I picked up a Dewalt 740 / 7740 RAS (the arm says 740, the base 7740). It
needs a new top, but I expected that.

I'm planning on using 3/4" MDF with a melamine coating. I haven't decided
whether to try a double-layer top right off, or go with just the one and
get some experience. I'm leaning towards the simple single-layer design,
then working on a more complex design after I get a feel for the saw. The
frame is 20" wide.

How far can I extend the top without adding more support? I think 6" on
either side would be ok, but would 10" work?

Puckdropper
--
Make it to fit, don't make it fit.

"Puckdropper" puckdropper(at)yahoo(dot)com wrote in message
b.com
I picked up a Dewalt 740 / 7740 RAS (the arm says 740, the base 7740).
It
needs a new top, but I expected that.

I'm planning on using 3/4" MDF with a melamine coating. I haven't
decided
whether to try a double-layer top right off, or go with just the one and
get some experience. I'm leaning towards the simple single-layer
design,
then working on a more complex design after I get a feel for the saw.
The
frame is 20" wide.

How far can I extend the top without adding more support? I think 6" on
either side would be ok, but would 10" work?

Sure, so would 20". So would 40". It doesn't much matter because
whatever you are cutting is going to be supported by the central portion
of the top and that is supported by the saw's frame.

If you have the room, the ideal (IMO) is side extensions that are about
10-12" wide and 96" long. The length is nice because RAS are basically
crosscutting machines and the length lets you put a stop anywhere along
it.

The table hanging out from the front of the saw doesn't need to be any
wider than what the saw can cut. However, if you plan to ever cut
anything wider by cutting, flipping over and cutting the rest, a table
hanging over more can be handy...you can mark the trace of the blade on it
and after you flip, line up the kerf with that trace.




--

dadiOH
____________________________

Winters getting colder? Tired of the rat race?
Taxes out of hand? Maybe just ready for a change?
Check it out... http://www.floridaloghouse.net

On 8/8/2014 1:59 AM, Puckdropper wrote:
I picked up a Dewalt 740 / 7740 RAS (the arm says 740, the base 7740). It
needs a new top, but I expected that.

I'm planning on using 3/4" MDF with a melamine coating. I haven't decided
whether to try a double-layer top right off, or go with just the one and
get some experience. I'm leaning towards the simple single-layer design,
then working on a more complex design after I get a feel for the saw. The
frame is 20" wide.

How far can I extend the top without adding more support? I think 6" on
either side would be ok, but would 10" work?

Puckdropper


Melamine is a tad slippery for my taste, I'd stick with plain MDF. Even
with a "try it out and see how it goes" top, I would add a sacrificial
layer on top - quarter inch plywood, hardboard or luan. "Temporary"
lash-ups tend to last longer than originally planned, and a new layer
can be essential to a clean cut, acting much like a zero clearance
insert on a table saw.

Lots of good tune up info available in the FAQ's he
http://people.delphiforums.com/snotz...awdust/faq.htm
Also lots of good knowledgeable people to answer questions in that forum.

"Larry Kraus" wrote

Melamine is a tad slippery for my taste, I'd stick with plain MDF. Even
with a "try it out and see how it goes" top, I would add a sacrificial
layer on top - quarter inch plywood, hardboard or luan. "Temporary"
lash-ups tend to last longer than originally planned, and a new layer can
be essential to a clean cut, acting much like a zero clearance insert on a
table saw.

Agreed, with the MDF as my first choice. I use two layers of 3/4" or 5/8"
MDF. The top layer is the sacrificial, screwed onto the saw from below and
through the bottom layer. The top layer can then be flipped over for a
fresh surface, and the bottom can also be cycled up to the top. You can get
2 - 2' x 8' strips out of one sheet, and 4 fresh surfaces for the saw top,
that way.
--
Jim in NC


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Larry Kraus wrote in
:

On 8/8/2014 1:59 AM, Puckdropper wrote:
I picked up a Dewalt 740 / 7740 RAS (the arm says 740, the base
7740). It needs a new top, but I expected that.

I'm planning on using 3/4" MDF with a melamine coating. I haven't
decided whether to try a double-layer top right off, or go with just
the one and get some experience. I'm leaning towards the simple
single-layer design, then working on a more complex design after I
get a feel for the saw. The frame is 20" wide.

How far can I extend the top without adding more support? I think 6"
on either side would be ok, but would 10" work?

Puckdropper


Melamine is a tad slippery for my taste, I'd stick with plain MDF.
Even with a "try it out and see how it goes" top, I would add a
sacrificial layer on top - quarter inch plywood, hardboard or luan.
"Temporary" lash-ups tend to last longer than originally planned, and
a new layer can be essential to a clean cut, acting much like a zero
clearance insert on a table saw.

I've got the Melamine, it's been waiting for a project. In this case, a
material I already have is better than a material I'd need to buy. We'll
see how that goes, though. I might have to make changes...

Good point about the temporary being rather permanent. I've been meaning
to do a couple projects for some time now, but have others that are
getting in the way.

Lots of good tune up info available in the FAQ's he
http://people.delphiforums.com/snotz...awdust/faq.htm
Also lots of good knowledgeable people to answer questions in that
forum.


I'm getting some good answers here. Looks like that forum requires
registration to even read, which makes it hard to get in to.

Puckdropper

--
Make it to fit, don't make it fit.

On 8/9/2014 12:18 AM, Puckdropper wrote:
snip

Lots of good tune up info available in the FAQ's he
http://people.delphiforums.com/snotz...awdust/faq.htm
Also lots of good knowledgeable people to answer questions in that
forum.


I'm getting some good answers here. Looks like that forum requires
registration to even read, which makes it hard to get in to.

Puckdropper

Well, it is a moderated forum. Upside is the S-N ratio is pretty good,
and I cannot blame my registration for any spam.