A Cat Update
Just a quick progress report for those of you who are regular followers.
Design work is going well with some very interesting insights already in the bag.
A promising hull concept has been identified and tests have started on a family of variants.
The opportunity came up to run some more advanced simulations than we had originally hoped for.
This will add four weeks to the schedule but will give even greater confidence in the final design choices.
While the design work continues we have been evaluating options for tooling and construction methods as well as choosing suppliers for materials and parts.
The first choice regards which parts and stages to machine using CNC/CAM technology vs. traditional pattern/mould making and hand finishing.
This decision is about striking the right balance between machine time cost and labour cost.
Interestingly, the optimum strategy will differ depending on local labour rates, competitiveness in the CNC/CAM market, and the complexity of each part.
Early in the project we decided that investment in tooling is warranted where it will reduce the time required to assemble/finish each boat to the desired tolerances.
Though the exact shapes have not yet been finalised, it is safe to assume that the foil tooling will have a non planar geometry requiring high precision (fine tolerances) whilst being difficult to build using traditional methods owing to the lack of a flat reference plane.
Finally, it makes sense to include in the tooling certain details to optimise beam junctions, stay attachments, and fitting mounting features, again to reduce time spent hand finishing each boat.
With all the above considerations, and given availability of competitively priced CNC/CAM service providers in Australia, the numbers come out decidedly in favour of automated machining straight from the digital 3D model. This approach is consistent with our standard practice of fully modelling all assemblies before manufacturing.
Initially we looked at machining female tools out of solid material (alternatives included tooling board, modelling foam with machinable putty skins, or MDF with a glass skin).
This would eliminate the step of laying up female tools over traditional male ‘plugs’, but would have the drawback of constraining the temperature and pressure we could apply during the curing of the final parts.
Traditional composite female moulds laid up over computer machined male plugs seem like the way to go. They give the freedom to use prepregs at reasonable temperatures and pressures to obtain better compacted and more stable finished parts.
Integral in this decision-making process was an evaluation of different core materials that led to some interesting conclusions…