Surface Roughness

end mill finish with SX2.7 and bracket

At a microscopic scale, no surface appears perfectly smooth. Surface roughness is determined by calculating Ra and Rz. Ra = average surface roughness Rz = information for any pore, hole or surface deformities. These can be detrimental to strength. Ra averages all peaks and valleys of the roughness profile and then neutralizes the few outlying … Read more

Propeller Size

Propeller on 5 cylinder rotary engine

The propeller size should be chosen to match the engine and airframe. However, it may take some trial and error before you get the right propeller for your particular installation. However, the following table may be used as a guideline for two-stroke engines with four-stroke engines in the next table. Propeller Sizes for Two-Stroke Engines … Read more

Model Scale and Sizes

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Model scale and sizes represent a copy of an object that is larger or smaller than the actual size of the object. The scale is the ratio of the model to the full-size object. A look across our gallery pages and you will see a wide range of scales being used. If the scale is … Read more

Cast Iron Piston Rings

piston rings

Some years ago I made cast iron piston rings, however, in the nearly 40 years since I have completely forgotten how. So, I’m reading lots of forums, references and articles on making cast iron piston rings. Whilst doing this I thought it was worth writing an article on the subject. I have listed references where … Read more

Camera Threads

polar duck mini tripod

There are a number of camera threads used for tripod mounts, lens mounts and a shutter release. C-Mount CCD camera lens connector thread 1″-32UN2A with a standard focal distance of 17.526mm. A C-mount lenses can be used in CS-mount configurations with a 5mm adapter. CS-Mount CCD camera lens connector thread 1″-32UN2A with a standard focal … Read more

How to Calibrate Your CNC Machine


A Step-by-Step Guide by Peter Jacobs at How to calibrate your CNC machine is one of the most crucial processes to maintain design accuracy, tool precision, and repeatability. It helps in maintaining the highest standards of quality of the manufactured product while also ensuring that the CNC router delivers optimum performance without causing any … Read more