Tiedown Bars are done..   May 9th, 2007

Here’s a couple of pictures of the completed tiedown bars. Now I just need to find a good torque wrench to bolt them to the spars..

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More Tiedown Bars…   April 30th, 2007

The tiedown bars have no holes in them, so they have to be match-drilled to the spar. You first drill a single hole according to the dimensions in the plans. Then you put a bolt through the hole and line up the bar perpendicular to the spar flange.

Once everything is lined up, the rest of the bolt holes are match-drilled using the spar as guide. I set the spar on two sawhorses and clamped the tiedown bar and spacers with C-clamps and some wood to keep from scratching anything.

Once the tiedown bar had all bolt holes in it, you have to drill in the four platenuts that will hold the aileron control bracket. I put a bolt through a platenut and clamped it in place. After drilling the clear hole, I put a cleco in it and drilled the other one. Note that I don’t have the spacer bar in there just yet.

Once all the platenuts are drilled to the tiedown bar, it’s a good idea to mark them and know which platenut goes in which hole — Since these are not match drilled, any small variations in drilling are going to make things hard later on if the same platenuts are not used in the holes for which they were drilled.

After drilling the holes through the tiedown bars, I match-drilled the spacers, with a bolt in place just to make sure things didn’t shift.

Finally, I went to drill the lightening holes in the tiedown spacers. the plans specify a 1″ diameter hole. My hole cutter will only cut holes to 1-1/4″, so I decided not to use it (the hole would get too close to the bolt and rivet holes.

I have a Unibit that will drill 7/8″ holes, so I used it, and figured it’s better than no hole at all…

Here’s a finished spacer…

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Tiedown Bars   April 25th, 2007

The next step in the process is fabricating the tie down bars. These bolt on the spars and hold the rings used to tie the plane down.

You get a piece extruded aluminum with a hole in it, and you have to tap it for a 3/8 bolt. So, I borrowed a tap from work and got busy. First time I’ve used a tap…not much to it as long as you use some cutting oil…

I don’t have the actual tiedown rings, so I just bought some 3/8 bolts to try out my new taps. Pretty nice…

Behind each tiedown bar there are two spacers that support the bar. These have to be fabricated from aluminum stock. I bought an abrasive cutter at Harbor Freight for $30, and it sure beats a hacksaw for making quick, clean cuts.

After making the cuts, I put them on the belt sander to straighten and smooth up the edges.

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