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Discussion Starter · #1 ·
So, I've been here before and want to avoid the unsatisfactory results I've had in the past.

I'm constructing a router table fence. The core will consist of two pieces of 3/4" mdf glued/screwed into an "L" shape. It will also have four 90 degree braces. The assembly is closely patterned after the New Yankee Workshop version.

All my cuts are square as close as I can determine with the measuring tools I have (basically some decent quality squares that check out to be actually square). Dry fit, everything lines up and the "L" is a perfect 90 degree angle.

As mentioned at the beginning, I've been here before. In the past, after glue up, fastening and clamping and after the glue dries I've been disappointed with an assembly that ends up not a good 90 degree "L".

Is there a sequence to follow to insure accuracy? I've got a couple of those Rockler plastic 90 degree assembly pieces - would those help. Should I glue it up and add the screws after the glue dries? Put the 90 degree braces in during initial assembly or after?

Appreciate some input from you guys who get the perfect 90 degree "L"'s every time.
 

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where's my table saw?
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gluing a 2 piece fence

If your pieces have 90 degree edges from your table saw, you are 99% there already. :thumbsup: You can either hold a square into the corner to check it as you glue them together OR you can use a 90 degree block and glue them in as you go, OR use a gluing guide, that's plastic to clamp your pieces together which will be removed when they dry.

If you made a rabbet on the bottom edge and then butted the horizontal piece to it, that would insure a square corner. You can make the rabbett with 2 cuts on the table saw, one up from the bottom the other up from one face. The rabbet must be the same depth as your horizontal or flat piece however.

You could also use some dowels to insure a good 90 degree joint as shown in this video:
 

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Discussion Starter · #3 ·
If your pieces have 90 degree edges from your table saw, you are 99% there already. :thumbsup: You can either hold a square into the corner to check it as you glue them together OR you can use a 90 degree block and glue them in as you go, OR use a gluing guide, that's plastic to clamp your pieces together which will be removed when they dry.
Yeah, it's that last 1% that seems to get me. I'll be using both the 90 degree blocks and the plastic gluing guide - and maybe try not drilling the screw holes and inserting the screws till the whole thing is clamped up.
 

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bzguy
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Add another parallel piece 6" to one side of fence.
Use a 6" horizontal bottom piece sandwiched in with vertical square blocks of the same width in between, much easier square glue up.
Keep blocks a few inches away from both ends, this leaves a handy surface to clamp fence solidly to table.
Position two of the spacer blocks 6" or so apart over the router, these can be completely boxed in (6" X 6") for top dust collection hole.
Cut a 3/16" X 3/16" kerf in bottom of fence for stray sawdust to slice into and insure consistent results.
 

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Discussion Starter · #5 ·
OK, all glued up. I used my corner guides on the inside of the angle as shown in the first photo. Removed all the clamps after the glue dried and, perfect 90 degree angle on the inside. OK, now check the angle on the outside, which will be the business end. Arrrrgh! Not 90 degrees - off almost 1/8" at the extremities.

After initial reaction took a closer look. Had some glue squeeze out at bottom joint. Also, the edge of the front piece was about 1/64" below the edge of the base (I guess biscuits don't give perfect alignment after all :( ).

Cleaned up the bottom joint area and checked again. Still not a perfect 90 degrees. Now about 1/16" off at the extremities. This doesn't make sense (does it?). I assume the mdf is a pretty precise 3/4", so the surfaces are parallel to each other. Yet the inside angle is a perfect 90 degrees and the outside angle is not. Oh yeah. Both pieces are perfectly flat. What's going on here?

If I do this again I'll try using the corner guides on the outside of the angle (the business end) as shown in the second photo.

Anyways, I did a lot of checking and sanding and finally got the assembly to a nice 90 degree angle and a nice 90 degrees to the table surface.

My plan was to do the glue up and then put the screws in. After thinking about it, I'm not sure I even need the screws. I think the main use of screws in Norm's fence was to provide clamping. Oh well. Only take a few minutes so I might as well add them.
 

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