This is a pick-up/shooter for the 2022 rapid react season. This device will both pick up and shoot the roughly 9.25 in diameter ball (cargo) of the game the files referenced below are located at https://grabcad.com/library/rapid-react-3/details?folder_id=11939286
Proper material to print this items include HIPS, ABS, PETG and possibly a hard Nylon for all structural parts. The “tire” referenced later is to be printed in TPU. All parts will fit on a printer with a build plate size of 300×300 or bigger. The biggest part – the housing – is 283×283. The parts printed below have been printed in HIPS and TPU on an anycubic Chiron with a .8 nozzle. 0.4mm layer height, 1mm outside perimeter width 1.25mm inside perimeters, 6 perimeters 100% infill. Except the tire – the TPU part that was printed 2 perimeters of .88mm and 10% infill.
For the body you will need to print 2 of the file ShooterHousing.stl and 1 of ShooterHousing_Center.stl. You then will connect them with 1/2 in square aluminum or steel tubing and M5 or 8/32 bolts of the proper length . The front and back square cut outs also get 1/2 in square tubing as reinforcement
Then assemble each Shooter hub/wheel assembly. As they are getting most of the stress make sure they are printed with 100% infill (except the TPU tire
File Name: MotorHolder_small.stl. Mount CIM, miniCIM or NEO to the 3DP bracket as shown and press fit a 6805 bearing
Then Press fit the 6805 bearing into the Bottom Bearing holder
Next cuta 1/2 in square tube to fit flush With Hub_small.stl and Hub_smalltop.stl and drill the 2 holed. The bolt in Hub_small will not get a nut a M5-20mm will cut its own thread into the plastic and will be held in place by the tire
The top of Hub and Hub_small should make a tight fit in the 6805 bearing. In case you have some overprint use some sandpaper or other abrasive to make it a tight fit.
The Tires File is ShooterTire_small.stl. It is to be printed in TPU with about 2mm shell/wall/floor/Ceiling thickness. The whole assembly is slotted so it can be adjusted and shimmed to give the proper “squish” to the tire. After finding the proper “squish” 2 holes can be drilled through bracket, shim and square stock to properly fix it to the shooter housing
The whole Shooter Wheel/Tire assembly with motor and bering holder ready for assembly to the body. As both motors are to always spin in opposite directions the 2 motor wires could be connected red to black, black to red and then as the bottom of the “Y” to one motor controller
Next Mount the motor for the elevation. In this case either 1 or 2 PG-71 old style with 10mm round keyed shaft (we have a bunch and none of the newer kind) is used. The heads of the M4 bolts are recessed and should fit most machine or socket head screws. Press fit the 6805 Bearing(s) above that. Depending on where you mount the motor(s) you might need 1 or 2 PG-71 motor or less if you got a higher ratio gearbox. The nice thing of the PGs is that they have a quadrature encoder included that make elevation positioning possible in multiple positions
The Following is 2 of the 3 possible Mounting positions for the elevation Motor(s) in this case using one of the PG to square tube adapters. (Note from experience smaller then 1/2in HEX in HEX format skips easy in plastic under high torque. The plastic is quite capable to stall the motor on a 4mm key but not on a small hex)
There are multiple Dogleg assemblies/Motor Holders in the above folder. Which ones to select depends on how the shooter mechanism is going to be attached to the frame and what will fit without extending beyond the legal parameters. The sample holders in the folder are for the PG motors above and for Mini Limit switches like this one
They will mount to the hole pattern on the Shooter body.
Parts needed for the above assembly
less than 500g of TPU, about 3-4kg of HIPS,ABS or PETG, 15 to 20 ft of 1/2 in 16 gauge square tubing, Assortment of Nuts and bolts. preferably M4 and M5 with Nylock nuts and/or whatever the motors need.
The operation is as follows
To Shoot (ball assumed loaded and trigger dogleg in the back parallel to back plane of shooter body. )
1.) Spin up wheels (CIMs) takes about 1 sec to full speed
2.) asure proper elevation and aim (can happen simultaneously to 1)
3.) have intake dogleg out of the way in the “all up” position
4.) activate the trigger dogleg to feed the ball into the spinning wheels
To take in Ball
1.) have the trigger dogleg parallel to the back plane
2.) Spin up shooter motors to about 10-15 % max speed in reverse (oposite from shooting direction
3.) Aproach ball – drive into it and if necessary have an intake dogleg “help” the ball in
Depending on mount position and angle and driver skill from past years experience especially stronghold ball pickup is quite possible without a front dogleg with a good driver . Front doglegs no matter what they are made of often fall victim in collisions with other robots.
If the robot is used on a standard Andymark frame without a cutout then the only way to mount it is from the rear and the pick up angle becomes quite steep and a “dust pan” type ramp needs to be attached to the front or a front intake dogleg is advisable
The folder also contains the bigger 4 inch tires and hubs with motor mounts and an alternate shooter made out of 1/2in tube and 3dp Gussets. This shooter was not completed and is considered “work in progress”
Besides the stls the folder also includes all the inventor (.ipt) files