I have an Atlas 7" shaper -- far superior to my 10" lathe.  It's almost 
exclusively made of cast iron, and quite sturdy.  I enjoy using it to square up 
workpieces as it is easy to use and sometimes programming MDI codes in the mill 
just isn't worth the trouble for odd jobs.  I have been working on some iron 
castings, and they have a tough outer skin.  The flycutter was driving me mad, 
so I switched to the shaper.  Much easier!

As an aside, the viscosity of the Vactra #2 doesn't allow the clapper to move 
perceptibly on all but the longest of strokes, especially in low speed.  Low is 
WAY faster on mine than the one in the video.  I don't know about his claim of 
slower feed for better surface finish, my experience is that tool geometry has 
more to do with it than speed, but then again I have fairly limited adjustments 
on that score!

One of the key features of a shaper is its ability, with the right attachments, 
to cut true generated involute profiles for gears.  This is possible with a 
mechanism, but is better accomplished with a CNC controlled rotary axis.  It 
offers the advantages of hobbing with a single point tool instead.  Entirely 
possible to make a gear of ANY number of teeth assuming your single point tool 
has the correct pressure angle and tip radius for the module/diametral pitch 
you are using.  The tool is then a simple triangular tool with radius, rather 
than an involute profile.  Much easier to grind, and could even be done on the 
bench grinder with a gauge of the proper angle, just like threading tools!  
Great flexibility in prototyping gears, but with the downside that generating 
the gears takes FAR longer than hobbing.

As I see it, the shaper offers several advantages.  1) Ability to use HSS tool 
bits to perform a wide range of jobs that milling machines could only do with 
specialized tooling.  I.e. dovetails, T-slots, and many others I can't think of 
off hand.  2) Internal keyways/splines/etc, which mills are basically unable to 
do without a 'shaper' attachment.  3) Generated profiles can be readily 
obtained (i.e. gears, as mentioned previously) with simple attachments.  4) As 
mentioned, surface finish is excellent.  I haven't perfected some of the tool 
geometries, but it can be nearly mirror without much effort.

Disadvantages are 1) Can't shape a blind slot unless you drill out the end of 
it first, 2) can't shape a pocket, at least not easily, 3) time.  The saying 
goes "you can make anything with a shaper but money."

I would like to (someday) build a CNC shaper w/ rotary axis on the table 
specifically for shaping prototype gears, splines, etc.  I wonder, though, 
whether the idea of a rotary axis on the ram would be worthwhile.  If you 
define the tool's geometry and have a rotary axis on the table, would you 
really need the CNC control of the top slide angle?  The only problem with a 
CNC shaper is that it requires a lot of adjustments (stroke length, stroke 
position, top slide travel - if you have one, knee travel, cross travel, and 
possibly rotary axis).  If you can bear to automate them all, then writing the 
code may be a bit tricky.  If you can't, then you'd have make adjustments 
between program segments.  Not dissimilar from tool changes, I suppose.

Matt
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