What could a 1-1/2hp shaper do that a 3+hp table mounted router could not for a non-professional woodworker? Do you really need a 3/4" spindle? Are the motors on shapers rated true hp and the router is funny hp?
IIRC most shapers can run backwards, not so on any router.
Since you can't put wood back on by running the tool backwards that would seem to me to be of limited utility but could help to reduce tearout.
Also STR that for the same HP, shapers have more torque.
Not only have I not used a shaper, but never saw anyone use the shaper at the Vienna, VA woodworker's club I used to frequent. When they mover to Springfield, they did not set the shaper up in the new shop.
A. Handle larger and reversible cutters.
B. Depends on the rating and the manufacturer. I'd not get a 3/4" spindle shaper w/ less than 2 hp, however, particularly if it's a Chinese motor variety...
The major advantage of the shaper over the router is simply the extra mass that makes it more solid for heavy shaping jobs and the ability to handle the really large cutters safely--panel raisers come to mind. The disadvantage can be fewer profiles and higher cost. For the average rec user, the router will probably do all he's like to want to do although I'd hate to give up the shaper(s). (I've two, the LD 1/2" Delta and a PM Model 27 w/ the 1/2 & 3/4 interchangeable spindles. But, I do a bunch of things like windows and entry doors so the setup of the small one to do the stub spindle coping cut while leaving the large one set up for the main sticking cuts is a real advantage.)
HTH...
Router or shaper?
One formula for horse power is ...Two pi nt /33000 where n = rpm, and t = torque
In the case of the router which runs at about 20,000 rpm torque is sacrificed for rpm or cutting force at the cutting edge [torque being force times distance].As most router bits are small the effects low torque [force times distance] are minimized . When the larger cutters are in use torque does become a factor as the cutting edge is farther from the axis of rotation . As a consequence the force at the cutting edge is reduced and so shallower cuts are in order if the machine is going to operate efficiently.
The shaper on the other hand operates at considerably lower rpms and there for for the same HP generates a much higher torque and thus cutting edge force .........mjh
"mike hide" wrote in news: snipped-for-privacy@comcast.com:
Mike, that's the best simple description I've ever heard regarding the reason for using one of these tools over another.
Thank you.
Patriarch
Except, of course a loaded router slows down....
I did mention efficiency , a router running essentially bogged down ,well below it's design operating speed will overheat the motor and be short lived .
Several years ago some manufacturers to cover their tracts offered simpl;e chucks for their shapers to facilitate the use of router bits .The shaper operates at too low a speed to be used as a router consequently the performance was lacking.......mjh
mike hide wrote: ...
Depends on the bit diameter...large panel-raisers, for example, have as large or larger cutting radii as do shaper cutters so the tip speed is equivalent. But, for small diameters the lower rotational speed does lead to poorer performance in general, correct.
You answer is wonderful, but as with the flowers that bloom in the spring (tra la), it has nothing to do with the case.
Feed rate and depth of cut have more to do with the process than whether it's an induction or universal motor, or equations of efficiency. In many respects, the universal motor, with its constant-speed circuitry, will produce a better cut as long as the feed rate is constant.
Seems to me what we are trying top achieve is a quality cut whatever machine we are using .Regardless of the spring flowers, type of motor, or circuitry, too deep of a cut or too high a feed rate will exceed the available "work" output of the motor which in the worst cast will stall it .At the least it will slow the motor down thus negating the cutter efficiency. Cutters are designed to produce a quality finish by a combination of geometry for a given speed and feed rate. Overloading , exceeding the given work output of the motor on a regular basis will will end up reducing its life .
As far as constant feed rate goes I thought that is why we use power feeds .....mjh
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