Top interface

The top interface holds a chute that rotates on a lazy-susan bearing to aim incoming parts at whichever bin layer is currently selected. A NEMA 23 stepper drives the rotation through a small gear train (steps 6 and 9), and a limit switch and hammer (steps 4, 6, 8) give it a fixed reference point to home against, since the stepper alone has no way to know which way it is pointed. Everything on this page bolts onto the Top plate, which then sits on the hex frame built on the bin-frame page.

The fasteners and quantities are in the parts list above and are called out inline at each step.

Fastener icons match the parts list: the silhouette is the head shape, the colour is the thread size. M3 M4 M5 M6

Several steps below refer to holes in the Top plate by name (S2 and S3 for the stepper mount, I1 to I6 and O1 to O6 for the interface brackets). This map shows which hole is which:

Step 1 Preparation

Before assembling anything, press all the heat inserts listed below into their parts while the parts are still loose — this covers every insert used on this page. Fusing them in afterwards is much harder, for example once the Interface upper fixed section is mounted to the Top plate. Later steps repeat each insert count as a reminder only; you don't need to press anything a second time. See installing heat inserts for the technique.

Step 2 Attach the interface ribs to the upper fixed section

Heat inserts first: press the 4 × M4 inserts into the Interface upper fixed section and the 6 × M5 and 1 × M3 inserts into the Interface NEMA 23 bracket before you assemble anything here.

Attach the Interface rib (switch gap) to the Interface upper fixed section, two positions counterclockwise of the stepper-mount notch when viewed from above (see photo). Use two M5 × 16 mm socket / button head screws, tapping directly into the plastic.

Attach the remaining 5 Interface ribs to the Interface upper fixed section, two M5 × 16 mm socket / button head screws each, again tapping into the plastic.

Slot the Interface NEMA 23 bracket into the Interface upper fixed section and secure it from below with an M3 × 12 mm countersunk screw.

Attach the whole assembly to the bottom of the Top plate with 2 M5 × 22 mm countersunk screws, one through hole S2 and one through hole S3, into the Interface NEMA 23 bracket's pair of M5 inserts. Hole S1 stays empty.

Alternative: whether these need a countersunk head depends on how your Top plate was cut. If the S2/S3 holes have a countersink cut in, use a countersunk head; if they don't, M5 × 20 mm socket / button head screws work here instead. Builder's call depending on their plate, the same as the I1-I6/O1-O6 screws in step 5.

Step 3 Prepare the interface brackets

Heat inserts first: each Interface bracket takes 3 × M5 inserts. Press them in before fitting the extrusion.

These six brackets are what the vertical extrusion legs (piece F, step 13) will anchor into once the framing goes on.

Align an Interface bracket with a length of aluminum extrusion, piece E (Interface spoke, long), 238 mm.

Place T-nuts in the extrusion, lined up with the 4 holes on the side of the Interface bracket. See Fitting T-nuts for how they go in.

Slide the extrusion into the Interface bracket, careful not to dislodge the T-nuts, and drive four M5 × 16 mm socket / button head screws into them.

Repeat for all 6 Interface brackets.

Step 4 Prepare the limit switch interface bracket

Heat inserts first: the Limit switch housing takes 2 × M3 inserts. Press them in before assembling it.

This switch is the chute's home reference: because the stepper motor that will drive the chute (step 9) has no inherent sense of position, the machine homes against this switch and hammer on startup to know which bin the chute is aimed at.

Push the Printed dowel pin into the Limit switch housing.

Attach the Roller lever limit switch (the "endstop-mechanical" part in your kit) with two M3 × 16 mm socket / button head screws (into the housing's 2 M3 inserts) so the roller sits next to the dowel pin.

Align the switch housing with the extrusion of one of the prepared Interface brackets so the limit switch is on the same face as the sloped side of the bracket. Slide 2 T-nuts into the extrusion and fasten the Limit switch housing to the extrusion with two M5 × 16 mm socket / button head screws. Slide it as far toward the Interface bracket as possible for now; it gets aligned properly later.

Step 5 Install the brackets

Slide a T-nut just into the end of the extrusion of the limit switch interface bracket. Slide the extrusion into the Interface rib (switch gap) and Interface upper fixed section, securing it loosely with an M5 × 8 mm countersunk screw. Slide the extrusion slightly in and out to align the holes on the Interface bracket with the holes on the Top plate, then tighten the screw.

Repeat with the 5 other prepared Interface brackets into the 5 other Interface ribs.

Flip the whole assembly and screw all 6 Interface brackets into place with 12 M5 × 22 mm countersunk screws, one through each of holes I1 to I6 and O1 to O6.

