Stanley #3 and #5 1/4
Partner planes are planes of different lengths that have interchangeable parts, from the blades on down. The most common example is the Stanley #4 and #5, both with 2″ wide cutters, which make a versatile duo at 9″ and 15.” Less common is the Stanley #3 and #5 1/4, which makes an attractive alternative to the 4-5 combination.
What we have here is a closer match in the length of the two planes, at 9″ and 11 1/2″ (the #4 and #5 are 9″ and 15″ respectively). The idea for the 11 1/2″ inch length, often referred to as the “Junior Jack,” actually came from the Ohio Tool Company. Logically it makes good sense, as the gap between the standard Smoothing and Jack planes is large at 6.”
With either combination you can do the following. I deep sixed the #3 low quality standard cutter, and replaced it with a Lee Valley 1 3/4″ one–a considerable upgrade (Lee Valley just purchased Hock Tools of California, giving them a huge market share for quality blades.) I took the also not-so-great factory cutter from the #5 1/4, and reground it to an exaggerated camber shape, turning the plane into a long scrub plane. I also have a #5 with a re-ground blade as an extra long scrub plane.
At any rate, I can just switch cutters on these partners and have a really long smoothing plane (or a short Jack plane), and a short scrub plane. The best thing about the #5 1/4, no matter how it is used, is the weight–it’s a full pound lighter than a #5. To me it’s a case of bigger is not necessarily better.