Replies

1. 
   mudman | Oct 19, 2004 01:04am | #1

   Do you have a jointer? I am geussing not. If you start with a piece of 1x6 poplar and then rip it on each side a couple of times untill it is about 2" wide it should be pretty darn straight. Then glue nail the poplar to a piece if 1/4" ply or hard board that is the same length and about 8" wide. As you nail it make sure that it is straight however you can, the board will be easy to bend if it is not perfect. After the board an ply are glued up use the circsaw to cut the ply off. Now you have the perfect guide. It will stay true because of the ply, and the cut edge serves as a very accurate guide for the cut.

   Hope that made since,

   Mike

   please excuse my spelling.
2. 
   WayneL5 | Oct 19, 2004 02:29am | #2

   I bought a guide made of aluminum 8½ feet long.  It comes with clamps which attach and grip plywood underneath.  I've always been real careful with it not to drop it or damage it in any way.

3. 
   Dave45 | Oct 19, 2004 03:06am | #3

   I make one every few years and do it like this:

   1. Rip a piece of 1/4" plywood about 10"-12" wide. (Don't worry if it isn't pretty.)

   2. Rip a piece of 1/2" plywood about 3" wide.  (These edges need to be straight.)

   3. Glue and tack the strip of 1/2" to the strip of 1/4" so the amount of exposed 1/4" is more than the width of the sole of your circular saw.

   4. When the glue is dry, lay the contraption on some sawhorses and use the 1/2" strip as a guide to rip off the excess 1/4".

   5. TA-DA!!!  You have a rip guide that is exactly sized for your circular saw and the edge of the 1/4" is on the blade cut line.

   Here's a picture of my most recent one sitting on my workbench.  Mine are "free" since I always seem to have odd strips of ply laying around. - lol

   
1. 
   Fingrs | Oct 19, 2004 07:11am | #4

   I agree with Dave except I attach a 1X cleat 90 degrees to the front edge of the guide.  I also attach some sandpaper (leftover PSA from my random orbit sander) to the bottom of the guide to keep it from slipping around. 

2. 
   Michmesquite | Oct 19, 2004 09:28am | #6

   I have used Dave's method for about 30 years, beginning with plywood, then acrylic plastic (36" lehgth for cutting door bottoms) and then MDF.

   Use his instructions and you won't go wrong._________________________________

   Michael in San Jose

   "In all affairs it's a healthy thing now and then to hang a question mark on the things you have long taken for granted." Bertrand Russell 

4. 
   CRAIGCONEY_M | Oct 19, 2004 08:37am | #5

   First, you need to check why your cuts aren't straight.  Is  it  the guide rail or is your saw wandering?  Is the guide flexing during the cut?  If you get a string and pull it tight from one end to the other of the guide rail fence it will help you figure out what is going on.  If money isn't an issue get the Festool system.  You get a straight cut, clean cuts, and most importantly dust collection. 

5. 
   mrbird90 | Oct 20, 2004 03:44am | #7

   Hi Asennad,

   To get a good straight edge I went to a local cabinet shop that has a computer controlled saw for cutting big sheets of plywood and purchased a piece of 1/2" x 4" x 8' long birch. it is dead true, parallel and does a great job and it cost very little. I did this about 12 years ago and I am still using it on a regular basis. Hope this helps solve your problem.

1. 
   MarkRoderick | Oct 20, 2004 11:21pm | #8

   One note of caution. I bought an 8" wide piece of melamine (sp?) at HD and when I got home realized that the edge was actually bowed.

   But I agree with the others - the edges of plywood and MDF come perfectly straight.

1. 
   Senna | Oct 21, 2004 05:08am | #9

   I have found that MDF is often out by as much as 1/8 or more. And this is what has caused me the most grief.