Episode 09 Router Bit Review Compression Bit

Episode 09 Linbide TCT Compression Bit

Router Bit Review Compression Bit

Linbide TCT Compression Bit

First and foremost, this bit is touted as being the World’s first tungsten carbide tipped compression router bit. In the past, these have either had to be made of tool steel, or of solid carbide (and with a significant price tag).

So what is a compression bit, and why would you want one?

When you want to do a planing pass with a straight router bit, you generally use one with straight cutters, which chips away at the wood, and produces a reasonable finish – certainly at high speed (say 15,000 RPM, this means there are 30,000 cuts per minute, so that equates to a pretty smooth surface). However, if you try to do the same to a veneer, melamine or similar, you can get a lot of chipping of the top and bottom surfaces because of the near 90 degree angle and resulting chipping action of the bit.

So a slicing action is definitely preferrable, and that is achieved by using a spiral cutter, so the material is pared (or shaved) away, rather than chipped. The spiral slices the material from the outside edge towards the centre, so the edge itself is always supported, and therefore not prone to chip-out. But what happens when you get to the opposite edge – the spiral is encouraging the material to chip-out due to the direction of the cutting action.

The solution is a compression bit – twin spirals, one a left-hand thread, the other a right-hand thread, so both top and bottom edges are attacked from the correct direction. the material is pulled towards the centre, and this will result in a worse finish there, but when working with veneers / melamine etc, we don’t care about the core, so long as the surfaces are perfect.

So that is what this bit is – 4 flutes – 2 top, 2 bottom, spiralling towards the centre, and each with a tungsten carbide tip (or edge). What is particularly clever, is although the cutting edge is a spiral, it has been made in such a way as to allow for easy sharpening – the front face of the TCT is flat.

Linbide are a New Zealand company, known for their quality router bits, and particularly the tungsten carbide. They also use generous amounts of carbide – their bits are generally very chunky, almost agricultural, so there is a lifetime of carbide available on each bit.

This bit is quite finished – machined nicely, and the carbide bought to quite a shine (shiny = flat/polished, and the meeting point of 2 flat, polished surfaces is very sharp!)

It is available from The Woodworking Warehouse, Braeside, Melbourne (Australia) +61 3 9587 3999 for around $A22. Tell ’em where you heard about it, and we’ll get some kudos for Stu’s Shed!

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