Thursday, August 16, 2012

Miter Sled & Finger Joints

     Any of you that are also teachers know that the profession usually doesn't give you that immediate gratification.  On occasion I do run into former students and they tell me how they enjoyed the industrial arts or construction classes I've taught them in the past.  Keep in mind though that these were students from grade 6 to grade 12.  Since retiring and now teaching the occasional class plus giving private lessons the things I've taught to adults give me quicker feed back.
     As an example, I had a fellow woodworker take some one on one instructions on how to set up, sharpen, and use a hand plane.  That's one of the basic hand tool processes for those of us who aren't infatuated with machinery!  He shared with me how he had made a bracelet holder which needed to be oval in shape.  He started with a round form and by using the hand plane he had so carefully sharpened and tuned up was able to achieve the required shape.  Some of it still needed sanding because he wasn't able to get the plane in all of the places.  When I saw him last night he told me about that and how the planed area took the finish much better than the sanded area.  We had talked about that; a surface cut with a sharp plane versus one that's been abraded with sandpaper will have a sheen to it.  He shared that with me and I could sense his excitement and pleasure about conquering the plane.
     That brings me to the Urban Ranch Box I'm currently working on.  It's made of common, knotty pine from the local big box store.  Even that though will respond to the plane.

Surfacing the Inside

Sizing the Top on the Shooting Board

     This is an instance where as the builder and designer of the piece I can choose the lumber and decide where it will look the best.  This is the largest box of the series and will feature a full size, lift out tray.  A good sharp plane will have no problems with the knots and sap found on this fairly common lumber.
     Leroy also makes boxes and at our Sin City Woodworkers monthly meeting last night, the focus was on different jigs and fixtures we use in our craft to make work go smoother and safer.  He brought in his miter sled that he uses on his tablesaw.  We got to talking about the box making procedure and he mentioned having to set up the stops so that each piece would be sized accurately.
     The first rule of box making is that opposite sides of a box must be exactly the same size for your corners to be nice and tight.  Another important consideration is that you want the grain to flow around the box in a continuous manner.  In other words, if you cut a long side first your next piece will be a short side, then another long, then the last short.  You can't set a stop for the long side and cut both at the same time.  There are several solutions, one is a hinged stop that you can flip up or down depending on the piece being cut.
     Here's the solution I use to overcome this problem.  My miter sled is fairly short but sized for what I want to do.  After setting the sled on the tablesaw I slide the rip fence towards it.

Ready for a 6" Piece

     After mitering the first end I put in an MDF spacer.  It's identified and says that if my fence is locked at 9" and the spacer is butted up to it I will have a piece 6" long.  To make the next cut all that needs to be done is to switch to another spacer:

Spacer for a 3 3/4" Piece

     Each piece will need to have the smallest amount cut from it to have the miter go the correct way, that's what those small scrapes on the upper right are.  I've laid the cut pieces on the sled so you can see how the grain will flow around the box once it's assembled.
     If you have a larger sled and the pieces you plan to cut won't extend off the end like they do on my short sled you can easily clamp a stop block to your sled for the longest piece you need.  For an example, suppose you want a box that measures 8" x 12".  Clamp a stop block to your sled for the 12" piece and make your first cut.  Next, make a 4" long spacer to put between the piece being cut and the stop block and you'll have a perfectly sized, 8" piece.

     Very Important Safety Note
Do not leave the spacer in place when you make the cut, remove it before cutting.  You should never use a miter sled or the miter gauge that comes with your saw in conjunction with the rip fence.  It'll bind and you'll end up with a piece of wood flying back at you at about 100 mph!

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