Drill press mortising attachment

Darren Wright

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I need to do some mortises for my high chair project. A dedicated mortiser is not in the budget, nor do I think I'll use it that often. I've opted for the kit that you can add onto your drill press. The one I've ordered is one from Northern Tool (http://www.northerntool.com/shop/tools/product_200312050_200312050).

Just curious if anyone has had any "gotchas" with one of these or tips to make using it easier? From others reviews it seems to work fine and the measurements fit my DP. Worst case I have to use the gas to return it, which we do have a local store. I got it with a coupon, so shipping was only $7, which I'd spend in gas going to get it if I shipped it to the store, so just paid the extra to get it sent to the house.
 
Biggest issue is to probably re-engineer how the workpiece is held down. Any flex there and you can have some issues with it 'twisting' as the bit wants to come out. The more you can make that a solid clamp, the happier you will be. Also, make sure the chisels are sharp.

I'm sure some of the more experienced guys will have more info.
 
One biggie is to make sure that one flat side of the mortise is dead parallel with your fence. Or the sides of the mortise will be serrated. Don't overwork the tool. It will overheat and kill the sharp edges on the mortise chisel. Paper dollar bill clearance between the drill bit and the chisel works well.
 
One biggie is to make sure that one flat side of the mortise is dead parallel with your fence. Or the sides of the mortise will be serrated. Don't overwork the tool. It will overheat and kill the sharp edges on the mortise chisel. Paper dollar bill clearance between the drill bit and the chisel works well.

I allow a bit more clearance 'twixt chisel and bit. I install the chisel, and use a nickel at the shoulder as a spacer. Then, I install the bit, snug to the chisel. Then, I loosen the chisel and seat it fully home.

The bits are usually sharp enough out of the box, but the chisels usually need some work. Polishing the outside surface helps a lot, but using a cone-shaped stone on the inside surface is where the real work is usually needed. LV, Rockler, and others sell the 'dedicated' cone-shaped stones, but careful work with a Dremel polishing stone works well, too.
 
Thank you all for the advice/suggestions. Jim I saw a youtube that the gentleman did the same as you describe with leaving some buffer space when setting up the bit/chisel. He also showed a "strut" that he used to steady the table and prevent flexing of it. The strut wedged between the base and the table to support it.

I know these setups take some fiddling, so if it doesn't work out, it will get returned. I remembered this morning that my FIL has a dedicated mortiser I'll borrow if need be.
 
I wrote a web page about using my drill press mortising attachment 11 years ago. At that time I liked the setup. When I got my combo machine with the slot mortiser I couldn't sell the drill press attachment fast enough. See www.plesums.com/wood/tips/mortise.html

The slot mortiser is similar to a plunge router with a simple jig. When I had a big job recently where I needed integral rather than floating tenons, I played around with rounding the ends of the tenon to go with the round end mortises vs. squaring the mortise with a chisel, and keeping the tenons rectangular. The square tenons and chisel work on the mortise won. The pictures below are the prototype I did - the one leg has both types of mortises, the one apron piece has both types of tenons.

StuSqTenon.JPG


StuRoundTenon.JPG
 
The latest issue of Fine Woodworking actually had some tips on setting up the chisel and bit.

Basically, it talks about using a dowel and some fine sandpaper and sanding smooth the inside of the chisel to facilitate chip extraction.
They also use a buffer to buff the flutes of the bit for the same reason, and use some paraffin wax on them as well.

Nice little tips.

http://www.finewoodworking.com/tool-guide/video/sharpening-hollow-chisel-mortising-bits.aspx
 
I don't have a mortiser but do use the chisels for other things. I can vouch for the sharpening cones and the sandpaper on a dowel trick. Super sharp chisels and bits and a clean ejection path are your friend.
 
Well, will be returning the mortiser this week. Got it all the way setup, but found my chuck is too big to allow the chisel fit correctly. The 1/4" chisel wouldn't go in also, found the shaft was turned at a taper and the end was too big to fit. I did remember that my FIL has a dedicated one, I may stop over and use it. Also may see if he wants to part with it since he's giving up woodworking.
 
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