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Tip: HOW TO EASY Measure "X" dist. from edge...(marking a line along a long piece...)

jcmcdowell

Well Known Member
Tip: HOW TO EASY Measure "X" dist. from edge...(marking a line along a long piece...)

How frustrating to try and mark and measure a specific dimension off the edge along a long piece- marking center for AEX wedge, marking the splice for the leading edge, etc etc etc...

OK- take a plain old tape and use your Awl (sorta like a ice pick) to poke a hole just big enough for a fine sharpie tip on a nice round dimension (like on the 4" mark- Why I chose 5-3/8", I don't know) :).

Debur the back (get used to this...)

Use a long clamping cleco "thingy" to clamp the distance from the hole- align both sides of the cleco to the marks to get a straight edge.



Slide the tape back to the cleco- hold the tape in your hand and the pen top with your index finger to slide the material along the edge of the cleco the entire length. For long stuff- your can clamp the tape and run the materials on the cleco the length...



A little practice and works like a champ- doesn't hurt the tape a bit.
 
edge lines

I use 2 different methods depending on how much accuracy I need. For just a rough line parallel to the edge of a piece, I grasp the sharpie between thumb and index finger and using my longest middle finger as a guide running along the edge, I run the pen down the length of the piece. Make a starting mark and several intermediate marks to check your progress.

For real accurate precise lines like layout for a line of rivets, I use an adjustable machineists square and set the slide to the exact depth I want to the nearest 1/32 inch and lock it down. Then run the square down the piece with the square firmly against my work, and the sharpie pen held firm against the end of the slide. You can set the slide as small as the width of the pen tip, or up to 10 inchs from the edge of your piece. It works for me.
 
I've always used the method that Claude describes with the machinest square.
 
I made a homemade tool to use to mark long straight lines like on the fuselage J-channels. I believe I saw it on someones website but do not remember who's or I would give them credit.

It is just a 1 inch piece of 3/4x3/4x.063 angle with a piece of scrap riveted to it and then a series of offset holes drilled in it. Easy to hold to the edge, put a fine tip Sharpie in the appropriate hole and mark away. I find no need to even measure, I usually just pick the correct hole by looking.

edgemarker.jpg


edgemarker1.jpg
 
exact center

Another use I found for the Machineists square is to find exact center of a symetrical part. Say you want to drill a hole in the center of a piece of angle. When I use a tape measure, I will usually be off center by as much as half milimeter. And when setting the square I still get a small error. So what I do is for lets say a 3/4 angle, set the square at 3/8 to mark the center, but then the width of the pen makes it to fat. :eek: I measure it from both sides. :eek:

If you have a slight error, and u measure from both sides, then you will have a double line revealing the exact center. It dosent matter if you set the square a little to long, or to short, you still get a double line and the exact center is between the lines.
 
Reference to the cleverly designed edge distance tool I described here: http://www.vansairforce.com/community/showthread.php?t=7551
You could just as easily rivet or even superglue a (thickish) piece of aluminum over another piece of aluminum at any desired stand off distance and then run it along the edge of your part marking its surface with a Sharpie or similiar and be assured you are maintaining a consistent and accurate e.d.
 
I think a flexible C-Thru ruler is easier. Typical one here is 18 inches and marked in 1/8 ths.

412cPMBPbsL.jpg


Simply use the red lines as a guide to keep the line you are marking parallel to the edge. Then use the same ruler to mark the rivet locations at the required spacing.

$8 or so well spent. :)
 
Laser Level

A cheap laser level in a darkened shop works well for projecting a straight line on an curved surface.
 
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