G0645 Mortiser Issues

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Forum topic by Mike posted 12-25-2012 02:49 PM 1272 views 0 times favorited 5 replies Add to Favorites Watch
View Mike's profile


406 posts in 2713 days

12-25-2012 02:49 PM

Topic tags/keywords: mortiser mortise g0645 grizzly chisel

So I picked up the Grizzly G0645 Mortise Machine over this weekend and I am running into a small issue that I am hoping someone has a work around for. When I setup the chisel and bit into the chuck and bushing and tighten the set screw to hold the chisel, the set screw forces the chisel out of alignment (I have tried this with 2 different chisels and bit sets). When I manually turn the chuck, I can feel the resistance from the bit on the chisel. I have checked that the drill bits are in the round and not bent. When I perform a very short powered test I hear what I consider a lot of metal on metal screeching.

Now page 25 of the manual, the Troubleshooting section on noise and smoke, says that this is somewhat normal. It is unclear as to what is considered an average amount of noisy though. Am I over thinking the problem or is this a real issue? Thank you for the help!

PS: I would have called Grizzly Tech support but they have been closed since I have picked the machine up due to the holidays.

-- look Ma! I still got all eleven of my fingers! - -

5 replies so far

View MJCD's profile


542 posts in 2397 days

#1 posted 12-25-2012 03:35 PM

I hope this is NOT considered normal. There should never be metal-on-metal contact. The next worst thing is that the bit somehow catch the chisel, with you in the path of metal parts flying.


-- Lead By Example; Make a Difference

View AlanBienlein's profile


159 posts in 2700 days

#2 posted 12-25-2012 04:22 PM

Chisel and Bit Spacing

The combination of a square chisel preceded by a round drill requires a specific gap between the two for proper operation. Because chips are evacuated through a slot in the chisel housing, there must be sufficient space between the drill bit and the tip of the chisel for the chips to be carried up to the slot by the specially designed flutes on the drill.

Most manufacturers give a range of bit to chisel clearances, sometimes indicating the range of settings are meant to accommodate different woods. Unfortunately, they seldom describe what setting is for what type of wood.

(left) Trapping the right coin between the chisel and it’s boss is a very simple, but effective trick.
(right) Lift the bit all the way up and secure it in the chuck. Remove the coin and seat the chisel up against the boss and the bit-to-chisel spacing is set.
Click images to enlarge The logical interpretation is that the greater bit to chisel clearance is for softer woods that produce larger chips and shavings. Hardwoods, which normally generate much finer chips when drilled, can use the smaller end of the tolerance range. While researching this story I cut mortises in every species of wood I could find and this bit to chisel concept seems to hold up.

In reality, most woodworkers use a bit to chisel setting in the middle of the range for all of their work. This one-setting-fits-all approach usually works, but remember this setting in case you encounter a problem with chip extraction in the future as it might be the cure.

While manufacturers sometimes provide instructions on how to attain this bit to chisel setting, they are often more complicated than need be. Enterprising woodworkers discovered that American coinage provided an alternative that simplifies the set up task.

Locate the recommended bit to chisel clearance in the instructions that came with your mortiser, and then find a coin with a thickness that most closely matches that number.

Insert the chisel into its bushing and raise it up to the bushing face trapping the appropriate coin between the bushing and chisel face (see photos) before tightening the setscrew to secure the chisel. Insert the drill bit through the chisel and into the chuck, holding the tip of the bit fully up against the end of the chisel. Tighten the chuck to secure the bit. Loosen the chisel set screw, remove the coin and slide the chisel up, butting it against the bushing. Make sure the chip port in the chisel faces to the right or left, not front or back, before tightening the setscrew to secure the chisel housing.

You should now have the proper bit to chisel clearance for your machine.

View Mike's profile


406 posts in 2713 days

#3 posted 12-25-2012 06:03 PM


Thank you sir! That was the trick. I need to replace the set screw, but other than that, the machine now works great!

The last question I have is the bushing on mine is floating. Can I raise the bushing all the way up then place the quarter between the bushing and the chisel, or should I place the quarter between the bushing and the head stock for the best results?

-- look Ma! I still got all eleven of my fingers! - -

View AlanBienlein's profile


159 posts in 2700 days

#4 posted 12-25-2012 06:30 PM

Does the bushing stop and seat against a flange of some sort? If it does then push it in till it seats and then reset the mortising chisel like described above.

You can read the rest here.

I should have posted the link previously but forgot to.

View a1Jim's profile


117119 posts in 3603 days

#5 posted 12-25-2012 06:37 PM

Alan covered it very well .

-- wood crafting & woodworking classes

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