Cicular Saw Plunge Cuts - Router Forums
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post #1 of 25 (permalink) Old 01-04-2020, 11:27 AM Thread Starter
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Default Cicular Saw Plunge Cuts

I'm working on a project where I need to make multiple, short plunge cuts (~40) in 2X lumber, for making oval shaped hand holds in the stringers of a ladder. The cuts will be part of removing waste, to be finished with a straight router pass to size, followed by a 1/2" radius roundover bit. The plunge cuts will be 11" long and as through as I can get them.

A couple questions:

1) Because I want the cuts as deep as possible, the blade needs to be extended, potentially to its maximum. This requires the saw start the plunge at a fairly steep angle. The way my template is built, there is little "guidance" at the start of the plunge. My question is, should I make some vertical guides to help keep the saw lined up with the guiding side of the template? Such a vertical guide would be at the rear of the saw base plate and might need to be 3-4" high. Or, do I just eye-ball the alignment as the plunge is started?

2) Should I set the saw to its desired depth (max.) and make the cut full depth in a single pass, or set the saw depth at less, say 1/2 max. and take two passes? I see some potential issues with multiple passes?

The circular saw is a Skil Model 77 worm drive. I am having the saw blade sharpened before tackling this.

Thanks,

Rick

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post #2 of 25 (permalink) Old 01-04-2020, 11:35 AM
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You could always drill thru, at each end of the cut, then use a sabre saw.

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post #3 of 25 (permalink) Old 01-04-2020, 11:48 AM Thread Starter
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Originally Posted by JOAT View Post
You could always drill thru, at each end of the cut, then use a sabre saw.
I did not mention, but the ends of each handhold will be drilled out to 1 3/8" prior to the saw cuts, using a forstner bit. A portion of the saw cuts (at the top) may break into the drilled out holes. I am planning on finishing the cuts with a crosscut hand saw (which I'm also having sharpened).

I don't have a sabre saw. I have a reciprocating saw, but am not thrilled with the notion of using it for all these cuts. Too much chance of wandering off the cut line. I probably could use it to finish the cuts.

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post #4 of 25 (permalink) Old 01-04-2020, 12:03 PM
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I've done lots of those with standard circ saws but never with a worm drive. They are much heavier and therefore might be harder to control as you roll the saw downward. It isn't that hard to stay straight as you rest the saw on the end of the shoe and just lever it down but getting it to line up perfectly with you cut line might require a reposition or two as you start down and find it's off a bit.

You could easily do that job with a pullsaw instead and it would be much safer and more accurate possibly. If you clamp a board down on your line you can use it to guide the saw and it will keep you vertical as well. Once you own a pullsaw your old north american style saw will collect rust hanging on a nail like mine does.

Here are 2 types, straight handle with two different cutting edges and tooth patterns and pistol grip with one set of teeth.
https://www.amazon.ca/Shark-10-2205-...SIN=B000078ONO

https://www.amazon.ca/Shark-Corporat...SIN=B00004TBQ0

The double edge is a bit more versatile. The fine teeth really do make a fine cut (suitable for hand cut dovetails) but the coarser teeth on either saw also do a pretty good job. I demonstrated the pistol grip handle one for an uncle by sawing a slice off a 2 x 4 and you could see light through it. He went out and bought one after and those are all he uses now too.
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post #5 of 25 (permalink) Old 01-04-2020, 12:03 PM
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set the saw on the 2xw/ the blade fully retracted..
loosen the depth lock ...
start the saw...
now plunge while keeping the saw's plate/shoe in full contact w/ the 2x..

better yet...
be safer an get yourself a jigsaw....

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If only new layers hadn't been added....

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post #6 of 25 (permalink) Old 01-04-2020, 12:46 PM
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Hmmm, I think I understand what you are trying to do. Essentially you are making through cutouts for a hand for holding the ladder. If I'm wrong then ignore the rest of this.

I have done something similar a number of times but used a router with a template. Forstner bit to hog out the the waste. Here are some pictures when I was making some trays. These were done on a router table but could easily be freehanded. This certainly makes for a clean cut.
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Measure twice, cut once and CROSS OUT THE WRONG MARKS.

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post #7 of 25 (permalink) Old 01-04-2020, 01:20 PM
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Thinking on it, I do not believe I have ever seen a wooden ladder with handholds like you want. Using the rungs for handholds would be easier to use, and I'm sure faster. #1 shows fire department ladders, with no handholds cut in. #2 shows how the San Francisco does for at least part of their wooden ladders, you will note they use spacers, not cut holes, and they are bolted in. I'm not sure if this is to provide cutout handholds, or just a way to strengthen the ladders. I'd go with that if I wanted hand holes.
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post #8 of 25 (permalink) Old 01-04-2020, 02:29 PM
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Hmmm, you have a point. I'd be concerned that the holes would weaken the ladder. Here's another approach that could be made to look nice and is a bit more natural vis-a-vis hand/wrist positioning.

Measure twice, cut once and CROSS OUT THE WRONG MARKS.

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Last edited by PhilBa; 01-04-2020 at 02:42 PM.
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post #9 of 25 (permalink) Old 01-04-2020, 03:47 PM
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What size 2x, 6 or 8? You need an inch and a half for the hand to go through, plus and inch for the hand rail, and you want another 3.5 inches for the main body of the ladder., so that's a total of 6 inches, which would mean starting with a 2x8 and removing about 1.5 inches. That is going to be a pretty heavy ladder. I'd use a 2x4, spacers and work out some sort of hand rail, possibly a 1 inch diameter dowel. I trust you're using kiln dried wood. Will this be used or store outdoors?

I found the attached drawing of a ships ladder, which is metric, but might help you plan. I think that the side rails on firemens ladders aren't so much for holding on to as to keep hoses from falling off. Handrails also make sense if the ladder is at a steep angle.
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post #10 of 25 (permalink) Old 01-04-2020, 03:59 PM
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I have the Mag77 also and use it often to plunge into 2x's...I typically plunge it to start a rip cut in 2x6's to hold it together, then go back and finish the first couple of inches...

For what you are doing I would use the 24T thin kerf demo blade...

Mark your line with a pencil...then do as Stick suggested...put the index mark where it belongs, make sure your depth adjustment is loose, line up your index mark and blade where you want it, hold the toe as you normally would to keep the index mark on the line, lift the saw a bit, pull back on the blade guard so it stays out of the way, turn it on, go for it. If you screwed the direction of the initial cut, do not try to correct it once the blade is in by twisting the saw...it will bind and it will try to counteract the Earth's gravitational pull...

This operation is more an issue of hand/eye coordination than anything else...

Be careful as the deeper you plunge, the slower the feed rate...the M77 is powerful enough but you want to make sure you're not running into any funny grain as you plunge...the weight of the M77 is your friend...don't push it in, let the saw do the work...
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