Riving Knives
 

I was just reading about Powermatics new table saw, the PM2000. One of
the new features highlighted was a riving knife, a feature that the
predicted would become mandatory in the next ten years. To me it looks
like a splitter only it is attached to the trunnion rather than the
fence. Is there something more to the difference or is the name change
just to differentiate the mounting location?

A riving knife is a common feature on European saws. Its main
attribute is that it rises and falls and tilts with the blade, allowing
you pretty much use it for almost all cuts. Its more complicated
mechanically and more expensive to manufacture. I looked into buying
parts from Europe to add a riving knife to my table saw. I finally gave
up. One of the barriers to making such a device standard in the USA is
working through the safety and legal barriers.

Bob

Woops. I meant blade guard, not fence.

Ken

"Lobby Dosser" wrote in message
news:73tVe.3700$XO6.3576@trnddc03...

It's actually pretty simple and inexpensive. I've got an Old (~8yrs) Ryobi
BT3000 that came with one and All the Ryobi BTXX saws have them.

The BT3000 implementation is an American *******ized implementation. Its
got those dreadful anit-kickback pawls and its taller than the blade. These
facets prevent using leaving the knife in place for a number of cuts,
including tenon cuts. Admittedly the BT3000 is ahead of its time in the US
marketplace in this particular area.

Bob

On Tue, 13 Sep 2005 05:01:55 GMT, Lobby Dosser
wrote:

wrote:

A riving knife is a common feature on European saws. Its main
attribute is that it rises and falls and tilts with the blade, allowing
you pretty much use it for almost all cuts. Its more complicated
mechanically and more expensive to manufacture. I looked into buying
parts from Europe to add a riving knife to my table saw. I finally gave
up. One of the barriers to making such a device standard in the USA is
working through the safety and legal barriers.

Bob



It's actually pretty simple and inexpensive. I've got an Old (~8yrs) Ryobi
BT3000 that came with one and All the Ryobi BTXX saws have them.

As do shopsmiths (Models 510 and 520 since the mid 1980s, not the old
no longer made model 500s).

Dave Hall
Dave Hall

"The power of accurate observation is commonly called cynicism by those who
have not got it." -- G.B. Shaw

"Ken" wrote in message
oups.com...
I was just reading about Powermatics new table saw, the PM2000. One of
the new features highlighted was a riving knife, a feature that the
predicted would become mandatory in the next ten years. To me it looks
like a splitter only it is attached to the trunnion rather than the
fence. Is there something more to the difference or is the name change
just to differentiate the mounting location?


Does anyone know of a source for riving knives that one could adapt for the
US made (or sold!) saws? I too am most interested in installing such a
beast but don't have the patience (read: time) to try to figure one out at
the moment.
Cheers,
cc

On 13/09/2005 11:38 AM, James "Cubby" Culbertson wrote:

Does anyone know of a source for riving knives that one could adapt for the
US made (or sold!) saws? I too am most interested in installing such a
beast but don't have the patience (read: time) to try to figure one out at
the moment.

You might also be interested in microjig splitters:

http://www.microjig.com/

Dave Hall wrote in
:

On Tue, 13 Sep 2005 05:01:55 GMT, Lobby Dosser
wrote:

wrote:

A riving knife is a common feature on European saws. Its main
attribute is that it rises and falls and tilts with the blade,
allowing you pretty much use it for almost all cuts. Its more
complicated mechanically and more expensive to manufacture. I
looked into buying parts from Europe to add a riving knife to my
table saw. I finally gave up. One of the barriers to making such a
device standard in the USA is working through the safety and legal
barriers.

Bob

It's actually pretty simple and inexpensive. I've got an Old (~8yrs)
Ryobi BT3000 that came with one and All the Ryobi BTXX saws have them.

As do shopsmiths (Models 510 and 520 since the mid 1980s, not the old
no longer made model 500s).

Dave Hall

I'm not certain how this applies, regarding the Shopsmith. The Shopsmith
uses a tilting _table_, rather than an arbor, and otherwise has a blade
guard just as clunky as any US-delivered Delta or Powermatic. The tilting
table arrangement makes for some high pucker factor mitered cross cuts, and
effectively precludes its use on anything longer than about 12".

Patriarch,
embarrassed owner of a Model 520, who learned better...

BillyBob wrote:


"Lobby Dosser" wrote in message
news:73tVe.3700$XO6.3576@trnddc03...

It's actually pretty simple and inexpensive. I've got an Old (~8yrs)
Ryobi BT3000 that came with one and All the Ryobi BTXX saws have them.

The BT3000 implementation is an American *******ized implementation. Its
got those dreadful anit-kickback pawls and its taller than the blade.
These facets prevent using leaving the knife in place for a number of
cuts,
including tenon cuts. Admittedly the BT3000 is ahead of its time in the
US marketplace in this particular area.

