OK I'm looking for a little help on cushions! 
I may have mentioned replacing my softwood rubber rebated lining blocks with custom hardwood versions, so I've been taking measurements tonight from one of the cushions I intentionally haven't stripped down yet for this very reason. However! I noticed something weird on the rubber support fillet strip, it seems to be slightly tapered..... take a look at the pic. I've tried to highlight the angle with a red line...
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I checked the ones removed from the other cushions and they all the same. I'm not sure if they are made/sold like this originally or whether a fitter has planned this tapper into the wood for a reason? Assuming the Northern Rubber doesn't have a tapered bottom edge I can only think maybe by having a pointed/sharper edge to the fillet it digs into the rubber and stops it sliding and breaking free if someone sits on the cushion?

I may have mentioned replacing my softwood rubber rebated lining blocks with custom hardwood versions, so I've been taking measurements tonight from one of the cushions I intentionally haven't stripped down yet for this very reason. However! I noticed something weird on the rubber support fillet strip, it seems to be slightly tapered..... take a look at the pic. I've tried to highlight the angle with a red line...

I checked the ones removed from the other cushions and they all the same. I'm not sure if they are made/sold like this originally or whether a fitter has planned this tapper into the wood for a reason? Assuming the Northern Rubber doesn't have a tapered bottom edge I can only think maybe by having a pointed/sharper edge to the fillet it digs into the rubber and stops it sliding and breaking free if someone sits on the cushion?
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