On Tuesday, January 27, 2015 at 7:04:59 PM UTC-8, DerbyDad03 wrote:
I tried my hand at stub tenon joints tonight and ran into an issue.

(curved-bottom cut causes nonparallel tenons)

A wobble-type dado will cut a flat bottom of the width at which it was
sharpened; you can set it to the flattest-bottom cut, then use a
sacrificial fence to reveal the cutters to your tenon depth.

For a short stub, you could just use two or more cheapo blades (with washers
to adjust for the tooth set) instead of a complete dado set. I've bought
multiple on-sale blades for this purpose, but never got around to trying
it. Hey, if they were all sharpened in the same batch, the diameters WILL
match, just like a good dado set! This won't work well for wide
cuts, though, it takes extra motor power.

On Wednesday, January 28, 2015 at 7:16:37 AM UTC-8, dadiOH wrote:
"DerbyDad03" wrote in message



I took the shot from
above to show the shoulders left by the wobble dado.

In another reply, you said you were going to reduce the width of the dado.
Good idea. If you had it set to way beyond the 1/4" you need, reducing it
to a hair over 1/4" will markedly reduce the curve.

This may be misguided; wobble-dado blades are sharpened at the factory in
a manner that will be a bad match for either extreme (wide or narrow)
of the width setting. There IS likely a setting at which the wobble-blade cuts
a flat bottom.

For my (Sears Craftsman 720.3261) blade, the instruction sheet indicates
that width is 3/4" (0.750 inches).

DJ Delorie wrote in :


My dad's advice - either buy the least expensive tool you can, or the
best quality tool you can.

Wish my dad had had that advice. He was consistant - always
bought the least expensive tool. I threw them all out after
he passed on (actually, saved a set of screwdrivers and a
hammer, just in case my Mom ever needs to hang a picture or
tighten a loose knob).

John

On 1/29/2015 5:05 PM, whit3rd wrote:
On Wednesday, January 28, 2015 at 7:16:37 AM UTC-8, dadiOH wrote:
"DerbyDad03" wrote in message



I took the shot from
above to show the shoulders left by the wobble dado.

In another reply, you said you were going to reduce the width of the dado.
Good idea. If you had it set to way beyond the 1/4" you need, reducing it
to a hair over 1/4" will markedly reduce the curve.

This may be misguided; wobble-dado blades are sharpened at the factory in
a manner that will be a bad match for either extreme (wide or narrow)
of the width setting. There IS likely a setting at which the wobble-blade cuts
a flat bottom.


It will be less pronounced but it will NOT be a flat bottom dado.

The only time a wobble blade will cut a flat bottom is if the kerf is,
let's say, 1/8" and you have it set for a 1/8" dado. In other words NO
WOBBLE and the blade tip remains perfectly perpendicular to the workpiece.

Just think about the path that wobbling blade takes for a minute or so
and visualize it sweeping back and forth like a pendulum.

Wobblies are handy for removing large amounts of wood quickly and for
dadoes where it doesn't matter if the bottom is curved, as in door panel
inserts or drawer bottoms.

"Leon" wrote in message
...

On 1/29/2015 12:53 PM, DJ Delorie wrote:

My dad's advice - either buy the least expensive tool you can . . .


My dad's philosophy, common I've always thought among many who grew
up in during the depression. Always suspected that had my folks won a $100
million lottery, Dad would have gone to his grave with $99,990,000 unspent.
And, he would have begrudged my mother for foolishly spending the other
$10k.
I'll always buy the best tool/toy I can afford but, alas, it's more
often than not like pulling teeth.

Dave in SoTex

On 1/29/2015 5:05 PM, whit3rd wrote:
On Wednesday, January 28, 2015 at 7:16:37 AM UTC-8, dadiOH wrote:
"DerbyDad03" wrote in message



I took the shot from
above to show the shoulders left by the wobble dado.

In another reply, you said you were going to reduce the width of the dado.
Good idea. If you had it set to way beyond the 1/4" you need, reducing it
to a hair over 1/4" will markedly reduce the curve.

This may be misguided; wobble-dado blades are sharpened at the factory in
a manner that will be a bad match for either extreme (wide or narrow)
of the width setting. There IS likely a setting at which the wobble-blade cuts
a flat bottom.

For my (Sears Craftsman 720.3261) blade, the instruction sheet indicates
that width is 3/4" (0.750 inches).


Regardless of how a wobble blade is sharpened at the factory or where
ever, if it wobbles/cuts wider than the width of the teeth on the blade,
it will not produce a flat bottom.