Bob
An inventor and user of the BT came out with a much better version. The
shark gaurd, the reason IT is taller, is due to it being the place to mount
the blade gaurd to. I've thought about getting his and modifying the
original as a more normal riving knife.

"James "Cubby" Culbertson" wrote in message
...

Does anyone know of a source for riving knives that one could adapt for
the
US made (or sold!) saws? I too am most interested in installing such a
beast but don't have the patience (read: time) to try to figure one out
at
the moment.

I'll be so bold as to say there are none. Adding one requires machining or
replacement of existing parts. Its not a simple bolt-on affair. A well
designed riving knife has mechanical linkages that keep its position and
distance from the blade constant, as the blade is raised and lowered. This
is a non-linear linkage, since the back edge of the blade-table intersection
shifts forward as the blade is lowered. Jet makes commercial parts to
support a Riving knife on some of their saws. I actually got the manual and
parts numbers through a contact in Ireland. But actually buying and getting
the parts is an impossible task. The european and american operations have
no relationship with each other. I gave up.

Bob

On Tue, 13 Sep 2005 11:00:22 -0500, Patriarch
wrote:

Dave Hall wrote in
:


It's actually pretty simple and inexpensive. I've got an Old (~8yrs)
Ryobi BT3000 that came with one and All the Ryobi BTXX saws have them.

As do shopsmiths (Models 510 and 520 since the mid 1980s, not the old
no longer made model 500s).

Dave Hall

I'm not certain how this applies, regarding the Shopsmith. The Shopsmith
uses a tilting _table_, rather than an arbor, and otherwise has a blade
guard just as clunky as any US-delivered Delta or Powermatic. The tilting
table arrangement makes for some high pucker factor mitered cross cuts, and
effectively precludes its use on anything longer than about 12".

Patriarch,
embarrassed owner of a Model 520, who learned better...

While I understand that you do not like your Shopsmith there are lots
of people who have made very nice furniture and other projects with
them. I can assure you that they often have to make mitered crosscuts
on boards longer than 12". My crosscut sled is wider than 12" and it
works quite well on mitered crosscuts. In fact I would not be
concerned in the least in making a 45 degree mitered crosscut on
boards 4 or 5 foot long. After that the physics do limit you since the
other end of the board might drag on the floor or hit the ceiling, so
I use either my compound miter saw or my RAS. Contrary to popular
belief, you can also make mitered rip cuts on long boards quite well
on a Shopsmith. In any case, the issue was riving knives - and
Shopsmiths have them. They stay the same distance from the blade no
matter the depth, they are in place for all miter cuts and they are
extremely easy to take off and reinstall as needed. If a tool as lowly
in some people's eyes as a Shopsmith can have a functioning riving
kinife, then why can't a $2,000 Powermatic? (Said with a wink since a
new Shopsmith costs more than $2,000).
Dave Hall

"The power of accurate observation is commonly called cynicism by those who
have not got it." -- G.B. Shaw

Dave Hall wrote:

If a tool as lowly
in some people's eyes as a Shopsmith can have a functioning riving
kinife, then why can't a $2,000 Powermatic? (Said with a wink since a
new Shopsmith costs more than $2,000).


Or even lower, the BTXX. I'm a real sucker for gadgets and the BT sliding
table reeled me in.

"BillyBob" wrote:


"James "Cubby" Culbertson" wrote in message
...

Does anyone know of a source for riving knives that one could adapt
for
the
US made (or sold!) saws? I too am most interested in installing
such a beast but don't have the patience (read: time) to try to
figure one out
at
the moment.

I'll be so bold as to say there are none. Adding one requires
machining or replacement of existing parts. Its not a simple bolt-on
affair. A well designed riving knife has mechanical linkages that
keep its position and distance from the blade constant, as the blade
is raised and lowered. This is a non-linear linkage, since the back
edge of the blade-table intersection shifts forward as the blade is
lowered. Jet makes commercial parts to support a Riving knife on some
of their saws. I actually got the manual and parts numbers through a
contact in Ireland. But actually buying and getting the parts is an
impossible task. The european and american operations have no
relationship with each other. I gave up.

Bob

Take a look at the BTXX mount. Two bolts and some shims to center the
knife on the blade. The distance between the knife and blade is fixed and
it moves up and down and tilts With the blade. No complexity.

