Over the last few days I've had plans to get back on track with other projects such as the ASETNIOP keyboard and the podcast with Joe Robertson. However these are both things which are done from the comfort of my own apartment and that was not where I felt like being so I spent some time at hardware stores and the hack space.
Enough background.
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Marked 1 inch from the end
Set up on drill press
Freshly drilled 5/16" hole
Pulley in PVC
Moving the corner brace around to determine the necessary size of the hole
Hinge-catch portion
Cutting a groove with a radial arm saw
Position of hinge hole
Drilled hinge hole
Lines indicating where to drill the hole
1 1/16" hole drilled in catch-hinge
Enough background.
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Hardware
stores were visited to find parts for the Tennis Ball Launcher. Some hardware, such as 1 ½” PVC pipe, 5/16-18
nuts, 5/16-18 lock nuts, washers, and aluminum bar stock was already
owned. More 5/16-18 x 2” bolts were
purchase, 1 1/4” metal pulleys, 48” bungee cords, and a flat corner brace were
purchased for the project.
Bar
stock: $5.00
PVC 1
½”: $3.00
Miscellaneous
hardware: $5.00
Corner
brace: $1.19
5/16-18
bolts: $1.89 (pack of 10)
Pulley
1 ¼”: $5.90 (2 @ $2.95)
Bungee:
$5.98 (2 @ $2.99)
Parts
The
available PVC was cut into two pieces each 26” long. They were cut on a radial arm saw.
Clamped PVC pipes
Freshly cut PVC
5/16”
holes were drilled all the way through the PVC 1” from one end. This hole will hold the rear pulley.
The
corner brace was drilled to 5/16” in the corner where it can act as a hinge. The wiggle room for the hinge was calculated
by shifting the corner brace around the hinge, sketching the placement and
measuring the greatest distance from the hinge point.
5/16" hole drilled into corner brace
The
corner brace, as shown on the drawings, will serve to push the tensed bungee
off the catch, similar to a crossbow.
The
first attempt at the hinge-catch portion resulted in an unusable block of
wood. It is important to use a large
enough bit when drilling down through the hinge-catch for the corner brace and
even more important to keep that hole aligned with the hinge hole drilled for a
bolt.
A new
hinge-catch was cut to length on a radial arm saw and shaped with a band saw.
The
piece had a groove cut down the middle using a radial arm saw raised up so the
piece was not split.
The bolt
hinge position was marked by holding the corner brace in place. The 90° will need to be rounded on a grinder
since it sticks out. The hole was
drilled to 5/16” like the corner brace.
Above
and in line with the bolt hinge hole a 1 1/16” hole was drilled with a Forstner
bit.
A 5/16”
bolt was inserted into the hole and the corner brace should work well to push
the elastic off the catch when moved.
This movement will likely be initiated by the user pulling a bicycle
brake handle mounted as the trigger.
Movement of corner brace
A
phone discussion with my teammate also explored the idea a spring-loaded model
which would have a very simple/elegant design.
To
do:
- Grind corner brace
- Revise design to use pulleys I place of bearings
- Build
- Test
- Revise
- Document
Journal page 1
Journal page 2
Journal Page 3
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