Design suggestions/ideas for fixing this jig

[Benjamin Brown]

Hello all!

I am currently working on a project out of a mag I subscribe to, and I am to a point where I need to cut some 1/4" grooves in some of my wood, and then 1/2" mortises in nearly all the lumber. The instructions calls for making a jig using a small piece of clear plastic attached to a plunge router with some guide blocks and wing nuts for fine adjustment. That's all well and good but I don't own a plunge router and I didn't know where to get a plastic face plate with rails in it, so I set about to try and figure out how to make my own. My first foray, seen below, did OK at first.

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Basically two pieces of scrap that I can clamp tight and hold the workpiece in place, along with a guide in the back that the flat edge of the router can butt up against to keep it straight

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Cut out a few blocks to use as starting/ending guides

But I had a really hard time being precise and ended up with cutout and misalignment all over my pretty, clean poplar legs.

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In addition to probably compromising the structural integrity of my final piece, I just don't like how this turned out and want to find a better way to do it. Does anyone have any suggestions for a better way? I experimented with punching holes with my drill press but it turned out way worse

[Dominique Meuris]

The thing is if you do not have a hollow chisel mortiser or a fixed upper fraze, then it's really not easy to do this.
A few years ago when I started my own factory I was not so well equiped either.

I used to make mortises with a bench drill.

take a size that's a little smaller then the cut that you need. draw the entire mortise lines on your piece of wood.
Then fix the piece on the bench drill. cut holes of 1-2cm depth max. and do the entire pieces.
Then do the rest of the required depth.

You may want do build a fence on your bench drill, otherwise it's hard to do so.

After this is done, take a chisel and make the mortise perfect.

[John TenEyck]

W/O a plunge router or mortising machine, I would first cut the mortises by drilling out the bulk of them at the drill press, and then cleaning up the ends and sides by hand with chisels. It doesn't look like your mortises go all the way through so none of it probably shows after the mating piece is installed, so it just has to be dimensionally correct but not cosmetically perfect. There's really not a lot more to say about it. Layout the mortises, drill out the bulk, clean them up by hand. After the mortises are done, then I'd go back and cut the 1/4" dados, most likely using my router table, but it could be just as well with an edge guide installed on a hand held router, or a jig similar to what you built. Generally, however, I avoid building jigs that will only be used one time unless there's no other way. For your application, I don't think one is needed but maybe you don't have a router table or edge guide. But an edge guide would a great addition you should consider purchasing for your router. For that matter, a plunge router is highly recommended. It's truly amazing the things you an do with one.

John

[Benjamin Brown]

The thing is if you do not have a hollow chisel mortiser or a fixed upper fraze, then it's really not easy to do this.
A few years ago when I started my own factory I was not so well equiped either.

I used to make mortises with a bench drill.

take a size that's a little smaller then the cut that you need. draw the entire mortise lines on your piece of wood.
Then fix the piece on the bench drill. cut holes of 1-2cm depth max. and do the entire pieces.
Then do the rest of the required depth.

You may want do build a fence on your bench drill, otherwise it's hard to do so.

After this is done, take a chisel and make the mortise perfect.

Yeah I'm probably not in a place where I want to spend $1500 on a mortising machine =D

I did want to build this slot mortiser one day -

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But I had hoped I could get through this project before starting another on the side :P Maybe I just have to suck it up

[John TenEyck]

If you want to build a horizontal router mortiser, I think you'll find mine to be a lot easier to build. Fast, very accurate, cheap. It doesn't have 3D capability, but I don't find that to be a disadvantage. https://sites.google.com/site/jteneyckwoodworker/current-projects/horizontal-router-mortiser

John

[Ruperto Mendiones]

The less material the router has to remove, the easier it is to guide it and the more precise the cut. That said, mark the mortise margins, drill, jigsaw (if a slot or through mortise), and chisel out as much of the waste as you can. Then make two passes using your router and jig or guides with a router bit smaller than the mortise width. This will make it very much easier to control the router path.

[J.R. Rutter]

Capture the router base on both front and back, not just the back.

[Prashun Patel]

Definitely capture the back edge of the router per JR's rec.

Then, if you cannot get a plunge base (your best chance for success), then 'pre-plunge' a starter hole with a drill. Insert your router bit carefully into the hole and then start up the router. You will get more precise results if you make your groove slightly wider than your router bit, then using a bigger drill bit to drill the pilot. This will mean you have to cut the groove in two passes butting up against the front and then rear fence, but (critically) you'll also have a larger pilot hole into which you can plunge. I wouldn't plunge into an exact-sized hole.

[Lonnie Gallaher]

My thought would be to attach a square or rectangular shaped sub-base on your router. This will provide better registering along your jig. Make sure that both sides of the sub-base are equal distance from the router bit, if you plan to use it to cut mortises wider than the bits that you have. I mention this because I know my router's stock plastic sub-base is not concentric with the spindle. A fence on the sub-base would help out a lot too.

[Shawn Pixley]

You might want to chop the mortises with hand tools. Drill out most of the waste and clean up with hand chisels.

[Chris Padilla]

Ruperto/J.R. nailed it. Any time you use a handheld router, the best way to control it is to guide it on all sides AND remove as little material as possible. Remove as much wood waste as possible with any of the number of suggestions already made and then clean it up all pretty with your router removing as little material as possible.

Another suggestion is to pay attention to the DIRECTION your router bit spins relative to the direction the whole router moves as you are cutting. Routers spin, looking down on them from above, clockwise. So the router always wants to move to its left HENCE you want to move the router to its right for control. See this handy link at Rockler for some tips on routing...they have diagrams that explain this more clearly: http://www.rockler.com/how-to/10-tips-clean-cuts-router-bits/ I would invite you to route in both directions so that you can FEEL the difference. BTW, moving the router left is known as "climb-cutting" and it is a technique used to minimize chip-out on edges: http://www.finewoodworking.com/how-to/article/climb-cutting-don%E2%80%99t-believe-the-naysayers.aspx