Delta prof. benchtop mortiser cut issue

[davidtu]

I'm using the 1/2" chisel and I am seeing a bit of roundness at the edges where the auger is apparently cutting wider than the chisel. Is it possible that the auger is misaligned w/ the chisel (looks OK to me... how to determine it?) OR am I just seeing the effect of material getting jammed up in the auger (even momentarily) and thus in effect making it "wider" and rounding the edges. Could it be the auger is too low (or high) relative to the chisel?

I can post a photo if needed.

[bmyers]

Sounds like the auger is too low? Have you tried this trick?

1) Release the auger
2) Release the chisel, put a business card between the chisel and the stop it slides in to.
3) Raise up the chisel snug to the biz card, tighten the chisel, leave the business card
4) Raise the auger unil it hits the chisel, tighten it down, tight!
5) Loosen the chisel, remove the business card
6) Raise the chisel until it hits the stop, tighten.

Important!! Spin drill by hand and make sure it moves freely!!

You might play with the thickness but some around that should do the job. If there is a spec on how man thousandths space and you have feeler gauges, use that.



Bill

[Imadunatic]

I occasionly get those as well, and when asked i claim it was on purpose so I didnt have to flute the tenon, lol. I will try the business card trick tho, thanks bill.

Kevin

[LCHIEN]

sounds to me like the auger is too low.
The tip of the auger is flared to match the opening of the chisel.
If you push the auger almost all the way up the flare should match the
chisel, but if the chisel is too low then the auger may have some play realative to the chisel causing your problem.

[Tom Hintz]

I agree that the first thing to do is to check the setup of the bit and chisel. I have a story at the link below with photos that shows an easy process to do this alignment. The gap between the auger and chisel is important as it is designed to get the chips up and out of the hole.
Next, the sharpness of the chisel itself is also important. If this is happening in softer wood, the chisel may be compressing the edges of the hole before it tears through which can result in a rounded appearance. Mortisers actually work better in harder woods like oak and maple that is stiff enough to allow a sharp chisel to slice the fibers before they bend or compress.

http://www.newwoodworker.com/setupmort.html