Skip to content

Arpeggio Anchor Build Guide

Hardware Version: Arpeggio

This is a rough draft of how to assemble the arpeggio anchor (double damiao anchor) TThe design is not finished, particularly wrt how the cover attaches.

Print time: unmeasured Build time: unmeasured

Bill of Materials

TODO

Tool list

Spools

Assemble three fishing line spools and one powerline spool Spool side A is different on the powerline spool, it has a wider center hole.

Glue side A to side B

For regular spools

Press the dry spool onto the motor until fully seated. twist until the holes align, secure with 3 M3x8 screws.

Put an M4x12 screw through a 4x13x5 bearing follow by 2 M4 washers, then screw it into the 4 mm hole in the center of the spool.

For powerline spools

Solder a JST ZH female plug housing onto the fixed end of the slip ring.

Use an "imp" pipe cutter to cut an 10 mm long peice of 10 mm diameter ABS tube. The same tube used on the marker box of the arp gripper. Glue the piece of tube in the hole on spool side A. You can use a coin to press it in.

When dry, put 3/8 * 7/8 stainless steel washer on the plastic tube, followed by a 10x15x4 bearing.

Place the slip ring into the slip ring block and secure it using 2 M3x8 screws with an m4 washer on each in the 2/3 accessible screw holes.

Thread the rotating wire end through the tube in the spool about half way, and using the access you still have to the back of the spool, thread the wire out the side of the spool through the wire hole. don't sinch it all the way down yet in order to leave room for the screws that secure the motor.

Press the motor into the spool, align the holes and secure with 3 M3x8 screws. Now fully seat the slip ring against the side of the spool by gently pulling the wires through.

Electronics

Assemble a Raspberry Pi Zero 2W with a Stringman imaged SD card and heat sink. If the pi does not have header pins, solder on a full set.

Carefully unpack the a Camera Module 3 standard FOV and remove whatever ribbon cable came attached to it.

Screw a camera angle mount piece (printed) to. (front right when looking at the lens with the ribbon connector on top) The angle can be chosen from 22, 26, or 30 degrees of downwart pitch from horizontal. The camera pitch should be chosen to keep the floor well centered. It can be changed out later but the config must be updated to inform the software of the chosen pitch.

Install a 4cm mini ribbon cable on the camera. the gold pads always face down towards the board. Attach the smaller end of the ribbon cable to the pi. Be very careful with the delicate connector.

Press a Stringman Anchor Hat onto the pi. put spacers in the corners between the two boards and insert four M2.5x18 screws.

Screw the raspberry pi into the conical standoffs in the electronics box on the bottom of the frame. The camera should hang out of the window at the front

Screw the camera angle mount to the frame with 1 M2.5x6 screw. The small protrusion is what determines the final angle of the camera. It only fits one way.

Frame

Flip the frame over. From this point on it can be very helpful to have a beanbag to place the mechanism on at any angle while driving screws.

Install the lower spool first. Insert the plug downwards through the rectangular hole on the lower spool side of the frame. Align the motor's shaft so the gap points down and the flat sides are vertical. slide it into the slot, pulling the wire through as you go. seat it fimly in the slot, and in the bearing cup on the other side. spin and confirm it's not crooked. Secure the motor from the outside of the frame with 3 M3x8 screws.

If the higher spool is a regular spool, print the variant of the slip ring block made for regular spools instead of slip rings. press it onto the bearing that protrudes from the unmounted spool.

If the higher spool is the powerline spool, it already has a bearing block on it. sinch the wire down firmly by pulling it through the spool till the slip ring cannot get any closer to the spool.

Same as the other one, thread the plug, align the shaft, and align the bearing block on the other side. secure the motor with with 3 M3x8 screws from the outside of the frame, and secure the bearing block with two M3x8 screws.

Secure the "sunglasses" rounded side down with 4 M3x14 screws.

Spool winding

If a powerline is present, on this anchor thread the slip ring's JST-ZH connector through the vertical hole in the frame and plug it into the board in the header marked "slip ring 24v"

For the powerline spool, with solder seal wire connectors, splice the end of a 7 meter length of FEP cable onto the spools slip ring wire, tighen heatshrink and secure with tape.

Or if working from a spool of wire, like I do, splice the spool end on, let the script wind the correct amount, then power off and cut it.

For fishing line spools, tie a peice of braided fishing line (Power Pro Super 8 Slick V2 40lb test is my reccomendation) onto the small tie off point on the spool with a buntline hitch.

Power on the device and ssh into it with 

ssh pi@<hostname or ip>

run

/opt/robot/env/bin/qa-anchor-arp

And follow the prompts. It will ask you to plug in one motor at a time and wind the spools.

When you have both wound, power off.

Warning

When trimming the power line to length, pull the motor power first. the wire is live when winding.

Feed the end of the wires/lines through the hole in the sunglasses.

For fishing lines, tie on a small carabiner with a palomar knot. For power lines, tie on a carabiner above the splice with a buntline hitch.

Create the Eyelets

Create two eyelets. Print the body on the flat edge on the lower left side, for strength. print two retainers. Press a size 20 Alconite ring into the ring slot. Put a drop of superglue into the remaining space, and press on the retainer with a coin and a pair of pliers.

Mount on the wall

Pick two opposing corners to be where the anchors are mounted. they should be the corners with the best view of the floor.

prepare

Print the wood/stud mount bracket at 100% infill. (2x) Start two 3in self tapping wood screws in the holes of the peices. Plug in the power supply and barrel jack extension cable into an outlet near the corner where you are mounting.

on the step ladder

Bring up the ladder

  • drill
  • bracket peice
  • the anchor you assembled
  • the end of the power plug
  • the decorative cover

Screw the bracket into the wall corner. Don't overtighten if the piece appears to bend. it must be straight to function. Slide the anchor down onto the bracket from the top. plug in the power.

Snap on the decorative cover.

Grab the end of both lines and bring them down with you enough that you can reach them without the ladder. leave them hanging.

repeat in the opposite corner.

eyelets

In the two other corners of the room, mount ceramic eyelets with a single wood screw into a stud in the wall corner.

From each anchor, pull it's leftmost line over to the adjacent wall corner on the same side, thread it through the eyelet, and let it hang there.