Folks --

I was planning on making some utility storage towers out here, and
the question cam out - how much kerf is enough?

The towers are 6 foot tall 3/4 plywood, each "chamber" about 18
inches square. The sections that divide it up were to be set into
some dado cuts in the sides and back ( about half of 3/4 in ). glue
and some wood screws were to hold the assembly together. The unit is
not destined for high mass items. More like a general sort box for
light to medium goods as the battle of entropy in my household moves
to different rooms. Some bracing may be in the picture for the
shelves.

Once I finished this plan in sketchup, the reviewed it for
reasonableness ( habit from software engineering ). The question that
came up was -- how deep do you need to make a dado slot so it works as
support?

Thanks for your replies!

--d

------------------------------------------------------------------------------------
Yes -- I am installing the google kill file system from penney dot
org.

On Sat, 19 Apr 2008 08:04:25 -0700 (PDT), Dan
wrote:


Once I finished this plan in sketchup, the reviewed it for
reasonableness ( habit from software engineering ). The question that
came up was -- how deep do you need to make a dado slot so it works as
support?

In 3/4" ply, I usually go 3/8" deep.

---------------------------------------------
** http://www.bburke.com/woodworking.html **
---------------------------------------------

dado dado

Daylight come and me wanna go
Day me say day me say day Me say day me say dado
Daylight come and me wanna gohome
work all night and a drink a rum
(daylight come and me wanna go home)
Stack banana till the mornin come
(daylight come and me wanna go home)
Come mister tally man tally me bananas
(daylight come and me wanna go home)
come mister tally man tally me bananas
(daylight come and me wanna go home)
lift six foot seven foot eight foot bunch!
(daylight come and me wanna go home)
six foot seven foot eight foot bunch!
(daylight come and me wanna go home)
day me say dado
(daylight come and me wanna go home)
Day me say day me say day me say dado(daylight come and me wanna go
home)
A beauitful bunch of ripe banana!
(daylight come and me wanna go home)
hide the deadly black tarantula!
(daylight come and me wanna go home)
lift six foot seven foot eight foot bunch!
(daylight come and me wanna go home)
six foot seven foot eight foot bunch!
(daylight come and me wanna go home)
Day me say dado
(daylight come and me wanna go home)
Day me say day me say day me say dado(daylight come and me wanna go
home)
come mister tally man tally me banana
(daylight come and me wanna go home)
come mister tally man tally me banana
(daylight come and me wanna go home)
dado dado(daylight come and me wanna go home)
day me say day me say day me say dado
(daylight come and me wanna go home)

.....one of those days...

On Sat, 19 Apr 2008 08:22:00 -0700 (PDT), Robatoy
wrote:

You've got a really sick mind, Robo..
I wanna be you if I grow up!

dado dado

Daylight come and me wanna go
Day me say day me say day Me say day me say dado
Daylight come and me wanna gohome
work all night and a drink a rum
(daylight come and me wanna go home)
Stack banana till the mornin come
(daylight come and me wanna go home)
Come mister tally man tally me bananas
(daylight come and me wanna go home)
come mister tally man tally me bananas
(daylight come and me wanna go home)
lift six foot seven foot eight foot bunch!
(daylight come and me wanna go home)
six foot seven foot eight foot bunch!
(daylight come and me wanna go home)
day me say dado
(daylight come and me wanna go home)
Day me say day me say day me say dado(daylight come and me wanna go
home)
A beauitful bunch of ripe banana!
(daylight come and me wanna go home)
hide the deadly black tarantula!
(daylight come and me wanna go home)
lift six foot seven foot eight foot bunch!
(daylight come and me wanna go home)
six foot seven foot eight foot bunch!
(daylight come and me wanna go home)
Day me say dado
(daylight come and me wanna go home)
Day me say day me say day me say dado(daylight come and me wanna go
home)
come mister tally man tally me banana
(daylight come and me wanna go home)
come mister tally man tally me banana
(daylight come and me wanna go home)
dado dado(daylight come and me wanna go home)
day me say day me say day me say dado
(daylight come and me wanna go home)

....one of those days...


mac

Please remove [dot]splinters before emailing

On Apr 19, 11:32*am, mac davis wrote:
On Sat, 19 Apr 2008 08:22:00 -0700 (PDT), Robatoy
wrote:

You've got a really sick mind, Robo..
I wanna be you if I grow up!

I kinda screwed myself with that one, the damn song is stuck in my
head.
Is it in yours?
If it is, then:
http://i123.photobucket.com/albums/o...flol_seal1.jpg

"Robatoy" wrote

dado dado

Things a little slow up there in the frozen north?

