A Sliding Door #5: Grooving the panels

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Blog entry by Mark Kornell posted 11-06-2014 05:19 AM 1381 reads 1 time favorited 4 comments Add to Favorites Watch
« Part 4: Mortising, part 2 Part 5 of A Sliding Door series Part 6: On the glue »

When I got up this morning, Spawn had coughed up a hairball overnight. Right in front of my coffee station. I think he knows I’m writing about him.

The next step in the door build was the panels. First making the panels and then cutting grooves into the rails and stiles to accept the panels.

The panels are 1/2” MDF. I’ll spare the reader the details on cutting the sheet down. Suffice it to say, I’ve got 5 identical panels sized to fit their openings.

I decided to see exactly how thick 1/2” MDF is:

That works out to 12.9 mm, for the metricheads. This is a factor in making the grooves – the router bit is 1/2”, so the panels may end up being slightly thick. Considering that all routers have at least a little bit of runout, and the jig I’m using might have a bit of slop, so we’ll see.

I built a jig for my router a few years ago for plunging mortises into thick stock. Can’t remember if I stole this idea from somewhere or if I came up with it myself, but it effectively is a dual edge guide.

Runners that adjust to solidly capture a piece between tied to an adjustable router platform. Perfect for this task.

It works pretty simply. Drop it onto a piece and adjust the runners. Then adjust the platform to put the router bit in the right spot. In this case, I laid out a couple of lines and adjusted the placement by eye. The placement isn’t super-critical as long as I make sure I reference the same side (i.e. front or back) of each piece. I’ll reference the front.

Test it using a cutoff:

A scrap of the MDF does fit into the groove, but very tightly.

I’ll probably have to run the MDF panels through the sander to take off half a hundredth or so.

Onto the real piece. Cut the groove and check the fit:

Fits about the same as the test cut. That’s good, means the jig is consistent.

First stile done:

Onto the rails. Hard to clamp down, as the groove runs from end to end. I settled on using my quick clamps as tightly fit stops, which works well.

For the rails, I tried hogging out the groove in one pass. The bit is sharp and the router seemed to keep up. But when I got to the end I had a problem:

My first thought was that the depth stop had loosened. Checked that but it was still tight. Then I realized that the bit had pulled out of the collet some.

Spiral upcut bits want to pull the router into the piece. I guess that trying to take all the material in one pass allowed the bit to grab enough to overpower the collet’s hold. I checked the collet and it was as tight as I could make it. So I decide to do the groves in 1/8” passes.

Soon enough, everything was done:

I had to remember that the top and bottom rails only got the groove treatment on one edge:

Hoping to start the glue-up tomorrow.

-- Mark Kornell, Kornell Wood Design

4 comments so far

View terryR's profile


7137 posts in 2305 days

#1 posted 11-06-2014 01:49 PM

Very impressive work, Mark. Gotta remember the centering jig…

Love the outfeed table table for your saw…

-- tr ...see one, do one, teach one...

View stefang's profile


15881 posts in 3330 days

#2 posted 11-06-2014 06:54 PM

Great work process Mark and I like your mortising jig too along with the well done and clear photos.

-- Mike, an American living in Norway.

View BigRedKnothead's profile


8515 posts in 1978 days

#3 posted 11-08-2014 03:30 AM

That jig is pretty slick. Your rollin on this baby.

-- "At the end of the day, try and make it beautiful....because the world is full of ugly." Konrad Sauer

View Mark Kornell's profile

Mark Kornell

1169 posts in 2527 days

#4 posted 11-08-2014 08:23 AM

Thanks, Red. This is the first time in almost 2 years that I’ve been able to have a quality week in my shop. It feels good to be getting stuff done.

-- Mark Kornell, Kornell Wood Design

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