Onsrud HSS Up-Cut Spiral Mortising Router Bit - 3/4'' Dia x 1-1/4'' H x 1/2'' Shank

This bit is the perfect way to start very clean 3/4" holes in a workbench. It may not be long enough to finish going through since a robust bench-top is usually 1.5" to 3.5" thick. No problem. Finish the hole with a spade bit. The combination of the top inch being very smooth and the rest of the hole being a bit rough is perfect for many hold-downs and bench dogs.I got this idea from Ron Paulk. His workbench tops are 1/2" or 3/4" plywood so this bit is long enough to complete the holes if you are building one of the Paulk Workbenches.Awesome bit. Hungry. Sharp. Stays sharp, too. Love it.

I bought this after reading all the reviews and with plans of making several MFTs. I was barely able to get through one only 3’x4’. The table top was 3/4” MDF and 1/2” plywood. It started out great but after 50 holes I was having to push the bit to cut and by the end I was having to put a lot of force on the top of the router. It started to burn the plywood instead of cutting. I called Rockler and was basically told, “should have gotten a carbide one.” If you’re going to go through plywood get a carbide bit .... live and learn a $90 later

The edges are very sharp, and the cut is a wonderful flat-bottom and very clean and smooth dado. There is tearout on the edges of the dado, as would be expected since the cutting edges draw the material up out of the cut. This removes all the waste so the bit isn't clogged up with cuttings.What was odd was the amount of pressure needed to feed the wood. When using a straight flute bit the tearout was only on the ends of the cut, and the feed pressure about half what this one required. But then again almost all the cuttings remained in the dado causing the straight-bit to heat up.

I found this tip on Darrell Peart's blog ([...]/). He mentioned tht Bob Van Dyke pointed out this way of creating a great bottom bearing flush trim spiral router bit. I agree. Works great! Here are parts:Bit : Onsrud ¾” spiral bit #40-141Bearings: (2 each) Whiteside B19 ¾” OD , ½’ IDBearing Stop Collar: Whiteside LC-1/2

Super fast for plunge routing mortises. Be sure to have the piece clamped down fully as this bit will pull the work towards the router (like any up-spiral bit does). Ran through a bunch of mortises in maple and couldn't notice a difference between the first mortise and the last one.

Great product. Great quality. Worth it

Worked great as expected

My husband love this tool.