CNCCookbook: Mill Enclosure

After getting a note from a reader that got me to looking over my enclosure idea notebook, I couldn't resist getting started on an enclosure for my own IH CNC mill. For one thing, I've reached a stage where between G-Wizard's ability to tee up superior speeds and feeds and my own learning curve with CAM and various toolpaths and finish techniques, my material removal rates have gone WAY up. I expect better surface finish and even higher material removal rates will be possible with full flood coolant, but the biggest advantage is not having to deal with the mess. With the feedrates and material removal rates way up there, my mill throws chips as far as the eye can see. They get into everything from my hair to the keyboard on the laptop I run to control the machine. Simple shielding barriers don't seem to deter them in the least as the laptop hides behind a pretty good shield in addition to its own screen yet it still constantly picks up chips.

I started with the mill's footprint travel-wise and being mindful of how far the servo's protrude. I also gave thought to the table height relative to the door opening of the enclosure. Some sketching in Rhino3D led me to this result:

IH CNC Mill Enclosure

This rendering gives a flavor for the enclosure. Mill table (blue) is shown in its full forward and centered position...

More views...

Some dimensions...

On the dimensions, note that we let the pan bottom left/right and the short right and left sides run slightly long. The center of the pan was cut to size. This allowed us to cut the angles for these pieces to meet up, fit them up against the front and rear pieces, mark off the actual measurements, and then make a final cut to size. Leaving this room for adjustment was a good idea!

More dimensions for the door...

And side window dimensions...

You can download my Rhino model here. Republish the model or use as you like provided you give credit for where you got it from!

One further requirement is I wanted to be able to hinge down at least three of the sides of the enclosure to make it easy to work on the mill or to deal with workpieces that hang over too far to fit inside the enclosure. When I drew the sketches, I made no allowance for how the mounting of the walls was to be engineered. I plan to work that out right after I build the chip pan and cut the sides so I can experiment. Ever since having seen a Deckel with the hinge-down feature, it's been on my must-have list for an enclosure.

Deckel with Enclosure up...

Convenient to be able to put the enclosure down...

After looking over the dimensions of the enclosure, and the space I have available, I decided not to go with a hinged design. Instead, there are two means of gaining further access:

- Each side is individually removable.

- The side windows can be opened.

That should provide quite a lot of leeway. The issue with hinging is the spot I want to put the mill enclosure won't leave room to clear the big sides if they're hinged.

The stand is rock solid and quite heavy. The chip pan will sit directly on the stand, and the mill base will sit on the chip pan. The wooden chip pan should help absorb some vibration as well, though I expect to bolt the enclosure to the stand just to make sure it doesn't go anywhere.

As you can see from the design drawings above, the IH has a pretty good-sized footprint, so I built a largish chip pan for it. The materials are furniture-grade 9/16" plywood (on sale at Home depot, so I couldn't resist picking up 5 sheets of it). Waterproofing will be 3 coats of West Marine Epoxy. This is what the boat builders, who have to deal with a lot more water, use for wooden boats. In addition, I have a fair amount of left over epoxy from my adventures in filling the mill base with epoxy-granite. You want the 3 coats to be rolled on pretty thin.

My brother runs a picture framing business, so he handles the woodworking end of our projects...

I would estimate we have about 5 hours in the pan to this stage, including an hour visit to Home Depot...

We used a holesaw to create some rounded corners. The straight edges were cut with a RotoZip and a straightedge guide clamped to the plywood. When RotoZipping, be sure to consider whether you're making a Climb or Conventional cut. Handheld tools have a lot of "backlash" so Climb is preferred!

The back wall is structurally the strongest anchor of the 4 walls. In addition to the corner braces, it has this back brace made with some plywood and attached via T-nuts and through bolts...

Here is a look at the corner braces. These are just standard house framing braces. Once you've got one top and bottom it adds a huge amount of rigidity without adding weight or bulk...

Here you can see the top and bottom corner braces. Bottom ones are anchored in the chip tray. Once all four sides are bolted together in this way, the enclosure is solid!

If you go sniffing around the web, there's quite a lot of information about coolant systems. One of the things you notice pretty quickly is that flood coolant seems to fall into two categories. First, the low end systems look like they're just pouring the coolant through the line loc without an awful lot of pressure. Many of the hobbyists who've hooked up pond pumps to reservoirs get this effect as do machines that lack enclosures. I'm sure these systems do a decent job and you don't want much more going on unless you have a full enclosure. But, being from the school of "too much is not enough", I wanted more. If you go look at videos of commercial VMC's, you will see that they have more. That raises the question of, "How much is 'more'?"

Again, the Internet makes it easy to check these things out. My IH is no full-sized VMC. It's more similar to something like a toolroom mill. The Haas TM-2, for example, sports two coolant options. The stock is a 1/8HP pump. The upgrade is a 3/4 HP pump delivering 5.25 gpm @ 30 psi. Now there is a spec to aim for. I'll be researching pumps in the over 1/8 HP and closer to 3/4 HP range. I'll let you know what I come up with.

Chiptrap: I want a tray arrangement that sits on top of the reservoir, catches most of the chips, and is easily cleaned.

CNCZone Gravity Separator: Like the gravity separation of the real fine stuff with something like the Chiptrap for the bigger stuff.

CNCZone Haas VMC Notes: "Aluminum tends to float on the coolant." Hmmm, that bears some thinking about!

I'll be running an aquarium-style aerator stone in the reservoir to keep the bad bacteria (anaerobic means they depend on a lack of oxygen to thrive) at bay. It agitates and aerates the water enough to keep the bacteria from getting too crazy on a low volume setup like mine.

Love this cheap long entension nozzle setup from Harbor Fright. Will have to see how well it works with coolant, but seems like a handy way to wash down the chips. OTOH, a garden spray nozzle may work just as well with coolant, so might save the long nozzle for air.