Tuesday, December 7, 2021

Planing the Wing and Aileron Spars

 

I decided to install new knives in the planer before planing the spars.  There are 3 knives in the Shopsmith planer.  Each blade is held in by 2 wedges, with 4 screws each.  Below each knife there are 3 screws for adjusting the height of each knife and for leveling it end to end.

It takes about an hour to replace and/or adjust the knives.  They can be lightly sharpened (honed) without removing them.  The new knives are sharp, I cut myself on one.
When I packed everything a couple years ago to build the wall between the 2 rooms in the attic, I packed up the adjustment gauge and can't find it.  I ordered a new gauge and found they had changed the design.  The original had a curved edge (7) that the knife needed to just clear.  The new one has a straight edge.  They didn't send any instructions and they were closed so I winged it.

It turns out I came pretty close to how they wanted you to use this gauge.  I put a piece of tape on the gauge and marked where a knife touched it, then made sure all knives touched at the same point.  The correct instructions are to put this mark 7/16" from the bottom corner.

I have an idea to make a label to do this more accurately, more on it another day.

The attic is 44 feet long but the wall limits how long a board you can plane without working through the outside door.  The 17 foot and 18 foot boards just fit.  The 20 foot boards will probably need the door open.  I wanted to plane the full length of the board so I could cut out the best section for each spar.

I put 2 rollers on each side of the planer.  It worked out well except that the 1/2" thick aileron spar boards drooped enough that I could have used an assistant to lift the end onto the rollers.

It actually worked quite well even without an assistant.

You really need the vacuum.  This make a lot of chips and sawdust.

The board on the right is the aileron spar from the second board.  You can see where the high spot, caused by the bandsaw blade curve, has started planing first.

The picture below is the wing spar from the other side of the cut.  You can see where the low spot hasn't planed down.

You can't plane 2 boards at once, but if you do multiple boards between each thickness adjustment they will come out the same thickness.

I found I could keep it straight if before each change in height I put an X on the start of each board so I knew which ones had not been planed yet.

I set the board, waiting it's turn, to the left side where it couldn't accidently get into the planer.


The boards tended to slowly rotate as they went through the planer.  I found it only took the slightest touch with my thumb nail to hold them so they feed straight through.
I checked the thickness of each board after each pass using my Vernier calipers.  The planer adjustment wheel has markings for every 1/128" (0.008").  You can easily plane to whatever thickness you want within a couple thousandths of an inch.
All the wing and aileron spars are cut to width and planed to thickness.  The task now is to layout all the bolt holes, rib locations, routing, etc.  I've been waiting almost 2 years to get back to this point.  It took a bit to remember what I was doing with this layout process.

I've call Aircraft Spruce and cancelled my spar order.  

It's great to be back to making wings and ailerons, YEA!

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