Router Extension

This is a very simple router extension thing made out of mild steel. It has an 8 mm shank, 32 mm long to go into the biggest collet for my trim router (which came with 8 mm and 1/4" collets). The outer end is 22 mm diameter, 27 mm long, threaded 1.5 mm pitch and with an ER16 taper inside.

The router sled that I made is great but the limited plunge travel of the trim router meant that I couldn't "plane" really thin material without pulling the cutter out too far for comfort. I bought a router extension that uses ER16 collets from a Chinese seller on ebay, but it was FAR too long (the body was 50 mm compared to the 27 mm of mine) so I decided to just make my own. I also changed it to use a different sort of nut (that I already had) to the Chinese one: the Chinese one used a mini nut (19 mm by 1 mm pitch thread) for which the spanner is inserted from the face end. That meant that the cutter couldn't be fitted too close to the collet or the spanner had no access.

The flats on the shank were added to give me an easy way of getting the two ends concentric: I made the shank to be a very close fit in a test piece with a reamed 8 mm hole, then got a bit of scrap, cross-drilled and tapped M6 and then I put the cross-drilled piece in the lathe and drilled and reamed a hole 8 mm. That could then stay on the lathe and guarantee concentricity when the fledgling part was fitted. The flats (which were added with a hand file) gave the screws that held it in place something to hold on to.