Picture of Circular Saw Rip Guide--My Version
Rip guides like this one can be found on YouTube and in other Instructables here. They are very handy for precise ripping of large panels and for trimming things like doors. I am including a couple of modifications, though, that I think readers will find very beneficial. One is a cost reduction. A second is no need for making a precise cut during the construction of this guide. Another is a way to clamp the guide so the clamps do not interfere with the motor housing on the saw. The fourth is two working edges in case one should be damaged.

In the photo you see my rip guide prepared to trim 1/8 inch from the bottom of a door. 
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Step 1: Materials and tools

Picture of Materials and tools
  • 1 MDF trim board 3/4 x 3 1/2 x 96 inches 
  •  Tempered Masonite 3/16 x 15+ x 96 inches
  •  Bevel-headed wood or sheet metal screws: # 8 x 3/4 inch

  • Rule
  • Drill with bit and countersink
  • Screwdriver
  • Sawhorses 
Lowe's Home Improvement Stores in the USA sell painted MDF trim boards in various widths. These trim boards are very straight. Since the trim board will be mounted with screws to a piece of Masonite almost 15 inches wide after trimming, the piece of MDF does not need to be completely resistant to bending under lateral pressure. The Masonite will add sufficient rigidity.

Have the store rip 15 or 16 inches from the long side of a sheet of 4 x 8 feet Masonite. It does not matter if the cut is not completely straight, but the panel saw will likely yield a straight cut. (My saw's base is wider than some with almost exactly 5 inches between the edge of the base under the motor housing to the nearest side of the saw blade. If your saw's base is smaller, the Masonite could be narrower. But, the Masonite needs to be twice as wide as the base dimension on the motor side of the base plus the width of the trim board. Leave a little extra on both sides to be trimmed away.)

I had a car, not a truck, when I went to the store. I had the store cut the remainder of the Masonite so I had two pieces about 33 x 48 inches each. They may not go into a car trunk, but will slide through a rear car door and not rise above the seats to obstruct your rear view on the way home. (The panel saw at my store is poorly aligned and corners on crosscuts are not square. The operator has tried several times to get the management have the saw aligned again, but has been unsuccessful. Be aware.)

Plans for rip guides like this often suggest ripping about 6 or 8 inches from the long side of a sheet of 1/2 inch plywood. This is aligned along the edge of a sheet of Masonite. That means you may be buying both a sheet of plywood and a sheet of Masonite. One advantage to my version is that you buy a sheet of Masonite and a trim board only, which makes for a lower cost. (Also, if you are cutting the piece that will actually guide the saw, you will need a means of guaranteeing that cut is perfectly straight. That may not be possible in a beginner home workshop. The straight trim board will be a big advantage for getting a straight guide without a large table saw the beginner workshop may not have.)

Center the trim board on the long Masonite piece and clamp with "C" clamps. Support this sandwich with enough sawhorses to keep it from bowing. 
feiwulfli6 months ago

Can I substitute masonite with another material?
What would you recommend to keep that straight edge?

ldenicola made it!8 months ago

REALLY wish I'd had this during my "trio of bookcases" construction 18 months ago, but I'm working on a long/low ottoman now and this is making shorter work of it!

Phil B (author)  ldenicola8 months ago
Thank you for the photo and for the comment. It looks good. I am glad it is working well for you.
mbecks10 months ago

I made an instructable for a similar thing, but seeing this you method seems much cleaner and less time consuming when done. Im sold on it and will build one soon. thanks

Phil B (author)  mbecks10 months ago
I hope you enjoy the one you make and it serves you well.
gnach1 year ago
Well done, Phil. I'm with the glue and screw camp. Tempered hardboard (masonite) is best for these guides. I use both edges of my saw and so I cut the guide from both edges. I've drilled small holes in the center strip to use brads when I can't get a clamp to reach. Oh, and I wouldn't trust neoprene not to move, my skil wormdrive is not forgiving.
Phil B (author)  gnach1 year ago
Someone made one of these guides to handle his saw on one side and his router on the other. Your idea of making a guide for both sides of the saw is good, too. I also like to be sure things will not move while I am using them.
Hello Mr. B,
I know this question may be ridiculous and that I am very much so over thinking this jig construction. My dilemma is that I had purchased a brand new, factory….errr….”factory” milled 96” piece of red oak to be used as a straight edge. When I got home to use it as such, I discovered it was not straight. I have a limited workshop consisting of a table saw / router table combo (connected to a joint tech system), a circular saw, a scroll saw, a small drill press and a floor standing drill press (with lots of run-out). How do I obtain or create the straight edged board needed to build this jig with my tools? I am currently not a wood worker, but rather a tinkerer / aspiring jeweler who is in the process of building my Jeweler specific work bench from some very nice up-cycled Bocote and misc. other wood components. Thank you in advance for any advice.

