I love my mortiser except for... --- followup

Many thanks for all the suggestions. Let me tackle them in order.
1. Bit following the grain: I don't think so -- it does the same thing in plywood.
2. Check the auger diameter: It's dead-on the chisel diameter for all bits.
3. It shouldn't happen: I agree.
4. You'll have the same problem with all mortisers: I hope not.
5. Half-moons are normal: see 4. above.
6. Scary-sharpening might have thinned the chisel: I doubt it -- I began with 15u paper, and some of the old score marks left from manufacture are still there. Could be, tho.s
7. Sharpen chisels at the inside only: See 6. above. I have the Lee Valley sharpening cone set but haven't used it yet.
8. Auger may be set too low: I was using the 1/6" gap suggested by Delta. I tried the nickel/dime approach but it didn't seem to help.
9. Try reseating the auger at a different angle: This does make a difference. I'm beginning to think the axis of the chisel is not parallel to the auger. It's hard to see if the augers are not quite straight because their tips are just blunt pyramids.
10. Make sure augers are not set too low: I think this is an important point. Nickel, dime spacing is OK, but what really matters is how far the auger protrudes from the chisel and whether its shoulder is nearly resting on the corresponding shoulder on the chisel. Not touching, not squealing, but almost.
I'm going to complain to Delta, and at the same time buy one better-quality bit to see if that helps.
Any suggestions at to which brand is best?
--
Vince Heuring ECE Department, University of Colorado - Boulder
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: : Many thanks for all the suggestions. Let me tackle them in order. : : 1. Bit following the grain: I don't think so -- it does the same thing : in plywood. : : 2. Check the auger diameter: It's dead-on the chisel diameter for all : bits. : : 3. It shouldn't happen: I agree. : : 4. You'll have the same problem with all mortisers: I hope not. : : 5. Half-moons are normal: see 4. above. : : 6. Scary-sharpening might have thinned the chisel: I doubt it -- I : began with 15u paper, and some of the old score marks left from : manufacture are still there. Could be, tho.s : : 7. Sharpen chisels at the inside only: See 6. above. I have the Lee : Valley sharpening cone set but haven't used it yet. : : 8. Auger may be set too low: I was using the 1/6" gap suggested by : Delta. I tried the nickel/dime approach but it didn't seem to help. : : 9. Try reseating the auger at a different angle: This does make a : difference. I'm beginning to think the axis of the chisel is not : parallel to the auger. It's hard to see if the augers are not quite : straight because their tips are just blunt pyramids. : : 10. Make sure augers are not set too low: I think this is an important : point. Nickel, dime spacing is OK, but what really matters is how far : the auger protrudes from the chisel and whether its shoulder is nearly : resting on the corresponding shoulder on the chisel. Not touching, not : squealing, but almost. : : I'm going to complain to Delta, and at the same time buy one : better-quality bit to see if that helps. : : Any suggestions at to which brand is best? : : -- : Vince Heuring ECE Department, University of Colorado - Boulder : To email, remove the Vince.
I missed the other thread, but is the chisel square to the table in both planes ?
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Dear Vince:
We have 6 Delta units here at the school and have used them reqularly in many classes, mostly cutting white oak. You will find that the nature of the units do not cut a perfect hole and must be cleaned up with a chisel, just part of woodworking. I have found that if one hones the chisels, that will help greatly. Check your technique and good luck from Mike at American Sycamore.
If you still are having serious problems I would be glad to help and you will find Delta to be most helpful as well.
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Vince - I have a Delta Mortiser also, and am getting "squealing" when I run it. It seems to cut fine, but the squealing noise doesn't sound right. I'm going try to adjust the auger as you've indicated and see if that helps.
Otherwise, it does a great job. I find that I do need to do a very minor amount of clean-up in the corners, and sometimes on the bottom. I've used it mainly on BE Maple.
If you wouldn't mind, could you post Delta's response? I'd like to make sure mine continues to work well.
Thanks for the help. Good luck -
Nick B

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Besides everything being sharp and square to the workpiece, do you have the opening in the chisel facing forward or backward? It often helps to minimize the tendency to squeal if you have it facing sideways into the void as you cut. That way your waste get ejected into the part of the mortise you've already cut.
--
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better-quality bit to see if that helps.
Delta sells bits that are made in Austria, they are quite good.
Suggestion, clean out your holes with a chisel and add some glue and go...
--
Rumpty

Radial Arm Saw Forum: http://forums.delphiforums.com/woodbutcher/start
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The it's either a poor design Hong Kong Fooey Mortiser, poor quality bit or your technique.

I cut about 100 mortises yesterday afternoon. Since these were to be visible "holes" I concentrated on my technique. I use a Multico Mortiser which has substantial ways and no side to side slop, and a 5/16" Delta Austrian Bit. The 5/16" bit being so small in dia has a bit of flex in the drill so half moons can easily happen. I found the half moons were minimized if you slowly lower the bit into the wood and let the point of the drill grab the wood then continue pushing slowly until the chisel engages the wood. If you are hand holding the work against the fence hold tighter and you might consider a taller fence if necessary. Technique will minimize the half moons.

Don't waste your time scary-sharpening a mortise bit/set.
--
Rumpty

Radial Arm Saw Forum: http://forums.delphiforums.com/woodbutcher/start
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Thanks to all for the advice, much of which I took, except that which was contradictory. :-) I cut a bunch of mortises in quartersawn oak yesterday and today:
http://www.heuring.org/mortises.jpg
All in all I'm pleased with the results. Lessons learned so far:
1. The position of the auger relative to the chisel is important. The squealing may be due to the shoulder of the auger rubbing on the chisel. A *tiny* bit of squeal may not be bad, it indicates that the two are aligned. An auger that's too low can wobble, one that's too high will quickly burn up the auger and the chisel.
2. It helps clean up the mortise to go up and down with the bit several times after the initial cut before withdrawing the bit.
3. Make the mortise 1/4" deeper than the tenon if possible, that way you won't have to clean out the corners.
Thanks again to all.
--
Vince Heuring To email, remove the Vince.

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snipped-for-privacy@dimensional.com wrote:

Does this have any effect on the strength of the joint?
-- Regards, Doug Miller (alphageek-at-milmac-dot-com)
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