RS

Roy Smith

23/04/2006 5:24 PM

Attaching extension to cast iron table saw top?

I've got a Unisaw that I want to attach an extension table to the rear of.
There's two holes (approx 3/8" diameter) already drilled in the rear flange
of the cast iron top (it came from the factory that way), but they're not
tapped; just through-drilled. They're a little too small for clearance of
a 3/8" bolt; it would be nice if they were whatever the tap drill diameter
for a 3/8 UNC is supposed to be, but I haven't measured them exactly, so
I'm not sure.

I suspect the easiest way to attach something would be to tap those two
holes and bolt on a piece aluminum angle, to which my plywood table would
get attached. How difficult will it be to tap these holes? I've tapped
holes before, but never in cast iron. Does it go easy? Is there any risk
that I'll damage the top? What if I end up having to drill some additional
holes in the flange?


This topic has 16 replies

bb

"bent"

in reply to Roy Smith on 23/04/2006 5:24 PM

23/04/2006 11:02 PM

in order:
5/16-18 NC is F (.2570"/6.528mm)
8-1.25mm is H (.2660/6.756mm)
5/16-24 NF is I (.2720"/6.909mm)
8-1.00mm is J (.2770"/7.036mm)
5/16-32 NEF is 9/32" drill hole size
9-1.25mm is 5/16"
3/8-16 NC is 5/16"
9-1.00mm is O (.3160"/8.026mm)
9-0.75mm is 21/64"
3/8-24 NF is Q (.3320"/8.433mm)
10-1.50mm is R (.3390"/8.611mm)
10-1.25mm is S (.3480"/8.839mm)
10-1.00mm is 23/64"

from kbctools.com catalogue, not double checked/verified. Letter equiv's
from Machinery's Handbook. If you want to know if, consult it. If you need
to know how to make the tool to make the tool, consult it.

If you screw up you can use a heli-coil, etc.



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Td

"Teamcasa"

in reply to Roy Smith on 23/04/2006 5:24 PM

24/04/2006 3:06 PM


"Roy Smith" <[email protected]> wrote in message
news:[email protected]...
> I've got a Unisaw that I want to attach an extension table to the rear of.
> There's two holes (approx 3/8" diameter) already drilled in the rear
> flange
> of the cast iron top (it came from the factory that way), but they're not
> tapped; just through-drilled. They're a little too small for clearance of
> a 3/8" bolt; it would be nice if they were whatever the tap drill diameter
> for a 3/8 UNC is supposed to be, but I haven't measured them exactly, so
> I'm not sure.
>
> I suspect the easiest way to attach something would be to tap those two
> holes and bolt on a piece aluminum angle, to which my plywood table would
> get attached. How difficult will it be to tap these holes? I've tapped
> holes before, but never in cast iron. Does it go easy? Is there any risk
> that I'll damage the top? What if I end up having to drill some
> additional
> holes in the flange?

Maybe I'm not understanding this question very well. You want to attach an
extension to the BACK of your Unisaw? For use as an outfeed? If you do,
the miter slots will be useless, unless you have a way to cut them through.
Either way, drilling and tapping holes in cast iron is easy and explained in
other replies.

Dave

Td

"Teamcasa"

in reply to Roy Smith on 23/04/2006 5:24 PM

25/04/2006 9:02 AM


"Roy Smith" <[email protected]> wrote in message
news:[email protected]...
> "Teamcasa" <[email protected]> wrote:
>> Maybe I'm not understanding this question very well. You want to attach
>> an
>> extension to the BACK of your Unisaw? For use as an outfeed?
>
> Yes, exactly.
>
>> If you do,
>> the miter slots will be useless, unless you have a way to cut them
>> through.
>
> I figure I'd just cut two dados in the top to line up with the slots.
>
I'm sorry! I pictured you asking about adding a cast iron extension to the
back of your saw! I re-read the original post again and realized you did
not say what I thought it did.

Dave



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CF

Chris Friesen

in reply to Roy Smith on 23/04/2006 5:24 PM

24/04/2006 3:47 PM

Roy Smith wrote:
> I've got a Unisaw that I want to attach an extension table to the rear of.
> There's two holes (approx 3/8" diameter) already drilled in the rear flange
> of the cast iron top (it came from the factory that way), but they're not
> tapped; just through-drilled. They're a little too small for clearance of
> a 3/8" bolt;

Why not just use a 1/4" or 5/16" bolt with a nut on the back side?

Chris

c

in reply to Roy Smith on 23/04/2006 5:24 PM

24/04/2006 6:58 AM


>I suspect the easiest way to attach something would be to tap those two
>holes and bolt on a piece aluminum angle, to which my plywood table would
>get attached. How difficult will it be to tap these holes? I've tapped
>holes before, but never in cast iron. Does it go easy? Is there any risk
>that I'll damage the top? What if I end up having to drill some additional
>holes in the flange?


