Subject: Variable Speed Routers?

From: Jim <[email-masked]>
Date: Tue, 11 Feb 1997 08:04:04 -0800

Before I buy my first router I was wondering if anybody could give
reasons for the variable speed function found on some models.  All I can
think is that it is to slow the router down to avoid burning some
materials.  Is this correct?  Are there other reasons?

Thanks in advance

Jim Martin
[email-masked]

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From: Tom Christian <[email-masked]>
Date: Tue, 11 Feb 1997 09:03:02 -0700

> materials.  Is this correct?  Are there other reasons?

	Being able to reduce the tangential velocity of large,
	panel-forming (and other) bits might be one reason.  In
	general that's why shapers have high and low speeds, too.

	My router is a variable speed model, but I rarely use it.
	Then again, I tend to use the shaper for cuts where I
	might be inclined to reduce the speed.

					Tom

======================================================================
Tom Christian					E-Mail:	[email-masked]
Hewlett-Packard Laboratories			 Phone:	(970) 229-3531
External Research Program			   FAX:	(970) 229-6198
3404 East Harmony Road
Fort Collins, CO 80525-9599

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From: [email-masked] (Explodey2)
Date: 11 Feb 1997 15:40:28 GMT

Well, you're partly right. Speed control is also to slow down larger bits.
At a given speed, a larger diameter bit will have a much higher cutter
speed than a small bit. Rabbeting bits, panel raising bits, large profile
bits, all can stand to be slowed down some with speed control. Just to
give you an example,  a 1/4" bit spinning at 22,000 RPM has a linear cut
speed of  Pi x D x RPM / 60 = 288 inches/sec
                                                    3.1416 x .25 x 22,000
/ 60 =288

A 1" dia bit at same speed would yield: 1150 inches/sec.

You can see what would happen for 2" diameter, etc. It is a linear
relationship, if you  double the bit diameter, you double the cutter speed
on the wood.

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From: [email-masked] (Sra817)
Date: 11 Feb 1997 19:37:24 GMT

I've been wondering the same thing. just bought a var speed myself. I know
when using large diameter bits, ex: raised panel, a slower speed is
prefered. What about when using soft woods like pine,aspen, or cedar. Any
answers out there?

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From: Termite <[email-masked]>
Date: Tue, 11 Feb 1997 16:56:58 -0500

I should've gone on to say - There are many factors (like everything)
that influence the speed that you'd choose. Ok, it's not just because at
high speed that you might burn the wood, or worse the bit, it's also the
speed at which you continue to move the router. You can set you router
to it's lowest speed and still burn stuff up. Try a rip or crosscut on a
TS, you must move the material at a rate that is consistent with the
capacity of the motor without overloading it, and not so slow that heat
builds up on the blade, least you burn the wood, or worse the WWII.
Whith your router it's a little more sensitive ( I believe) because if
you move the router to fast you'll get a rough cut and perhaps a lot of
tear out, just a little to slow (like inside corners) and you'll burn
the wood. I find it harder to provide a constant rate of travel with the
router. Not that I burn things up, but there's always those little
tale-tell signs to remind me. Nothing a little sandpaper doesn't fix.

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From: Termite <[email-masked]>
Date: Tue, 11 Feb 1997 15:42:21 -0500

It's kinda like a jointer or planer. The faster the bit turns the
cleaner the cut. Or the more knives and the faster = more cuts per inch
which equals CLEAN CUT. 
However you have to take into consideration the density of the material
and the size of the router bit. The softer the wood and the smaller the
bit the faster you can spin it and get a cleaner cut.

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From: "T. W. Clapp" <[email-masked]>
Date: 12 Feb 1997 04:51:21 GMT

Since this is your first router, I'd suggest you forget about features like
variable speed.  Get a decent router and use for a while on various
projects.  You will soon learn the limitations and the "occasional" need
for slower speed.  For example, I find cherry a fine wood to look at, but a
bitch to work with unless you have VERY sharp bits.  It burns very easily
until you slow down the router.  When that time comes, go buy a $30 router
speed controller (available from MCMS) and attach it to the side of your
table.  works fine.

PS: If I were buying my first router, I'd go with a PC or the little Dewalt
610.  Both around $150.

Jim <[email-masked]> wrote in article <[email-masked]>...