23


Cutting and drilling subchassis
subchassis dimensions
Preparation
Gather any salvaged blind-nuts from original subchassis.
Make Carbon fibre/end-grain balsa sandwich if necessary.
[see notes for construction if not obtainable ready-made]
Wear a particle filter mask when cutting Carbon Fibre!
Tools
Jigsaw with c/f specific blade
Pillar drill
10mm, 8mm, 6mm drill bits for wood/metal/laminates
Holesaws: 29mm, 30mm, 64mm.
13mm countersink
Sanding block, emery paper, sandpaper
Black indelible marker
Wide masking tape
Note on drilling carbon fibre sandwich
Support underneath with scrap wood/MDF.  Use light pressure all the way through through to reduce tearing and splintering, backing drill out to clear swarf.
Note on attaching fittings in carbon fibre sandwich
Balsa is soft, so it is best to use a filling adhesive (e.g hot-melt glue or epoxy) on fittings such as grommets and blind nuts which fit or screw into holes in the panel.
Materials
1 sheet 330 x 245 mm 1/2" Carbon fibre/end-grain balsa sandwich
4 x M5 blind nuts (flanged)
3 x M4 blind nuts (flanged)
3 x 10mm diameter (6mm interior diameter) grommets
Construction
Time:
1.5 hours mark and cut
0.5 hours sand and polish
?? hours drill pilot holes
?? drill final holes
?? fix fittings
Cover panel top and bottom in masking tape.
Mark out sub chassis shape using template.
Cut out sub chassis, smooth edges
Mark hole centres for:
armboard mounting: 4 x 8mm for M5 threaded blind nuts, 10mm for PT standoffs
Suspension mount points: 3 x 10mm
Spindle: 10mm
Motor assembly
23mm Escap motor
Motor gap: 30mm hole
Motor mounts: Three 6mm holes for M4 threaded blind nuts centred equilaterally at 25mm on motor gap.
40mm Earlier motor
Motor gap: 44mm hole for the earlier motor
Motor mounts: Three 6mm holes for M4 threaded blind nuts centred equilaterally at 27mm on motor gap.
Vector pulley mounts: (if fitted) holes for M6 threaded mounts.
Arm pillar holes; 64m and 25mm holes as marked (drill smaller first).
Drill holes, smooth and clean edges and insides
Remove masking tape
Colour outside edge of balsa with marker pen