🔍 The kit is optimized for the included 1/8\" and 1/4\" spiral bits – those sizes correspond to the offset created by the bushing and collar. Using a different diameter bit would change the offset, and your inlay might not fit correctly. For example, Whiteside and similar kits always use a 1/8\" bit, because the math of the collar’s offset is based on that. SpeTool wisely also provided a 1/4\" bit, which doesn’t change the fit since you typically do final cleanup with the 1/8\" anyway. If you tried, say, a 3/16\" bit with the collar system, you’d likely throw off the dimensions. So it’s best to stick to 1/8\" (for detailed cutting) and 1/4\" (for bulk clearing) when using the collar system. If you need a larger inlay and want to use a larger bit, you could technically do so by cutting the recess without the collar and then freehand fitting, but that defeats the precision of the kit. In summary: use the bits that come with the kit (or identical-sized replacements) to guarantee a proper fit.

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