the threaded rod? If it's in a tapped hole that should get it out.

I wouldn't worry too much about the hand lever. I tend to remove the hand levers on my mill when I'm using it with CNC since they have a tendency to hit stuff (or me) if I don't!

[diy-john]

A small update:

- the pinion gear eventually came out by punching the bearing out, slowly and carefully, from the opposite side


- here is the gear/bearing that came out - this is all obsolete now


- now the Z-axis looks mean and lean (LEFT: BEFORE, RIGHT AFTER)


- Now, I have bought a pile of these sort of building materials, and plenty of short 5mm bolts/nuts
-- They are made from galvanized iron, (or the more expensive ones, are stainless steel, very rigid)
-- Aim to attach bearing mounts to structures made from these building materials
-- This is cheap, but thought would make a running mock up with them.
-- Hope that way one could run the machine a bit, check dimensions again, check where to improve --> then make rigid, nice looking parts from aluminium.

Maybe this ugly duckling will turn to a beautiful swan some day.