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Workbench Build #15: Leg Into Top Mortises

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Blog entry by Mark Kornell posted 12-09-2014 05:05 AM 1737 reads 1 time favorited 3 comments Add to Favorites Watch
« Part 14: Leg Tenons Part 15 of Workbench Build series Part 16: Leg Vise Install »

To cut the mortises for the leg tenons, I went back to the masking tape. Laid some strips down, and lined up the first leg to be flush with the front of the bench. This leg will ultimately be the leg vise.

I had deliberated left some extra space between two of the dog holes to ensure the leg would fit.

It was easy to knife the outer faces of the tenons, but the inner faces are a bit harder. Because I know the tenons are dead straight, I simply knifed about 1” in on both ends. After removing the leg, I used my 6” ruler to complete the line.

Like the condor tails, I used the small router with a 1/4” spiral bit to freehand waste out the first ~3/8” close to the outline, then chisels to finish this part of the task.

Check the fit:

A couple of tips. First, apply some wax to the bottom of the router plate. It will make it much smoother to run over the tape. And helps it avoid catching and tearing tape.

Second, leave the tape on until final fitting. Makes it easier to see the outline.

Once I was sure the tenons would fit, I wasted away the bulk of the rest of the mortise with the 1/2” spiral bit in my big router. Simple plunges, could be done with a drill. But this is faster :-)

Next, start to extend the mortise walls. I tried my longer pattern bit, but it vibrated too much. The shorter bit worked well, but only went down about halfway.

I went back to the longer bit to try to finish up, but it still vibrated. Plus, it didn’t reach far enough. The solution was to just use the 1/2” spiral bit relying on the shaft above the cutting edge as the pilot. That worked pretty well.

You can see a bit of what appears to be burning at the top of the mortise. This is where the bit’s shaft was rubbing against the top of the mortise walls. There was some buildup on the shaft, too, which I cleaned off between mortises. I found that moving faster helped.

I chiselled the corners square. Could’ve rounded the corners on the tenon, too. But a sharp chisel works quickly.

Does the leg fit? Initially, it wouldn’t, and I spent 1/2 hr trying to get a perfect fit. As it stands now, seems like it will fully seat but with an extremely tight fit. Too tight, probably. I may need to do a bit more tuning.

The next leg was the back leg on that side. The mortises are oriented at right angles to the edge, with a bit of extra room on the edge to allow for the top to move

This leg fits much better.

The third leg was the one by the wagon vise. The leg is wider than the spacing between dogs. This was planned – I figure I’ll use the first 2 or 3 dogs on a regular basis and didn’t want to have odd spacing. The solution will be to cut a channel at the top of the leg to give access to the dog.

The tenon layout on the leg was different, too. When I cut the tenons, I increased the spacing between them to avoid interfering with the dog hole.

Routers and chisels later, the leg fits:

You can see that I had to remove the wagon vise rails to work on these mortises. The astute among you probably realized that at the time I installed them.

And the fourth leg:

Well, that looks a bit odd. How about?

Those legs make the top look a little thin. :-)

-- Mark Kornell, Kornell Wood Design



3 comments so far

View RoadHogg's profile

RoadHogg

124 posts in 1387 days


#1 posted 12-09-2014 05:12 AM

Hey Mark. What’s the overall finished height you’re shooting for?

-- "The difference between school and real life is that in real life the tests come first, and then the lessons" -- Robert Lang, ReadWatchDo.com

View Mark Kornell's profile

Mark Kornell

1061 posts in 1990 days


#2 posted 12-09-2014 05:29 AM

Finished height will be 33 1/2”. Although that will shrink over time as it sinks into the floor :-)

-- Mark Kornell, Kornell Wood Design

View terryR's profile

terryR

6313 posts in 1768 days


#3 posted 12-09-2014 04:10 PM

^Yeah, you already added floor jacks UNDER this bench, right? :)

Looks like a ton of quality work to me. Very inspiring!

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

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