The only setting that the wobble blade will create a flat bottom is when
it is adjusted to not wobble at all.


Actually, the wider the cut the more extreme the cup in the bottom of
the cut.

Sears/Craftaman power tools say a lot of things to sell their product.
Remember the 6.5 hp shop vacs?

On Friday, January 30, 2015 at 1:43:01 PM UTC-8, Leon wrote:
On 1/29/2015 5:05 PM, whit3rd wrote:
On Wednesday, January 28, 2015 at 7:16:37 AM UTC-8, dadiOH wrote:
"DerbyDad03" wrote in message



I took the shot from
above to show the shoulders left by the wobble dado.

In another reply, you said you were going to reduce the width of the dado.
Good idea. If you had it set to way beyond the 1/4" you need, reducing it
to a hair over 1/4" will markedly reduce the curve.

This may be misguided; wobble-dado blades are sharpened at the factory in
a manner that will be a bad match for either extreme (wide or narrow)
of the width setting. There IS likely a setting at which the wobble-blade cuts
a flat bottom.

For my (Sears Craftsman 720.3261) blade, the instruction sheet indicates
that width is 3/4" (0.750 inches).


Regardless of how a wobble blade is sharpened at the factory or where
ever, if it wobbles/cuts wider than the width of the teeth on the blade,
it will not produce a flat bottom.

Not true. The sharpening of a wobble blade is NOT RIGHT ANGLE at
all the tooth faces. That analysis holds only for straight-blade sharpened
blades used with wobble washers, not for wobble-dado assemblies.
Standard blades are sharpened in the zero-wobble-angle state, of course.

The only setting that the wobble blade will create a flat bottom is when
it is adjusted to not wobble at all.

That depends on the manufacturer's wobble-setting when the blade was
put into the tooth-grinder. For my blade, flat cuts occur at 3/4".

Think of it this way: to cut a flat bottom dado with a 24T blade tilted at 10 degrees,
the leftmost edge has to be cut by tooth #1 whose crest is 80 degrees to the
left sawblade face, and 100 degrees to the right blade face. The rightmost
edge has to be cut by tooth #13 whose crest is 100 degrees from the left
face, 80 degrees to the right blade face. And the middle of the cut
is made by tooth #6 which is 90/90 degrees, regular square-cut, but
at a slightly smaller distance from the axis of the blade rotation.
Dado blade teeth for wobble-dado assemblies are sharpened exactly
as required to make a flat-bottom cut, but ONLY AT ONE SETTING.

On 1/30/2015 5:40 PM, whit3rd wrote:
On Friday, January 30, 2015 at 1:43:01 PM UTC-8, Leon wrote:
On 1/29/2015 5:05 PM, whit3rd wrote:
On Wednesday, January 28, 2015 at 7:16:37 AM UTC-8, dadiOH wrote:
"DerbyDad03" wrote in message



I took the shot from
above to show the shoulders left by the wobble dado.

In another reply, you said you were going to reduce the width of the dado.
Good idea. If you had it set to way beyond the 1/4" you need, reducing it
to a hair over 1/4" will markedly reduce the curve.

This may be misguided; wobble-dado blades are sharpened at the factory in
a manner that will be a bad match for either extreme (wide or narrow)
of the width setting. There IS likely a setting at which the wobble-blade cuts
a flat bottom.

For my (Sears Craftsman 720.3261) blade, the instruction sheet indicates
that width is 3/4" (0.750 inches).


Regardless of how a wobble blade is sharpened at the factory or where
ever, if it wobbles/cuts wider than the width of the teeth on the blade,
it will not produce a flat bottom.

Not true. The sharpening of a wobble blade is NOT RIGHT ANGLE at
all the tooth faces. That analysis holds only for straight-blade sharpened
blades used with wobble washers, not for wobble-dado assemblies.
Standard blades are sharpened in the zero-wobble-angle state, of course.

The only setting that the wobble blade will create a flat bottom is when
it is adjusted to not wobble at all.

That depends on the manufacturer's wobble-setting when the blade was
put into the tooth-grinder. For my blade, flat cuts occur at 3/4".

Think of it this way: to cut a flat bottom dado with a 24T blade tilted at 10 degrees,
the leftmost edge has to be cut by tooth #1 whose crest is 80 degrees to the
left sawblade face, and 100 degrees to the right blade face. The rightmost
edge has to be cut by tooth #13 whose crest is 100 degrees from the left
face, 80 degrees to the right blade face. And the middle of the cut
is made by tooth #6 which is 90/90 degrees, regular square-cut, but
at a slightly smaller distance from the axis of the blade rotation.
Dado blade teeth for wobble-dado assemblies are sharpened exactly
as required to make a flat-bottom cut, but ONLY AT ONE SETTING.

