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canopy frame drilling centerlines help

EdRv7

Member
I am building an RV-7 slider, and have done the big cut (whew!) and am about to drill the canopy to the frame. Numerous people have mentioned the trick of using masking tape on the frame, then clamping the canopy onto the frame, with the idea of this marking the contact line visible on the masking tape. I've tried this using both regular masking tape, and blue painters tape, but in neither case can I discern a clear line on the tape even after making sure there is good contact with the canopy. Anybody have any suggestions as to what I am doing wrong?
 
Hi Ed,

I just did this step in the last couple of weeks and I got to tell you that I either didn't understand the masking tape trick or I wasn't doing it correctly (both I'm sure), because it didn't work for me either. I tried three different types of tape.

So, after tearing off the tape and pealing back the protective plastic, I began clamping the plexi to the white powder-coated frame. To my amazement a fine, gray contact line appeared through the plexi. I almost couldn't believe it; dumb luck struck again! So, upon contact with the frame a visible line could be seen through the plexi and that was my center point for drilling.

There are points where a little more clamping pressure was needed in order for the plexi to make contact with the frame, so I carefully used a stronger clamp pressure. If needed, I used a fine sharpie to "connect" the tow points and draw a line through where my 2" mark was for the drilling point.

I have the upgraded SC 15 Low UV canopy, so I don't know if that's why I could see a faint, visible, gray line upon contact; but, it worked. I fear the day dumb luck leaves me!

Hope this works for you.

Ryan
 
I used white electrical tape on the frame. When the canopy bubble was clamped to the frame a well defined line appeared at the tangent point.

 
Tape trick didn't work for me either. I made some plastic 'U' shaped pieces about 1/2" thick with the middle of the 'U' the same diameter as the tube (there are several different tube sizes in the frame). With the canopy clamped to the frame, I inserted the 'U' around the tube and then marked on the outside of the canopy where the inside edges of the 'U' contacted the canopy. Then measured halfway between these marks and used this as the centerline to drill through the canopy.
 
Centerline

I didn't use a centerline. Doh! My plane is gonna fall out of the sky!:D
I just put the frame inside the bubble till it looked like a natural position then drew lines on the plastic outside with a grease pencil.
 
drilling holes in canopy frame before canopy

Since I am planning to drill the canopy frame holes first, I want to make sure I get those holes properly centered on the contact line. I have heard that putting dark electrical tape underneath the masking tape will make the line on the masking tape stand out better after clamping it to the canopy. I will try this weekend and report back. If that works, my plan is to remove the canopy frame and mark the holes on the hopefully visible contact line on the tape, then use a spring punch to mark the holes through the tape to the canopy frame. Then I'll drill the holes in the frame and then clamp the canopy back on. Then I can use a #40 drill bit to drill through the canopy aiming towards the holes in the frame. At least that is my plan!
 
I just finished drilling my canopy several weeks ago.

Sometimes the trick would work but most of the time I had to press uncomfortably hard to get that line to show up. Sometime it would not show up at all and I had to extrapolate to find center.
 
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