Newsgroups: rec.woodworking
Date:         Mon, 16 Nov 1992 12:26:30 EST
From:         Jim Morgan <JMORGAN@BROWNVM.BITNET>
Subject:      Re: Router Table Inquiries

>Posted on 16 Nov 1992 at 08:20:30 by Bob Haar
>
>Re: Router Table Inquiries
>
>Date:         Mon, 16 Nov 1992 13:12:14 GMT
>Reply-To:     rhaar@albert.cs.gmr.com
>From:         Bob Haar <rhaar@ALBERT.CS.GMR.COM>
>
>In article 15620@adobe.com, bennett@adobe.com (Bennett Leeds) writes:
>|>Stan Armstrong writes
>|>> If it is ease of cutting mortises you are after, consider one of the
>|>> horizontal router mounting jigs that allow you to mount your router
>|>> at the back of the table with the bit parallel to the top. The
>|>> height of the bit above the table is regulated by swingine the router
>|>> about a pivot. This would let you use your plunge capability and
>|>> thus eliminate the need to pivot the workpiece.
>|>
>|>So, we clamp the wood to the table, plunge the router horizontally,
>|>then unclamp the wood so we can slide it along the vertical fence,
>|>then clamp the wood back down, and then unplunge the router?
>|>
>|>Sounds awkward to me.
>|>
>|>And, if you don't clamp the wood down, you've got to have a hand holding
>|>it while you use the other to plunge the router in.
>|>
>|>Sounds dangerous to me.
>|>
>
>I am not sure about the mortising table design Stan was discussing,
>but I built one from the WoodSMith plans. In this one, you
>don't plunge the router, you move the wood.
>
>The big advantage of this setup is that the work piece is resting flat
>on a table surface. This makes it much easier to control. And you can
>clamp temporary guides pieces to the table to act as stops.
>
>
>---
>        Robert Haar               InterNet : rhaar@gmr.com
>        Computer Science Dept., G.M. Research and Environmental Staff
>DISCLAIMER: Unless indicated otherwise, everything in this note is
>personal opinion, not an official statement of General Motors Corp.

Well, I'll weigh in on Bennett's side here - the horizontal mortising jig
(BTW, Spielman describes one in 'Router Jigs & Techniques') seems dangerous
to me, given that the bit is completely exposed.  Also, in feeding the wood
into the bit, you still have the arcing problem I was concerned with in my
earlier post - you need to hold the board against a fence at one end and
pivot it into the bit in order to have any control.

On the other hand, it's not too difficult to solve a problem that Bennett
brought up about beginning and ending stops for mortises on long boards.
I built a jig that had a base board with a hinged outlier and a second board
with two 'feet' that fit around the base board.  In use, the base board
is clamped to the router table so that the wood to be mortised is held
snugly between the base board and the router table fence.  The base board
is adjusted along the fence so that when the hinged piece is down, the
board is located at the beginning of the mortise (The hinged piece is angled
at about 7 degrees to compensate for the arcing problem).  The second piece
is adjusted and clamped so that the foot on the side of the fence provides
a stop for the end of the mortise.  To cut the mortise: the hinged piece is
flipped down, and the wood is lowered into position against the first stop
(the angle forces the wood _backwards_ at the bottom of the arc, ensuring, in
theory a square-sided mortise).  Then, the hinged stop is flipped up, and
the wood is slid over to the end stop.  Then the wood is pivoted up, using
the stopped end as the pivot end, again ensuring a square-sided mortise.

I think that this system is superior to the wood-attached mortising jig/
hand-help plunge router solution that Bennett suggested for two reasons:
the router table provides a stable surface for the wood, and my jig needs
to be set up only once for production runs.  On the other hand, I find that
my mortises do tend to come out belled on the ends, which is the reason I
was thinking about a treadle mechanism for raising the plunge router.
Wood for a treadle, a couple pulleys, some cable, and a locking mechanism
(that's the bit I'm need help with) should cost less than $50 - considerably
less than the commercial systems Bennett mentioned.

Jim Morgan
James_Morgan@brown.edu