EANOSIC Spiral Router Bits Up Down Compression Bit 1/4 inch Cutting Diameter with Nano Blue Coated, 1/4 inch Shank Solid Carbide CNC End Mill for Wood Carving Engraver Milling Cutters for Mills Machines

great bit for the money

I ran one of these at around 300ipm in walnut today and it held fine. No tearout either top or bottom with no chatter. I probably could’ve pushed it harder.If you’re gonna sand your edges anyway, these are superior to a down cut. I could’ve gotten a cleaner cut on the bottom surface but I set my machine to just expose the spoilboard and not cut deeper. To take advantage of these they have to have all flutes engaged.

cut accurately and smoothly in my ancient router.

Works great for circle cutting without leaving splinters on either surface, especially on plywood

This seems to be a very sharp router bit. The blue coating should keep it sharp for a long time. The bit geometry is as described except the total flute length on the one I received is closer to 1 1/4" (as opposed to the 1” dimension in the description), which I consider to be a good thing.An important piece of information is missing in its description. That is the length of the up-cut portion of the tip. I can’t find it anywhere in the description. On the bit I received, the up-cut tip is slightly less than 1/4”. The remaining 1” of the fluted portion of the shank is down-cut.In order for this bit to work properly, the depth of cut must be at least slightly more than the length of the up-cut tip. This results in the surface of the material being exposed to the down-cut portion of the bit, resulting in smooth cuts with little or no tearing. I believe this bit is intended primarily for plywood where the surface laminate is thin and delicate. The up-cut portion of the bit clears chips, and the down-cut portion “compresses” the surface lamination and keeps it from tearing. This only works if the depth of cut exceeds the length of the up-cut portion of the bit far enough for the down-cut portion of the bit to engage the surface lamination. If used at a cutting depth less than the length of the up-cut tip, it is essentially an up-cut bit. So, it would not be appropriate to use this bit to make shallow cuts in plywood.I tested this bit in various cuts and materials (see photos). Both the hardwood cuts were made with at least a 0.02” offset, and then a finishing cut on the final line. Cutting tenons and mortices in hardwood worked well, but could probably have been done with any spiral bit with essentially equivalent results. Deep cuts in plywood (in this case 1/2" Baltic birch) worked particularly well. However, as I expected, a shallow cut in plywood was pretty ugly. The third photo shows a perpendicular to grain groove at top with 1/8" cut depth, and at bottom with 3/8" cut depth, both with a single pass. A down-cut spiral bit would clearly be more appropriate for the shallow cut.Bottom line is that this is an excellent bit for deep cutting in plywood, and works well for general cutting in hardwoods. It will probably be my “go to” bit for cuts over 5/16” deep in plywood.