Max

On Apr 19, 12:13*pm, "Max" wrote:
"Robatoy" *wrote

dado dado

Things a little slow up there in the frozen north?

Max


LOL

I wish.
Angela's 41st birfday,
prepping a shipment for Toronto
for Monday's installation,
main guy wanted a day off
up to me arse in work.

On Apr 19, 12:13*pm, "Max" wrote:
"Robatoy" *wrote

dado dado

Things a little slow up there in the frozen north?

Max

80 F here today.

On Sat, 19 Apr 2008 08:48:07 -0700 (PDT), Robatoy
wrote:

On Apr 19, 11:32*am, mac davis wrote:
On Sat, 19 Apr 2008 08:22:00 -0700 (PDT), Robatoy
wrote:

You've got a really sick mind, Robo..
I wanna be you if I grow up!

I kinda screwed myself with that one, the damn song is stuck in my
head.
Is it in yours?
If it is, then:
http://i123.photobucket.com/albums/o...flol_seal1.jpg

Nope... it was but I fixed it!

We do karaoke, and sometimes I couldn't sleep that night because a song was
running in my head..
She taught me a cool trick.. The song runs like that until you FINISH it..
Just sing or think the song until the end and it really does go away.. kind of
like you've reached the end of a tape and it stops spooling..


mac

Please remove [dot]splinters before emailing

"Robatoy" wrote in message
...
dado dado

Daylight come and me wanna go

BETTLEJUICE!

BETTLEJUICE!

BETTLEJUICE!

SHOWTIME!

Dave in [Floresville] Texas

"Dan" wrote in message
reasonableness ( habit from software engineering ). The question that
came up was -- how deep do you need to make a dado slot so it works as
support?

I've always used 1/3 of total thickness as my benchmark for a dado. So with
3/4" plywood, I'd dado 1/4" for shelving. The only thing that would make
that depth insufficient is if the shelves sagged enough for it to pull out
of the dado.

Save yourself a little grief.

Don't start doing a full width dado that is a pain in
the wazoo to ever get correct.

Use a smaller rabbet joint.

Cut the dado with a "known" width.. like 1/2"
using a dado stack or a router bit.

I like 3/8" deep but a 1/4" will do nicely.

Now just trim your rabbet slowly until you get a
perfect fit.

Practice this a couple of times and you will
not attempt to get a "odd size" piece of plywood
fit a perfect cut 3/4" dado.



Dan wrote:

Folks --

I was planning on making some utility storage towers out here, and
the question cam out - how much kerf is enough?

Pat Barber wrote:
....
Use a smaller rabbet joint.

Cut the dado with a "known" width..
Now just trim your rabbet slowly until you get a
perfect fit.
....

And if the shelving is ply rather than solid material as I gather it is,
put the rabbet on the bottom so the weight of the stuff on the shelf
doesn't tend to cause split-out or delamination.

For light duty applications, aethestically more pleasing to do other way
as it's a cleaner-looking joint if the shelf disappears into the dado,
but a shop storage unit may carry a pretty good load and durability
trumps in that case...

imo, etc., ...

--

On Apr 19, 11:04 am, Dan wrote:
Folks --

I was planning on making some utility storage towers out here, and
the question cam out - how much kerf is enough?

The towers are 6 foot tall 3/4 plywood, each "chamber" about 18
inches square. The sections that divide it up were to be set into
some dado cuts in the sides and back ( about half of 3/4 in ). glue
and some wood screws were to hold the assembly together. The unit is
not destined for high mass items. More like a general sort box for
light to medium goods as the battle of entropy in my household moves
to different rooms. Some bracing may be in the picture for the
shelves.

Once I finished this plan in sketchup, the reviewed it for
reasonableness ( habit from software engineering ). The question that
came up was -- how deep do you need to make a dado slot so it works as
support?

Thanks for your replies!

--d

------------------------------------------------------------------------------------
Yes -- I am installing the google kill file system from penney dot
org.

The strongest overall joint will be with a dado no more than 1/4" deep
in 3/4" plywood. You want to leave plenty of thickness for the screw
body and to not weaken the sides. In solid wood the strongest joint
is even shallower, around 1/8", but you need to go at least 3/16" deep
in plywood because of the thin plies.

When I use this method, I put the rabbet on the top side of the shelf ..
... keeps the weight of the load from pulling the plies apart.



And if the shelving is ply rather than solid material as I gather it
is, put the rabbet on the bottom so the weight of the stuff on the
shelf doesn't tend to cause split-out or delamination.

For light duty applications, aethestically more pleasing to do other
way as it's a cleaner-looking joint if the shelf disappears into the
dado, but a shop storage unit may carry a pretty good load and
durability trumps in that case...

