Narrow Plunge Cuts with Circular Saw

[bgavin]

Is there a specific blade I can use in my circular saw to make skinny plunge cuts?

When cutting access holes, I want to use the cut-out piece as the cover. I make a small plunge cut in each of the four sides, the finish the cuts with a saber saw and guide board. The problem is the plunge cut kerf is wider than the saber saw blade.

I can trim the cover to flush, but this makes for a larger gap. I can wood fill the plunge area, but this seems kinda weak and somewhat lame.

Q: does anybody make a skinny blade that I can use on the circular saw just for plunge cuts?

[Tim A]

Use a fine cut plywood blade. The kerf will still be wider than the jig saw, but not by much. Finish the corners to the outside of the saw kerf so difference is on the cover. A sander will knock the corners down quickly and the kerf will match all the way around.

Tip: Ease the edges of both the opening and the cover with a sander. Not a lot, just knock the edge off. It looks better and will help hide any wobbles in your cut.

[Bill Fitzmaurice]

I do all plywood cutting with a cordless, which are far easier to handle and come with narrow kerf blades.

[Mark Coward]

I do all plywood cutting with a cordless, which are far easier to handle and come with narrow kerf blades.

+1, and I like using a hand saw to finish the plunge cuts - thanks to Harley for that tip.

[bgavin]

Thanks for the replies.

I did employ an old, non-carbide plywood blade I inherited from my Dad. It makes a fairly narrow kerf.
I have both the circular saw and saber saw measured to cut a flush line on the panel side of the kerf. As Tim noted, this leaves high spots on the corners of the cover. A quick touch with the sander does bring them down, but also increases the total kerf size.

I guess the trick is shopping around for the thinnest ply blade I can find. My steel blades produce a smaller kerf than the carbide tipped blades, so I will hunt for that also. The blade will only be used for plunge cuts, so it should last awhile. I have another circular saw that I can dedicate to this purpose. Plus... that will let me buy that new (Bosch ?) circular saw to replace my ancient Craftsman saw.

[Tim A]

A quick touch with the sander does bring them down, but also increases the total kerf size.

It shouldn't change the kerf at all. Just knock the nibs down, don't sand the part cut with the circular saw.

[LelandCrooks]

I do all plywood cutting with a cordless, which are far easier to handle and come with narrow kerf blades.

+1, and I like using a hand saw to finish the plunge cuts - thanks to Harley for that tip.

+1
I sent all my antique hand saws off to be sharpened. It's pretty amazing how fast a really well sharpened hand saw will cut, once you get the hang of lifting on the backstroke. I find myself reaching for them more than the power saws.

[Harley]

...I sent all my antique hand saws off to be sharpened. It's pretty amazing how fast a really well sharpened hand saw will cut, once you get the hang of lifting on the backstroke. I find myself reaching for them more than the power saws.

+1 We get a Swedish brand of hand saw here with tungsten tips for under $20 so taking them to get sharpened is hardly worth it - plus they last ages anyhow.

[Harley]

Bruce - do you want me to re-post my plunge cutting instruction pics?

[LelandCrooks]

...I sent all my antique hand saws off to be sharpened. It's pretty amazing how fast a really well sharpened hand saw will cut, once you get the hang of lifting on the backstroke. I find myself reaching for them more than the power saws.

+1 We get a Swedish brand of hand saw here with tungsten tips for under $20 so taking them to get sharpened is hardly worth it - plus they last ages anyhow.

$6. SIX BUCKS to sharpen 5 saws. The old timer that did it said it was fun. He hadn't sharpened handsaws in years. I didn't even ask before I sent them to him, I figured it would be $10 a saw. I just wanted them useful, and like new. They're basically family heirlooms that I like to use.

[bgavin]

I probably have the plunge instructions, but feel free to post for the community benefit.

My ancient Craftsman foot does not quite retract far enough to sit on the work without the blade touching. If I went to a smaller diameter blade, this becomes a non-problem. I use a guide board for plunging, so I'm 100% accurate in placement of the kerf. I do this so the cutout edges (not the panel) are uniform when finished with the saber saw.

I have the cuts all done, and the opening is framed in. As of this writing, I'm routing a 1/4D x 3/8W" recess in the framing to accept high density weather stripping. If I don't recess for the stripping, it does not let the cover sit down flush. Normally I do covers as a separate cutting from a tracing of the opening. I'm coming to the end of my baltic stock, and have already come to the end of my cash, so I have to make do with the cover cutout. It will work.

Framing the cover opening, etc, is a damn sight easier when not installed on the cabinet. I did the cover on my T30 after it was assembled. Dumb.