Bosch 84623M 4 Inch Tongue Bearing Review

This industrial and scientific router bit was a complete disappointment. Despite the high price tag, it failed to deliver the promised performance and quickly became dull after minimal use. The only positive aspect is its sleek design, but that doesn't make up for its overall poor quality. Save your money and look for another brand with a better reputation.

Agree with other reviewers over the years (visit the Bosch website in particular), it's confusing that Bosch sells this bit without enough spacers for the grooving tool to work. Otherwise it is difficult to control the cutting depth with this attachment. Everything else is pretty decent quality. I appreciate the 1/4" shank as most of these bits require a 1/2" socket.

I was able to make a pair of poplar shaker doors with relative ease using this piece. Be sure to pay attention to the placement of the spacers provided - when the bit arrived the tongue was too thin and I had to move the small brass spacers to get a solid connection. As with any plate set, make a few test cuts to ensure everything lines up well. Oddly enough, I got the best cut by running the wood through the bit fairly quickly. If I slowed the feed too much it would set the wood on fire a bit…