Geared & Corner Braces
by George Langford, Sc.D.
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Ultra-Rapid hand-drilling machine
designed for the
Argentine, Brazil & Philippine-Islands markets

Ultra-Rapid spur-geared breast drill
Another view
This drill might very well be termed an ultra-light portable post drill.  It is the most complex breast drill that I have ever encountered.

The frame is cast aluminum, painted a dark olive drab, which looks lighter in  these images than it actually is.  In the two images at left, it is mounted in a vise, using a block of handy wood and the special clamp supplied with the drill.

The gears are set for the higher speed here.  Yes, there is plenty of knuckle room for cranking.

The crank is counterbalanced passably well, as spinning the handle and letting go while holding the frame with the other hand does not produce much oscillation of the drill.

It is very easy to get pinched by the gears, even when just picking up the drill.  Grasping the drill blindly while it is coasting could result in loss of a finger, as the flywheel stores quite a lot of kinetic energy.

There is also provision of a grinding wheel for sharpening the drill bits.

This drill was apparently being marketed in regions (such as Brazil, Argentina, and the Phillippine Islands) where electric power wasn't widely available, as the accompanying booklet compares it to an early electric drill as well as to a conventional breast drill.  Probably cheap labor gave it another advantage.
Gearing - 051
Gearing - 053
Gearing - 054
The drill has complex spur gearing, with a flywheel to help one through the hard spots.  There are two speeds - about 1:1 (center image) and about 5:1 (right-hand image). There's a little pin & spring, more clearly visible in the left-most image, that one depresses in order to slide the cluster gear.

It is claimed (see the separate ephemera) that the straight cut spur gears are more efficient than bevel gears like those in most breast drills.  See this video clip to judge for yourself.
Ultra-Rapid spur-geaqred breast drill in original box
The cases that the Ultra-Rapid drills came in (at least, all the ones that I have seen) are crudely made of rough-cut boards like an orange crate.  However,they do have a dust shield around the opening.  This one, as well as the drill inside, are both in unused original condition (except that I added a few suitable nails to hold the case together a little better).  The fixture at upper left in the opened box is the special clamp that allows the drill to be affixed to a workbench.  The side handle and chuck key are at upper right. 
Spindle nose and chuck
The chuck will hold up to 10mm (0.394 inch) bits. The spindle turns with minimal run-out on ball bearings which are lubricated through the oil holes seen in the images at the top of this page.  I do not know how dirt is kept out of the bearings ...  The chuck is quite rigid, and there was little give when the key was used to tighten the chuck on the bit as shown at left.