I'm waiting for some decent weather to do some painting
so I took the opportunity to fit the spinner to the prop and prop extension. I had purchased a spun aluminium spinner "new old stock" intended for a Piper Cherokee 180. These are very expensive but I got this one at a good price. The problem was that the backplate and frontplate were cut out for a SAE #2 prop fitting and my engine is a SAE #1. I started by drilling a new set of SAE #1 spaced holes in the two plates using the CNC router. These were set 30 degrees out from the originals. Then the rivets holding the fillets underneath the propellor were drilled out and the fillets also moved 30 degrees, re-riveted and re-shaped to fit my propellor. The cut-outs in the spinner were also then shaped to fit and the spinner match drilled through the existing holes to the backplate. An additional 4 nutplates were riveted to the backplate and the spinner screwed to it. The existing holes were then used to match drill new holes in the spinner. This means there are now 8 screws holding the spinner to the backplate rather than the original four - should be stronger. Next the front plate was screwed in place in the spinner and the gap between the prop and the front plate measured. This was 8mm so a piece of 8mm aluminium plate was procured and a crush plate cut out on the router. A 1/8" aluminium spacer, the front plate
, the crush plate the propellor and the backplate were then bolted to the prop extension and the spinner screwed into place. New holes were then drilled in the edge of the front plate through the existing holes in the spinner - again 30 degrees round from the originals. The original nutplates in the frontplate were then removed and re-riveted into their new positions. Finally the length of bolts needed to attach the propellor to the extension was accurately measured and AN bolts with drilled heads procured. These need to be exactly the correct length to ensure that the threads don't bottom but do show through the propellor lugs in the extension. The final job looks pretty good - a spun aluminium spinner for less than half the cost of the cheapest fibre-glass alternative. The only slight compromise is that the original cut-outs in the spinner were for the metal prop on the Cherokee and are about 1/4" too high leaving a slight gap above the front of the propellor. The sides and bottom are a perfect fit. I'll have a think about whether and how I could close these gaps for cosmetic purposes but they won't effect the performance in the air
I'm waiting for some decent weather to do some painting 
so I took the opportunity to fit the spinner to the prop and prop extension. I had purchased a spun aluminium spinner "new old stock" intended for a Piper Cherokee 180. These are very expensive but I got this one at a good price. The problem was that the backplate and frontplate were cut out for a SAE #2 prop fitting and my engine is a SAE #1. I started by drilling a new set of SAE #1 spaced holes in the two plates using the CNC router. These were set 30 degrees out from the originals. Then the rivets holding the fillets underneath the propellor were drilled out and the fillets also moved 30 degrees, re-riveted and re-shaped to fit my propellor. The cut-outs in the spinner were also then shaped to fit and the spinner match drilled through the existing holes to the backplate. An additional 4 nutplates were riveted to the backplate and the spinner screwed to it. The existing holes were then used to match drill new holes in the spinner. This means there are now 8 screws holding the spinner to the backplate rather than the original four - should be stronger. Next the front plate was screwed in place in the spinner and the gap between the prop and the front plate measured. This was 8mm so a piece of 8mm aluminium plate was procured and a crush plate cut out on the router. A 1/8" aluminium spacer, the front plate
, the crush plate the propellor and the backplate were then bolted to the prop extension and the spinner screwed into place. New holes were then drilled in the edge of the front plate through the existing holes in the spinner - again 30 degrees round from the originals. The original nutplates in the frontplate were then removed and re-riveted into their new positions. Finally the length of bolts needed to attach the propellor to the extension was accurately measured and AN bolts with drilled heads procured. These need to be exactly the correct length to ensure that the threads don't bottom but do show through the propellor lugs in the extension. The final job looks pretty good - a spun aluminium spinner for less than half the cost of the cheapest fibre-glass alternative. The only slight compromise is that the original cut-outs in the spinner were for the metal prop on the Cherokee and are about 1/4" too high leaving a slight gap above the front of the propellor. The sides and bottom are a perfect fit. I'll have a think about whether and how I could close these gaps for cosmetic purposes but they won't effect the performance in the air