Here's a link to the manual:
http://www.bt3central.com/articles/layoutpage.asp?ArticleId=65

"BillyBob" wrote in message
k.net...
I'll be so bold as to say there are none. Adding one requires machining or
replacement of existing parts. Its not a simple bolt-on affair. A well
designed riving knife has mechanical linkages that keep its position and
distance from the blade constant, as the blade is raised and lowered.
This
is a non-linear linkage, since the back edge of the blade-table
intersection
shifts forward as the blade is lowered. Jet makes commercial parts to
support a Riving knife on some of their saws. I actually got the manual
and
parts numbers through a contact in Ireland. But actually buying and
getting
the parts is an impossible task. The european and american operations have
no relationship with each other. I gave up.

Bob

Hmmm, I lived in Ireland for 3.5 years and my wife is from there. Might
have to look into this a bit. It actually might be easier for me to just
make my own in the long run. I've got a Griz. cabinet saw so not sure if
the Jet stuff is interchangeable.
Cheers,
cc

"Doug Payne" wrote in message
...

You might also be interested in microjig splitters:

http://www.microjig.com/

I've got one but haven't yet installed it. I figured I'd better get an
overhead guard build first but am looking forward to using it.
Cheers,
cc

"Lobby Dosser" wrote in message
news:9yGVe.3113$YI6.192@trnddc05...

Take a look at the BTXX mount. Two bolts and some shims to center the
knife on the blade. The distance between the knife and blade is fixed and
it moves up and down and tilts With the blade. No complexity.

With simpleness comes compromise in function. I described a riving knife
that does more. Its not so complex if its built from the factory to begin
with. But retrofitting requires disassembley of many things and replacement
of some major cast parts.

Bob

"James "Cubby" Culbertson" wrote in message
...

Hmmm, I lived in Ireland for 3.5 years and my wife is from there. Might
have to look into this a bit. It actually might be easier for me to just
make my own in the long run. I've got a Griz. cabinet saw so not sure if
the Jet stuff is interchangeable.

I lived there as well and would gladly use a parts hunting trip as an excuse
to get back there. I might not get the parts, but it would be fun anyway.

Bob

"BillyBob" wrote in message
ink.net...

I lived there as well and would gladly use a parts hunting trip as an
excuse
to get back there. I might not get the parts, but it would be fun anyway.

Bob



Yeah, fortunately, my wife has family there so we try to get back once a
year if possible. I lived in Dublin just shy of City Centre and loved
every minute of it. Great fun and close to just about anywhere in Europe.
I'd move back if I thought I could afford it but unfortunately, it's gotten
ridiculously expensive. I do miss the "true" pint of Guinness....this crap
they serve in the states just doesn't do justice to it.
Cheers,
cc

Dave Hall wrote in
:

On Tue, 13 Sep 2005 11:00:22 -0500, Patriarch
wrote:

Dave Hall wrote in
m:


It's actually pretty simple and inexpensive. I've got an Old (~8yrs)
Ryobi BT3000 that came with one and All the Ryobi BTXX saws have
them.

As do shopsmiths (Models 510 and 520 since the mid 1980s, not the
old no longer made model 500s).

Dave Hall

I'm not certain how this applies, regarding the Shopsmith. The
Shopsmith uses a tilting _table_, rather than an arbor, and otherwise
has a blade guard just as clunky as any US-delivered Delta or
Powermatic. The tilting table arrangement makes for some high pucker
factor mitered cross cuts, and effectively precludes its use on
anything longer than about 12".

Patriarch,
embarrassed owner of a Model 520, who learned better...

While I understand that you do not like your Shopsmith there are lots
of people who have made very nice furniture and other projects with
them. I can assure you that they often have to make mitered crosscuts
on boards longer than 12". My crosscut sled is wider than 12" and it
works quite well on mitered crosscuts. In fact I would not be
concerned in the least in making a 45 degree mitered crosscut on
boards 4 or 5 foot long. After that the physics do limit you since the
other end of the board might drag on the floor or hit the ceiling, so
I use either my compound miter saw or my RAS. Contrary to popular
belief, you can also make mitered rip cuts on long boards quite well
on a Shopsmith. In any case, the issue was riving knives - and
Shopsmiths have them. They stay the same distance from the blade no
matter the depth, they are in place for all miter cuts and they are
extremely easy to take off and reinstall as needed. If a tool as lowly
in some people's eyes as a Shopsmith can have a functioning riving
kinife, then why can't a $2,000 Powermatic? (Said with a wink since a
new Shopsmith costs more than $2,000).
Dave Hall

"The power of accurate observation is commonly called cynicism by
those who have not got it." -- G.B. Shaw

Not to drift TOO far off topic, but...

Maybe it's a user error. Tilt the table to 45 degrees, down on the
right. Can't go left, because the motor unit's there. At some, fairly
quick length limitation, you run into the tubes and/or right table
support. Move everything to the end, like one would on a bowl lathe?
On that undersized table? Clamping everything to a sled, so it doesn't
slide off? Get me a freakin' hand saw & a good plane!

