I decided to have another fiddle about refining my new big sash window today. I am aiming for fingertip lightness on the sashes.
As an aside, I wish I had asked Dan about this before I started. Although the on-line advice was weigh the window sashes in situ on scales (as per my previous thread), his advice was take the sashes out and weight them separately. Lesson: listen to Dan. I learnt as I went along but it has taken time to do this job perfectly.
My in situ method gave a weight that certainly worked. However, to get fingertip lightness, with a full clean out and application of non-silicon lube, required an additional 4.22 kg on the lower sash. I was amazed, but you can now practically blow it up and down. The upper sash is the same size but needed far less lead.
Had plenty of spare lead as I bought extra just in case, having sold the load that came with the window (too damaged) and had to cut it. What a performance! There must be a better way. This was 50mm square section lead and I cut it with a large rigid frame hacksaw. It took ages. I scored all round, and turned the block regularly, and used a new blade in my old eclipse large (12" I think) hacksaw, but the cut clogged constantly and both lead and blade got quite warm. It took me almost 2 hours to cut 4 pieces neatly, file up and fit.
The factory cuts looked like a circular saw was used. Is there a method for hand cutting that I should be aware of?