Cast iron is one of the easier metals to both drill and tap.

CT

Chuck Taylor

in reply to Roy Smith on 23/04/2006 5:24 PM

23/04/2006 5:34 PM

On Sun, 23 Apr 2006 17:24:21 -0400, Roy Smith <[email protected]> wrote:

>I've got a Unisaw that I want to attach an extension table to the rear of.
>There's two holes (approx 3/8" diameter) already drilled in the rear flange
>of the cast iron top (it came from the factory that way), but they're not
>tapped; just through-drilled. They're a little too small for clearance of
>a 3/8" bolt; it would be nice if they were whatever the tap drill diameter
>for a 3/8 UNC is supposed to be, but I haven't measured them exactly, so
>I'm not sure.


Mine (a 1987 model) is tapped to accept an M10-1.0 bolt, which is what
was used to attach a Jet-Lock fence rail.


--
Chuck Taylor
http://home.hiwaay.net/~taylorc/contact/

PB

Pat Barber

in reply to Roy Smith on 23/04/2006 5:24 PM

24/04/2006 7:05 PM

Those are designed "exactly" for that purpose. Those holes
match the Biesemeyer back rail, which an outfeed table can
be attached.

The Biesmeyer rail is attached with thru bolts and nuts.

Go here for detailed instructions on how to build the
outfeed and bolt sizes....

http://www.biesemeyer.com/print/comm_fence/Commercial%20%20Fence%20Manual.pdf

No drilling required......


Roy Smith wrote:

> I've got a Unisaw that I want to attach an extension table to the rear of.
> There's two holes (approx 3/8" diameter) already drilled in the rear flange
> of the cast iron top (it came from the factory that way), but they're not
> tapped; just through-drilled. They're a little too small for clearance of
> a 3/8" bolt; it would be nice if they were whatever the tap drill diameter
> for a 3/8 UNC is supposed to be, but I haven't measured them exactly, so
> I'm not sure.

Uu

"Upscale"

in reply to Roy Smith on 23/04/2006 5:24 PM

24/04/2006 9:29 AM

"Roy Smith" <[email protected]> wrote in message news:roy-
> > Cast iron is one of the easier metals to both drill and tap.
>
> Thanks, that's what I was hoping to hear.

Just make sure you go slow, with lots of oil and backing out frequently to
remove the waste. Cast iron likes to crack under the wrong conditions.

RS

"Rick S. Carusi"

in reply to Roy Smith on 23/04/2006 5:24 PM

23/04/2006 5:04 PM


"Roy Smith" <[email protected]> wrote in message
news:[email protected]...
> I've got a Unisaw that I want to attach an extension table to the rear of.
> There's two holes (approx 3/8" diameter) already drilled in the rear
> flange
> of the cast iron top (it came from the factory that way), but they're not
> tapped; just through-drilled. They're a little too small for clearance of
> a 3/8" bolt; it would be nice if they were whatever the tap drill diameter
> for a 3/8 UNC is supposed to be, but I haven't measured them exactly, so
> I'm not sure.

My guess you have the required tap. 3/8-16 tap drill is 5/16. If not, why
not use a bolt & nut that will pass? May need to go metric for a better fit
>
> I suspect the easiest way to attach something would be to tap those two
> holes and bolt on a piece aluminum angle, to which my plywood table would
> get attached. How difficult will it be to tap these holes? I've tapped
> holes before, but never in cast iron. Does it go easy? Is there any risk
> that I'll damage the top? What if I end up having to drill some
> additional
> holes in the flange?

FB

Frank Boettcher

in reply to Roy Smith on 23/04/2006 5:24 PM

24/04/2006 4:21 PM

On Sun, 23 Apr 2006 17:24:21 -0400, Roy Smith <[email protected]> wrote:

>I've got a Unisaw that I want to attach an extension table to the rear of.
>There's two holes (approx 3/8" diameter) already drilled in the rear flange
>of the cast iron top (it came from the factory that way), but they're not
>tapped; just through-drilled. They're a little too small for clearance of
>a 3/8" bolt; it would be nice if they were whatever the tap drill diameter
>for a 3/8 UNC is supposed to be, but I haven't measured them exactly, so
>I'm not sure.
>
>I suspect the easiest way to attach something would be to tap those two
>holes and bolt on a piece aluminum angle, to which my plywood table would
>get attached. How difficult will it be to tap these holes? I've tapped
>holes before, but never in cast iron. Does it go easy? Is there any risk
>that I'll damage the top? What if I end up having to drill some additional
>holes in the flange?


I don't know where you get your Unisaws, but where I get mine those
holes are tapped.

