Question on Woodpeckers Mortising Jig
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| Posted in Jigs, Fixtures, Tips & Tricks on
I watched the videos on Woodpecker’s mortising jig described in the recent article in Fine Woodworking. The article didn’t mention the need to add a bit on each end of the setup to account for the guide bushing. The way the article describes it the mortise will be short on each end. What am I missing? And, anyone know what this measurement should be?
Replies
Just received mine, haven't yet had a chance to use it but I do have it squared up.
This is only a guess at this point, but by my reading, I believe they're saying that because of the guide bushing, which will stop the bit at the end of the length you have set up, you'll need to add, to the length of the jig's slot, the distance from the outside of the bushing to the edge of the bit to yield the length of mortice you're milling.
I may not have explained that very well, but it's my best shot. I hope to use mine this weekend, I'll let you know how it sorted out.
Seems to me the distance between the two stops should be the length of the mortise plus 2 times the distance between the edge of the bit and the outside edge of the wall of the bushing.
For example, if you have a 5/8" outside diameter bushing and a 3/8" diameter bit, the distance from one edge of the bit to the outside wall of the bushing would 1/8". Two times 1/8" is 1/4". If your mortise is 1 1/2", add the 1/4" to get 1 3/4" space between stops. Once you have the measurement, make a spacer that length to place between the two stops. That will give you consistent spacing whenever you need to set up the jig for a mortise with the same length. Write the bit and bushing diameters on the spacer.
The exactness of the length of a mortise is not something to excessively worry about, at least it's not as critical as the thickness/width of the mortise.
OP - Pete did a much better job of explaining it than I. I forgot there are 2 ends to the length of the mortise. I believe he's dead on.
It turns out that the additional space you need to add at end is 1/2 of the diameter of the router bit you are using. (The guide bushing that is included can accommodate several sized bits.)
In my case I'm using a 10 mm bit so I need to add 5 mm at each end.
Right, similar to the Mortise Pal (no longer made) you add the offset of the bushing times two to position the stops. Mortise Pal made it easy and simply labeled the templates with the resulting size based on bit diameter. The same setup will have a different result with a 1/4" bit versus a 3/8" bit. I would have thought Woodpeckers would include a table with that info in the instructions(???).
Found it in the manual. Pic attached.