Step 6 Prepare the interface chute gear and mount

Heat inserts first: the Top interface chute mount takes 4 × M4 and 7 × M3 inserts, and the Limit switch hammer takes 1 × M3. Press them in before assembling.

Slot the Limit switch hammer into the Top interface chute mount, then secure it from below with an M3 × 6 mm countersunk screw (into the hammer's M3 insert).

Align the Chute gear on the Top interface chute mount with the notch by the screw for the Limit switch hammer. Attach it with five M3 × 12 mm countersunk screws.

Align the Top interface lazy Susan washer with the 4 inner heat inserts on the Top interface chute mount. Align the inner ring of the Lazy Susan with these 4 heat inserts too. Screw the Lazy Susan into position through the washer and into the Top interface chute mount with four M4 × 16 mm countersunk screws.

Once complete, the free section of the Lazy Susan should rotate freely.

Step 7 Attach the interface chute to the assembly

Place the Interface big spacer on the Interface upper fixed section with its 4 holes lined up with the 4 heat inserts.

Rotate the free part of the Lazy Susan on the chute mount assembly from step 6 so that 3 of its holes line up with the holes in the Top interface chute mount. Place the assembly on top of the Interface big spacer with the 3 holes aligned with 3 of the heat inserts. Screw these together tightly with three M4 × 16 mm countersunk screws.

Rotate the Top interface chute mount 90 degrees relative to the Interface upper fixed section to reveal the 4th screw hole in the Lazy Susan (it should also line up with a hole in the Interface big spacer and a heat insert). Drive a fourth M4 × 16 mm countersunk screw tightly through this hole.

Once done, check that the chute rotates freely relative to the Interface upper fixed section.

Step 8 Adjust the limit switch

Loosen the screws attaching the Limit switch housing to the extrusion. Slide the housing so the Limit switch hammer passes between the Roller lever limit switch and the Printed dowel pin. The hammer has to strike the switch from both directions of rotation, and it must not run on the dowel pin. Rotate the chute slowly to each limit by hand: you should feel and hear the switch click just before the hammer would otherwise hit the dowel pin. If the hammer rubs against the dowel pin, slide the housing slightly further away and re-test. Tighten the screws to keep the housing in this position.

Step 9 Install the chute stepper motor

The idler gear bridges the gap between the spur gear on the motor shaft and the chute's ring gear (built in step 6), so the motor can sit off to the side of the chute mount rather than driving it directly.

Slide the prepared Timing pulley over the shaft of the NEMA 23 stepper motor and tighten its two set screws (grub screws). Slide the Interface spur gear onto the Timing pulley and secure it with five M3 × 8 mm countersunk screws: three tapped into the Interface spur gear and two bracing against the Timing pulley (exact split may vary — check the hole pattern in the photo).

Push the prepared Interface idler gear — bearing, inner retainer cap, and outer retainer already fitted, see step 1 — onto the Interface NEMA 23 bracket with the bearing facing outwards.

Drive an M3 × 20 mm countersunk screw through the middle of the gear and into the bracket, so its head lands on the inner retainer cap. Tighten until it's seated, then check that the idler gear still spins freely.

Use a countersunk (flat/pancake) head here, not a socket or button head. If you only have a pan head on hand, hand-rotate the chute past this screw and check it clears the Limit switch hammer before closing everything up.

Slot the NEMA 23 onto the Interface NEMA 23 bracket and secure it with four M5 × 12 mm socket / button head screws.

At this point the chute should still rotate, but you will now feel resistance from the stepper motor. Rotate the chute fully in both directions by hand: it should turn smoothly against that resistance, with no catch or scrape as the idler screw head passes the Limit switch hammer.

Step 10 Attach the cable cage top

The cable cage (top, bottom, and clamps) is the channel the ribbon cable (RIB1) runs in while the chute rotates.

Heat inserts first: the Cable cage bracket (cable mount) takes 1 × M3 insert. Press it in before assembling.

Slot the Cable cage top over the Top interface chute mount, with the corners of the hexagon aligning with the Interface brackets. Of the two cage plates, the one that goes on here is the one with the plain round centre hole. The plate with the keyed cutout in its centre hole is the other one, and it goes on at step 12.

Screw the Cable cage bracket (cable mount) to the tail end of the Interface bracket opposite the Limit switch housing, using an M5 × 30 mm socket / button head screw into the M5 heat insert. This clamps the Cable cage top firmly in place.

Screw the remaining Cable cage brackets to the other 5 corners of the Cable cage top with M5 × 30 mm socket / button head screws.

Step 11 Put the ribbon cable (`RIB1`) in the cable cage

Place an M3 nut into the bottom of the Cable clamp (outer) (the video skips this), then push it into the recess in the Top interface chute mount. Fasten it with two M3 × 12 mm socket / button head screws.