OK then...........
I think you have read some hocus pocus info promoting wobble blades.

But to be clear, I am not talking about a smooth bottom, I am talking
about a bottom that is the same measurement in the middle of the cut as
the outer edges of the cut.

In order for a wobble blade to not cut a round bottom, when adjusted to
wobble, the blade would have to elongate where the outer cutting teeth
come in contact with the outside of the cut and shorten where they come
in contact with the center of the cut. The wider the blade setting, the
longer the part of the blade with the teeth cutting the outer sections
of the dado will have to be. If the wobble blade was manufactured to be
non adjustable it could be made to cut a flat bottom but it would not be
perfectly round. The outer teeth would be farther from the center of
the blade than the teeth in the center of the cut.

Think of a ladder standing straight up in the air. It stands 10' up in
the air. Now lean the ladder over 12", how high up in the air is it
now. This is how a wobble blade works the farther away the teeth are
from dead center the shallower they cut. Those teeth that are still
located near the center of the blade will cut deeper.

On 1/31/2015 9:49 AM, Leon wrote:
On 1/30/2015 5:40 PM, whit3rd wrote:
On Friday, January 30, 2015 at 1:43:01 PM UTC-8, Leon wrote:
On 1/29/2015 5:05 PM, whit3rd wrote:
On Wednesday, January 28, 2015 at 7:16:37 AM UTC-8, dadiOH wrote:
"DerbyDad03" wrote in message



I took the shot from
above to show the shoulders left by the wobble dado.

In another reply, you said you were going to reduce the width of
the dado.
Good idea. If you had it set to way beyond the 1/4" you need,
reducing it
to a hair over 1/4" will markedly reduce the curve.

This may be misguided; wobble-dado blades are sharpened at the
factory in
a manner that will be a bad match for either extreme (wide or narrow)
of the width setting. There IS likely a setting at which the
wobble-blade cuts
a flat bottom.

For my (Sears Craftsman 720.3261) blade, the instruction sheet
indicates
that width is 3/4" (0.750 inches).


Regardless of how a wobble blade is sharpened at the factory or where
ever, if it wobbles/cuts wider than the width of the teeth on the blade,
it will not produce a flat bottom.

Not true. The sharpening of a wobble blade is NOT RIGHT ANGLE at
all the tooth faces. That analysis holds only for straight-blade
sharpened
blades used with wobble washers, not for wobble-dado assemblies.
Standard blades are sharpened in the zero-wobble-angle state, of course.

The only setting that the wobble blade will create a flat bottom is when
it is adjusted to not wobble at all.

That depends on the manufacturer's wobble-setting when the blade was
put into the tooth-grinder. For my blade, flat cuts occur at 3/4".

Think of it this way: to cut a flat bottom dado with a 24T blade
tilted at 10 degrees,
the leftmost edge has to be cut by tooth #1 whose crest is 80 degrees
to the
left sawblade face, and 100 degrees to the right blade face. The
rightmost
edge has to be cut by tooth #13 whose crest is 100 degrees from the left
face, 80 degrees to the right blade face. And the middle of the cut
is made by tooth #6 which is 90/90 degrees, regular square-cut, but
at a slightly smaller distance from the axis of the blade rotation.
Dado blade teeth for wobble-dado assemblies are sharpened exactly
as required to make a flat-bottom cut, but ONLY AT ONE SETTING.

OK then...........
I think you have read some hocus pocus info promoting wobble blades.

But to be clear, I am not talking about a smooth bottom, I am talking
about a bottom that is the same measurement in the middle of the cut as
the outer edges of the cut.

In order for a wobble blade to not cut a round bottom, when adjusted to
wobble, the blade would have to elongate where the outer cutting teeth
come in contact with the outside of the cut and shorten where they come
in contact with the center of the cut. The wider the blade setting, the
longer the part of the blade with the teeth cutting the outer sections
of the dado will have to be. If the wobble blade was manufactured to be
non adjustable it could be made to cut a flat bottom but it would not be
perfectly round. The outer teeth would be farther from the center of
the blade than the teeth in the center of the cut.

Think of a ladder standing straight up in the air. It stands 10' up in
the air. Now lean the ladder over 12", how high up in the air is it
now. This is how a wobble blade works the farther away the teeth are
from dead center the shallower they cut. Those teeth that are still
located near the center of the blade will cut deeper.


