220 Mower - Chassis and Sensors Build Instructions
Lawn Mower 220
STL Files can be purchased here to print
Using a parts slicer such as CURA, the parts should be prepared for printing. I used a 0.4mm print nozzle with a 0.2mm layer height. 40-50% infill. Most parts can be positioned with the flat side on the print bed. Exceptions are the main covers.
The construction of the mower is fairly easy and can be easily done just based on the pictures provided. Here the parts are labelled should you be unsure where a certain print should go.
The 220 Mower has 2 rear cover shelves. These shelves hold the rear cover to in place and complete the part by extending it into the wheel arches..
The 220 Version of the mower has a split rear back plate. This plate is joined together with M3 bolts and locking nuts.
To attach the blade disc you will first need to make the adapter:
The blade disc is then attached with 2 M5 bolts into the adapter. the cutting blades are then attached using the M3 bolts and nylon safety nuts provided in the pack.
Arduino Parts 220 Mower
The Arduino parts are assembled in the following positions:
15mm bearings are pressed into the wheel arches and secured from moving using some screws and washers. The 1:200 geared 12V wheel motors are then fitted into the chasis of the mower using the motor brackets. the 70mm 15mm diameter wheel axle are fitted through the 15mm bearing and secured to the wheel motor using a locking screw.
To attach the rear wheel you will first need to make the adapters . The rear wheels are then pushed over the adapters and fixed with an M4 bolt through the wheel hub (hole provided) into the wheel axle adapters.
Front Wheel Casters & Wheels
The 625ZZ Bearings are pressed into the casters. The casters are then fixed to the frame using flat head M5 bolts through the M5 holes provided at the front of the mower. Spacer washers are required on the M5 bolt to allow the bearings to turn against the frame. An M5 nylon lock nut is used so the M5 bolts dont need to be over tightened. Leave them a little loose to allow free movement of the wheel.
For the front wheels I used 50mm rubber wheels fro the DIY store with an M6 axle. Front wheel STL files are provided but I have not tested them yet...
220 Bumper Bars
The bumper bars are optional and the 220 STL's can be purchased in the store:
The bumper bars are a simple construction:
The small microswitches are available in the store here
Video showing the bumper bar in action. In this test the sonar modules have been disbaled in the settings.
220 Sliding Rear Cover Mod.
To protect the control panel from initial rain the sliding cover mod can be added to the 220 Mower. This is a 2 part cover and a sliding door. The control panel can host the LCD screen and keypad (later a new control panel will be added for the TFT touchscreen).
When printing these parts we need to take advantage of the glass heat bed to produce a flat smooth surface on the 01 UPPER COVER where the sliding door can run on.
Ensure the parts are placed flat in CURA!! They have a slight angle to them to ensure the sliding parts are printed flat.
Use the lay flat tool in CURA to do this. Click the icon then click on the surface to lay flat.
The COVER Upper and COVER Lower should be sanded where required to ensure a smooth movement of the sliding cover. Soft Velcro can also be used on the sliding door to ensure a rattle free and smooth mechanism.
The rain sensor is installed in the slot provided. The plastic pin holder will need to be removed from the rain sensor to fit.
Once all parts are moving smoothly. Glue the rear cover together and fix with M3 screws. The M3 screws for the control board pass through the control board, lower cover and fix into the upper cover. This ensures a good fix of all parts.
Rear wheel Prints
Rear wheels were printed with the following settings
Line width 0.8
Layer Height 0.3mm
No support structure used.
Main Cover Prints:
To print the large front main covers I used the flat side of one of the edges as shown here. In CURA I enabled "Support" on and set the "Support overhang angle" to 85% with a "Support density" of 15% which creates a small tower to support the top curl of the cover.
Layer height was 0.2mm and infill 40%
Ensure that the snap rotation is turned off in CURA and rotate the part so it fits onto the 220mm² bed. Also ensure that 'Build Plate Adhesion :SKIRT' is turned off otheriwse the part will print outside the bed.