What do you all two bits of rebated plastic held together with a thumbscrew? A Trim Gauge, of course. The name is derived from its American role, where architrave is often referred to as ‘trim’. This gives you an idea of its primary function: offsetting or gauging a quirk line around frames to set the architrave margin.
The rebate overlap of each part is equal to 5mm (3/16 in.), and sliding the pieces across each other one way gives the same margin. Scales in metric and Imperial can be used as a guide to set wider margins, up to 76 mm (3 in.), sliding the pieces in the opposite direction. A thumbscrew locks the position.
For extra value there are two spirit vials embedded in the Trim Gauge, one for plumb, one for level. Although the right colour, I wouldn’t expect these to be up to Stabila’s standard, but they’re still useful on the odd occasion.
Great for quickly gauging pencil lines, the Trim Gauge can also be used to set cutter depth on routers and rebate depths. The plastic is hard, so it shouldn’t wear easily as it’s dragged along an edge. If there’s a fault with it’s that the measuring scales are printed on to clear sticky-backed plastic, so will probably wear in time. I wouldn’t rely on these measurements for precision, more of a quick setting option. Keep this in the toolbag and you may find yourself reaching for it quite regularly. A useful little device.