Try the activity calculator at www.caloriesperhour.com/index_burn.php
It has a pretty comprehensive list of activities.
But I would caution against counting this as exercise, for a number of reasons:
* these calculators assume continuous activity. You may well burn 6.5 calories per minute of sanding, but by the time you set-up the vice, replace the paper, blow away the dust, test the finish, etc, there may only be 20-30 minutes active sanding in a task that took you one hour, and thus only burned 130-200 calories.
* Spark already includes an allowance of 20% for typical daily non-exercise activities, and this would probably fall into this category.
* the standard convention for calculating calories also includes your underlying metabolism, which is technically a double-count. For short duration high intensity exercise, this double count is pretty small and can be ignored. But counting an afternoon of low intensity woodwork as exercise is likely to lead to a significant overestimate of calories burned
* While hand sanding is definitely better activity that using a power sander, it doesn't really get your heart rate high enough for long enough to be an effective substitute for the health benefits of more focussed exercise.
The way I see it, we all got to the weight we are by doing what we do, so to lose weight we need to do more. Tracking things you would do anyway as 'exercise' may lead you into a false sense of security as to your overall activity level.