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Default Can laminated hardboard be used to make zero clearance throatplates for a table saw?

On 8/10/10 11:10 AM, Kevin wrote:
On Sun, 08 Aug 2010 08:47:58 -0500,
wrote:

If you are needing downward pressure on a jig or stock, enough to bend a
1/2" MDF ZCI, there is either something very wrong with your saw or you
are doing something very wrong.


Okay I dare you or anyone else that's said I'm doing something unsafe
to cut a piece of 1/2" MDF that is 14" long and 2.5" wide (The width
of my insert on the right side of the blade), support it at the ends
and then try to flex it with ONE FINGER.

Then try the same thing with 1/2" Baltic Birch ply. You can use your
whole hand this time.

Then come back here and tell me I'm doing something wrong by using the
one that doesn't flex.



-Kevin


I didn't say you were doing anything wrong by using the one that didn't
flex, but nice attempt at trying to change the subject without anyone
noticing. :-p

What we're saying is that any operation (and specifically your tenoning
technique) which causes you to push the stock downward to the table and
subsequently, the blade, is not only bad woodworking technique, but very
dangerous technique.



--

-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

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Default Can laminated hardboard be used to make zero clearance throat plates for a table saw?

On Mon, 9 Aug 2010 01:13:24 +0000 (UTC),
(Larry W) wrote:

In article ,
Morgans wrote:

"Kevin" wrote

I didn't notice the flex until using my tenoning jig that rides the
fence. I don't bother clamping the stock in place as it takes too
much time when you have a lot of parts to cut, so you have to put some
significant force to keep it from riding up during the cut. But I
wasn't getting consistent cutting depths and that's when I tested out
pushing down on the insert and could see the sucker flex.


I put it to you like this; if you continue to improperly use a jig (as far
as I am concernened, not making use of a clamp constitutes improper use)
then almost any material is going to have some flex. Reinforce the insert
with a rib alongside the blade. Either that or get a metal insert made with
a sacrificial wood edge added by the blade.

I would urge you to reconsider using the clamp on a tenioning jig. Take the
time to be safe and accurate. One day, that will bite you.


It may not be clear that unlike a cast iron type jig that rides in the
slot that just has a face and a clamp, my jig has a stop at the back
edge so it's being held against two faces. My hand is way above the
cut. I consider it to be as safe as a cut with my cross cut sled.

--
Jim in NC



To the OP: Check your saw setup as previous posters have advised for
fence being parallel. And, consider modifying or making a new
tenoning jig with a base long enough so that the fore & aft ends are
always resting on the cast iron table, not on the insert.


It's not an alignment issue, the stock rises up before reaching the
back teeth. The jig doesn't flex the insert, the stock does. I work
with narrow stock, sometimes it might only be 3/4" wide. That makes
any downward pressure into essentially a point load. It also means
there isn't a lot of friction between the stock and the jig due to the
low surface area, and of course it doesn't weigh very much either, so
I have to supply the force. I use the same jig with a 45 degree block
added for miter splines, and I'd never had it rise up in that
circumstance, I don't know if that's just due to the extra weight and
friction or the different grain direction.

-Kevin





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Default Can laminated hardboard be used to make zero clearance throat plates for a table saw?

On Sat, 07 Aug 2010 21:44:38 -0500, "
wrote:

You really found that 1/2" flexed too much? How wide is your throat - or
how long? I can't imagine a throat that is so big that 1/2" would flex....
but I'be been wrong before... once...


I think it's about 15". Probably about a foot span from the support
ledges. Doesn't take much to flex 1/2" MDF over that and as far as
I'm concerned when it comes to the TS that insert ought not to budge
if I put any reasonable force on it, because when the sh*t hits the
fan why throw one more variable into the equation?


15" wide throat? That's the size of the table on most saws! What sort of saw
do you have?


It's 14", ends are semi-circular. It's a Ridgid contractor saw,
nothing special.


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Default Can laminated hardboard be used to make zero clearance throat plates for a table saw?

On Tue, 10 Aug 2010 11:17:46 -0500, -MIKE-
wrote:

On 8/10/10 11:10 AM, Kevin wrote:
On Sun, 08 Aug 2010 08:47:58 -0500,
wrote:

If you are needing downward pressure on a jig or stock, enough to bend a
1/2" MDF ZCI, there is either something very wrong with your saw or you
are doing something very wrong.


Okay I dare you or anyone else that's said I'm doing something unsafe
to cut a piece of 1/2" MDF that is 14" long and 2.5" wide (The width
of my insert on the right side of the blade), support it at the ends
and then try to flex it with ONE FINGER.

Then try the same thing with 1/2" Baltic Birch ply. You can use your
whole hand this time.

Then come back here and tell me I'm doing something wrong by using the
one that doesn't flex.



-Kevin


I didn't say you were doing anything wrong by using the one that didn't
flex, but nice attempt at trying to change the subject without anyone
noticing. :-p


I'm staying focused on the original point, that 1/2" MDF is a little
flimsy for this application, rather than the example I used where it
became evident to me that was the case. You may find yourself in a
different situation where it comes into play. How much do you save
using MDF instead of baltic birch ply? 10 cents? The OEM insert is
steel and they ribbed the hell out of it. They could have made it out
of plastic and saved some money, and you know that'd make the
accountants happy. But they didn't. For some reason they thought it
was important that it be very rigid and I've never seen a saw that
came with one that wasn't.

What we're saying is that any operation (and specifically your tenoning
technique) which causes you to push the stock downward to the table and
subsequently, the blade, is not only bad woodworking technique, but very
dangerous technique.


