2-axis Sharp knee mill revival - Now with 50% more axes!!

[FlySox]

Back to regularly scheduled programming: a few more posts to finish up this build log. Let's start with a mercifully quick summary of the Elrod Z-axis kit install:

You take a bunch of stuff off of your mill’s head, including the quill stop thread and the quill auto-feed speed selector:

After some prep (paint removal, possible grinding), you bolt on the ball nut holder, tram the mill and then carefully align the face of the kit, using an alignment tool that is un-helpfully not included (I 3D printed one, not having access to a lathe):

You then install the top piece, connecting it to the face and to the mill head via a right-angle connector that bolts into holes formerly used to hold the quill feed engagement boss:

Next, you install a support bracket where the quill auto-feed speed selector once was:

Slip in the ball screw assembly (after realizing the bearing holder was pre-installed upside-down *sigh*), and tighten down with a locking star washer:

Install and wire limit switches:

CONTINUED...

[FlySox]

[Elrod Kit install CONTINUED]
Next, you have to ensure that the ball screw pulley and the motor pulley line up. This means you have to at least test-mount the motor to the motor mount provided with the kit. I wasn’t able to do this, since the holes in the faceplate of my motor did not line up with those of the motor mount. I knew this even before buying the motor, thanks to Marty’s responses to my pre-sales questions.

Turns out, I have access to a machine that can help here… Hardly a rigid setup, but these are oversized clearance holes, so a bit of imprecision doesn’t matter:

You can see from the picture above that the motor faceplate has a raised boss around the shaft, 3” in diameter. This prevents it from seating nicely on the mount. I was going to make a 6061 adapter plate with a 3.05” bore to accommodate it, but I came up with an easier solution. I laser cut some gasket material, which when installed on the motor, created a flush surface for mounting:

After that, it was a matter of lining up pulleys, mounting the motor, and tensioning the belt:

Added the new axis and set limits via the wizard; all went smoothly. Here’s the final result:

Contrast that with the first picture of this mill before I started the conversion. It’s come a long way!!

[FlySox]

Next item on the check list: Spindle speed control.

I punched a hole in the cabinet that houses my Automation Direct GS2 VFD using a Greenly knockout punch. These punches are nice in that they split the slug making removal from the punch die very easy.

I used shielded Cat6 Ethernet wire from the VFD to the Acorn. Might be a bit thin in gauge, but the run is less than 15 feet, so I think it’ll be OK:

I wired the VFD per this tech bulletin and tuned it according to this post, confirming RPM with a handheld tachometer (the required reflective strip for which is pictured):

While I was messing with the control box, I figured I’d add the $50 wireless DT02 tool setting gauge to the Acorn, too.

The issue with this probe is that you have to touch it once as you start up the machine or your VCP will appear stuck in “turtle mode”. Forum member cncman172 came up with a way to remind you to touch it during startup, but I have yet to implement that. My idea is more hokey: I’m going to put a little sticker on the probe that has a fingerprint graphic and says “authenticate for high speed”

That’s essentially the build to date. I’m going to add a Fogbuster and a power drawbar. In fact my first “real” CNC job from Fusion 360 CAD—> F360 CAM—> Centroid Post processor —> G-code file —> machined part was a series of plates to convert a butterfly pneumatic wrench to a power draw bar mechanism. Perhaps I’ll post a few pics of that project (teaser below), but the bottom line is:

I’m making chips!

Thanks to all the helpful forum members and to Centroid for the wonderful Acorn board and CNC12 software. Couldn’t have done it without you!

[Muzzer]

Thanks for posting that. I'd have loved to have seen this level of detail when I was trying to figure something out for my own Z axis. That Elrod system is maaahassively and impressively overdesigned but perhaps some of that comes from having the whole chebanc hanging out the front of the machine. All it's doing is pulling / pushing the ballnut up and down the ballscrew, so unless you plan to use the machine as a press, the forces are fairly limited (you can calculate them from the motor torque and ballscrew pitch).

The weakness remains the overhang of the ballnut from the quill, with one machine screw (yoke to quill) taking a significant load. That was the motive for moving my ballscrew as close to the quill as possible and taking the thrust bearing loads directly onto the head casting.

I doubt I'll use the machine in manual mode, so being able to loosen off the ballnut from the yoke may have little benefit in the end. With an MPG you can pretty much do what you need manually anyway. So for the next version, I am doing away with that option.

Hopefully you will be able to post some pics soon!

[martyscncgarage]

Back to regularly scheduled programming: a few more posts to finish up this build log. Let's start with a mercifully quick summary of the Elrod Z-axis kit install:

You take a bunch of stuff off of your mill’s head, including the quill stop thread and the quill auto-feed speed selector:


IMG_1423.jpg


After some prep (paint removal, possible grinding), you bolt on the ball nut holder, tram the mill and then carefully align the face of the kit, using an alignment tool that is un-helpfully not included (I 3D printed one, not having access to a lathe):


IMG_1335.jpg


You then install the top piece, connecting it to the face and to the mill head via a right-angle connector that bolts into holes formerly used to hold the quill feed engagement boss:


IMG_1344.jpg
IMG_1338.jpg


Next, you install a support bracket where the quill auto-feed speed selector once was:


IMG_1340.jpg
IMG_1343.jpg


Slip in the ball screw assembly (after realizing the bearing holder was pre-installed upside-down *sigh*), and tighten down with a locking star washer:


IMG_1345.jpg


Install and wire limit switches:

IMG_1352.jpg

CONTINUED...

Flysox, check your PM.
I'm looking for the instructions for the Elrod Z axis quill drive kit. I have to take one off an older Bridgeport head and reinstall it on a new head. You mention an alignment tool you made or there are dimensions for. That would be belpfl6.
Thanks,
Marty

[RJS100]

Just a quick question. When you wired your probe to input 7, did you use the header screw connector terminals or the DB25 connector?

Thanks... Richard