Two machines, twelve sheets. Part one, motorized column press, inches. Part two, spring press brew head, millimeters. Each part ends with its bill of materials.

Concept study, motorized press, side elevation

Sheet one. Retracted position solid, plunged position phantom.

Sheet two. Force limiting cartridge, twice scale.

Sheet three. What the donor tool contributes.

Sheet four. Solid model, near quarter removed, running one plunge cycle.

Sheet five. Exploded along the drive axis, fifteen pieces.

Sheet six. Parts list for the motorized column press.

Every made part on sheet six carries the stock it gets cut from, not just the finished size, so the turned parts read as bar diameter first and finished diameter second. The exploded model on sheet five shows fifteen of the forty five pieces, the ones large enough to be worth pulling apart on screen.

The machine is a countertop column. A one liter glass carafe sits in a locating ring on a cast base, a post carries the drive head over the center of the carafe, and the sealant gun rack rod comes straight down through the lid instead of straight back through a tube cradle.

Four parts move over from the donor tool with no change at all. The brushed twelve volt motor, the reduction gearbox behind it, the toothed rack rod, and the six position speed dial that already turns down to a crawl. The slowest two settings put the screen through the coffee in something between twenty and forty seconds, which is the range that keeps fines on the bottom and out of the cup. The trigger becomes a press and hold button on the head, so letting go stops the plunge exactly the way letting go of a caulk gun does.

The one part that has to be invented is the red cartridge on sheet two. A sealant gun pushes several hundred pounds because cold sealant needs it, and a glass carafe would break long before that motor felt anything. So the rod does not touch the screen. It threads into a sleeve, the sleeve holds a compression spring, and the spring pushes an inner stainless shaft that carries the screen. The spring is picked to start collapsing at about five pounds, so a wedged grounds bed or a hand in the way just compresses the spring while the rod keeps traveling, and the glass never sees the motor. That single component is the difference between an appliance and a hazard.

Travel stops twice over. An adjustable collar on the rod up inside the shroud trips a switch that cuts the drive with the screen four tenths of an inch off the carafe floor, and the collar slides for people who use a smaller carafe. The anti drip reverse that already exists in the donor tool backs the screen up a few tenths when the button releases, which is convenient here because it unloads the grounds bed before pouring.

Everything that touches coffee comes apart in one motion. The screen assembly is a quarter turn off the shaft, and it is the stock mesh and silicone rim from an ordinary press, so replacements are two dollars at any grocery store. The stainless shaft is the only metal that ever goes below the water line.

Power is a twelve volt wall supply at the back of the base, which keeps the machine light and the price low, and the same voltage means a slide on pack can hang off the rear of the post for anyone who wants it cordless. That option adds two and a half inches of depth and about a pound.

Building the solid model on sheet four caught something the flat drawing hid. At full plunge the rack rod climbs so far out of the carafe that its upper end nearly leaves the pinion, so the shroud grew about an inch to keep four or five teeth meshed at the bottom of the stroke. That is the whole reason to model a thing before cutting metal. The running cycle also shows the anti drip retract doing real work, lifting the screen a quarter inch off the grounds bed the moment the button releases, which is what keeps the puck from being disturbed while pouring.

Sheet five separates the fifteen pieces along the drive axis. Reading top to bottom, the shroud and travel collar, the head with the motor and gearbox and pinion inside it, the rack rod, the spring cartridge, the stainless shaft, the bayonet and screen, the carafe, the lid collar, the post, and the base with its locating ring. Only six of those need to be made new. The rest are either stock press parts or come straight out of the donor tool.

Standing size is fourteen and three quarter inches tall, eight deep, six wide. That clears the eighteen inch gap between a countertop and the upper cabinets, which is the constraint that actually decides whether a gadget like this lives on the counter or in a closet.

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xxxxxxxxxx / spring press brew head, drawing set

Sheet seven. Full section, brewer resting on a 150 ml cup, piston shown cocked with the end of stroke phantomed.

Sheet eight. The seal and the lock, the two places this design lives or dies.

Sheet nine. Cycle timing, one stroke.

Sheet ten. Solid model, near quarter removed, cup filling stroke after stroke.

