Assembly of the wood frame for the vandegraff generator is as
per figures 20 ,21 and 22. The main dimension of the wooden frame is
configured on a 300mm cube shape. If you have purchased the wood ply or
panel board in one large sheet you will need to cut 3 individual 300mm x
300mm square panels from the main board. 1 of these board will have a
further 40mm removed from one end. This panel will then become
the back panel where you will mount the motor. To save on time and money I
decided to build the wood frame with only three sides. As you can see from
figure 21. The frame has a top panel a bottom panel an a back panel. There
are two 25mm dia round dowel uprights that support the very front of the
wooden frame. Building the frame this way allows for different motor sizes
and choices. It also allows for maximum access around the motor and bottom
roller assembly where adjustments and changes can be made. You may also
enclose this wooden frame further with acrylic or perspex plastic for a
more cosmetic look and feel. Cutting the hole in the top panel is much the
same as cutting the hole in the bottom stainless bowl. Using a pencil,
mark a cross from diagonal to diagonal across the top panel board, this
will give you the absolute centre of the board. Using the bottom 80mm(i/d)
PVC flange, align the flange over the centre mark of the top panel, scribe
a pencil mark around the outside circumference of the flange. This circular mark should be
about 150mm from any edge. You can cut this hole with a hand jigsaw or
large holesaw in a drill machine.The final hole should be 85mm in dia. Be
sure the flange fits neatly into the hole. Do not be too worried about the
hole being ragged or over size. The 135mm rim of the flange will cover
over any mistakes made. You do not need to fix the 80mm PVC flange
into position at this stage. Leave this flange until last where we
will also glue it to the main centre tube. This will then fix the centre
tube into its final position.
Mark and Drill The Panel Screw Locations.
Remove the above PVC flange and secure the top and bottom wood panels
together with a clamp or vice. Make sure all edges are flush to each
other. Mark out the fixing screw location from the top view of figure 20.
Use a 2mm drill bit, drill right through both the top and bottom panels at
the same time. This will allow a more accurate alignment of the 25mm dowel
uprights and the 40mm x 25mm wood strengthening battens to be fixed to the
back panel. Once drilling is complete you can remove the clamp from panels
and separate them.
Fixing The Battens To The Panels.
Cut the 2 @ 40mm x 25mm x 300mm battens to length.Do not confuse the
battens with the round dowel uprights. Align the two battens to the top
and bottom panels inside surface face, flush with the edge where you
drilled 3 screws holes. Apply PVA wood glue to the 40mm underside of the
aligned batten.
Hold the batten secure with
a clamp while fixing the batten from the top down through the 3 drilled
holes. Fix the batten to the underside of the top panel with 3 fixing
screws. Fix the batten to the topside of the bottom panel with 3 fixing
screws.(see figure 21) Be sure you have the panels and drilled holes
orientated an aligned the correct way before you glue and fix the two
battens.
Assembling The Panels
If you have not cut the back panel to size then, resize the back wood
panel to 300mm x 260mm. by removing 40mm from one edge. Leave the back
panel lying flat on the bench top. Be sure you have the 300mm
edge align to the 300mm edge of the top and bottom panel. Stand the top
and bottom panels up at right angles to the bench. Be sure that the fixed
battens on the top and bottom panels are sitting down on the bench. Lift
the back panel up and slip the top an bottom panel 25mm batten edge under
the back panel. The back panel is now siting up off the bench and on the
25mm x 40mm wide battens. Using the top panel apply glue to the 25mm edge
of the batten. Hold the top panel-batten and the back panel into position
with two clamps. Drill 3 holes @ 2mm dia along the inside top edge of the
back and top panel into the batten. Be careful not to drill into the
original screws coming from the other side of the top panel-batten. Fit 3
fixing screws into the drilled holes. This will fix the back panel and top
panel together. Repeat the steps for the back and bottom panel. Ie. Glue,
clamp, drill and fix the back panel to the bottom panel and batten using
the same procedure as the top panel. (see figure 21)
Fitting The Uprights & Flange
The final part of the wooden frame is to fit is the 2 @ 260mm x 25mm
dia wooden dowel uprights. Cut both of the dowels to length. You should
have already drilled the two holes to fit the dowel uprights into the
panels.(see figure 20) These two holes are 30mm in from the front corners
of the frame. Apply PVA wood glue to the very ends of each of the dowel
uprights. Using a fixing screw down from the top panel and up from the
bottom panel fix the uprights permanently into their final position. Flip the box into the upright
position with the flange hole toward the top. You are now ready to fix the
bottom 80mm PVC flange into the hole of the top panel. Place the PVC
flange down into the hole and fix the flange into position with 4 fixing
screws.(see figure 24). Once you have complete the last piece of the
wooden frame you should have an assembly that looks something like figure
23. I chose to place the batten supports to the outside of the frame in my
design. This allowed better freedom and movement when mounting the
electrical motor. The battens could pose an obstacle to the motor mount
when fitting or adjusting the motor position. You may chose to place the
battens towards the inside of the frame, that is quite okay as it
shouldn't make a lot of difference.
