Tuesday, February 9, 2010

Tréteau XIX

Holy crow! nineteen posts on this freakin' sawhorse and I'm still not done. You know, when I tell people I am, oh, 800 or more hours into the study of a sawhorse, they often look at me a little askance, and perhaps assume, based on their idea of what constitutes a sawhorse, that I must have a brain injury of some sort. Hmm, if I didn't have one before, I feel like I might be developing one now!

Today I reached a milestone in the process of building this tréteau. Where I last left off, it was at the start of the mortising work on the two remaining legs. That mortising is now done, and for the most part it was a lot more straightforward than the mortising work I had to do on the faces aplomb legs.

Here's the first of the legs in this set, leg BN, which is rotated to meet the plan along the short axis, and thus, as the following picture indicated, the parts which relate to it along the long axis of the plan travel at an angle through the piece:

In the photo, you can see that the tenon on top of the leg, due to the rotation of the leg relative to plan, is not oriented parallel to the sides of the stick. That means that the mortise for the long side brace also travels through the stick at the same angle. So that means that the one long side brace mortise is a little tricky, while the mortises for the short side x-braces, are as simple as they get, pretty much, as they are orthogonal to the face. Here's the lower mortise, which is blind:

And here's the upper, which is through:

The mortise for the long side brace, was through, so it was a matter of drilling it out, and then chopping and paring to process it:

Here's the remaining leg, which I label DP:

Leg DP is oriented to the long axis in plan, so the tenon on top, along with the mortise for the long side brace, travel parallel to the sides of the stick. For the mortise on that long side brace, I used my router and chisels to clean it out:

In reverse to leg BN, on the short side, the x-braces meet the leg and travel into (and through) it at a slight angle. Once again, the through-mortise was simple enough to deal with:

The blind mortise was another matter. Here's how I tackled it: first I used double stick tape to affix a shim to the leg:

Then I planed the shim down at the required angle:

As I worked the shim down, I frequently checked with a bevel gauge to judge my progress:

The planing was done when the blade of the bevel met the opposite corner of the stick, checking at several points along the length:

That shim then carried my router at the correct angle - here I'm using an 8mm collet and a solid carbide spiral cutter, also 8mm:

I was able to reach target depth of 1.25"accurately:

A little free-plunging with the router as I worked it back and forth and I have roughed out the mortise:

You can see at the bottom corner of the above mortise that there is an opening - the tenons slightly interfere with one another inside the post, and I'll be taking a small section out of the corner of the tenon which fits in the above mortise to achieve the fit. The mortise was finished off with the usual chisel work:

And here we are, the four legs with all the mortising complete!. I chopped and pared all 12 of these mortises without needing to re-sharpen my two chisels (it's time now mind you):

So....28 mortises complete, more than 20 of which were compound angled, can only mean one thing: now it is time to cut 28 tenons. That's the next order of business, and when the tenons are done, then I can move to fitting and assembly. Whew!

Thanks for your visit today. --> Go to post XX

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