__ Bøb __ wrote:
When I use this method, I put the rabbet on the top side of the shelf ..
.. keeps the weight of the load from pulling the plies apart.


That's backwards -- the load in the center is pushing down on the lower
plies creating tension load at the bottom. Other way up, the center is
resting on the lower plies.

--

Doing it your way, a heavy load could separate the plies at the edges
where the rabbet ends. The sides of the rabbet are not supported ..
only the tongue .. this is where separation is most likely.

dpb wrote:
__ Bøb __ wrote:
When I use this method, I put the rabbet on the top side of the shelf
.. .. keeps the weight of the load from pulling the plies apart.


That's backwards -- the load in the center is pushing down on the
lower plies creating tension load at the bottom. Other way up, the
center is resting on the lower plies.

--

On Apr 19, 11:04 am, Dan wrote:
Folks --

I was planning on making some utility storage towers out here, and
the question cam out - how much kerf is enough?

The towers are 6 foot tall 3/4 plywood, each "chamber" about 18
inches square. The sections that divide it up were to be set into
some dado cuts in the sides and back ( about half of 3/4 in ). glue
and some wood screws were to hold the assembly together. The unit is
not destined for high mass items. More like a general sort box for
light to medium goods as the battle of entropy in my household moves
to different rooms. Some bracing may be in the picture for the
shelves.

Once I finished this plan in sketchup, the reviewed it for
reasonableness ( habit from software engineering ). The question that
came up was -- how deep do you need to make a dado slot so it works as
support?

Thanks for your replies!

--d

------------------------------------------------------------------------------------
Yes -- I am installing the google kill file system from penney dot
org.

1/4 to 1/3 thickness of the vertical board, or 1/4" max.

"Father Haskell" wrote:

1/4 to 1/3 thickness of the vertical board, or 1/4" max.

About the same as: "Any thing more than a mouthful is a waste".

Lew

__ Bøb __ wrote:
Doing it your way, a heavy load could separate the plies at the edges
where the rabbet ends. The sides of the rabbet are not supported ..
only the tongue .. this is where separation is most likely.

I think you're backwards, still -- when the rabbet is at the top, the
load causes a deflection downward which introduces tension on the end.

When the rabbet is on the bottom, the support is on the bottom and the
bending load is compressive.

Sorry I brought it up, I guess...

--


dpb wrote:
__ Bøb __ wrote:
When I use this method, I put the rabbet on the top side of the shelf
.. .. keeps the weight of the load from pulling the plies apart.


That's backwards -- the load in the center is pushing down on the
lower plies creating tension load at the bottom. Other way up, the
center is resting on the lower plies.

--

On Tue, 22 Apr 2008 07:39:47 GMT, "Lew Hodgett" wrote:


"Father Haskell" wrote:

1/4 to 1/3 thickness of the vertical board, or 1/4" max.

About the same as: "Any thing more than a mouthful is a waste".

Lew

or a handful..


mac

Please remove splinters before emailing

In article
dpb writes:
__ Bøb __ wrote:
Doing it your way, a heavy load could separate the plies at the edges
where the rabbet ends. The sides of the rabbet are not supported ..
only the tongue .. this is where separation is most likely.

I think you're backwards, still -- when the rabbet is at the top, the
load causes a deflection downward which introduces tension on the end.

When the rabbet is on the bottom, the support is on the bottom and the
bending load is compressive.

I was on your side until he explained it a second time and something
in my head clicked. If the rabbet is on the top, then the tongue
is on the bottom. I kept misreading "rabbet" as "tongue," or at
least misenvisioning it.

Full plys on the bottom, shortened plys on the top.


--
Drew Lawson | If dreams were thunder,
| and lightning was desire,
| This old house would have burnt down
http://www.furrfu.com/ | a long time ago

Drew Lawson wrote:
In article
dpb writes:
__ Bøb __ wrote:
Doing it your way, a heavy load could separate the plies at the edges
where the rabbet ends. The sides of the rabbet are not supported ..
only the tongue .. this is where separation is most likely.
I think you're backwards, still -- when the rabbet is at the top, the
load causes a deflection downward which introduces tension on the end.

When the rabbet is on the bottom, the support is on the bottom and the
bending load is compressive.

I was on your side until he explained it a second time and something
in my head clicked. If the rabbet is on the top, then the tongue
is on the bottom. I kept misreading "rabbet" as "tongue," or at
least misenvisioning it.

Full plys on the bottom, shortened plys on the top.

THAT's WHAT I've been saying, all along -- but writing to cross
porpoises, I guess. I was writing rabbet when I meant and was thinking
of the side dado, sorry.

--

dpb wrote:
....
THAT's WHAT I've been saying, all along ...

Well, more correctly that was what I was _intending_ to say...

--