OK, I'll step back and retract the hocus pocus comment. ;~)
I can see how a wobble blade can produce a flat bottom but only at one
particular width setting. It does in one way as I indicated have
properties that the cutting surface of the outer teeth are farther from
the center of the blade as those that are closer to the center.

But with that in mind, is a blade that only cuts one width well worth
having? While a 3/4" setting seems like a common size to cut, in the
real world it only works well for cutting dado's to receive 4/4 S4S
lumber and possibly MDF but not for receiving the common 3/4" piece of
plywood.

On 1/31/15 10:24 AM, Leon wrote:
On 1/31/2015 9:49 AM, Leon wrote:
OK then........... I think you have read some hocus pocus info
promoting wobble blades.

But to be clear, I am not talking about a smooth bottom, I am
talking about a bottom that is the same measurement in the middle
of the cut as the outer edges of the cut.

In order for a wobble blade to not cut a round bottom, when
adjusted to wobble, the blade would have to elongate where the
outer cutting teeth come in contact with the outside of the cut
and shorten where they come in contact with the center of the cut.
The wider the blade setting, the longer the part of the blade with
the teeth cutting the outer sections of the dado will have to be.
If the wobble blade was manufactured to be non adjustable it could
be made to cut a flat bottom but it would not be perfectly round.
The outer teeth would be farther from the center of the blade than
the teeth in the center of the cut.

Think of a ladder standing straight up in the air. It stands 10'
up in the air. Now lean the ladder over 12", how high up in the
air is it now. This is how a wobble blade works the farther away
the teeth are from dead center the shallower they cut. Those teeth
that are still located near the center of the blade will cut
deeper.


OK, I'll step back and retract the hocus pocus comment. ;~) I can
see how a wobble blade can produce a flat bottom but only at one
particular width setting. It does in one way as I indicated have
properties that the cutting surface of the outer teeth are farther
from the center of the blade as those that are closer to the center.

But with that in mind, is a blade that only cuts one width well worth
having? While a 3/4" setting seems like a common size to cut, in
the real world it only works well for cutting dado's to receive 4/4
S4S lumber and possibly MDF but not for receiving the common 3/4"
piece of plywood.



Bottom line is: no one who has ever gone from a wobbler to stacked dado
blades ever even thought of going back.

Heck even when I had a wobbler, I switched to a regular rip blade on my
table saw to cut cove molding because if left me with less sanding to do.


--

-MIKE-

"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com

---remove "DOT" ^^^^ to reply

On Saturday, January 31, 2015 at 7:49:31 AM UTC-8, Leon wrote:
On 1/30/2015 5:40 PM, whit3rd wrote:
On Friday, January 30, 2015 at 1:43:01 PM UTC-8, Leon wrote:
[about wobble-blade adjustable dados]
There IS likely a setting at which the wobble-blade cuts
a flat bottom.

For my (Sears Craftsman 720.3261) blade, the instruction sheet indicates
that width is 3/4" (0.750 inches).

The only setting that the wobble blade will create a flat bottom is when
it is adjusted to not wobble at all.

That depends on the manufacturer's wobble-setting when the blade was
put into the tooth-grinder. For my blade, flat cuts occur at 3/4".

OK then...........
I think you have read some hocus pocus info promoting wobble blades.

But to be clear, I am not talking about a smooth bottom, I am talking
about a bottom that is the same measurement in the middle of the cut as
the outer edges of the cut.

Precisely: I've read the instruction sheet that came with my own blade; I find
no copy online, but this article has the basic info, too (see Figure 1d especially)

http://www.woodworkingseminars.com/wp-content/DadoBlades.pdf

On Saturday, January 31, 2015 at 8:24:48 AM UTC-8, Leon wrote:

...is a blade that only cuts one width well worth
having? While a 3/4" setting seems like a common size to cut, in the
real world it only works well for cutting dado's to receive 4/4 S4S
lumber and possibly MDF but not for receiving the common 3/4" piece of
plywood.

My dadoes are usually rough straight from the saw, and sandpaper and a knife
or chisel always come out for step #2. I don't mind doing some
cleanup by hand.

The original poster was making tongues (tenons); a fixed setting would
work for him.

My stacked dado set is steel, the wobbler is carbide; maybe I'll use the
wobbler again someday.

But, I have stacked dado blades, and would usually use those instead.

On 1/31/2015 10:24 AM, Leon wrote:
OK, I'll step back and retract the hocus pocus comment. ;~)
I can see how a wobble blade can produce a flat bottom but only at one
particular width setting.