I happen to have shot some video of a project and I have me in action
using the jig. So here is a still frame of the horrible accident
waiting to happen. Please cover the eyes of any small children or
shop dogs so they don't have to live with the shock.

http://www.krtwood.com/tenonjig.jpg

Does it look like I'm pushing down hard? Cause I'm not. But if that
had been an MDF insert the cut depths would have been inconsistent.

Some amount of down pressure is a normal part of most operations at
the table saw, you just don't think about it. Don't try running some
1/8" plywood through the saw without pushing down on it. It'll bounce
like crazy and then almost certainly kick back. Whatever force you
apply is NOTHING compared to the force the blade can generate into the
table. It's just common sense to make the insert as rigid as you can
practically make it. MDF is a poor choice.

-Kevin
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Default Can laminated hardboard be used to make zero clearance throat plates for a table saw?

On Tue, 10 Aug 2010 12:47:07 -0400, Kevin wrote:

On Sat, 07 Aug 2010 21:44:38 -0500, "
wrote:

You really found that 1/2" flexed too much? How wide is your throat - or
how long? I can't imagine a throat that is so big that 1/2" would flex....
but I'be been wrong before... once...

I think it's about 15". Probably about a foot span from the support
ledges. Doesn't take much to flex 1/2" MDF over that and as far as
I'm concerned when it comes to the TS that insert ought not to budge
if I put any reasonable force on it, because when the sh*t hits the
fan why throw one more variable into the equation?


15" wide throat? That's the size of the table on most saws! What sort of saw
do you have?


It's 14", ends are semi-circular. It's a Ridgid contractor saw,
nothing special.


14" front to back? ...or side to side? What's the smallest dimension?


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Default Can laminated hardboard be used to make zero clearance throat plates for a table saw?

On Tue, 10 Aug 2010 18:01:13 -0500, "
wrote:

On Tue, 10 Aug 2010 12:47:07 -0400, Kevin wrote:

On Sat, 07 Aug 2010 21:44:38 -0500, "
wrote:

You really found that 1/2" flexed too much? How wide is your throat - or
how long? I can't imagine a throat that is so big that 1/2" would flex....
but I'be been wrong before... once...

I think it's about 15". Probably about a foot span from the support
ledges. Doesn't take much to flex 1/2" MDF over that and as far as
I'm concerned when it comes to the TS that insert ought not to budge
if I put any reasonable force on it, because when the sh*t hits the
fan why throw one more variable into the equation?

15" wide throat? That's the size of the table on most saws! What sort of saw
do you have?


It's 14", ends are semi-circular. It's a Ridgid contractor saw,
nothing special.


14" front to back? ...or side to side? What's the smallest dimension?


Front to back. Side to side is more like 4" but there are no supports
on the sides, only at the front and back.

-Kevin
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Default Can laminated hardboard be used to make zero clearance throatplates for a table saw?

Kevin wrote:
On Tue, 10 Aug 2010 18:01:13 -0500, "
wrote:

14" front to back? ...or side to side? What's the smallest dimension?



Front to back. Side to side is more like 4" but there are no supports
on the sides, only at the front and back.

-Kevin


If it the typical Ridgid table saw insert the supports are on the sides
about 3" from the front and the back leaving about 8.5" between the
leveling screws.

--
Jack Novak
Buffalo, NY - USA

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Default Can laminated hardboard be used to make zero clearance throat plates for a table saw?

On Tue, 10 Aug 2010 20:23:54 -0400, Kevin wrote:

On Tue, 10 Aug 2010 18:01:13 -0500, "
wrote:

On Tue, 10 Aug 2010 12:47:07 -0400, Kevin wrote:

On Sat, 07 Aug 2010 21:44:38 -0500, "
wrote:

You really found that 1/2" flexed too much? How wide is your throat - or
how long? I can't imagine a throat that is so big that 1/2" would flex....
but I'be been wrong before... once...

I think it's about 15". Probably about a foot span from the support
ledges. Doesn't take much to flex 1/2" MDF over that and as far as
I'm concerned when it comes to the TS that insert ought not to budge
if I put any reasonable force on it, because when the sh*t hits the
fan why throw one more variable into the equation?

15" wide throat? That's the size of the table on most saws! What sort of saw
do you have?

It's 14", ends are semi-circular. It's a Ridgid contractor saw,
nothing special.


14" front to back? ...or side to side? What's the smallest dimension?


Front to back. Side to side is more like 4" but there are no supports
on the sides, only at the front and back.


Ah, this is making a lot more sense now. When you were asked how _wide_ the
throat was and replied 15" it threw me off completely. I was imagining a
man-hole sized plate. ;-) Thanks.
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Default Can laminated hardboard be used to make zero clearance throatplates for a table saw?

Kevin wrote:

I happen to have shot some video of a project and I have me in action
using the jig. So here is a still frame of the horrible accident
waiting to happen. Please cover the eyes of any small children or
shop dogs so they don't have to live with the shock.

http://www.krtwood.com/tenonjig.jpg


Looks fine to me. You might consider gluing some sandpaper to your jig
so your work won't easily slide. Also, either a toggle clamp or those
handy spring clamps will be fast and effective.

--
Jack
Got Change: Global Warming ====== Global Fraud!
http://jbstein.com

Does it look like I'm pushing down hard? Cause I'm not. But if that
had been an MDF insert the cut depths would have been inconsistent.


Some amount of down pressure is a normal part of most operations at
the table saw, you just don't think about it. Don't try running some
1/8" plywood through the saw without pushing down on it. It'll bounce
like crazy and then almost certainly kick back. Whatever force you
apply is NOTHING compared to the force the blade can generate into the
table. It's just common sense to make the insert as rigid as you can
practically make it. MDF is a poor choice.

-Kevin

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