Circular saw -- bevel angle precision

[omark]

Hi,
This is about finer usage than cutting construction lumber to length so I hope the question belongs here


Recently I have bought circular saw, no previous experience with such tool.
I attempted to cut particleboard - 14in 'crosscuts'.
I was a little surprised when my cuts were off from 90deg bevels.
Manual states that bevel scale  is calibrated at the factory, but I measured and had to correct this a little.
After that bevels improved but still not 90deg ...

I think this comes from flexibility of the body against base - saw has (usual) only bevel lock at the front not two like track saws.
When I rest my hand on the saw it flexes a little. Also the base might be not flat but it is difficult to check without disconnecting it from the body.
Are my expectations too high?

I would expect this is normal, and circular saws are mostly for cutting construction lumber.
But I have seen some Youtube reviews of equipment like Kreg Accu-cut and it seems like regular circular saw
can be used to join two 8ft boards (e.g. nice review from 'Doresoom tool reviews' ).

Thanks in advance for your opinion.

[FS7]

They aren't precision tools. If you're talking about a Festool or Mafell track saw ($$$$$), then maybe. It's not an easy task.

For what it's worth, I have needed to use a track (or edge guide, rather) and a circular saw to joint long boards. It's not feasible to joint long boards by yourself, depending on the size, so I can't. I've done OK with the circular saw in this regard (cleaning up with a sander or a plane).

[barryvabeach]

They aren't precision tools. If you're talking about a Festool or Mafell track saw ($$$$$), then maybe. It's not an easy task.

+1 .   Most circular saws have quite a bit of flex in the base. If the board is 1 inch thick or less, you can use your edge guide with a circular saw to cut it slightly oversize, then come back with a router running against a straight edge to get a square cut.  The other option for long boards is a handplane.

[R Clark]

Higher quality circular saws will likely perform better, but still come up short in the precision department when it comes to the finer aspects of woodworking.

I use mine (mid-range Porter Cable) to break down sheet goods, but final cuts for joining work pieces are always done on the table saw.

A few ideas.

- You might see some improvement in base flex by fitting the saw with a zero clearance base (easily made and how-to found on YouTube).  You would have to fit that and then adjust the base to be perpendicular to the blade.

- You might also try a few cuts with a "light touch" on the saw.  By that, I mean control the saw with only the force necessary to keep it against a straight edge fence and downward pressure enough to keep it pointed in the right direction.  If you're muscling the saw, you might be causing deflection between the base and the saw body.

- Is the plane of the blade parallel to the edge of the saw's base?  If it's not, then you may be exerting a lot of force to keep the saw going straight.  The blade may be flexing and throwing the "squareness" out of whack.

- Blade factors should be considered.  Cheap blades may flex and affect cut quality.  Dull or dirty blades may heat up and distort slightly.  Use good quality carbide-tipped blades.    

If the issue is really a weak attachment point where the base connects to the saw body, and it can't be made more rigid, then I'm not optimistic that the saw will ever provide the performance you desire.

Good luck.