Chain Drilling Jig

stock image of Chain Drilling Jig

I was asked to see if I could repair a conservatory made of hardwood that had rotted mostly around the base. Other trades people had given quotes for complete replacement in UPVc. My approach was to support the top part of the conservatory and replace the lower part with brick which made a neat job at a quarter of the price of a complete replacement.

However, one of the hardwood window frames above the replacement level had rotted a small way up. Using some of the unrotted wood from the lower part of the conservatory already replaced was ideal as a insert to replace this wood. But this part of the frame was between two double glazed toughened glass panels which will shatter at a slight touch with a cutting tool. To accurately cut away the rotted part of the frame avoiding the use of a saw, I made this chain drilling jig. To use it you firstly screw the jig to the wood with one pair of the four countersunk holes. Drill through using the upper drill holes which guide the drill straight through the wood. Then re-screw the jig into the wood using the set of countersunk holes not used and into the same screw holes already made in the wood. You then find the drill holes are positioned to drill between the holes already drilled, cutting through the wood completely. A careful trim of the wood surface with a sharp chisel (protecting the glass edges) and the new wood insert could be cut to fit.