Post by Ron Walker on Sept 11, 2022 19:38:11 GMT -7
The purpose of this thread is to share progress on the Bridge Planetarium Project and pick up the story from two other threads - ‘Experimental Home-Made Projectors (three different ones)’ and ‘Plywood and Tissue Paper Dome’.
The projector and dome from those threads were put to work in my attic in the run up to last Christmas in a very amateur star of Bethlehem show for friends and family.
A good friend, Phil the farmer, really enjoyed the show. He has a wonderfully optimistic ‘can do attitude’ and basically insisted we expand from the confines of the attic to a bigger audience.
He approached a small local Methodist charity and secured funding for materials (thank you Brotherhood) so that we could build a bigger dome at our church and community center (the Bridge, Launceston). The first target is to be ready for a nativity / star of Bethlehem show by Christmas.
The design attempts to balance construction difficulty, work/ storage space, and cost with audience size and grandeur. We settled on a 4.6m diameter plywood dome made up of 8 gores so that can be packed away and is transportable (rather than fully portable). The projection surface is foamex/ foamcore instead of tissue paper (thanks Ron for the recommendation).
The plan is to use a mix of analogue and digital projectors:
a) ‘type 3’ projectors from the experimental projector thread for artistic impression
cool.gif a Homestar for the milky way
c) a home-made OHP with cardstock silhouette characters for story telling
d) a L’houmeau Sky System type projector running Stellarium to do some accurate sky sequences.
Progress so far:
We started back in May and initially used the Warehouse part of the church as a temporary workspace. The first step was to build a sturdy routing/ work bench from surplus timbers pallets and plywood from a decommissioned skate park in the community center.
The bench has a protruding arm with a series of holes drilled in it. A small round metal peg can be inserted into any of the holes to act as the pivot /focal point for the routing ‘arm’. The peg can be advanced along the series of holes so that a routing arm can get to further reaches of the plywood sheet as you progressively cut more and more arcs (easier to see in the pictures than to describe)
The routing arm is simply a long plank of wood with a hole at one end to fit on the peg and a router bolted to the other end so that beautiful uniform arcs can be routed from plywood sheets.
In fact, the arm has a series of holes in it so that the radius of the arc can be set for inside curve, outside curve and a the complete set of other radii needed to cut the lesser circles in the dome structure.
The projector and dome from those threads were put to work in my attic in the run up to last Christmas in a very amateur star of Bethlehem show for friends and family.
A good friend, Phil the farmer, really enjoyed the show. He has a wonderfully optimistic ‘can do attitude’ and basically insisted we expand from the confines of the attic to a bigger audience.
He approached a small local Methodist charity and secured funding for materials (thank you Brotherhood) so that we could build a bigger dome at our church and community center (the Bridge, Launceston). The first target is to be ready for a nativity / star of Bethlehem show by Christmas.
The design attempts to balance construction difficulty, work/ storage space, and cost with audience size and grandeur. We settled on a 4.6m diameter plywood dome made up of 8 gores so that can be packed away and is transportable (rather than fully portable). The projection surface is foamex/ foamcore instead of tissue paper (thanks Ron for the recommendation).
The plan is to use a mix of analogue and digital projectors:
a) ‘type 3’ projectors from the experimental projector thread for artistic impression
cool.gif a Homestar for the milky way
c) a home-made OHP with cardstock silhouette characters for story telling
d) a L’houmeau Sky System type projector running Stellarium to do some accurate sky sequences.
Progress so far:
We started back in May and initially used the Warehouse part of the church as a temporary workspace. The first step was to build a sturdy routing/ work bench from surplus timbers pallets and plywood from a decommissioned skate park in the community center.
The bench has a protruding arm with a series of holes drilled in it. A small round metal peg can be inserted into any of the holes to act as the pivot /focal point for the routing ‘arm’. The peg can be advanced along the series of holes so that a routing arm can get to further reaches of the plywood sheet as you progressively cut more and more arcs (easier to see in the pictures than to describe)
The routing arm is simply a long plank of wood with a hole at one end to fit on the peg and a router bolted to the other end so that beautiful uniform arcs can be routed from plywood sheets.
In fact, the arm has a series of holes in it so that the radius of the arc can be set for inside curve, outside curve and a the complete set of other radii needed to cut the lesser circles in the dome structure.