Strengthening HL Tiger lower hull
Posted: Mon Aug 24, 2009 9:04 pm
At the recent Cobbaton meet I picked up a pair of Asiatam strengthened gearboxes for my Tiger, but after fitting them I realised that 12 months of use with metal tracks and suspension was taking its toll on the chassis. The boxes were dragging backwards causing the tracks to jump off the rear idler particularly on the long grass. The time had come for some serious rebuilding! >:(
The first step was to strip out the lower hull and get rid of the battery box and all the other lumps and bumps that clutter up the bottom using the dremel and hacksaw. Messy and time consuming but worth the effort. I also glued in the battery cover after removing the high points leaving me with a pretty flat surface. I left in place the front gearbox mounts as reference points for alignment and measured the mounting pegs as 6mm high.
Step 2 was to acquire a piece of 1mm aluminium sheet from evilbay and cut this down to 10 x 25 cms - ideally it should have been longer but the sheet was 25 x 25cms so I mounted it at the front leaving a section at the rear. I araldited this to the lower hull then used 4 b&q corner brackets screwed through the hull and araldited to the side spars to reduce the effect of twisting. (Pic 1)
To mount the gearboxes I built a platform of plasticard 5mm thick and glued this on top of the aluminium sheet at the front edge. (Pic 3)
To prevent the axle shafts wearing their way backwards I built bearing mounts from 2mm plasticard and fitted 8 x 12mm bearings from the model shop and glued these in place after mounting the boxes to make sure that the alignment was right. This was the trick bit and it took 3 attempts to get the left box aligned satisfactorily. (Pic 2)
The next shot shows the boxes screwed in place. For extra rigidity I bolted right through the lower hull and up into the lugs on the side of each gearbox. Where possible I also used self-tapping screws to hold the boxes in place. Finally a spar was put as a top brace between the boxes to reduce twisting further using a piece of aluminium sheet cut to length, bent up at each end and drilled. It also became apparent that with the bearings it was no longer possible to get the gearboxes past the post the is used to screw the upper and lower hull together so this had to go and I need to make a bracket to secure the upper hull in place at the front (not shown).
The next pic shows the bulkhead to prevent grease spraying back into the hull. This also mounts the RX14 board and allows space behind for heat loss. I think also that the vertical mounting is better for cooling the Fets which are usually below the board and can trap heat. The cooling fan is powered off the main board and aids air circulation. (Pic 5)
Finally with all the electronics reinstalled we have a much stronger and more spacious Tiger with little weight gain!
Chris
The first step was to strip out the lower hull and get rid of the battery box and all the other lumps and bumps that clutter up the bottom using the dremel and hacksaw. Messy and time consuming but worth the effort. I also glued in the battery cover after removing the high points leaving me with a pretty flat surface. I left in place the front gearbox mounts as reference points for alignment and measured the mounting pegs as 6mm high.
Step 2 was to acquire a piece of 1mm aluminium sheet from evilbay and cut this down to 10 x 25 cms - ideally it should have been longer but the sheet was 25 x 25cms so I mounted it at the front leaving a section at the rear. I araldited this to the lower hull then used 4 b&q corner brackets screwed through the hull and araldited to the side spars to reduce the effect of twisting. (Pic 1)
To mount the gearboxes I built a platform of plasticard 5mm thick and glued this on top of the aluminium sheet at the front edge. (Pic 3)
To prevent the axle shafts wearing their way backwards I built bearing mounts from 2mm plasticard and fitted 8 x 12mm bearings from the model shop and glued these in place after mounting the boxes to make sure that the alignment was right. This was the trick bit and it took 3 attempts to get the left box aligned satisfactorily. (Pic 2)
The next shot shows the boxes screwed in place. For extra rigidity I bolted right through the lower hull and up into the lugs on the side of each gearbox. Where possible I also used self-tapping screws to hold the boxes in place. Finally a spar was put as a top brace between the boxes to reduce twisting further using a piece of aluminium sheet cut to length, bent up at each end and drilled. It also became apparent that with the bearings it was no longer possible to get the gearboxes past the post the is used to screw the upper and lower hull together so this had to go and I need to make a bracket to secure the upper hull in place at the front (not shown).
The next pic shows the bulkhead to prevent grease spraying back into the hull. This also mounts the RX14 board and allows space behind for heat loss. I think also that the vertical mounting is better for cooling the Fets which are usually below the board and can trap heat. The cooling fan is powered off the main board and aids air circulation. (Pic 5)
Finally with all the electronics reinstalled we have a much stronger and more spacious Tiger with little weight gain!
Chris