The scrub plane blade has an arc-profiled cutting edge, with more or less marked radius according to the job required. This profile makes it more difficult to sharpening by guides so many people prefer sharpening it by hand. 
Im not very good at this job, so I searched for sharpening guides available that could serve the purpose. The Record 161 is a guide which is easy to find on ebayUK for few pounds. It has only one central contact point (a rolling ball in the middle) and this permits to incline to the right and left allowing to follow the cutting edge profile easily.
The blade is held firmly in place by a clamp screw that allows unrestricted iron orientation, useful even if it was necessary to sharpen skewed blade. The dark side is that you have to ensure the correct blade position by hand.
For bigger curves the guide can be moved to the sides of the sharpening stone to allow for greater tilt, as seen in the short movie. The result was satisfactory with 35 ° bevel. To re-sharpen exactly to the same angle Ill use a simple self made jig.
I have sized the grip to suit my own hand size which is 4" across the palm. The grip itself feels extremely comfortable in use. Now to cover the basics. The handle wood is Tas. Fiddleback Blackwood. I have orientated the curly grain to flow quite nicely through the neck of the handle to maximize the handles strength. The saw blade length is 12" long, and its been sharpened 16tpi rip. 
And here are the completed shots of the finished backsaw. 
As a final wrap up I am very happy with the look of the new handle design. Its not quite traditional. But it does has a great feel to it and works extremely well with smaller depth saw plates. It would also look quite compatible for use on even deeper saw plates say up to 3". I also enjoyed working with an open handle design this time round. 
