Questions about Hollow Chisel Mortiser

[Jerome Hanby]

I looked at a craigslist Craftsman Mortiser last night. It's Craftsman, so I wasn't expecting top of the line, but I wasn't able to make a half-inch mortise through a piece of pine 2x10 (may have been SYP). It basically got to the point where the chisel would engage, then it pretty much stopped and eventually started to burn the wood. I didn't do an exhaustive examination, but the chisel seemed fairly sharp. I'm wondering now if maybe it wasn't set up properly. How much of the bit should protrude beyond the chisel at the start? I assumed that the drill bit would engage, drill pretty much to depth, then further action on the handle would slide the chisel down and shear off the sides of the hole to give you the square. This is the first time I've touched a "live" mortiser and any information I have, I read here, thought out myself, or picked up watching Norm. Speaing of which, Norm doesn't seem to be putting nearly the force I used last night. From the plate, the mortiser was half HP, didn't have the micro adjustment for the fence, appeared to be an older version of the current model with a straight handle instead of the new (longer ?) one with the right angle handle at the end.

I offered the guy $80 for it (asking $150) figuring I could eventually tune it up, but I'm not really excited about the $80 after last night's experience. Unless I really missed something, I'm back to waiting for the spare cash to buy a ShopFox instead of picking this thing up as something to play with in the mean time.

Any helpful info? If I just handled the tool incorrectly, it might be worth it to me to spend $80-$100 and have something to with which to work. I could probably get my money back out of the thing when I'm ready to buy a "good" model.

[Mike Sheppard]

Jerome
It sounds to me the chisel is dull and maybe the bit also, I have the 3/4 hp. Shop Fox and got some cones from L.V. to keep the chisels sharp and a file on the bitts, that seems to be the key to make it work good.
I put the chisel in 1/16 down push the bitt up to it then lock it and move the chisel up and lock it. Hope that is clear.
Mike

[Cody Colston]

A hollow-chisel mortiser is basically just a drill press. All it does is spin the bit while also holding a square chisel. As long as it's spinning and the press mechanism is working, then it's doing it's job and the problem lies with the bit, chisel or both.

Put the chisel in the mortiser while inserting a nickel between the top of the chisel and the mortiser. Now put in the bit, keeping it flush with the bottom of the chisel. Lastly, release the chisel and slide it all the way up before re-tightening.

That should leave the bit sticking out the thickness of a nickel. If it still doesn't cut, then the bit is dull and possibly the chisel, too. Even though the points are sharp on the chisel, that doesn't mean that the rest of the cutting surface is the same.

[JohnT Fitzgerald]

Yeah, what he (Cody) said. :)

[george wilson]

There are sharpening cones you can get for sharpening mortice chisels. I don't have a morticer,so can't tell you offhand where to get one. It would be well for you to look into it. Srarpening those chisels by hand gets their geometry fouled up. Nest to use a cone. They rotate,you present the chisel to them. Maybe Forrest has them.

[Jerome Hanby]

Thanks for the replies. I didn't measure, but the amount of bit protruding past the chisel was in the ballpark of a nickel's thickness worth. I bet sharpening is in order. Woodcraft has a sharpening kit for hollow chisels. If the guy come way off his asking price, I might consider it, other wise I'll keep feeding my piggy bank and buy something better.

[Lee Schierer]

The hollow morticer works by drilling a round hole and then squaring it up with the chisel. All the chisel should do is make the four corners. If the chisel is dull it won't cut the corners. Also if the outside surface of the chisel isn't shiney smooth it will create a lot of drag making it hard to press into the wood. Morticing chisels are not self feeding and you have to apply some significant downward pressure to push the chisel into the wood. The harder the wood, the more pressure you need. Sharpening the chisels isn't hard, but can be a bit tricky. I was amazed when I tuned up the outside surface of my chisels about how much easier they went in and pulled out of the wood.