making cuts?

[dromos]

Tonight, I attempted to cut the pieces for my control panel.  While it didn't go that bad, it didn't go great either.  Most of the dimensions are about 1/4" - 1/2" off.  I'm finding that it is very difficult to make precise cuts using only a circular saw and a straight edge.

What do most of you use to make these kind of cuts?  Ideally what would you use?  Do any special tools exist to help align the blade along your pencil markings (my main problem)?

Thanks!

-- Justin

[rockhopper]

Are you clamping the straight edge to the wood you are cutting?

If so just make sure it is the correct distance from the cut line, ie measure this directly from the saw.

[TrickyFishy]

I make all my cuts with a circular saw and they are always right on.  I always put my pieces on a saw horse.  If I cut more than one piece at a time, I clamp them together.  I always clamp the pieces down onto the saw horse as well so nothing moves.

I clamp my straight edge at both ends as well.  As you can tell, I clamp everything!  Every cut requires at least 4 of them for me  

Other than that, make sure you use the short side of the blade offset.  For most saws I've used the offset is 1 1/2".  The other side is 3 1/2" but the motor usually sticks out that side and will hit the clamps as you make your cut.

[meta87]

Like everyone else said, as long as you use a straight edge clamped to the wood, I don't see how you can go wrong.

[Brax]

Using a straight edge and a circular saw you should be able to get within a 64th!!! Really, there's no reason you can't be that accurate. Measure more carefully the distance your blade needs to be away from your straight edge. Clamp down the straight edge and go to it! Measure twice, cut once. (By the sounds of your past experience....... Measure 4 times, cut once.  

[Tailgunner]

Look carefully at the front edge of your circular saw's base. Most of them have a notch that lines up with the blade. Use your measuring tape to mark where you want to cut on both edges of the panel. Then use your straightedge to draw a line connecting those marks. Then you want to measure from the edge of the sawbase on the side closest to the blade to the other side of the blade. (This allows for the blade's thickness) Now make marks that distance from your cutline, these are where you place the straightedge and clamp it down.

Remember that notch on the saw's base? When you place the saw against the straightedge, the notch should line up with your cutline on the panel. If it doesn't something's wrong so stop and recheck your measurements.

[u_rebelscum]

Other than that, make sure you use the short side of the blade offset.  For most saws I've used the offset is 1 1/2".  The other side is 3 1/2" but the motor usually sticks out that side and will hit the clamps as you make your cut.

The short side distance (on the 2 circle saws I used) varied depending on how thick the circle blade was.  I found out the hard way after switching the blade.

Here's how I get the exact distance.  (Change blade if you are going to, rare.)  Get spare piece of wood.  Clamp straight edge to it and cut a little way into the wood (with saw against straight edge of course), leaving the wood as one piece.  Stop cutting, let blade stop spinning, then remove saw from the wood.  Measure distance from straight edge to the notch you just cut.  
You can also find out how thick your circular saw blade cuts from this test cut; most blades are ~1/8, but they do vary.

[dromos]

Thanks for all your replies.  They were very helpful.

One thing I tried that I found to work very well for me personally, was a straight edge with a built in offset.  Basically, it's just a piece of 1/4" plywood with a 2x4 attached to it so that the saw blade just hangs off the edge.  You can orient the 2x4 so that whichever way you face the saw (using the short or long end of the saw casing) hangs off properly.

[AlanS17]

I used a jigsaw and I eyeballed it. That probably doesn't help much, though...