PS- Your take on this jig is very interesting as compared to other similar jigs that I have seen elswhere. Once I feel that I can properly produce it...I plan on using it until both sides are worn out!!! - God Bless!!!
Phil B (author)  Avasar100001 year ago
It is a fundamental law of the universe that wood will always move and change with changes in humidity. I used a trim board made from a wood composite because it is not affected by changes in humidity. Then I mounted it on Masonite which is also a composite not affected by humidity. You could make a stable straight piece from your red oak, but it would be a tremendous amount of work. You would need to rip the oak into at least two narrower pieces and true them with your joiner. Then you would need to glue them back together with the tree rings flipped over in every second strip so tensions in one piece are cancelled by tensions in the neighboring piece. You would also need to clamp them in place so the assembly is straight when dry.
Thank you Mr. B!

I appreciate your timely response. I believe it will be better for my current level of woodworking skills to simply use the red oak for another project and make a trip to one of the Big Box stores to pick up the prescribed materials. I did not discover this jig until after I had purchased the oak or I would have purchased the correct materials initially. Funnily enough, I too have the very same aluminum jig described in step 6. After I determined the oak was not straight enough I recalled that I had this "jig". I marked my $45 per sheet birch plywood and triple checked my measurements, then I clamped the jig down. I noticed that it did deflect in the center. So I placed weights all along the rail to hold all in place. It still did not give an accurate enough cut. At that point I referred to the web for more info on cutting straight using a circular saw. The birch plywood will not be a total waste as I can now build the jig in your Instructable and ultimately salvage the majority of the panels. I wish I had, had the foresight to check here first. Lesson learned….I hope.

God Bless!!!
Phil B (author)  Avasar100001 year ago
We have all had things that did not go right the first time. I misread your original post and thought you had a joiner. The red oak is too good to use as a saw guide. It will make a nice project for other rhings. Let us know how your rip guide works for you.
Moltroub2 years ago
Very good instructable Pastor Phil! I truly enjoy reading your efforts. For me, it's like having my father and uncles explaining things to me. Do you think the vinyl trim would be strong enough to be the guide or would it present too much bow to the Masonite?
Phil B (author)  Moltroub2 years ago
Thank you. I am glad you enjoy these things. I enjoy doing them. The trim board I used is not vinyl, but a composite material similar to MDF. It is available in greater widths, like a nominal 6 inches. That is wide enough to resist bowing. I hope that answers the question you are asking.
Horsehockey2 years ago
I use a piece of 1x4 longer than the piece to be cut. My Milwaukee saw is 5 1/2 inches beteen the inner surface of the blade and the outyer edge of the saw base. I mark the piece to be cut at the cut is to take place, measure another 5 1/2 inches back and clamp the 1/4 in place. Using metal spring clamps to secure the 1/4 in place allows the saw motor to clear the clamps.
Simple, fast, and cheap. I cut a lot of 1 1/2 styrofoam board (4x8 and 4x10 sheets) on the ground. A 2x4 under where the saw will run keeps the blade out of the dirt or grass and provides a rigid surface for the cut.
The saw guide dedpicted would be really useful in a cabinet shop but wouldn't last long in a construction site with the foremans whip on a workers back.
Phil B (author)  Horsehockey2 years ago
For the last 40 years I have often done what you describe. It always demanded more mental effort from me to be certain I was reading the measurements correctly and making them identical on both ends of the rip guide board. I always wanted something like this and find it much easier with more certain results. But, if you have something you like, go for it.
mikem3602 years ago
i put 2mm neoprene type foam on the bottom, no longer need to clamp it in place
Phil B (author)  mikem3602 years ago
Thank you for the comment and the idea. I would not have guessed the neoprene foam would be dependable enough to guarantee no movement.
fjr_scoot2 years ago
NICE! Great ideas that I will implement the next time I make one of these
Phil B (author)  fjr_scoot2 years ago
Thanks. Apparently you have used these guides before.
Very nice phil
Phil B (author)  coolbeansbaby682 years ago
Thanks, Jim. I wish the original idea had been mine.
Thats ok yours looks just as good
Bill WW2 years ago
Thanks Phil, a useful Instructable.

