Phil Thien
04-15-2011, 12:15 PM
I wanted one because last weekend I was working on a walnut medicine cabinet using some beautiful straight-grained walnut I had found the previous weekend at my hardwood supplier. I was assembling the face frame with pocket screws when CRACK. The 2nd to the last screw cracked the stile going in. BADLY.
I had enough wood left to make one more frame, so I used dowels to assemble it. I like dowels enough, but positioning the jig can be tedious (IMHO). I know others disagree, but having side to side play in the joint and then being able to align things during glue up, like a biscuit jointer or a Domino with an oversize (wide) cut takes a lot of the worry out of getting things perfect while cutting the joints.
ANYWAY, I've been thinking about making a mortising jig to use with my little DeWalt DW611 plunger. It has great dust collection. It plunges nicely. It seems like it would be perfect.
Many of the jig plans out there (Shop Notes, etc.) are for larger jigs. I wanted something smaller. Something I could "take to the wood" if desired. Something I could use at the bench (clamped) like a full-size jig, but also something that I could clamp to a large workpiece out of the driveway. I also decided that using multiple floating tenons (like using multiple biscuits or multiple dowels or multiple Dominos) was preferred to adjusting the size of the mortise to the size of the stock. So for a face frame, I'd use a 1" x 1.5" x .25" floating tenon. For attaching an apron to a leg, I might use two or four. I can mass-produce my own tenons and always have plenty on hand.
My I'm rambling. Apologies and intermission here if you need one.
My first attempt was a failure. My template was simply a slot in a piece of wood that a brass bushing would ride in. I discovered that the dust from the small mortise would accumulate in the sides of the template and prevent the bushing from moving to both extremes after a pass or two. That bushing really prevented adequate dust evacuation.
Looking at the bottom of the router, I decided the trick would be to remove two of the screws that hold the plastic sub-base, and use longer screws with plastic spacers to create guides that could ride in 3/8" wide slots. A picture is worth a thousand words, I encourage you to look at the pictures now.
This worked better than expected. With the bushing out of the picture, dust was properly evacuated. And the 3/8" spacers I found at my local hardware store fit in a 3/8" wide slot cut by a router bit PERFECTLY. Like it is on rails. I'm not kidding you.
The width of the mortise is controlled by the center (non-wasted) part of the slot. As the 3/8" spacers I've attached to the bottom of the router reach the end of the slot, they stop the router from moving any further.
My current incarnation uses a board clamped in the vise to hold this jig. But I can just as easily make a small fence that could be clamped to a larger workpiece. I plan to make a couple this weekend just so they're ready when needed.
The distance from the edge is controlled by two screws (the black ones) that you see on top of the jig. These are those furniture knock-down screws. They thread into cross-dowels in the fence. If you look at the pic from the bottom, you'll see some pencil lines I've used to make sure that the slot is parallel to the fence.
I was surprised when I assembled the first joint and saw just how nicely it fit together. I normally impress myself, but not THIS much. :)
This design should be adaptable to many different types of routers. Anything that has holes for mounting a sub-base.
Ready to make a mortise, and router lifted for clarity. I normally use two clamps (one on either side), but had removed one here...
191547 191543
The slots in the jig, and the spacers on the bottom of the router that ride in the slots...
191548 191546
The screws that control the spacing from the edge, and a shot from underneath
191550 191544
The three parts of a joint, ready to be assembled, and the completed joint (unglued)
191545 191549
I can think of several modifications, for example making the width of the mortise adjustable through screws that would adjust the length of the slots. But you'd probably have to make the jig wider, and I really like the idea of multiple smaller tenons.
Also, additional fences. Right now it is just clamped in the vise. I'll make something that clamps/bolts to the bench and is a little more flexible. I can even imagine a way that a piano hinge would allow me to accomodate angles.
My only real concern is whether the spacers might rotate during use and come lose. The spacers are slightly less than 3/8" (I'd say they are .371 or .372"). So they don't bind in the slot. And binding is the only thing I think might cause them to loosen. I'm going to keep an eye on it. I can also switch to a bar fence made to go between two screws. But I'm not going to go through the trouble if this works. And I've made about 40 practice mortises with no problem.
