Sunday, March 23, 2014


Asy ou know I have been struggling with the picture frame. The carving was the easy part. The hard part is doing the miters. My shooting jig is now very accurate. But it has a real problem. The plane follows the miter. If this is not exactly 45 deg then the plane tends to follow the (erroneous) angle. And one degree is far too much error. I tried a commercial miter box and it had far too much slop. Well, desperate situations demand desperate measures. I resorted to Cecil B. de Mille.

 I packed up the frame pieces on home-made parallels. This is so that you don't try to mill your priceless mill table along with the wood. I stuck my faithful 3 mm carbide end mill in the chuck. I then set the wood at 45 deg with the X-axis of the mill; that goes right to left in the picture. I tried the Y axis (90 deg from interfere X) but I did not have enough travel. Setting this thing up was a bear.  The clamps interfere with measurement. And my protractors keep slipping their settings.  In fact the clamps can slip too.  I finally overcame these difficulties. A whole day's work to do all the pieces. They were badly off; a degree is far too much.  Only problem is that the end mill is ever so slightly too short. Had to make several passes, varying the depth of cut (Z-axis). The part nearest to the left-side clamp is a bit too thick for the end mill. In this business a tenth mm a gross error.

When I clamped it up (in the homemade jig) there were some errors. I went back and "shot" the corners. See previous posts. It now fits quite well. Not absolute perfection. But not bad for a first frame.
Now I am putting some bamboo skewers (at bottom left) through the corners. Commercial framers use corrugated knock-in steel pieces; but I don't have any and am not sure I'd use them if I did. A miter joint is a very weak joint (if indeed it is a joint) and it needs reinforcement. I made a drill jig to make sure the holes went where I wanted them. I couldn't do this on the drill press; the frame is too big for my little drill press. Must use a hand drill, a very imprecise tool. The drill jig is at lower right corner in the picture above.

When I finish this operation I will plane off the pegs and give it to John. He has far more paintings than frames! I have learned a lot from this experience. Unlike other woodwork things, a miter jont is unforgiving. Get it wrong, never get it straight again. Next time I will do the joints before carving anything at all.

I must make a miter box. But to do so I must find some aluminum channel. Easy, you say. Go to Home Depot/Lowes.  Not so in Alaska. Well, eventually something will turn up.

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