Best as doorstop for a very small door….

I bought one, years ago, and found it totally useless.

Regards, Frank

I would not say they were totally useless or you can throw every router cutter away as these are mainly parallel.
They are good for light finishing cuts.

If you are doing any maching using the edges on the end of the cutter, the helix angle will be related to the material it's intended for. So aluminium would require a fast helix, copper and brass a slow (or parallel) helix and you can even buy a reverse helix. I suspect the latter is actually best used for thin sheet material, as it will push the work against the table.

Of course, you could have a parallel flute cutter with any kind of cutting angle if you are mainly cutting radially and I expect you can get different combinations of helix angle and cutting angle according to both material and type of cut. But one advantage of the spiral is a smoother cutting force which is presumably why parallel edged cutters are best used for light finishing cuts.

Murray