Alternative
This panel will then become
the back panel where you will mount the motor. To save on time and money I
decided to build the wood frame with only three sides. As you can see from
figure 21. The frame has a top panel a bottom panel an a back panel. There
are two 25mm dia round dowel uprights that support the very front of the
wooden frame. Building the frame this way allows for different motor sizes
and choices. It also allows for maximum access around the motor and bottom
roller assembly where adjustments and changes can be made. You may also
enclose this wooden frame further with acrylic or perspex plastic for a
more cosmetic look and feel. Cutting the hole in the top panel is much the
same as cutting the hole in the bottom stainless bowl. Using a pencil,
mark a cross from diagonal to diagonal across the top panel board, this
will give you the absolute centre of the board. Using the bottom 80mm(i/d)
PVC flange, align the flange over the centre mark of the top panel, scribe
a pencil mark around the outside circumference of the flange. 
This circular mark should be
about 150mm from any edge. You can cut this hole with a hand jigsaw or
large holesaw in a drill machine.The final hole should be 85mm in dia. Be
sure the flange fits neatly into the hole. Do not be too worried about the
hole being ragged or over size. The 135mm rim of the flange will cover
over any mistakes made. You do not need to fix the 80mm PVC flange
into position at this stage. Leave this flange until last where we
will also glue it to the main centre tube. This will then fix the centre
tube into its final position.
Be sure you have the 300mm
edge align to the 300mm edge of the top and bottom panel. Stand the top
and bottom panels up at right angles to the bench. Be sure that the fixed
battens on the top and bottom panels are sitting down on the bench. Lift
the back panel up and slip the top an bottom panel 25mm batten edge under
the back panel. The back panel is now siting up off the bench and on the
25mm x 40mm wide battens. Using the top panel apply glue to the 25mm edge
of the batten. Hold the top panel-batten and the back panel into position
with two clamps. Drill 3 holes @ 2mm dia along the inside top edge of the
back and top panel into the batten. Be careful not to drill into the
original screws coming from the other side of the top panel-batten. Fit 3
fixing screws into the drilled holes. This will fix the back panel and top
panel together. Repeat the steps for the back and bottom panel. Ie. Glue,
clamp, drill and fix the back panel to the bottom panel and batten using
the same procedure as the top panel. (see figure 21)
Flip the box into the upright
position with the flange hole toward the top. You are now ready to fix the
bottom 80mm PVC flange into the hole of the top panel. Place the PVC
flange down into the hole and fix the flange into position with 4 fixing
screws.(see figure 24). Once you have complete the last piece of the
wooden frame you should have an assembly that looks something like figure
23. I chose to place the batten supports to the outside of the frame in my
design. This allowed better freedom and movement when mounting the
electrical motor. The battens could pose an obstacle to the motor mount
when fitting or adjusting the motor position. You may chose to place the
battens towards the inside of the frame, that is quite okay as it
shouldn't make a lot of difference. 