Replies

1. 
   LRutherfor1 | Dec 10, 2002 12:45am | #1

   The only thing I can think of to help is to draw a true 90 degree corner, square off of that line, and cut just above the line with whichever saw you can fit the panel on.  Run the panel through a joiner to true the edge.  With one good side, you should be able to run it through your tablesaw.  Hope this helps.

   Len (Len's Custom Woodworking)

2. 
   BG | Dec 10, 2002 02:03am | #2

   Scott,

   The easiest way is to make sure you start out with two sides already straight and square.  I use a fresh sheet of 4x8 ply and a 71/2" circluar saw..and a straight edge. I make all measurements from the store bought edges.  Hope this helps

   
   

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   Edited 12/9/2002 6:05:41 PM ET by BG

1. 
   JeffKurtz | Dec 10, 2002 09:49pm | #8

   BG,

   Watch those "factory edges"; they're not always straight or square.

   Jeff

3. 
   observer | Dec 10, 2002 02:05am | #3

   If you have an accurate tape and can get one square corner, you can layout and use a straightedge with a template bit/router to get straight, square and finished edges.

4. 
   Glendo | Dec 10, 2002 02:35am | #4

   Use a skill saw and a straight edge. Get a good blade for starters. Then, build the straight edge by attaching a 2" wide piece of plywood on to a 7" wide piece at whet ever length you need. Run the saw over it using the 2" piece as your guide. This will cut the excess off of 7" and give you your cutting edge. Clamp this on to your work with the cutting edge on your hopefully acurate pencil marks, lower the blade, and cut! If you only need to square an and, a router, a patern bit and a straight edge is quick and clean. A 3'+4'+5' triangle will give you square. I have a slider but when what I'm cutting is too heavy to move or might have metal in it, these methods will work.

   Glendo.

5. 
   Andrew | Dec 10, 2002 07:36am | #5

   Starrett makes a square that big, and it's accurate to withing a few thousandths i beleive. it costs as much as a cheap slider though :)

   I made a guide for my circular saw that functions similar to the festo system, and it's very accurate. I made it out of a peice of cold rolled steel and some plywood. the cuts are gluejoint quality with a good blade. as long as you have an accurate layout you could square up a panel twice that size with no problem. i use a sacrificial peice of styrofoam underneath to protect everything. hope this helps

6. 
   mrles | Dec 10, 2002 08:04am | #6

   Scott

   In my shop my ts fence is true, I would put on my splitter, clamp a 10' piece of aluminum 2" u channel to my fence and true up the 60" inch length first. I would then take a square and mark from both sides on each end and clamp a straight edge and use my circle saw.

   Good Luck and God Bless

   les

7. 
   ian | Dec 10, 2002 02:44pm | #7

   If I had this problem, I'd put it in the truck and take it to my plywood supplier who for $10 would put it through the Altendorf he uses for custom cutting 8ft x 4ft panels.

   There are all sorts of options involving straight edges, but short of a Festo saw and guide rail set-up using someone else's big panel saw is the easiest. 

8. 
   eddiefromaustralia | Dec 10, 2002 10:19pm | #9

   Scott,

   The easiest way is the Altendorf, but if this option isn't available, I agree with previous comments - a sheet of 5 ply should have a straight edge, if you have one of suitable length.  If you have to buy a straight edge, either a sheet of ply or steel bar, I would just take this panel to a shop. 

   If you have a straight edge already and you want to do this yourself, get an absolute square using your high school maths.  A triangle with edges in the ratio of 3:4:5 is square.  So, a triangle with edges of 3' and 4', with the long side being 5' is square.  Then just cut this triangle out with the straight edge offset from the line by the correct distance and a circ saw.

   Cheers, eddie

   edit:  change sheet dimensions - I misread original post

   
   

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   Edited 12/10/2002 2:22:47 PM ET by eddie (aust)

9. 
   booch | Dec 11, 2002 01:00am | #10

   Scottwherethe streetcarmakesthecornergoround,

   Plot it out on the full sheet by using a factory edge as your starter. Check it with a framing square. Then measure to the dimensions and mark a point where the opposite corner should be.

   Then do that axa + bxb = cxc thing. after you determine the hypotenuse (67.08") if you do the math, then draw an arcwith the side of the tape as someone holds the smart end on the starting factory edge corner.

   The arc should intersect the point you made. if not go back and remeasure the to-be-cut sides so that they intersect the arc.

   Use a straight edge to mark your lines (use a mechanical pencil .7 or .5mm it never strays)

   Finally hook up a straight edge offset from your router bit (mine is a PC 690 with a 1/4" straight bit so I use 2 3/4" aprox offset) put the straight edge on the side of the board you wish to save (that way if you oops with the router the piece is saved) and rout using the straight edge as your guide.

   I always check square by making measurements on the hypotenuse as those are a greater indicator of square than a carpenters square is.

   Boochindabay

1. 
   ScottInMadtown | Dec 11, 2002 01:15am | #11

   In da Bay of da Green, eh?

1. 
   booch | Dec 11, 2002 01:48am | #12

   Naw, In the one nort a da wood-oda-shore

   howsabyyou?