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Assembly Instructions

bdring edited this page Nov 5, 2018 · 13 revisions

Drawbot Badge Assembly Instructions


You will be assembling one of the world's smallest drawing machines, so all the parts will be tight and have limited access for fingers. It is very important to follow the instructions. Out of sequence assembly is not possible in most steps and you will have to disassemble and restart. Most screws thread into 3D printed parts, so be careful not to over tighten and strip them. You only need to get them snug. The friction of the plastic will keep them from loosening.

Avoid manually rotating the servos. This is hard on the tiny gears and on the linkages.

Included in the kit is a card listing some access information and passwords unique to your badge. Try not to lose this, but I have a master list in case you do.

The servos come with a little bag of parts. You only need the (1) 2.6mm x 0.45 screw in each bag to attached the arms to the servos. The rest of the parts and screws will not be used.

Powering Badge (Important)

The DrawBot badge can be powered via USB, 9-24VDC (12V recommended) barrel connector or the 3 pin battery connector. The USB can always be connected, but only use one of the battery or barrel connector at a time.

The battery connection and USB only supply low voltage power, so only the 3.3v and 5V stuff will work. The DrawBot is fine with that. If you want to use the stepper drivers, power FET or laser connectors, you must use a wall wart connector of 9-24VDC

A typical USB connection does not have enough power to run the badge with servos. If you using the USB for serial control, you should have a battery or barrel connection to power. Some high current USB battery chargers will power the badge.

The ESP32 gets slightly warm in use, so I added a few vents to prevent the enclosure from blocking all cooling.

Build Instructions

Label the Servos: After everything is assembled, you will not be able to tell what connectors belong to what servos, so they need to be labeled. Label the bottom of the servos and one side of the connectors with A, B and C using a silver Sharpie pen.

Prepare Servo Mounting Holes: This step will use screws to cut threads into the mounting holes, which will make mounting the servos a lot easier. Partially install (6) M2 x 8mm self tapping socket head screws into the servo mount locations of the servo box. Only need to screw them in about half way. There are (2) little slots in the side of the servo box for the tool to install the (2) horizontal screws. Now remove all the screws.

Route Servo A and B Cables: Route the wires for Servos A & B through the servo box. They go under the horizontal bar in the center of the box, then out the slot in the side of the box. Do not install the servos yet.

Important! Installing Servo Arms Do not push very hard when you install the arms. You can damage the gears inside. Just push them on enough that you can get the screw started, then use the screw to pull them on completely. The arms I provide in kits should have the servo spline shape hot pressed into them to help you. It is a 20 tooth spline, so it forces you into certain angles. Don't worry if you cannot mount in the exact angle you want. You can tune/calibrate it in software later. The screw to attach the arms come in the little bag of parts with the servos.

Install Z Cam on Servo C: The servo must be rotated to a specific location and the Z cam must be installed in a specific orientation on the servo. You will use the controller PCB to rotate the servo. Connect the servo C cable to the servo C location on the PCB. Be sure to get the color order right. See the image below. Power on the PCB and the servo should rotate to the correct location. While still powered, attach the cam and mounting screw so it points towards the other end of the servo. Don’t worry if you can’t get it exactly straight. When you tighten the screw hold the other end of the arm to prevent it from rotating and stressing the servo trying to hold the position. After you are done, disconnect from the controller.

Install Servo C: Route the cable out through the side of the box. While pulling the slack out of the cable, install the servo into the box. Be sure to note the orientation in the picture. The cam is towards the upper edge in the orientation shown. Install (2) M2 x 8mm screws. Be careful not to overtighten the screws or you could crack the box.

Install Servo A: This is the trickiest part. Install the screw closest to the box edge first. Now install the one near the Z cam. It helps to have some good light shining in to see the hole.

Install Servo B: Servo B is located towards the hinge boss side of the servo box.

Dress the A & B Cables: Pull any excess cable out of the box and try to route away from the Z cam, because it is a moving part. It moves slowly and only a few degrees, so it is OK if the cables touch a little.

Install Hinge Bearings in Base: With a vise or pair of pliers, press the 3mm bearings into the base from the inside: Note: This step may have already been done in the kits.

Attach Servo Box to Base: Using (2) M3 x 14mm button head screws assemble the servo box to the base.

Attach Servo Arms: Attach Like the Z cam, we need the controller to set the servo angle first. The cables from Servo A and B to the controller and power it up. Now attach the two arms as shown in the image with as close to the angles shown as possible. When you tighten the screw hold the other end of the arm to prevent it from rotating and stressing the servo trying to hold the position.

Attach Remaining Linkages: Attach the rest of the linkages as shown in the image below using (2) M3x10mm, (1) M3x14mm and (1) M3 washer. Notice that the bearings are all pressed in from the bottom in the orientation sown. Be sure to assemble them that way. The longer, 14mm screw goes into the middle of the pen arm. Be careful, the screw strip easily.

Mount The PCB: Use (6) M3 x 8mm self tapping screws to attach the PCB. Route the wires out the cut in the right side. Stuff the excess wire into the base after assembled.

[image of back]


The drawing machine will produce better results if it is calibrated. Follow the instructions here to calibrate your badge.

You can’t perform that action at this time.