Circular saw issue

[Chris Tolbert]

Mornin’ folks -

Im cross cutting some plywood using a guide and the saw keeps pulling towards the guide. I got so far into the cut and the saw bogged down due to side loading. Some detail:


Cutting a double thickness of 3/4 birch ply
Blade is tight and not warped. Maybe 2 years old. 60T Diablo
Saw is PC 20V
Blade looks to be parallel with the edge of the saw base
Guide was clamped tight


Any ideas?

470200

Thanks!

[Ronald Blue]

Sounds like the base isn't square to the blade. You might be able to adjust that depending on your saw. It's only an issue when you use the guide. You need to actually check the squareness. If you don't have an indicator setup you can probably use a combination square head and blade. Check one side then the other. A few thousandths could turn into a lot of error by the time you reach the other side of your work piece.

[Erik Loza]

Is the plywood sheet sagging in the area before that wandering cut? It looks like the cut is straight, then it's not, which would indicate either tool or workpiece movement.

Erik

[Chris Tolbert]

Thank you! Yes, when I cut freehand it’s fine. I’ll recheck the square.

[Chris Tolbert]

The cut was supported on both sides, so no sag. Poster above mentioned that the blade may not be completely square. Thanks!

[Robert Engel]

Sounds like the base isn't square to the blade. You might be able to adjust that depending on your saw. It's only an issue when you use the guide. You need to actually check the squareness. If you don't have an indicator setup you can probably use a combination square head and blade. Check one side then the other. A few thousandths could turn into a lot of error by the time you reach the other side of your work piece.

I think you mean parallel, not square.

Don't assume the plate is parallel to the blade - check it similar to bandsaw drift.

Make a careful free hand cut along a straight line, stop the saw and place a straight edge along the edge of the plate.

If the straight edge is not parallel to the line, the plate is skewed.

[Bill Dufour]

I try to clamp it so if the saw wanders off it goes into the waste. If it happens just cut it again without moving any thing. That sounds like a deep cut for a little saw. Maybe do it in two passes.
Bill D

[Ronald Blue]

I think you mean parallel, not square.

Don't assume the plate is parallel to the blade - check it similar to bandsaw drift.

Make a careful free hand cut along a straight line, stop the saw and place a straight edge along the edge of the plate.

If the straight edge is not parallel to the line, the plate is skewed.

Yes parallel. Wrong terminology. I think the OP understood my intent though.

[Earl McLain]

Sharp blade is good, but a clean & sharp blade is better. Doesn't take much sap/resin to make a saw behave funny--even if the blade still looks shiny. May not solve the whole problem, but i'd bet cleaning the pitch off you blade will help some--especially if it's been used to cut construction grade 2-x boards. I favor Trend's Bit & Blade cleaner, some like Simple Green, and many prefer to save $10 every 7 years by making home brews. Once i started cleaning blades on a regular basis, every element of my woodworking got better.
earl

[Kyle Iwamoto]

I will second that you're cutting too much wood if you're cutting 2 3/4" ply sheets at once.... Your saw also sounds like it's not parallel..

[Ron Citerone]

My only battery circular saw is a Dewalt 18V. It comes in handy, but I wouldn't cut double birch ply if it could be avoided. My 2 pennies.

[Lee Schierer]

Two things can cause a blade to wander off line. One is a blade that is dull on one side. The other is a base plate that is not parallel to the blade.

I agree with the others that a 1-1/2" cut may be a bit much for a 60 tooth blade. The small saw isn't helping your cause.

[Tom Bender]

Looks like your blade is flexing.

Or you may not have a strong enough clamp. Could the fence be flexing away and slipping back when the saw is removed?

Slow the depth of cut or the feed rate.

Are you pushing the saw crooked? Be sure you keep the saw base down tight to the plywood and tight to the fence, especially at the heel.

[Rich Engelhardt]

One too many of these (messed up cuts) is what made up my mind to sink a bunch of money into a Festool TS 55EQ track saw.