[SuperJdynamite]

I was wondering: why are chain drives so unpopular in wood and metalworking machinery? Is there a disadvantage to using sprockets and chain for the motor -> spindle power transfer in machinery? Or is it just the happenstance of the marketplace (i.e. pulleys are easier to make than sprockets)?

[Al_The_Man]

A few things I would think that deters the use is backlash, inertia, noise etc.
Personally I would much sooner prefer timing belt and pulley over chain and sprocket for a similar method.
Al.

[MIKEL12]

Also if you overload a belt it usually just slips, the same on a sprocket can be catastrofic.

[ajm11]

If you look at the Sieg X2 mini mills you will see that they have a complete gear train in the mill head. If you use to much force when cutting and stall the spindle it destroys the gears and you need to order more. Where as a belt will allow for slip and not destroy anything.

Also with all the metal chips and debris flying around a chain is much more likely to wear out than a belt. Chains also need constant attention to their wear and also need routine greasing. Most metal/wood working equipment run at very high rpm. This could likely cause grease to splatter all over the shop if the improper grease is used (many people dont follow factory instructions and "run whatcha brung".

[Torsten]

I was wondering: why are chain drives so unpopular in wood and metalworking machinery? Is there a disadvantage to using sprockets and chain for the motor -> spindle power transfer in machinery? Or is it just the happenstance of the marketplace (i.e. pulleys are easier to make than sprockets)?

Actualy they have been used a lot for the same purpose before Timming belts became widespread available. They are still a suitable substitude and quiet a bit cheaper to implement then Timming belts and pulleys.
The reasons a lot of people prefer to use Timming belts now a days is as AL has stated smother run and noise also no grease needed to run them.
Earlier Homebuild CNC and retrofits often used chain and sprockets.