Problem Solving of the Bonding of Components

Original technique Which Fails

The original technique to pond components was to use Zap a Gap professional modelmakers super glue with activator spray, Whilst, this can stick near instantly with what feels like a strong bond it has some problems. Experience with the Tower Control prop highlighted the following issues:

• To work properly it needs flat surfaces, that ideally are porous.
• The surfaces to be paint free or what sticks is paint to paint.
• Some components such as those not resin cast, such as grills, speakers, Nerf gun and other panel parts hade very little surface area to bonds as were shells and thus only had a 1-2mm edge that was not complete to act as a mod surface with gaps handed could hook under and pull the component away
• The component glued need to be left alone, not to take knocks or impacts or held creating sheer forces.
• Problems here, more so with the trunk is that there is likely to be a fair number of knocks and pulls and sheer forces applies as it is moved around, pumps on walls, doorways, handled with hands, car boots hatches etc.
• An additional problem came up that the case shell can flex thus pull away from the joint.
  

Soft Flexible Joint

Previous experience with the tower props demonstrated that whilst superglue makes instant bonds with some firmness. With other glues such as glue gun or epoxy giving a more embedded bond but not much difference.

Adding the thin layer of 5mm Plastazote that is bonding one side to the prop and the other to the component makes the bond more elastic and tougher with some degree of bend and give before breaking. This makes it more impact resistant.

Switching to Contact glue that worked well for soft materials like foam and offered both flexibility and contact bonds.

A few issues came up:

In regards to the main front tech panel there was a complex set of very small components that needed very precise positioning and to be held in place till fully bonded. Small foam patches would not work well.

A better system here would be to use a large panel of foam, which would have the added advantage that it would appear to be one mechanism.

Ideally this would be in an alcove or recess to appear it was inside the machine box.

The next best thing would be for a raised boarder.

• The aim was to make the components stand out from back. If I stuck the component to the panel first then spray painted without a precision airbrush, everything would be sprayed the same.
  

• Spraying the back plate first means its all covered in paint. The problem there would be when gluing components, they stick to the paint, not the material surface.
  

• The solution seemed to be, first supergluing the components together to foam a large component.
  
  
• The bonds were pretty weak at this stage, but the components could keep potiion in relation to each other.

• Use this to make a stencil, then spray the background colour (Black) onto the back foam plate.
  
  
• This left the bond area foam exposed and then roughend up to be glue bonded with Evostick contact glue and some superglue with the smallest parts.

• The components could then be sprayed separately, primer, materials then distressing such as rust spray.

A frame was added and smoothed with a power file and chamfered.

The sprayed components with then glued into place, ideally with holes for later riveting already drilled.

The panel with component was then glued to the prop.

This was followed up by riveting most of the components

Riveting and Bumper Loops

In addition, experiments with riveting had shown huge benefits in structurally connecting components through the prop casing, not just gluing the surface. 5mm rivets were too tough to apply with a hand rivet gun so I went with 4mm.
 

Rivets were preferred to screws, or nuts and bolts as more permanent and looked like part of the components as well has having no bulk inside or outside the prop casing. Drilling holes on all the components also provided the alternative to riveting of allowing LED lights and electroluminescent string.

Where possible components were predrilled before gluing in place to minimise issue of torque ripping components off the panel and as there was more control for drilling individual components in vices than trying to drill sideways into the prop.

The pre-drilled holes also gave a means of holding the drill bits in place when drilling into the case without gripping the components and determining where to drill.
 

Metal door handle loops were added as well. Part of the reasoning was for aesthetic looks. But the pain reason was to provide bumper bars to protect the components to take the impacts first.