you could go to a place with a panel saw loke HD or something. If you brought your own piece of wood in, find out when the manager is on shift, arrange to run into him, which might take a while, and ask him to fill out a cut service charge only, maybe buy a $1.01 piece of cull to put on the bill. With that cut, which can be done geometrically and metrologically pretty darn good, you're either finished, or you could put it back on the TS. You could put an inch, or whatever against the fence and keep the outbound side as your finished cut. Or you could clamp something, screw, glue, nail, whatever to get a staright edge, or just wing it, and then cut the other side to match if possible. You could even do the rough cut with a jig saw if you have a good straight piece attached for a guide for your final finish cut. For that matter, just as long as there is a succession of max clearance points along the chalk line at a period (much) less than the lenght of the fence, your ok theoretically.
It makes the cutting a little difficult, you don't want it to bind. The important thing to remember is you have to make sure all of the forward momentum you imopart into the cutting is pointing parallel to the blade/fence, and when you get close to the cut-through area at the end of cutting, you can't use the outbound side of the blade to push any longer, because you'll be pushing sideways at the same time, and bind into the blade. You need to keep your hand between the fence and the blade while pushing forward, and make sure the outbound piece follows straight forward. This applies to all cutting. I learned the hard way.
Having an adjustable height roller stand is a good thing to have, placed somewhat centered to the cut, and rolling parallel to the cut. and also additional support table that you can clamp to the sides of the saw any time, extending support throughout the rear with a piece of plywood, or whatever handy. you just need to test the setup each time you're on different ground. And with the rollers always lower the blade under the table, and roll the piece over the roller to the final cutted-through position, and micro-adjust the angle of the roller so it rides without help, parallel. I use a level, straightedge, and a fairly flat 5' chrome steel pipe I garbage picked. You can clamp a wood rest to the side of the saw, and screw into it for a temp extension table. Its all in appropriate stable re-set-up capability.
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stands are sold with a single row of balls rather than a single roller. Roller stands like this can act as both a table and roller. Looking for one to link. These are the balls.
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