And I like your folding carpenter's rule, don't see these much any more.

Phil B (author)  Bill WW2 years ago

Thank you for the comment. That carpenter's rule was purchased new in 1970. I have used it a lot. The numbers on inside surfaces are still mostly like new. Those on the outside have suffered. Once a friend taught me how to unfold these rules in one speedy and continuous motion. I thought YouTube would have a video, but I do not find one. I may need to demonstrate here it one day.
Bill WW Phil B2 years ago
You said: "Once a friend taught me how to unfold these rules in one speedy and continuous motion.".

One of my strongest memories is when I helped my dad install an oil furnace at the family home in Indiana. 1951, I was 10. We were using his folding rule, which I tried to open in a speedy motion, and it broke in half. I was distraught, did not stick around to see my dad's reaction.
Phil B (author)  Bill WW2 years ago
"It's all in the wrist!" The movement involved with both hands needs to be carefully synchronized. If one hand gets ahead of the other, it would be very easy to break an otherwise good carpenter's rule. So far, I have not broken one, although I do not open one in rapid fashion regularly.
Goodluck2 years ago
A few things:

1) I find running the power cord up and over my shoulder does a nice job of keeping it out of the way and keeps it from snagging various things. If the wall with the plug is in front of you, use an extension cord long enough to loop it around behind you, then up over your shoulder.

2) In use, orient your clamps as pictured in steps 4, 5, and 6 (turning part down)as opposed to as show in step 3 (turning part up). Not only does that help prevent power cord issues, it also helps prevents the screw part from snagging clothing or poking you and surprising you while running a power tool (not good).

3) Long ago I realized cutting through the tops of my sawhorses wasn't a big deal (see a photo of them in my Treedle Lathe instructable). The biggest reason being that it supports both pieces after the cut. When they get worn out, I'll just build new ones. The ones I have are roughly 20 years old and I don't feel inclined to replace them yet.

4) Well done, I too wished I had known about such a guide many years ago. Without one, it is nearly impossible to cut a straight line. With one, a very simple operation. The only change I'd be inclined to make would be to glue the mdf trim board to the masonite. Screws may loosen or 'ream out' their holes with pressure and vibration over time.
Phil B (author)  Goodluck2 years ago
You make good points. I considered gluing the two pieces rather than using screws. One version on YouTube encouraged using screws because the edge of the Masonite could become damaged over time (in the estimation of the video's author). In that case, the screws could be removed and the Masonite could be shifted to one side a little. Then a new edge could be cut.

I did not want to cut into my saw horses because one of the supports is a steel roller I did not want to cut with my carbide blade.

Thank you for your comments and suggestions.
cobber672 years ago
Good idea Phil I am going to start off and make a 4' version as I feel it will be handier for skimming doors
Phil B (author)  cobber672 years ago
It is a good idea, but, it is not original with me. Only a few modifications to make it less expensive, easier to build, and more useful are mine.

I strongly considered four foot and eight foot versions, but decided to make the eight foot version and simply let the ends hang over both sides of shorter things like doors. I am not certain how many eight foot panels I will be ripping. Once we owned a big Mercury station wagon, and I could slide a whole 4 x 8 sheet of plywood into it with all doors and windows closed. Still, there have been times when I needed some very specific cuts from a sheet of plywood. Once I bought a nice sheet of oak veneer plywood at a specialty dealer. He let me plug in an extension cord in his parking lot and use my own circular saw to cut as I needed so the pieces would fit into the back seat of the '63 Chevrolet sedan we drove in those days.

Thanks for looking. I hope it serves you well.
rimar20002 years ago
What a good idea, Phil!

And well done, and well depicted.
Phil B (author)  rimar20002 years ago
Thank you, Osvaldo.
woodlina2 years ago
As usual Phil, your Instructable makes sense, is well written and will be very useful this afternoon when I start ripping panels for some utility shelves I'm building. Thanks for all the great work you do!! -Alan
Phil B (author)  woodlina2 years ago
Thank you, Alan. As I mentioned, this idea is not original with me. But, I tried to make some helpful modifications. It will be helpful for making your shelves, especially if you make dado joints in the uprights for aligning and supporting both ends of each shelf. Thank you for your comment.