Again, a riving knife on a tilting TABLE is a piece of cake. It's the
tilting TABLE that is an obsolete, questionable design.

What really ****ed me off about the Shopsmith really was that I got
taken in by the hype, and bought at a home show. I paid way more than
Unisaw money, and should have just walked away. The 'only works on
Shopsmith' accessories were a rude surprise, too. Every needed add-on
piece required another mail order, with a 10 day delay, and an expensive
charge.

Yes, folks can really do nice work on a Shopsmith. I did, too,
actually. But it was WAY more work than it needed to be, with a lot
more scrap. The Shopsmith sits in storage, replaced by real tools. One
of my sons wants it, when he gets out of his apartment space limits.

There. Sorry. That feels better. I'm going to the shop now.

Patriarch

On Wed, 14 Sep 2005 10:22:58 -0500, Patriarch
wrote:


While I understand that you do not like your Shopsmith there are lots
of people who have made very nice furniture and other projects with
them. I can assure you that they often have to make mitered crosscuts
on boards longer than 12". My crosscut sled is wider than 12" and it
works quite well on mitered crosscuts. In fact I would not be
concerned in the least in making a 45 degree mitered crosscut on
boards 4 or 5 foot long. After that the physics do limit you since the
other end of the board might drag on the floor or hit the ceiling, so
I use either my compound miter saw or my RAS. Contrary to popular
belief, you can also make mitered rip cuts on long boards quite well
on a Shopsmith. In any case, the issue was riving knives - and
Shopsmiths have them. They stay the same distance from the blade no
matter the depth, they are in place for all miter cuts and they are
extremely easy to take off and reinstall as needed. If a tool as lowly
in some people's eyes as a Shopsmith can have a functioning riving
kinife, then why can't a $2,000 Powermatic? (Said with a wink since a
new Shopsmith costs more than $2,000).
Dave Hall

"The power of accurate observation is commonly called cynicism by
those who have not got it." -- G.B. Shaw

Not to drift TOO far off topic, but...

Maybe it's a user error. Tilt the table to 45 degrees, down on the
right. Can't go left, because the motor unit's there. At some, fairly
quick length limitation, you run into the tubes and/or right table
support. Move everything to the end, like one would on a bowl lathe?
On that undersized table? Clamping everything to a sled, so it doesn't
slide off? Get me a freakin' hand saw & a good plane!

Guess I didn't say it didn't take a moment or two to set up, a little
planning and some fine grit sandpaper on the fence of your sled to
keep things from sliding. BTW you can go left because you can extend
the quill to get the table far enough away from the headstock to clear
it. I don't know if you can get the full 45 degrees though.

Again, a riving knife on a tilting TABLE is a piece of cake. It's the
tilting TABLE that is an obsolete, questionable design.

No argument that if you were buying a saw that a tilting table would
be a poor design. If you bought a Shopsmith, however, you were not
buying a saw, you were buying a multi-purpose tool. As with any such
beast some design compromises are requied for each purpose in order to
allow for the other purposes. There is just no way to produce a
machine that does those specific 5 functions without a tilting table.
I agree that if a person has the room for all stand alone tools and
the desire to dedicate that space to woodworking tools then a
Shopsmith is clearly not their best choice.

What really ****ed me off about the Shopsmith really was that I got
taken in by the hype, and bought at a home show. I paid way more than
Unisaw money, and should have just walked away. The 'only works on
Shopsmith' accessories were a rude surprise, too. Every needed add-on
piece required another mail order, with a 10 day delay, and an expensive
charge.

I can understand that! Too many things need Shopsmith specific stuff,
and they do seem quite proud of their stuff given the price. Actually
that would be expected for a niche product with a small market and
small volumes.


Yes, folks can really do nice work on a Shopsmith. I did, too,
actually. But it was WAY more work than it needed to be, with a lot
more scrap. The Shopsmith sits in storage, replaced by real tools. One
of my sons wants it, when he gets out of his apartment space limits.

There. Sorry. That feels better. I'm going to the shop now.

Patriarch


;-)
Dave Hall

"The power of accurate observation is commonly called cynicism by those who
have not got it." -- G.B. Shaw

BillyBob wrote:
"Lobby Dosser" wrote in message
news:9yGVe.3113$YI6.192@trnddc05...

Take a look at the BTXX mount. Two bolts and some shims to center the
knife on the blade. The distance between the knife and blade is fixed and
it moves up and down and tilts With the blade. No complexity.

With simpleness comes compromise in function. I described a riving knife
that does more. Its not so complex if its built from the factory to begin
with. But retrofitting requires disassembley of many things and replacement
of some major cast parts.

Bob


no compromise with that mechanism. arbor travel is linear in that saw,
rather than pivot. it works fine.

the problems with it are from the castings being aluminum, rather than
from configuration.