Hollow Chisel mortise bits

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Forum topic by woodsmith1 posted 09-12-2010 10:57 PM 3006 views 0 times favorited 7 replies Add to Favorites Watch
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58 posts in 2374 days

09-12-2010 10:57 PM

I picked up my first mortise machine at a local auction for $50, first auction as well (loved it!). The machine works well. It was still new in the box.

I also picked up a set of Shop Fox bits online for about $25. Four bits, 1/4”, 5/16”, 3/8” and 1/2”. As I never used a mortise machine before I could be wrong but these bits are junk. They were burning on the second hole.

Does anyone have experience with these and can tell me good bits to buy. Also the manual mentioned using a lubricant on the bit. What kind? Any info would be great!


7 replies so far

View richgreer's profile


4541 posts in 2493 days

#1 posted 09-13-2010 01:11 AM

Good mortising chisel bits are $20 and up each. If you got a set of 4 for $25 that should tell you something right there.

You’ll reasonably good bits from places like Rockler and Woodcraft. There are also places that sell the premium bits for $50+. I’d suggest that you start with some mid-level bits from Rockler or Woodcraft. You will probably also find that you do not need all 4 sizes. Almost every time I cut a mortise I am using 3/8”. I could get by with just that bit unless/until I run into a very special situation. When/if that happens, I can buy another bit then.

I’ve never heard of applying a lubricant to a chisel bit. Maybe someone else has.

Two important things: (1) Make sure you position the bit a little lower than the edge of the chisel – but not too low. I set the outside of the cutter on the bit about 1/16” below the corner of the chisel. (2) Keep your bits and chisels sharp. There are some tools designed expressly for sharpening these chisels.

-- Rich, Cedar Rapids, IA - I'm a woodworker. I don't create beauty, I reveal it.

View Peter Oxley's profile

Peter Oxley

1426 posts in 3293 days

#2 posted 09-13-2010 01:16 AM

I’ve heard that the Shop Fox chisels aren’t the greatest, but I’ve never used them. When I’m setting up my machine, I put the chisel in and tighten the set-screw. Next, I push the drill into the chisel as far as it will go and then let it back out about 1/16” before tightening the chuck. If the bit is too tight in the chisel, they can wear eachother down, and sometimes make a horrible screeching.

-- -- --

View ChuckV's profile


2872 posts in 2946 days

#3 posted 09-13-2010 01:51 AM

I second everything mentioned above. You should also try to leave the slot through which the chips are ejected clear. If there is just one opening on the chisel, you should install the chisel with the opening on either the right or the left as you face the machine. As you create the mortise, move the wood so that the slot faces the previous hole. For example, if the slot is on the right, start the mortise at the right end and move the wood to the right. This way, after the first hole, the ejection slot will be free.

-- “And the products of wealth push you along on the bow wave of their spiritless undying selves.” ― I. Anderson

View woodsmith1's profile


58 posts in 2374 days

#4 posted 09-13-2010 02:47 AM

Thanks to all so far. First off, it’s the auger bit that burns not the chisel.

I usually believe you get what you pay for. I just goofed and thought I’ld go the cheap route not using a mortising machine till now.

Most of whats been said is in the users manual. I feel at this point I have done all that is mentioned except moving away from the opening on the chisel and the lube. Next go around I will. I’ll also invest in some better bits and sharpening tools.

View Lee Barker's profile

Lee Barker

2170 posts in 2269 days

#5 posted 09-13-2010 03:17 AM

Here’s a trick I picked up, if I recall correctly, in FWW: I ground relief in the outside of the chisels so only about the bottom 1/4” is full width. There’s less friction on the wood, less heat transer, etc etc. I don’t think it’s a miracle thing, but every little bit helps.

When you address any power woodworking tool, there are five things to be conscious of:
1. Cutter speed
2. Cutter angle
3. Chip ejection
4. Rate of Feed
5. Condition of the cutter (sharpness)

Everything is fixed on the mortiser except #4, and it takes a lot of sensitivity to get that right. Too slow and too fast will generate too much heat. You want the warmth of your porridge to be “just right.”

When I was shopping for a mortiser, the only one in my price range that was 1725 rpm was the Jet, and that’s the one I bought. I’d be curious to know if anyone has owned both a 3450 and 1725 machine and has opinions about heat therefrom.

-- " his brain, which is as dry as the remainder biscuit after a voyage, he hath strange places cramm'd with observation, the which he vents in mangled forms." --Shakespeare, "As You Like It"

View Bob Kollman's profile

Bob Kollman

1798 posts in 2609 days

#6 posted 09-13-2010 05:40 PM

Great find, that’s an item on my wish list!!!! Gloat….

-- Bob Kenosha Wi.

View TheDane's profile


4932 posts in 3081 days

#7 posted 09-13-2010 07:57 PM

Rockler sells a set of mortise chisel sharpening cones … a little pricey at $30, but I use every time I do a setup on my mortiser, and they do seem to drastically improve performance. BTW, I have a Jet JBM5 ( ) and am still using the chisels that came with it … except for the mine my SIL broke!

-- Gerry -- "I don't plan to ever really grow up ... I'm just going to learn how to act in public!"

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