Frank

FB

Frank Boettcher

in reply to Roy Smith on 23/04/2006 5:24 PM

24/04/2006 5:21 PM

On Mon, 24 Apr 2006 08:46:38 -0400, Roy Smith <[email protected]> wrote:

>In article <[email protected]>, [email protected] wrote:
>
>> >I suspect the easiest way to attach something would be to tap those two
>> >holes and bolt on a piece aluminum angle, to which my plywood table would
>> >get attached. How difficult will it be to tap these holes? I've tapped
>> >holes before, but never in cast iron. Does it go easy? Is there any risk
>> >that I'll damage the top? What if I end up having to drill some additional
>> >holes in the flange?
>>
>>
>> Cast iron is one of the easier metals to both drill and tap.
>
>Thanks, that's what I was hoping to hear.


Check them again!! there tapped. 3/8" - 24. If they are not tapped
and you have a recent Unisaw, call your dealer and make him replace
the table.

Frank

Ww

WoodWizzard

in reply to Roy Smith on 23/04/2006 5:24 PM

24/04/2006 9:43 AM

On Sun, 23 Apr 2006 15:24:21 -0600, Roy Smith <[email protected]> wrote:

> I've got a Unisaw that I want to attach an extension table to the rear
> of.
> There's two holes (approx 3/8" diameter) already drilled in the rear
> flange
> of the cast iron top (it came from the factory that way), but they're not
> tapped; just through-drilled. They're a little too small for clearance
> of
> a 3/8" bolt; it would be nice if they were whatever the tap drill
> diameter
> for a 3/8 UNC is supposed to be, but I haven't measured them exactly, so
> I'm not sure.
>
> I suspect the easiest way to attach something would be to tap those two
> holes and bolt on a piece aluminum angle, to which my plywood table would
> get attached. How difficult will it be to tap these holes? I've tapped
> holes before, but never in cast iron. Does it go easy? Is there any
> risk
> that I'll damage the top? What if I end up having to drill some
> additional
> holes in the flange?

Cast iron taps fairly easy, but it clogs the tap, so back it out to clear
the chips, then tap anouther 1/4 - 1/2 turn or so.
DAGS comes up with this site for drill sizes:
http://www.newmantools.com/tapdrill.htm





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Using Opera's revolutionary e-mail client: http://www.opera.com/mail/

RS

Roy Smith

in reply to Roy Smith on 23/04/2006 5:24 PM

23/04/2006 6:22 PM

In article <[email protected]>,
"Rick S. Carusi" <[email protected]> wrote:

> My guess you have the required tap. 3/8-16 tap drill is 5/16. If not, why
> not use a bolt & nut that will pass?

Because it's danged near impossible to get to the back side of the flange
to hold a nut in place. The sheet metal cabinet is in the way. I tried
reaching in from the throat opening, but I'm not enough of a contortionist
to get my arm where it needs to go.

RS

Roy Smith

in reply to Roy Smith on 23/04/2006 5:24 PM

24/04/2006 9:57 PM

"Teamcasa" <[email protected]> wrote:
> Maybe I'm not understanding this question very well. You want to attach an
> extension to the BACK of your Unisaw? For use as an outfeed?

Yes, exactly.

> If you do,
> the miter slots will be useless, unless you have a way to cut them through.

I figure I'd just cut two dados in the top to line up with the slots.

RS

Roy Smith

in reply to Roy Smith on 23/04/2006 5:24 PM

24/04/2006 8:46 AM

In article <[email protected]>, [email protected] wrote:

> >I suspect the easiest way to attach something would be to tap those two
> >holes and bolt on a piece aluminum angle, to which my plywood table would
> >get attached. How difficult will it be to tap these holes? I've tapped
> >holes before, but never in cast iron. Does it go easy? Is there any risk
> >that I'll damage the top? What if I end up having to drill some additional
> >holes in the flange?
>
>
> Cast iron is one of the easier metals to both drill and tap.

Thanks, that's what I was hoping to hear.

Cs

"CW"

in reply to Roy Smith on 23/04/2006 5:24 PM

24/04/2006 3:47 AM

Cast iron drills, taps and machines great. When tapping, back out often. It
does tend to clog.

"Roy Smith" <[email protected]> wrote in message
news:[email protected]...
> I've got a Unisaw that I want to attach an extension table to the rear of.
> There's two holes (approx 3/8" diameter) already drilled in the rear
flange
> of the cast iron top (it came from the factory that way), but they're not
> tapped; just through-drilled. They're a little too small for clearance of
> a 3/8" bolt; it would be nice if they were whatever the tap drill diameter
> for a 3/8 UNC is supposed to be, but I haven't measured them exactly, so
> I'm not sure.
>
> I suspect the easiest way to attach something would be to tap those two
> holes and bolt on a piece aluminum angle, to which my plywood table would
> get attached. How difficult will it be to tap these holes? I've tapped
> holes before, but never in cast iron. Does it go easy? Is there any risk
> that I'll damage the top? What if I end up having to drill some
additional
> holes in the flange?


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