This system supplies cutting fluid to the cutting zone by gravitation.  A valve at the bottom of the plastic bottle controls the flow rate.  The fluid-delivery tube is made of silicon. 

Vertical posts provide for mounting the plastic bottle and  for positioning  the outlet nozzle.

Before trying this system I read in many books for the home machinist that a small amount of oil brushed onto the workpiece could effectively increase cutting efficiency.  However, when I tried this, I  did not see obvious differences between cutting dry and cutting with a thin coating of brushed-on oil. 

Based on this experience I decided to try this fluid delivery system and evaluate it with different cutting fluids.  The results are given below.

The nozzle is positioned to provide flow to the cutting area. The flow rate can be adjusted from a slow-drip to a steady flow, as needed. 

This system works well to apply the desired flow of cutting fluid to the cutting zone.  I have tried a number of different cutting fluids and my findings are given below:   

Emulsion Type Oil - Better than other oils I have tried.  No smell. Cheap. Clean.  Good lubricating properties. I have used it for lathe turning and drilling. Generous flow is recommended.

Soluble Type Oil - This product is similar to emulsion type oil.  One difference is the higher lubricity of the emulsion type, and the transparent colors of the soluble type.  

Salad Oil - When used on finishing cuts, surface finish is good, and the smell isn't offensive.  After machining; however, the mix of salad oil and swarf is an unwelcome mess. 

Motor Oil - This oil smokes when hot and has an offensive smell.  It is not suited for the home workshop. 

Diesel Oil/Coal Oil - I have not personally used these lubricants, but have read that they are effective for machining aluminum.  I have not tried them because I don't want these fluids splattered throughout the workshop.