Knee Mill CNC Conversion- Your thoughts???

[davo727]

I like your idea of making a new upper unit with linear rails and attaching the head to a Z slide. I am looking forward to seeing your design. I will make a few drawings too and will post if I come up with anything that looks good. Cool idea, using the Nice heavy bridgy base and lock the old knee down and make new upper with linear rails and slide Yeah!

[Moondog]

davo.

Thanks for your reply. glad u like the idea.. think it has some merit.

Assume you are referring to idea no 1 ???

Was thinking to use a 20mm ballscrew, 25mm linear rails and 30mm Alum plate. The base plate would be bolted very securely to the ram.

Would need to change the motor mount as it currently hangs over the back and would probably interfere with the Z movement downward??? maybe...

Do u think it would be rigid enough? any machine engineers out there?

cheers

Frans.

[davo727]

Hey moon, Will your head have an extention between the mill head and your new Z axis slide? Also where do you figure on putting the ballscrew? If you make a square column to bolt on top of your base, the ballscrew can be inside the column. Can you post a rough drawing of a side view of your mill with measurements of the base, head and everything so i can get an idea on where things might fit? Also Im thinking 3/4 ballscrews are too small. 1 inch much better. I added a pic of a SW Ind mill to show how they use a head similar to a bridgeport type on a bedmill. Also please post a pic taken of a direct side view of your mill if you can.

[Moondog]

Davo...

next time I go into work I'll take a pic.

The photo of the mill in your post would be ideal, but on my mill the column (dovetail) is not long enough to fix the head to it.

What I'm proposing is a Z Axis setup that is used on Routers. 2 * 30mm Alum plates with the Linear rails/bearings and ballscrew in between. One plate is fixed to the Ram and the Spindle Head attaches to the other plate. do you know what I mean?.

cheers

Frans

[davo727]

Umm , No I have to see a drawing to see what your plan is.

[Moondog]

Davo.

here is a real quick drawing, not to scale of the proposed Z axis.

cheers

Frans

[davo727]

OK, thats cool. simpler than what I was thinking. I was figuring on a longer vertical rail setup and having to space the spindle assy out but with your machine design thats not neccesary. What length rails and Z travel do you think you might do? So next you can figure out height of linear rail and block assys and figure out if thats enough gap for the ballscrew and nut or you might have to space the rails out a little. Anyway I bet it will work good. Dave

[Moondog]

Originally Posted by davo727 OK, thats cool. simpler than what I was thinking. I was figuring on a longer vertical rail setup and having to space the spindle assy out but with your machine design thats not neccesary. What length rails and Z travel do you think you might do? So next you can figure out height of linear rail and block assys and figure out if thats enough gap for the ballscrew and nut or you might have to space the rails out a little. Anyway I bet it will work good. Dave

Davo...Trying to keep it simple. Lenght of rails etc would only be around 400mm or less. Only want travel of around 150mm to lessen flex. the height of the rails, blocks and Ballnut will determine if the rails fit flush etc... Next will be to re-draw everything to scale to determine sizes of components etc...

Hopefully it will be stiff enough.

cheers

Frans

[davo727]

Sounds like a good plan, I look forward to seeing it go forward.

[chich2]

Yea I understand. Like you say, under that configuration it would pretty much eliminate all quill play the machine may have.

Great Idea. Now to build it.

Chich