2nd Generation CNC Mill

NexMill 15 -Part 6

Gantry, more "Z" & spindle mount

This is the 3rd and final welding session.

In an attempt to straighten a minor misalignment, I broke the main gantry assembly. This caused more grief, as the flaw I was trying to correct ended up being exaggerated rather than minimized.

Numerous welds were re-dressed to build more strength and rigidity.

This exercise took the better part of an evening, as it included drilling 7 mounting holes and careful shim placement.

The gantry looks fairly true from most viewpoints, but the most critical issue is that it forms a perpendicular plane for the X axis mount.

The Z-Axis casting was easily positioned once the gantry was securely fastened.

This shade of blue is the bottom of the can that was used on the steel cabinet that is the base for the mill.

I must not have shaken the can at all, as the base is far darker than this...

Regardless 2 coats are liberally slathered on to seal the metal and tie the project together.

The rails in the Z-axis are replaced with heavier 1/2" polished rod that is perfectly matched to the linear bearings scavenged from the unit below.

It's very hard to describe, and even harder to get a good picture of, but this is a dual stepper assembly that I recovered from a trashed Xray Film processor.

The unit was stored for a few years in a dry but unheated area, and has rust forming on various areas.

This portion will be the Gantry for the "Gen-3 Mill" that will start development should this unit ever go on-line.

This is a better shot of the rust that will need to be cleaned-up. This Gen-3 Mill gantry has a travel of approx 20" with a 4" mounting plate for a Z-Axis similar to the one in this project.

Above on the left is one of the Stepper/leadscrew assemblies that I removed. I was going to use it in it's entirety, but would have required more work to accommodate the existing Z-Axis casting which is actually far simpler and much sturdier.

The image on the upper Right is a close-up of the actual linear bearings, I assume that these are in fact linear bearings, as they have 3 rows of bearings spaced at 120 degree intervals.

I did cut off 6" of the lead screw and will use the driving nut from the second stepper assembly.

The end has just been turned down to 0.250" in diameter to mate to the stepper shaft.

The lathe is real time saver and far more fun than trying to reduce this by hand with a power drill and a file.

The driving nut was way too tall for the Z-Axis and had to be cut back by 2", I left almost 1/8" extra on the block so that it could be faced as a true flat for fastening to the spindle mount.

This is the tool-path for the spindle mount assembly.

I really enjoy using the existing mill to do things like position drill pattern for the bearings and driving nut.

Notice the "qualitycasting.ca", marker... theworkshop.ca will be splitting again to a new domain over the next few months as the foundry business site will become a greater focus, and theworkshop.ca will be the more personal interest hobby site.

Remember, the only casting is a qualitycasting.ca (go-live Mid to late April/2005)

Hopefully this design works well, the addition of pockets and ribbing were more esthetic than practical.

In theory the casting is marginally lighter and stronger, but still over kill for holding the spindle head.

This is a 3/4hp rotary tool with 2 speeds, 20,000 and 30,000 rpm, an external speed control will be added to offer a wider range of speeds.

Purposefully I ensured that the "Mastercraft" label is front and center as I'm still fishing for some sort of sponsorship deal to come through...

Look at how "Dremel" is hurting since they spurned the option of being the "mill-head of choice" at theworkshop.ca, I'm sure somebody got fired over that.

Remember "Mastercraft" the house brand of "Canadian-Tire Stores" from coast to coast to coast.

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