Propeller lathe

[ThePistolsmith]

The 1919 edition of Dyke's Automobile and Gasolene Engine Encyclopedia showed a photo of a propeller lathe, but gave no pertinent information. Does anyone have information on how this tracer machine worked?
I'm wondering if a gunstock tracer would work to make authentic propellers for RC aircraft that would make the bird fly at scale speeds.

[John McKenzie]

Hi Pistol' First off , I haven't seen the photo to which you refer , however , assuming it to be the " standard " type of prop. tracer mill ..:- It will have the master pattern in very hard wood or alloy' in a horizontal position , some 12" behind where the new blank half blade also lies horizontaly . ( the other 1 or 3 half blades await their turn for treatement on the LH side , and will be rotated into position by indexing , when the time comes ).
Running on the master blade is a roller / stylis , which is directly connected to a cutter block of similar outer diameter dimentions which opperates on the new blank . The cutter head is somewhat similar to a circular cutter block of a spindle moulder , with tube / gouge type cutters , these revolving at very high speed . Both master and blank blades , held in their respective fixtures , are inter connected , so that they rotate precisely together ,about their horizontal axis ,slowly, ( against the cutter direction ) , so that the new blank becomes the exact shape of the master . Interconnected with the rotary action is the slow horizintal travel along the length of the blades ,of both stylus/roller and the cutter head which all the time , is mimicking the movement of the latter . Thus a duplicate is formed .
The tip portion cannot be completed as it is necessary to hold both the tips of blank and master steady with what might be equated to tailstocks .
On completion of one blade , the blank is indexed around 90 (for a 4 blade ) or 180 deg. for a 2 blade prop' .Hand finishing is still necessary but a great deal of time is nevertheless saved for production work ..Ballencing / finishing etc then follows
I have no doubt that today , CNC has made obsolescent , this older process years ago !
Regards JM

[ThePistolsmith]

Thank you, John.