Sheet eleven. Exploded on the chamber axis.

Sheet twelve. Parts list for the spring press brew head.

Sheet twelve lists stock size before finished size on every turned part, so 78 dia bar x 24 is what gets ordered for a lid that ends up 76 by 18. That gap is the answer to the price of stainless. Bar is sold by the pound and most of the pound becomes chips, so a lid, a stand and a ball knob in 6061 save more through faster cutting than through the stock price, and neither of those three parts ever meets coffee.

This is a spring driven press that sits on top of a cup rather than a carafe. Ground coffee and water go in a 95 millimeter stainless chamber, a piston with a 61 millimeter face is cocked against a spring, and releasing it drives the brew down through a mesh filter, into a cone, and down the cone wall into whatever is underneath.

The whole machine is stainless. Structural parts are 304, and the two parts that touch coffee or a cup rim, the filter and the rest flange, are 316. The chamber is bored tube at 67 outside and 62 inside with a 2.5 wall, the piston is 61 by 14 out of billet, and the lock tabs come off 4.75 millimeter sheet. A laser and CNC service carries both alloys in these thicknesses, and the largest billet part here sits well inside a typical machining envelope.

The bore is the number everything else hangs from. Sixty two millimeters gives about thirty square centimeters of piston face, which puts a hundred newton spring at roughly a third to two thirds of a bar. That is the pressure band the review was aiming for, and it is also what keeps the seal in easy territory instead of asking a soft lip to hold back something it will take a set from.

One knob does everything. It is a ball on a hexagonal post, fixed to a rigid rod that runs down to the piston, and the hex keys into a matching bore in the lid collar. Twisting the ball twists the lid into the three tabs on the chamber rim. Pulling the same ball straight up slides along that hex and cocks the stroke. The painted mark on the ball is the only way to read where the lock is, since a sphere gives up no other clue.

The twist lock is now the only thing holding a cocked spring. An earlier pass had a spring loaded pin and notch doing the same job, and it is gone because it duplicated the tabs. That consolidation leaves an open item that matters more than any dimension on these sheets. Nothing yet stops a person from pulling the knob before the lid is fully twisted home, and nothing stops a twist while the stroke is cocked or running. That interlock is not modeled here and it needs to exist before anything gets cut.

Three other things are still undecided. The seal is silicone or FKM depending on how each behaves after compression set at ninety five degrees and after caustic dishwashing. The damper has to be settled on whether the oil is isolated from the brew path and whether descent speed is fixed or adjustable. The spring itself is drawn at a twenty millimeter cocked length as a placeholder, which is fine, because the finding was that the force matters and the coil geometry does not, so long as cocking stays at or under a hundred newtons.

The rest flange is the quiet piece of cleverness. It is a six millimeter 316 plate, 120 across with a 63 hole, and it catches the rim of any cup wider than the cone so the brewer perches instead of sinking into the drink. The funnel does the matching trick underneath by running coffee down its wall rather than dropping it off a flat face, so one cone serves a range of cup diameters. Both still want checking against real cup rims.

part drawings, motorized column press, inches

Nine made parts, each on its own sheet with material, stock size and quantity in the title block. The other twenty three items on that list are bought or carried over from the donor tool and need no drawing. Two of these are castings and one is molded, so those three carry tooling rather than a per piece cut price.

Item 01, base plate.

Item 04, post.

Item 06, head housing half, two required.

Item 13, rod shroud.

Item 14, travel collar.

Item 23, cartridge sleeve.

Item 25, cartridge end cap.

Item 27, inner shaft.

Item 28, bayonet collar.

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part drawings, spring press brew head, millimeters

Twelve made parts. The first two sheets are flat profiles that quote from a drawing today. The rest are turned or formed, so a cnc service wants a step file before it will price them, and these sheets are what to model from.

Item 05, rest flange. Flat profile, ready to cut.

Item 04, lock tab ring. Flat profile, ready to cut.

Item 01, stand.

Item 03, chamber tube.

Item 08, piston.

Item 17, lid.

Item 18, hex collar.

Item 12, hex post.

Item 13, ball knob.

Item 10, piston rod.

Item 21, damper rod.

Item 06, funnel and spout.