Parallax 28106 User manual

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Copyright © Parallax Inc. Product Name (#28106) v2.1 5/5/2009 Page 1 of 4
Boe-Bot Tank Treads
(#28106)
Treaded Addition for the
Boe-Bot® Robot
Introduction
Treads let the Boe-Bot access more varied terrain such as carpet, small rocks or imperfect surfaces. This kit
involves the removal of the Boe-Bot wheels and addition of a treaded drive train.
Packing List
Part # Description Qty
700-00002 4-40 Machine Screw, 3/8” 6
700-00003 4-40 Nut – 700-00003 22
700-00007 4-40 Machine Screw, 7/8” 8
700-00028 4-40 Machine Screw, 1/4” 8
700-00059 #4 Lock Washer 8
710-00008 1.5” Screw 2
713-00003 1.25” Standoff 2
720-28106 Metal Sides 2
721-28106 Plastic Wheel and Rubber Tread set 1
725-00013 Servo Horns – may be standard or round disc 2
Tools Needed
You will need a #2 Philips screwdriver, wrench, and a 3/32” drill (or hobby knife like an X-acto®knife).
Assembly
Step 1: From the set of wheels, cut out the following and trim off any burrs:
(2) large wheels (with teeth)
(2) large wheels (no teeth)
(6) medium-sized wheels (no teeth)
The remaining wheels are not used for this application. However, the wheels with sprockets can be modified
and used if there is a tread alignment problem; for details refer to the “Troubleshooting the Tread” section
on page 4.

Copyright © Parallax Inc. Product Name (#28106) v2.1 5/5/2009 Page 2 of 4
Step 2: The servo horn will need four of the holes enlarged for the 4-40 screws. The holes need to be
smaller than the screw so that when the screws are inserted they will make their own threads. You can drill
the holes using a 3/32” drill bit, or use an X-acto knife to enlarge the holes as shown below, depending on
which servo horns were included in your kit. If you are using the knife, be sure not to over-enlarge the holes.
By reaming with the knife a little from both the top and bottom, the hole will be more uniform in size.
3/32”
(2.2 mm)
3/32”
(2.2 mm)
Enlarge the Middle Holes
if using Disc Servo Horns Enlarge Inner Holes if using Standard Servo Horns
Step 3: Using the ¼”
length screws, attach
the two large wheels
(with teeth) to the
servo horns.
Step 4: Attach the 7/8” length screws and nuts to
the remaining wheels (2 large and 6 medium in size)
as shown below, and set aside.
Step 5: Remove the wheels from your Boe-Bot. The servos should be mounted with the head toward the
rear ball wheel as in Figure 5. The servo mounting tabs need to be on the outside of the Boe-Bot chassis.
Confirm that the servos are mounted correctly. If your servos are mounted the opposite way, or are
mounted from inside the chassis, remove them and remount as shown.
www.p ar a ll ax .com
continuousrotation
www. par a ll ax .com
co ntinuou s rotatio n
Servo head is mounted
toward tail wheel
←Wrong Way→
←Right Way→
Servo mounting tabs are
outside of chassis

Copyright © Parallax Inc. Product Name (#28106) v2.1 5/5/2009 Page 3 of 4
Step 6: Attach the sides first, using 3/8” length
screws and nuts as shown. Then attach the servo
horn (with wheel) using the screw that came with the
servo.
Step 7: Attach the remaining wheels by first
tightening the nut on the wheel then loosening it 1/4
to 1/3 of a turn. Attach the wheel assembly to the
frame with a nut and a lock washer on the inside of
the frame. When the two nuts on each wheel are
tightened, check to see that there is a very small gap
between the wheel and outside nut to allow for easy
rolling, as shown.
Step 8: Mount the remaining wheel assemblies with
lock washers and nuts. When tightening, leave a very
small gap on the wheel side so the wheel can turn
freely, as shown.
Step 9: Separate all the rubber tread pieces and connect together as shown below. Each loop contains 1
long, 2 medium and 2 short treads. Please do not pull the treads to disconnect from one another; please use
scissors or an X-acto®knife. Pulling on the treads will stretch them beyond use. Check each wheel to make
sure it rolls without binding. If any wheels bind, loosen the nut and remount to maintain a very small gap
between the wheel and nut. Carefully stretch the tread over the wheels.

Copyright © Parallax Inc. Product Name (#28106) v2.1 5/5/2009 Page 4 of 4
Step 10: The Boe-Bot robot’s breadboard circuit
can be protected by installing the (2) 1.5”
screws and (2) 1.25” spacers on the front of the
Board of Education®. The assembly is now done.
P15
P14
P13
P12
P11
P10
P9
P8
P7
P6
P5
P4
P3
P2
P1
P0
X2
X3 Vdd VssVin
Board of Education
© 2000-2003
Rev C
Vdd
Black
Red
X4 X5
15 14 13 12
To Servos
Troubleshooting the Tread
If the tread is loose and comes off, check to see
that all the wheels have very little movement when
pulled. They should roll easily but should not be
floppy. If the wheels are floppy, loosen the two
nuts and re-tighten. If the treads are still loose, the
servo mounting screws can be loosened, the servo
moved up, and the screws re-tightened.
Should the tread come off while turning and the
wheels have been adjusted and tightened, try
swapping the two bottom wheels (front to rear and
rear to front). The plastic might be too rounded.
Also check the tread connection joints. If the
interlocking rubber tabs are not pressed together
firmly, they could snag on carpet. If there is still a
problem, the two unused wheels with sprockets can
replace the two front bottom wheels. You will need
to drill or cut the end of the wheel so the screw will
go through.
If you experience any problems with the assembly
or use of your Tank Treads, you may contact us at
[email protected] or call 1-888-99-STAMP
(1-888-997-8267) M-F 7:00 am to 5:00 pm PT.
Example Code for Basic Maneuvers
The program below is a modified version of the
program ForwardLeftRightBackward.bs2. from
Robotics with the Boe-Bot. The FOR...NEXT loop
EndValue arguments have been increased, because
the Tank Treads cause a slower ground speed than
the regular Boe-Bot wheels. Any program from
Robotics with the Boe-Bot can be used with the
Tank Treads kit, but programs that rely on
maneuvers of a certain distance or rotation will
need to have these
EndValue arguments adjusted.
' Boe-Bot Tank Tread Kit –
' BasicTankMoves.BS2
' Drives forward, turns left, turns right,
' reverse
'{$STAMP BS2}
'{$PBASIC 2.5}
DEBUG "Program Running!"
counter VAR Word
FOR counter = 1 TO 100 ' Forward
PULSOUT 13, 850
PULSOUT 12, 650
PAUSE 20
NEXT
FOR counter = 1 TO 50 ' Turn left
PULSOUT 13, 650
PULSOUT 12, 650
PAUSE 20
NEXT
FOR counter = 1 TO 50 ' Turn right
PULSOUT 13, 850
PULSOUT 12, 850
PAUSE 20
NEXT
FOR counter = 1 TO 100 ' Reverse
PULSOUT 13, 650
PULSOUT 12, 850
PAUSE 20
NEXT
END
Download additional application examples and code
from www.parallax.com.