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Another spinner question

BravoAlphaRomeo

Active Member
Did a search for effective ways to locate the pre-drilled holes in the forward
spinner bulkhead. Some great ideas. My question is why can’t these 6 holes be match drilled in between the the factory holes to get rid of the risk of missing the predrilled hole. Locating the the bulkhead would not be that tough, the tiny hole…a little tougher. Anyway, was struggling to come up with the downside to this :confused:
 
I taped one of the ball magnets in the hole on the back side. I did one first to see if it worked well. Then clecoed the spinner onto the rear backing plate and used a nylon washer and another magnet to locate the hole. Then taped down the edges of the washer and pulled off the magnet and marked the center of the hole. I drilled undersized to #40 and it hit the hole dead center. Did this with the other holes and almost all were dead center. Clecoed as I went. I drilled shallow, just thru the spinner as much as I could so I could see how it aligned. I did have one hole that was slightly off, about a 1/2 a hole diameter. Something must have moved.

I then upsized the holes to the #30 and clecoed them. On the hole that was off slightly I was able to start it off center and side load the bit and was able to get a well centered hole on the backing plate. These all get final drilled larger for the screws.
 
Fix a laser to a fix location and point it to one of the predrilled hole. Install the spinner without making anything move and mark the location. Turn the prop for the next hole and then the next hole till all have been drilled.

The most accurate way I know how of locating the hole without removing the gel coat and shinning a light from inside.

good luck
 
As Jeff stated, the ball magnet technique worked great for me. I hit the center of the hole every time. I used this technique on the wheel pants as well.
 
Make it easy for yourself

Why add unnecessary time to your build. Does it really matter if you have extra holes in the bulkhead? Nope, even if the bulkhead has nutplates attached. Better yet, my spinner doesn’t have screws in the front bulkhead. When I bought the plane the front bulkhead had Velcro (only on the bulkhead not the spinner) to have a tight fit and works perfectly. Absolutely no wobble. However if your rear bulkhead is carbon fiber you probably should use screws for the front bulkhead because carbon fiber flexes a lot more than the aluminum bulkhead
 
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