Long rainy weekend

„Anstrengungen machen gesund und stark.“, Martin Luther 1566

It is a grey Sunday with lots of wind and rain. Perfect for building Schneewittchen. Tuesday is the 500th anniversary of the reformation day and, thus, an exceptional holiday in Germany. Happy those like us who can take Monday free and have a long weekend. Having a couple of free days does not mean that we bum or laze around. It is pretty much the contrary: We have finally time to do a couple of things on Schneewittchen that take longer.

Yesterday was a bad day. I thought we could quickly machine a couple of pieces for the next prototype of the elevon mixer. It turned out to be a mess ending in a broken milling tool—a 4mm solid carbide one-flute and by the way one of my favorites—and another shiny new solid carbide tool clogged. You can imagine I was not amused! This is the miserable rest of the one-flute:


Heartbreaking! I did not fasten the material correctly and it started to oscillate at some point. This loss is my fault, but how it came to the clogged tool is not explicable…

Anyway, I finished the pieces and adapted the elevon-mixer:


In contrast to the last version, I used two spherical bearings this time (less parts and a less complicated setup). Tightening the bolt on the left in the picture, which fastens the plate on the stick, results in a tighter fit of the spherical bearings. So this setup has some more friction than the last one, although the bearings run very smooth before installation. This shows that their internal clearance is small, which decreases slackness of the controls and is good when not excessive.

Today was, besides the weather, a great day. We started to cover the cabin’s plug with veneer. It was not the surface, but the bottom of the plug:

Sanding the border is much easier when it is reinforced. This is in particular true for the thin tail, which would else be pushed away when sanding. We used leftovers of abachi veneer and glass fabrics (feels like 80 g/m²). It will have to cure at least overnight before we can trim the border.

In one of the last postings I wrote that sanding the plug is a multiscale process. I made two pictures to show you what kind of scale we are working on now:

There is a change in curvature between the canopy and the aft of cabin. This is the kind of errors that need to be corrected at this step. It’s not about getting a perfect smooth surface. This kink has a large scale and extends over 25 to 50 cm (10″ to 20″). No veener in the world would make that disappear.

Nevertheless, not only large scale imperfections need to be corrected, as the plug has also many small defects. Some can be ignored and others would affect the shape even after covering. Large defects can be improved by glueing small pieces of XPS and sanding the surplus material. The following picture shows, for example, a larger dent which was improved as mentioned:


That’s good enough to be covered with veneer. The glue used was specifically designed for XPS and EPS foams (UHU® POR). There are many more similar defects on the plug, which have to filled and improved before covering. The next days won’t get boring…


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