circular saw using a guide, need help (solved)

  Ok I'm doing something stupid and I can't figure out what.  I have been cutting a lot of plywood lately with my circular saw.  I have a metal level that I have been clamping down as a guide.  I have also used a board to do the same thing.  For some reason after I get part way through the board the saw starts to stall.  When I pull the saw out I'm off my line and the cut is moving towards the guide.  It's like the saw is going straight but after a while the blade is moving towards the guide.  Any ideas what I'm doing wrong? I'm using a Ryobi  5-1/2 18V saw.

Now that I'm typing this I'm wondering if the piece I'm cutting off is pushing on the blade and pushing it off track. 

Thank you for any help

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mats-notes (author) 4 years ago
Ok I think I figured out the issue. I looked over my saw and noticed a few things. The blade is getting old and after I thought about it I think it's about 7 years old. I'm not a daily user but it doesn't cut like it use to. I looked at my base and it's at 0 which should set the base to a 90 degree angle to the blade. I put my speed square up to the blade and it was off just by a little bit. It was angled towards the left which is the side I usually put my guide on. I tightened down the base and I'm just about 1/8" away from 0. Most of the time it was to small to notice but with the long cuts I was doing it caused a issue.

Thank you for all the responses and the help!
CementTruck4 years ago
1) If the saw is old maybe the bearings are starting to go bad and the wood is the only thing keeping the blade from wobbling. If this is the case then the blade may wander towards the fence or away from it. If it wanders towards the fence then at some point the blade is getting leveraged towards the fence but the saws base plate keeps it from being able to move any more in that direction and is causing the stalling as it gets "pinched".

2) If you dropped the saw sometime in the past that somehow shifted the base plate the same issue as the blade pinch described above would occur.

3) Pay attention to the back of the saw base as you are cutting. Is it flush up against the fence or is there a slight gap? If there is a gap see 1 and 2.

4) have you tried just putting on a new blade?
mats-notes (author)  CementTruck4 years ago
I think I'm going to try 2-4. I have had the saw for years and the blade is probably due for a replacement. I will also check the base when I replace the blade. If I find issues and a fix I will post.
Also, there isn't one magic saw blade to cut all things. You will need an assortment and know which ones to use for which projects. Most of the time, blades with large(few) teeth will cut quick and rough. Small(many) teeth cut slow but smooth.

If you have had the saw for years and have never changed blades then I think that is your issue. Let me know how it turns out.
Rob3114 years ago
Are you clamping the level down?

You might be pushing your guide ever so slightly, causing pressure in the blade.
mats-notes (author)  Rob3114 years ago
Yes most of the time I have a clamp on both ends.
Kiteman4 years ago
I wonder if the clamping is uneven?

Can you post a photo of your typical set-up?