Rotate the chute until it hits the limit switch.

Fold your IDC ribbon cable (RIB1) around the Cable clamp (inner), following the guides on the clamp. Slide the cable and clamp together into the Cable clamp (outer), leaving a tail to connect to the chute above.

Leave about 80 mm (3 in) of tail, measured from where it leaves the clamp, which is what it takes to reach the layer adapter board on the chute core that sits on top of this assembly.

The connector goes on pins up. You should be able to see into the connector from above when the tail is lying where it will sit; if it is facing down at the bench, the cable is on the wrong way round. Getting this wrong is expensive: three steps have to come apart to turn it over.

Guide the rest of the ribbon cable (RIB1) around the side of the Top interface chute mount, in the direction the chute can rotate, back to the Cable cage bracket (cable mount).

Screw the Ribbon cable clamp lightly to the Cable cage bracket (cable mount) with one M3 × 12 mm socket / button head screw, clamping the ribbon cable (RIB1) between the two. Leave the clamp standing slightly off the bracket face rather than pulling it down hard, so the ribbon is not crushed.

Check that the chute can rotate fully to the limit switch in both directions, then tighten the Ribbon cable clamp screw. Use a long M3 × 40 mm flat head screw through the Cable clamp (inner) into the M3 nut in the bottom of the Cable clamp (outer) to secure that end.

Step 12 Attach the cable cage bottom

Place the Cable cage bottom over the Top interface chute mount. This is the plate with the keyed cutout in its centre hole, the pocket that bulges outward on one side. Use 6 M5 × 35 mm flat head screws and M5 nut s to clamp the Cable cage bottom, Cable cage top, and Cable cage brackets together.

After this step the chute should still rotate to each of its limits. Same as step 10: check after each screw rather than at the end, and back a screw off rather than forcing the chute past a tight spot.

Step 13 Attach the framing

Install four T-nuts and their M5 × 20 mm socket / button head screws in each Interface bracket, then fit in an extrusion piece F (Interface vertical support), 274 mm. The framing cut list has every length on this page. Leave 165 mm of the extrusion standing out of the bracket, measured from the edge where it exits to the free end. Step 14 shows the corner in section.

Slide an Interface spacer onto each piece of extrusion, with the lip at the top facing toward the center of the assembly.

Build a hex frame, then place it onto the interface assembly.

Roll 6 T-nuts into this hex frame's own extrusions while you are here, 2 each for the PSU box, the control board housing and the Orange Pi housing. All three bolt onto this frame later, and the layout render on installing the electronics shows where each one sits. Their screws and the rest of their hardware are listed on those pages, not here.

Attach an External bracket cover to each of the External bracket sides, then fasten each one with 2 M5 × 16 mm socket / button head screws into the holes at the base of the External bracket sides, bracing against the extrusion. These holes run parallel to the extrusion profile, and the screws are self-tapping. There is no External bracket — bottom vertical at this joint; see step 14 for what's different here.

Step 14 How the interface joins the top layer

This joint is not the same as the one between two layers, so it is worth naming what is different. There is no External bracket — bottom vertical and no flange here, and therefore none of the vertical screws that hold one layer to the next. Piece F is instead gripped at the interface end and clamped at the layer end, and it is sleeved the whole way between them, so no extrusion shows on a finished machine.

The numbers on the photo and the drawing:

1. Interface bracket, one per corner, a 120 mm channel around the extrusion. Piece F is held in it by 4 M5 × 20 mm socket / button head screws into T-nuts , the only place in the framing where a vertical is fixed with T-nuts rather than a self-tapping screw.
2. Interface spacer, a 129.7 mm sleeve, slid onto the extrusion with its lip at the top facing the centre. It takes no screws and simply sits between the bracket and the layer's collar.
3. Piece F, 274 mm cut (280 mm in CAD) against a layer's 154 mm, so the interface sits 120 mm further above the top layer than one layer's spacing.
4. The top layer's External bracket — side, with its cover, exactly the collar any layer has.
5. Two M5 × 16 mm socket / button head screws at the base of that bracket brace it against the extrusion, the same screws and holes a layer's own vertical gets. Nothing else fastens the interface to the layer.

Piece F does not reach the top of the Interface bracket, and it comes nowhere near the top plate. The 165 mm standing out of the bracket in step 13 is what sets where it sits.

The finished result

The top plate, its six bracket mounts and their extrusion, the rotating chute mount and its gear train, and a hex frame closed onto the bottom of the verticals.

The Distribution page contains the instructions for the entire assembly, and is where you should return once you're done here.