Z-Axis Advice Please...

[Zuni]

I'm preparing to build a slightly-modified version of the 4x4 kit offered by Fine Line Automation (FLA-300), and am hoping to tap into some of the vast experience of the membership regarding the Z-axis as well as cable management on the gantry.

The first modification is the use of the high z-axis plate, (hopefully) giving me 12" of travel on the z-axis before flexing/twisting comes into play. Use of this high Z-axis plate puts the Z-axis stepper motor atop the moving portion of Z-axis.

The second mod is a lower bed, as shown in the rendering below, allowing me to rout foam blocks up to 12" in height.

Problem #1 is that I'll also be working aluminum on this machine, so it has to pull double duty. I have the feeling that to work the aluminum cleanly and accurately, I want to be somewhere in the middle of the z-axis travel or shorter (as opposed to at almost the full 12" downware extension of the Z). Can anyone suggest an elegant way to handle this?

Problem #2: Since the z-axis stepper motor is atop the moveable part of the z-axis assembly, it travels up and down as well as across the y-axis, making the use of a cable chain impossible (I think...).

The rendering below shows the z-axis assembly in 2 extremes of travel (the machine won't have 2 independent z-axis ). To further complicate things, I'll also have to accomodate 2 cooling lines for the spindle along with the normal wiring to the z-axis stepper and wiring to the spindle.

I'm sure others have vertically-moving Z steppers and water-cooled spindles; Just wondering how you handled the cable mamagement along the gantry. I'm looking for something clean and self-contained as I'm hoping to avoid cables and hoses dangling down from my ceiling to the machine

Thanks!

--Mark

[DonFrambach]

I made a small router with back-to-back mounting using something very similiar to the high z-axis plate as marketed by CNCRouterParts.com. Although the z-axis motor moves up and down, I was able to make an echain for the cables that works just fine. Here's a link to a YouTube video: YouTube - Small Router cable management.MP4

Your Z-axis is most rigid when the spindle is closest to the bearings. I would suggest that you make a rigid structure to mount on your platform that will raise the base 6 (or more) inches to effectively shorten your Z axis when you cut aluminum.

Although you may have already taken this into account, I would suggest you consider beefing up the moving gantry supports (and consider using the longer bearings) because they will flex as well as the z-axis itself when you suspend a spindle 12" down.

[Zuni]

Thanks. looking at your video, I realize that I left out a key piece of information on my cable management dillema: The Y-axis is a rack and pinion unit, so the Y stepper moves along the gantry in concert with the Z carriage, but at a fixed height, while the Z stepper is going up and down above it:


I didn't show it in the rendering, but the gantry beam will be gusseted at the moving gantry supports to minimize the leaning tendency when the z-axis is fully extended.

My initial thought for raising the bed 6" was to mount some tabs, or better yet a calibrated (leveled and trued) rail, along each inside support of the machine, so I can slide in another higher bed in and out when needed, but that seems like a pain in the butt and is one more (large) piece to store somewhere:

[DonFrambach]

I think this is what you're looking for. Here's a beautiful router with moving gantry and moving Z axis motor with very clean cable management. http://www.cnczone.com/forums/diy-cn...ys_router.html
To whet your appetite, here's a photo from his build log:

[DonFrambach]

In keeping with the KISS principle. Assuming that you're going to mill smaller pieces of aluminum. Why not simply have a 12"x12"x6" (approx) block that you attach to the main bed of your machine?

[Zuni]

Originally Posted by DonFrambach I think this is what you're looking for. Here's a beautiful router with moving gantry and moving Z axis motor with very clean cable management.

Perfect, thanks! MrGilly's cable management is what everyone strives for. I never thought of 2 separate cable chains mounted like that. That'll work!

Originally Posted by DonFrambach In keeping with the KISS principle. Assuming that you're going to mill smaller pieces of aluminum. Why not simply have a 12"x12"x6" (approx) block that you attach to the main bed of your machine?

Unfortunately, I'll be cutting out large panels in sheet aluminum. In fact, I'll do more aluminum sheet cutting than cutting molds from 12" foam blocks.

Thanks for the tipoff about the cable management.

--Mark

[DonFrambach]

Good luck with your build. I hope you have time to post your build's progress.

Don