DIY Saw table for timber sheets
Those who use hand-held power saws (both circular and jigsaws) know how difficult it is to achieve straight accurate cuts, and the amount of work and time it takes to trim and plane such cuts.  After being increasingly frustrated with the inefficiencies of such processes, I decided it was time to look at a table saw.

Common amongst Australian DIYers, and professionals for onsite work, is the
Triton Workcentre.  This versatile unit features quite a number of add-on options for various operations, however is not really suited to continually working with 4' x 8' sheets of plywood.  I also looked at a few other more upmarket dedicated table saws and they had similar limitations, as well as being expensive..

A saw type which is at home with large sheets is the vertical panel saw.  However, whilst good at large cuts from large sheets, they are not suitable for small angular work, and tend to be rather pricey.

Whilst researching saw types, I came across the
Versatool Workcenter.  This ingenious saw is targeted at a similar group to the Triton (and has the same size limitations), but the layout and tooling options intrigued me.  Unfortunately, it seems to be no longer in production (have no idea why - appeared to be a brilliant unit).  The overhead layout with the tool head running on rails is similar to a panel saw in a horizontal format, and I thought a combination of these two types would be the ideal saw for my application.
The Australian Triton Workcentre
An example of a vertical Panel Saw
The Versatool Workcentre
After failing to locate something that would suit my needs, I decided (in true DIY fashion) that it shouldn't be too difficult to build a saw table based on the above units.  This project sort of just evolved, with no formal plans being drawn up.  I started with my existing circular saw (a 184mm Roybi), and built around that, starting with a rotatable mounting plate in a frame.  I investigated various methods of providing running rails for the frame and, upon looking around at local hardware stores, settled on heavy duty sliding door roller tracks.  However, these would still bow and twist with the large span required, and were reinforced with 1/4" steel angle.

For a support base, I pressed into service an old frame from a Sharp SD2060 photocopier I had stripped.  This 1" square RHS steel frame is quite sturdy and was fitted with casters.  I made a bed frame from 1" RHS and topped it with two layers of MDF.  The top layer of MDF was actually smaller separate sheets with the bottom edges routed, forming "T" slots across the table.  To reduce the size for storage, extensions would be used when dealing with full sheets.
At left is the completed table with its overhead runners and sliding tool frame.  Thumb wheels either side of the frame lock it into any position alond the rails when ripping.  The large steel angles at the closest end is the fence.  Various steel work stored underneath the table are the extension parts.  Also visible at the bottom of the frame are the overcentre levers for operating the feet.  Also shown at the closest end are two vertical protrusions - these support a spring tube for holding the power tool cable out of harms way.
A handle linked to a piece of threaded rod operates the rail height adjusting mechanism.  The view on the left shows the rails at the lowest position, and at right, the highest position.  This allows the saw to be set to any thickness timber.  The saw can also be lowered into the work piece to cut out rectangular sections.  The highest position allows some timber to be clamped vertically under the saw for radical angle cuts.
A view of the table with the extensions attached.  These increase the rip fence to some 3.5m long.  The braces ensure that the extension fence is square when attached.  The work support pieces across each end have wheels which run in angles along the fence, providing a smooth and easy feed when ripping.  The extensions are fitted using wing nuts and bolts (will get around to putting hand wheels on the bolts one day) and only takes a few minutes to set up.
Closer view of the tool frame.  The thumb screws on top secure the tool plate, and the locking thumbwheels can be seen on the sides.

The central cutout section in the bed allows the saw blade clearance in any position.  The cover piece just under the cutout keeps sawdust out of the height winder thread.
The circular saw attached to its plate in the frame.  Clamp plates allow the saw to be set up square in its plate.  The left photo shows the saw mounted across the rails and thumwheels tightened for ripping, whilst the right photo shows it mounted for crosscutting.  Note the cable tie to keep the saw's switch on.
The overall size of the table can be judged here - this is a 4' x 8' sheet of ply about to be crosscut.
For versatility, the table can accept other tools by swapping the tool plate.  Shown at left is the router plate, supporting my 1/4" Ryobi trimmer, routing a battery compartment into the back of a guitar body.  A drill stand can be mounted as shown at right, which is handy to drill a line of perpendicular holes.
This shows the purpose of the "T" slots in the bed - adjustable clamps can hold virtually any workpiece in any position on the bed.  The clamps were modelled on the Versatool clamps.
From start to finish, this project took me about 3 weeks to make, but that time was saved on its first job - making 8 of the 12" midrange cabinets.