'Bout damned time! LOL

--
eWoodShop: www.eWoodShop.com
Wood Shop: www.e-WoodShop.net
https://www.google.com/+eWoodShop
https://plus.google.com/+KarlCaillouet/posts
http://www.custommade.com/by/ewoodshop/
KarlCaillouet@ (the obvious)

On 1/31/2015 10:24 AM, Leon wrote:
On 1/31/2015 9:49 AM, Leon wrote:
On 1/30/2015 5:40 PM, whit3rd wrote:
On Friday, January 30, 2015 at 1:43:01 PM UTC-8, Leon wrote:
On 1/29/2015 5:05 PM, whit3rd wrote:
On Wednesday, January 28, 2015 at 7:16:37 AM UTC-8, dadiOH wrote:
"DerbyDad03" wrote in message



I took the shot from
above to show the shoulders left by the wobble dado.

In another reply, you said you were going to reduce the width of
the dado.
Good idea. If you had it set to way beyond the 1/4" you need,
reducing it
to a hair over 1/4" will markedly reduce the curve.

This may be misguided; wobble-dado blades are sharpened at the
factory in
a manner that will be a bad match for either extreme (wide or narrow)
of the width setting. There IS likely a setting at which the
wobble-blade cuts
a flat bottom.

For my (Sears Craftsman 720.3261) blade, the instruction sheet
indicates
that width is 3/4" (0.750 inches).


Regardless of how a wobble blade is sharpened at the factory or where
ever, if it wobbles/cuts wider than the width of the teeth on the
blade,
it will not produce a flat bottom.

Not true. The sharpening of a wobble blade is NOT RIGHT ANGLE at
all the tooth faces. That analysis holds only for straight-blade
sharpened
blades used with wobble washers, not for wobble-dado assemblies.
Standard blades are sharpened in the zero-wobble-angle state, of course.

The only setting that the wobble blade will create a flat bottom is
when
it is adjusted to not wobble at all.

That depends on the manufacturer's wobble-setting when the blade was
put into the tooth-grinder. For my blade, flat cuts occur at 3/4".

Think of it this way: to cut a flat bottom dado with a 24T blade
tilted at 10 degrees,
the leftmost edge has to be cut by tooth #1 whose crest is 80 degrees
to the
left sawblade face, and 100 degrees to the right blade face. The
rightmost
edge has to be cut by tooth #13 whose crest is 100 degrees from the left
face, 80 degrees to the right blade face. And the middle of the cut
is made by tooth #6 which is 90/90 degrees, regular square-cut, but
at a slightly smaller distance from the axis of the blade rotation.
Dado blade teeth for wobble-dado assemblies are sharpened exactly
as required to make a flat-bottom cut, but ONLY AT ONE SETTING.

OK then...........
I think you have read some hocus pocus info promoting wobble blades.

But to be clear, I am not talking about a smooth bottom, I am talking
about a bottom that is the same measurement in the middle of the cut as
the outer edges of the cut.

In order for a wobble blade to not cut a round bottom, when adjusted to
wobble, the blade would have to elongate where the outer cutting teeth
come in contact with the outside of the cut and shorten where they come
in contact with the center of the cut. The wider the blade setting, the
longer the part of the blade with the teeth cutting the outer sections
of the dado will have to be. If the wobble blade was manufactured to be
non adjustable it could be made to cut a flat bottom but it would not be
perfectly round. The outer teeth would be farther from the center of
the blade than the teeth in the center of the cut.

Think of a ladder standing straight up in the air. It stands 10' up in
the air. Now lean the ladder over 12", how high up in the air is it
now. This is how a wobble blade works the farther away the teeth are
from dead center the shallower they cut. Those teeth that are still
located near the center of the blade will cut deeper.


OK, I'll step back and retract the hocus pocus comment. ;~)
I can see how a wobble blade can produce a flat bottom but only at one
particular width setting. It does in one way as I indicated have
properties that the cutting surface of the outer teeth are farther from
the center of the blade as those that are closer to the center.

But with that in mind, is a blade that only cuts one width well worth
having? While a 3/4" setting seems like a common size to cut, in the
real world it only works well for cutting dado's to receive 4/4 S4S
lumber and possibly MDF but not for receiving the common 3/4" piece of
plywood.


That is why I got a stack up blade set - in metric. Plywood is mostly
if not all metric. The stack up does imperial as well. My very old
wobble is in the case - for the job just made for it.

Martin