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On Tue, 10 Nov 2009 18:48:52 +0800, "diggerop" toobusy@themoment
wrote:
http://www.flickr.com/photos/32473839@N02
diggerop
Noticed your IMG_3416 router jig there. Reminds me of a similar jig
except the two top pieces swivel and the jig is used for cutting
perfectly sized long dados in a board. The dado you have there appears
to be for cutting slots up to 4" wide. I was thinking about combining
the two jigs.
As long of course, I'm reading the image properly.
Yes it seems you are reading it properly. However, I'm not sure it could be
adapted to cut dado's in the long axis without sacrificing some inherent
accuracy that exists in it's present design and still remain adjustable.
I'll try and explain the rationale behind why it's built the way it is.
Firstly, I had a triangular shaped workpiece that presented problems in
clamping guide boards to it in the conventional fashion.
Because of the peculiarities of my split benchtop, I saw an opportunity to
create a jig that could be quickly clamped to the smaller section of the
benchtop, thereby giving a constant height for the router base, regardless
of where it was positioned. It is, for want of a better description, a fully
enclosed box with two sides removed. The workpiece is inserted through the
jig and the surface to be routed is also positioned co-planer with the
benchtop. It's relationship with the top of the jig is then not critical,
save for the need to ensure it is close enough for the router bit to reach
the required depth. The top of the jig and the surface to be routed are now
co-planer and will remain so, regardless of where the jig is subsequently
positioned.
The top is constructed with one side fixed, the other adjustable by means of
slotted guides running on the outside of the box, with a *very* snug fitment
and locked in place with 4 wingnuts. Within the range I have given it, the
faces remain parallel when adjusted. (I make a practice of completely
tightening one side before the other to reduce the chance of inducing a
small error through skewing.) Setup is always checked with a vernier.
Setting the top opening requires making an allowance for the difference
between the router guide bearing and the cutter width, in my case 7mm.
I set depth of cut by plunging the router until it just contacts the
workpiece, then adjusting the router depth stop to allow the required depth
of cut.
That setup will now cut identical dadoes anywhere along the length permitted
by the benchtop.Each movement to a new position only requires the two clamps
holding the jig to be released, jig moved to next cut line and clamped to
the benchtop again.
For subsequent pieces with the same dado width, it only requires re-setting
of the plunge depth for the first cut.
Accuracy of the construction of the jig is the most critical part, -
everything needs to be perfectly square. I got lucky and the first attempt
came out ok. I had built it for a one-off purpose, but it works so well,
I'll try and refine it a little, firstly by affixing some harder material to
the router bearing guide faces. It would also work with a plain router bit
and remain adjustable by affixing a guide board to to each top piece.
If the basic setup rules are followed, most potential errors are eliminated.
Setup time is actually quite quick, a lot less than it will have taken you
to read this long-winded discourse. : )
I've added another photo to the set, - different piece of wood and a better
view of the entire setup.
http://www.flickr.com/photos/32473839@N02
I'll look forward to seeing what you come up with. : )
diggerop