Machinist Toolbox #5: Carcass Joinery

Yesterday I was able to cut the tails on the carcass side parts. I used the bandsaw to cut the tails because the blade cuts straight and is narrow, although I did get some rough cut surface this time because I have a kink in the blade. I’m thinking in the future to use the Table saw with the blade tilted at ~10 degrees and the part passed vertically much like cutting box joints, but that will have to wait for future projects as for the time being -these tails are cut already.

Once the tails side lines are cut, I use a coping saw (mine if from Lee Valley and works really well) to remove most of the waste between the tails:

A coping saw is really a blessing in this situation, you can drive it real quick and turn it a sharp 90 to reach in narrow spaces. Before I had a coping saw I tried to remove the waste by chopping it all with the chisel – LOTS of work both for the woodworker and the chisel. If you remove most waste with a saw, the chisel work becomes real easy (single chop and it peels effortlessly).

to finish off the pin sockets, I marked the socket line with a marking gauge which helps position the chisel in the proper location as it sets right into the mark line. I then chopped half the socket off keeping the chisel not at perfect 90 degrees but slightly into the part being cut. The reason for this undercut is that the only part that matters on that line is the exposed line- the glue surface is end grain so does not really help much. If you try to keep it perfectly vertical then there is a chance that the angle will be slightly outwards making the joint not fit. With an undercut there is not much of a strength loss, and there will always be enough clearance behind the line so that the joint can slide easily in.

After chopping half the socket, I flipped the part to it’s other side, and repeated the process. the reason for this is to make both chopping cuts exactly from the marked line on both sides inwards that way there is no way to miss or misalign the opposite marked line when you are chopping from the opposite side. it also protects from tear out:

At this point I had to call it quits for the day as being outside in an unheated garage at 19 degrees F wasn’t exactly fun in the park, and 2-3 hours were the most I could endure. had to go back home and wait for 20 minutes to defrost before I washed up otherwise there is a risk of burning, or misjudging the temperature of the water – not a good thing.

While in the house though I was able to prepare the “panel” for the back. As I mentioned – I was planning on ‘cheating’ on this one. I took 1/4” plywood and laminated on one side of it the cutoffs from resawing the mahogany for the parts – I had some 1/8” leftovers that fit perfectly to make the back panel:

One Day Over

Today I got out and it felt WARM at 28 degrees F (after yesterday’s 19). It’s not the temperature – it’s the references that are the joy killers.

Although I was not able to accomplish today all that I wanted, I did manage to transfer the tail lines from the sides to the bottom part, and the front/back rails, cut those in the same manner I cut the tails with the only difference it was all done with hand saws since the cuts are angled (a Table saw type sled could have helped – I have one in my mind that I’ll design later on). and checked for a dry fit:

This is my 2nd dovetailed project. Some parts are a bit looser while other are a bit tighter – but I do notice progress and I can only expect it to continue in future projects. All in all – the fit is good, and the box holds well, is rigid, and does not come apart (still dry fit).

I was then able to route all the slots to house the panels and dividers. I was then able to fit the top panel that will be the bottom of the top compartment, and the rear ‘cheater’ panel which is still slightly too wide and will need to be trimmed (as you can see i the following picture it prevents the carcass from fully setting in):

The day was over, and the lights in the garage stopped working (it’s that cold that all the electric cables become stiff, and all the connections start to lose physical contact and it’s a bit finicky) so it was time to call it a day.

Tomorrow I hope to trim the back panel, fit the 2 remaining dividers, add the vertical dividers for the drawers, and route the drawer slides dadoes, and fit the top panel so that I could finally put the carcass together and glue it up leaving just the drawers to deal with.

It feels like I’m progressing real slow for some reason, on one hand I do realize this is no a-weekend-project, but on the other hand I had hoped I’d be already dealing with the drawers and be done with the whole thing tomorrow. maybe I need to focus on some smaller scale projects for a while (if only I could).

-- ㊍ When in doubt - There is no doubt - Go the safer route.