That is it for now. Thanks for reading all of this.
I had enough wood left to make one more frame, so I used dowels to assemble it. I like dowels enough, but positioning the jig can be tedious (IMHO). I know others disagree, but having side to side play in the joint and then being able to align things during glue up, like a biscuit jointer or a Domino with an oversize (wide) cut takes a lot of the worry out of getting things perfect while cutting the joints.
ANYWAY, I've been thinking about making a mortising jig to use with my little DeWalt DW611 plunger. It has great dust collection. It plunges nicely. It seems like it would be perfect.
Many of the jig plans out there (Shop Notes, etc.) are for larger jigs. I wanted something smaller. Something I could "take to the wood" if desired. Something I could use at the bench (clamped) like a full-size jig, but also something that I could clamp to a large workpiece out of the driveway. I also decided that using multiple floating tenons (like using multiple biscuits or multiple dowels or multiple Dominos) was preferred to adjusting the size of the mortise to the size of the stock. So for a face frame, I'd use a 1" x 1.5" x .25" floating tenon. For attaching an apron to a leg, I might use two or four. I can mass-produce my own tenons and always have plenty on hand.
My I'm rambling. Apologies and intermission here if you need one.
My first attempt was a failure. My template was simply a slot in a piece of wood that a brass bushing would ride in. I discovered that the dust from the small mortise would accumulate in the sides of the template and prevent the bushing from moving to both extremes after a pass or two. That bushing really prevented adequate dust evacuation.
Looking at the bottom of the router, I decided the trick would be to remove two of the screws that hold the plastic sub-base, and use longer screws with plastic spacers to create guides that could ride in 3/8" wide slots. A picture is worth a thousand words, I encourage you to look at the pictures now.
This worked better than expected. With the bushing out of the picture, dust was properly evacuated. And the 3/8" spacers I found at my local hardware store fit in a 3/8" wide slot cut by a router bit PERFECTLY. Like it is on rails. I'm not kidding you.
The width of the mortise is controlled by the center (non-wasted) part of the slot. As the 3/8" spacers I've attached to the bottom of the router reach the end of the slot, they stop the router from moving any further.
My current incarnation uses a board clamped in the vise to hold this jig. But I can just as easily make a small fence that could be clamped to a larger workpiece. I plan to make a couple this weekend just so they're ready when needed.
The distance from the edge is controlled by two screws (the black ones) that you see on top of the jig. These are those furniture knock-down screws. They thread into cross-dowels in the fence. If you look at the pic from the bottom, you'll see some pencil lines I've used to make sure that the slot is parallel to the fence.
I was surprised when I assembled the first joint and saw just how nicely it fit together. I normally impress myself, but not THIS much. :)
This design should be adaptable to many different types of routers. Anything that has holes for mounting a sub-base.
Ready to make a mortise, and router lifted for clarity. I normally use two clamps (one on either side), but had removed one here...
191547 191543
The slots in the jig, and the spacers on the bottom of the router that ride in the slots...
191548 191546
The screws that control the spacing from the edge, and a shot from underneath
191550 191544
The three parts of a joint, ready to be assembled, and the completed joint (unglued)
191545 191549
I can think of several modifications, for example making the width of the mortise adjustable through screws that would adjust the length of the slots. But you'd probably have to make the jig wider, and I really like the idea of multiple smaller tenons.
Also, additional fences. Right now it is just clamped in the vise. I'll make something that clamps/bolts to the bench and is a little more flexible. I can even imagine a way that a piano hinge would allow me to accomodate angles.
My only real concern is whether the spacers might rotate during use and come lose. The spacers are slightly less than 3/8" (I'd say they are .371 or .372"). So they don't bind in the slot. And binding is the only thing I think might cause them to loosen. I'm going to keep an eye on it. I can also switch to a bar fence made to go between two screws. But I'm not going to go through the trouble if this works. And I've made about 40 practice mortises with no problem.
That is it for now. Thanks for reading all of this.