From: jra@nsscmail.att.com (John R. Avery)
Subject: Re: CAREFUL WITH THAT PROPELLER!!!!
Organization: NCR Systems Support Center - New Jersey
Date: Wed, 2 Sep 1992 13:24:48 GMT

In article <9208311331.AA01219@e5sb.osdhw.syr.ge.com> talaga@E5SB.OSDHW.SYR.GE.COM (dave talaga x2752) writes:
>> On the subject of variable speed for routers, I purchased a Bosch 3HP
>> plunge router before Bosch introduced their variable speed model and
>> would like to make it variable speed. I've seen a couple of variable
>> speed controls on the market. Any experiences with these units,
>> particularly with higher amperage routers?
>>
>> Gary Betz
>>
>
>I too purchased the Bosch 1611 and purchased the variable speed controller
> (can't remember the brand off-hand) that sells for 39.95.  It is capable of
> controlling loads up to 15 amps, has a 3 prong plug at the top, a switch for
> variable speed and normal operations, and a large dial on the front with
> readings from 0 to 100% of power.
>
>This thing does control the power (rpm) output of the router to a point.  There
> is no way of telling how fast the bit is actually revolving since you're using
> % of power and not rpms.  I have found that it can't start the router unless
> the dial is around the 60% range, and then you can back it down to the 40-50%
> range before the router stops.  I have never tried using the router with the
> speed control so low and find I generally use it around 80 %.  Again, it is
> impossible to tell what the rpm of the spindle is and so you use it by "feel"
> (every time I use it I try to think of a way of calibrating the scale to rpms,
> then I think about selling the router and buying one with built in speed
> control).  Also, it seems to me that 100%  power does not equate to the power
> it seems to have plugged into the wall (highly unscientific since it's all by
> the sound the router produces--in fact, sound=feel when setting this up).
>
>I use this in my table for stile/rail bits mostly and various other bits that
> tend to take big bites (straight bits for dadoes, bullnose, slot cutters),but
> have yet to use one of the "propellers" that I've read about.  Frankly, for
> most applications, I can't imagine using the 1611 without it, and I would never
> by another router without speed control built in, but I wonder if you get the
> same "control" with this particular, or any other, addon controller as you
> would with a good factory setup.
>
>My recom':  If you're going to keep the router--buy it.
>
>Dave Talaga

I have the MLCS speed controller which sells fo $39.95. Your observation that
"100 % power does not equate to the power it seems to have plugged into the l
wall" is correct if you have the same unit because they use a half-wave device
which delivers a maximum of half power to the load. Interesting also is that 
the power device itself is rated at 8 amperes; it can be used with 15 amp loads
only because the half wave output makes the average current 1/2 of what would
be measured with the load plugged into the wall. Also, I found that the outlet
on the speed controller was wired backwards; i.e., hot and neutral reversed.
This could be a safety hazard under certain conditions.

Full wave speed control circuits are well known but I don't know of commercial
speed controllers that use them; they must exist however perhaps from industrial
al
suppliers. I'f your handy with electronics you can build one yourself. The 
performance is IMHO substantially better.

Bob Avery
attmail!javery 
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