Some reflections about CNC-made models/ CNC使用之經驗及迴響

I have been using CNC for more than 4 months since I joined this NMSI lab as a RA; after hundreds times of exercising on this machine, some problems and limits revealed.

In our lab, Acrylic plates and cubes are cut into appropriate size with manual rotating saw, the inaccuracy of hand-made materials sometimes severely affect the quality of the models we made.

What is more, the grid line on the drill base can not match accurately with driller, which leads to a common askew on all models. Drill base was fastened on Y-direction motor with screw nails, when replacing new base boards, inevitable displacement was made. The manually fixed drilling material aggravated the error, human hands are not precise enough at all to handle the size below millimeter. This inaccuracy also made both-side shaping impossible because of the difficulty of positioning.

However, I still found some ways to reduce the problem with an approach of model design. Regardless the errors on grid lines, the numerical-controlled motor is still very precise. By adding some aligning symbols or structures, such as tenons, to prevent grid line problem and errors by hand, multiple components can still combine perfectly with each other.

After all, the desire of better tools is infinite. Using tips and techniques will allow us to research more efficiently and economically.

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CNC用了蠻久了，我已經相當清楚它的能力與限制還有問題。

由於基板是用螺絲鎖在Y方向步進馬達上，一拆一裝之間格線的偏移問題相當嚴重，這不只造成位置不準同時也讓多個構件組合加困難。想要做更加複雜的雙面切削幾乎不可能，因為材料翻面後對準就成了大問題，只用人手定位會產生極大的誤差。

排除花錢修/買更好的機器，我認為在改良構件設計上可以避免許多此種問題。例如讓CNC鑽頭去完成材料外部塑形而不是預先用切割刀/雷射先把材料切好，如此減少一道用手移動的程序可以大大降低對歪斜問題。另外設計榫頭或其他輔助對準造型也是一個方法，如此可以相當程度克服CNC機台的根本問題。