Third Modification - Bean Hopper and Plunger/Weight
The dual objectives of this third and last modification are to (1) fit the grinder within the available cabinet clearance above the kitchen counter and (2) enable the best single-dose grinding possible without a hopper-full of beans.
The summarized steps below involve cutting the funnel, creating a cylindrical (straight-sided) insert and creating a matching plunger/weight.
Cutting the funnel was done by tracing a line at the measured height (whatever fits best fit under your particular cabinets). The easiest way is to steady a marker or scribe at the correct height (vise, stack of books, sleeping cat - whatever) and then mark the circle by turning the inverted hopper against the marker through the full 360 degrees. Apply masking tape right up to that line to protect the final product from scratching, hold the hopper steady (vise, clamps, teen-age volunteer) and cut. In a perfect life, one would own a band-saw for this, but a fine-toothed hacksaw works fine.
After cutting, you will have a short funnel for the top, and if you don't care about pop-corning you can stop right there: the Macap hoppers provide a neat sliding barrier at the hopper bottom, about 1¼" from the top of the burrs, preventing unauthorized escape of rogue bean shards. However, if you went so far as to procure a Titan grinder, I'm guessing that you do
care about pop-corning, so onward we go.
The cast metal grinder throat of the M7K is slightly conical; it does not have straight sides. So the part of the acrylic Macap bean hopper that fits into that throat is also conical - on the outside, but, critically, not on the inside
! Macap's acrylic gets progressively thinner toward the bottom, providing essentially straight sides on the inside. This enables construction and installation of an inner cylinder - with a constant inner diameter top to bottom - through which the plunger/weight can travel to control the beans all the way down to the burrs.
I got some clear acrylic tubing from my local plastics supplier with an outside diameter of 2 3/8" with 3/16" walls, leaving an inside diameter (for the beans and plunger/weight) of 2". Regarding these dimensions, only that outside diameter of 2 3/8" inches is critical, since that equals the inside
diameter of the Macap funnel throat into which the cylinder must fit.
You will also need to grind some plastic out the top of the funnel base (Dremel again), removing the channels for the aforementioned Macap sliding barrier. This is needed so the funnel will accept the full diameter cylinder, which is otherwise constrained by the presence of these slider channels.
For my own setup, I cut three lengths of the acrylic tube, the first one being 1" long, plus an additional 2" extension tube and finally a longer 6" extension tube (using the same scribing/tape/hacksaw routine used when cutting the funnel above).
The shortest 1" piece fits inside the bottom of the Macap funnel. This piece fits tightly enough without help, but you can keep it even more firmly in place by tightening Macap's original funnel retention set screw through
one of the slot-holes in the funnel base and tightening it against the wall of your new inner acrylic cylinder.
This is really all you need, just tossing the beans into the funnel base with this 1" piece installed, and using the plunger/weight. In this configuration, you'll be at the minimum height (for under the cabinets, remember) plus as the picture shows, it's the perfect storage location for an Orphan Espresso 58mm dosing funnel (if you don't already have one of these little genius gems, go order one from the OE Web site right now since it will change your life).
The 2" or 6" (or whatever size you like) extension tubes can be added on top, however, to give you a deeper total cylinder in case you want to grind more beans at a time, or you wish to give the plunger/weight more stability. To hold the extension in place, there's roughly half an inch of the Macap funnel base left above the bottom 1" tube to lock the extension in a nice tight press-fit - but it's easily removed whenever you want to slide the grinder back under your cabinets or use one of the other hopper options. Note that the same plunger/weight is used in all cases to maximize consistency.
This picture shows the 6" extension set into the funnel on top of the the 1" base tube:
You'll also discover that it's easier to pour all the beans into the extension tube's opening if you place or fasten another Orphan Espresso dosing funnel (49mm this time) on the top of the extension tube.
The final step of the project is making the plunger/weight. I used a solid cylinder of UHMW (u
eight) polyethylene rod stock with a 1¾" diameter that fits inside the new acrylic bean cylinders. For a half-pound weight, cut about 6".
Since the inside diameter of these cylinders is 2", that leaves 1/8" of play all around, which is ok but I'd have preferred the UHMW to be 1 7/8" for a slightly tighter fit. My local plastics supplier only carried the 1¾" diameter stock however, and the only place I located 1 7/8" diameter UHMW rod on the Web required a $600 minimum purchase. So: you may have an easier time if you use a slightly thinner wall (1/8") acrylic, which would leave a wider inside diameter of 2 1/8", enabling the more readily-available 2" diameter UHMW rod to be used for the plunger/weight and providing a slightly better fit.
To make the plunger, I started by cutting a 6" length of UHMW bar, then sanded the ends smooth. Advice: use a fine saw blade for the cut, which will make your sanding a lot
faster and easier. UHMW is great material to work with and it machines beautifully, but sanding out a coarse cut with deep scratches will take you some time since this stuff is dense-dense-dense. You also need
to sand it very smooth since otherwise, grinder fines will lodge in the scratches and the plunger/weight gets dirty-looking at the ends pretty fast - although you can always fix that via dishwasher.
In the top center I drilled a pilot hole for a stainless eye bolt which, while perhaps less than the acme of elegance, proves very easy to hold or pull out of the cylinder with thumb and forefinger. Make sure whatever hardware you choose for this purpose is stainless steel to withstand the aforementioned dishwasher.
On the opposite (bottom) end of the rod, center a relief hole about 1/2" deep and 5/8" wide to accommodate the grinder's top burr retention nut. On my M7K, this takes the form of round hex-key nut with a nice smooth washer underneath (see burr photo above), enabling the plunger/weight to ride all the way down to that washer while leaving 1/16" clearance above the burrs. (Note: the hardware and burr sets seem to vary depending on the vintage of individual M7Ks, so the particulars of your own burrs and their hardware may vary.)
Again, UHMW is great to machine, so if you're equipped with the tools and patience, you can probably mill the burr end very specifically, even enabling the plunger to extend down within
the open space below the top of the burr set to eliminate even more pop-corning area. With the big slow burrs augering the beans down anyway, I'm unsure how much difference this extra step would make. (But hey, if you've read this far, there's a pretty good chance you're certified OCD anyway, so why leave such an opportunity unexploited?)
You'll see in the photos I've added a pair of black neoprene washers to the plunger/weight. These keep it centered nicely within the hopper tubes, and prevent bean shards from creeping up along the sides or possibly causing the plunger/weight to stick in place, surely causing popcorn chaos to ensue. I intend to rout out a shallow groove just above the plunger's bottom edge so the lower washer won't move around, but you can easily roll the upper one up or down to best match the particular cylinder/tube length you're using at the moment.
if you're not too stoked on caffeine - it's time to get some sleep and look forward to using your tamed Titan to grind your morning coffees. I'm sure that many improvements can be made to this overall design and I'd like very much to hear what you come up with - and of course I'll be happy to do my best to answer any questions you PM or post here.