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Forum topic by lielec11 posted 09-21-2017 07:19 PM 269 views 0 times favorited 6 replies Add to Favorites Watch
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lielec11

2 posts in 28 days


09-21-2017 07:19 PM

Hello all. I am a relative newbie in the wood working world. I have completed a few projects (mostly floating shelving and a craft desk for my wife). To date, I’ve been able to knock those projects out with my table saw.

I just started working on a built in entertainment center using plywood and I am forced to breakdown the ply using a circular saw before I can safely rip/cut on my table saw.

I am having major issues cutting my plywood straight using the circular saw. I have cut a few pieces that aren’t square and end up 1/8”-1/4” off on one end of the board. I created a circular saw jig using a straightedge but my question is, how do I know exactly where to line it up on my board if the board isn’t square? How do I know that the jig will be straight when I line it up on my piece?

Thanks in advance.


6 replies so far

View papadan's profile

papadan

3584 posts in 3149 days


#1 posted 09-21-2017 07:35 PM

You have to measure from the opposite side if it is straight. What are you using for a straight edge?

View Kazooman's profile

Kazooman

842 posts in 1733 days


#2 posted 09-21-2017 08:00 PM

I don’t know just what sort of jig you have made. The best (IMHO) circular saw jig for putting plywood sheets is very easy to make. It is the first straight edge jig in this video.

http://www.woodworkersjournal.com/making-straight-cuts-with-a-circular-saw/

Once you have the jig you just draw the cut line on your plywood sheet, line up the jig and clamp it and then make the cut. Straight and perfectly positioned every time.

It sounds like your jig may be more like the second crosscut jig that acts like a tee square referencing one edge.

Here is another (long-winded) video that goes into a lot of detail if you need more information.

https://video.search.yahoo.com/search/video?fr=mcafee&p=plywood+cutting+jig#id=1&vid=348f7564f5f36889253d2b6fdcaf59db&action=click

View Rick_M's profile

Rick_M

10254 posts in 2160 days


#3 posted 09-21-2017 08:22 PM

My question is what jig and why isn’t your plywood square to begin with? If the jig is straight, if it is perpendicular, and if it doesn’t move during the cut; the resulting piece will be square. So those are your variables, if your cuts aren’t square then one or more aren’t true when you make the cuts.

http://www.woodworkersjournal.com/making-straight-cuts-with-a-circular-saw/
- Kazooman

+1

-- http://thewoodknack.blogspot.com/

View JBrow's profile

JBrow

1236 posts in 700 days


#4 posted 09-22-2017 03:01 PM

lielec11,

I have much more faith that straight and square plywood cuts can be made at the table saw than the mark and cut method with the circular saw. I have broken down 4’ x 8’ sheets of plywood on the table saw, but it is difficult. Therefore, I sometimes use the circular saw to break down the plywood to manageable sizes, but theses work pieces are cut a little oversized. I then get the work pieces to final dimension at the table saw.

Like papadan suggests, I make a pair of tick marks to align with the circular saw straight edge guide by measuring from a factory edge. If additional circular saw cuts are required on the plywood, I continue by measuring from the factory edge; otherwise any errors will be compounded.

When truing up the work piece, I recut the plywood on the table saw. The circular saw cut edge is cut first by placing the factory edge is against the table saw fence. A second table saw cut is made to clean up the factory edge and make the opposite edges parallel. Since the factory edges are generally square, the final panel will be square off the table saw.

If there is no factory edge to run against the table saw fence or the factory edges are out of square, then once the circular saw cut edges are dressed at the table saw, a panel squaring jig for the table saw would be needed to ensure the work piece edges are square.

In the past, I found it impossible for me to keep the circular saw firmly against the straight-edge guide. I finally solved that problem by buying a track system that retrofits to the circular saw. It not only helped keep the circular saw running straight but the zero-clearance strip on the guide made it easy to align the track guide to the tick marks. While it was less money than the Dewalt or Festool track saw systems, it was still expensive but worthwhile purchase.

If you are not inclined to buy a track saw system, then making a jig on which the circular saw rests when making plywood cuts, as others suggest, would allow the guide to be aligned directly with the tick marks and eliminate the error associated when figuring the required offset needed when clamping a simple straight edge to the plywood.

View lielec11's profile

lielec11

2 posts in 28 days


#5 posted 09-22-2017 03:07 PM

JBrow – I don’t have an infeed or outfeed table right now so breaking down a full size 4×8 is touch, especially by myself. Otherwise I tend to agree and use my table saw whenever possible.

View hotbyte's profile

hotbyte

987 posts in 2756 days


#6 posted 09-22-2017 05:28 PM

Due to space and lack of precision track saw, I do similar to JBrow. Break down to oversize pieces I can handle on my table saw as best possible. Then, cut to exact size on table saw. That usually means cutting the 8’ length down to 3 or 4 pieces with circular saw/straight edge. From one of those 3 or 4, I might then finish cutting out 2 to 3 finish sized pieces. I draw cut pattern out on full sheet from a Sketch-Up/CutList 4 drawing and determine best way to break down.

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