This circular saw guide is inexpensive, not too tricky to make, and you will wonder how you ever managed without it!
Step 1: Why You Need the SAW ‘O’ MATIC in Your Life
Especially if you only have a small workshop, or have to kick your car out and work in the garage, this compact circular saw guide will be a real bonus. In the past I’ve tried various ‘shop bought’ solutions for cutting sheet goods with a circular saw, such as a clamp on guide that the saw runs against. But these have several limitations -
* the saw can still wander off the line,
* you have to measure dead accurately to line up both ends of the guide rail
* It can be hard to predict exactly where the cut will be.
In contrast, this simple inexpensive home made tool has these benefits...
*It cannot wander left or right
*you know exactly where the cut will be
*It includes a stop block for accurate repeat cuts
*It can easily hang on the wall for storage.
Step 2: List of Materials
Here’s what you need for the main part of the tool:
*A ¾” (18mm) sheet of plywood cut down to 24” (610mm) by 60” (1500mm)
*From the same 24” wide board, 2 planks cut to 4” (100mm) wide.
*2 pieces of 1” (25mm) angle iron in mild steel, cut the same length as your main board. You want this fairly heavy duty, eg 5mm.
*Various screws.... you probably have in stock.
If you want to make the stop block, you will need a few bits of scrap wood you probably already have, together with...
*A ¼” large head Allen bolt (sometimes called a furniture connector bolt)
*A ¼” threaded insert nut
I can’t stress enough the importance of paying a timber yard to cut your plywood for you...this tool will only be accurate if your boards have dead straight edges and perfect 90 degree right angle corners!
Because in total the ply came from half a sheet, I only paid £25, and a got the angle iron for £4 for the two.
See handy image of materials list to print out and take to suppliers....
Step 3: Fixing the Crosspieces in Position
Glue and screw a 4” crosspiece to each end of your main board. Make sure they line up perfectly on all edges.
Step 4: Fixing the Steel Angle to the Crosspieces
Drill and countersink each end of the steel angles approx 2” from each end.
Take a couple of scraps of wood approx 1” wide and use these as spacers to position a piece of steel angle inset from the edge of your crosspieces... but absolutely parallel to your main board. Using the scraps is more accurate than just measuring and marking, as you can clamp everything in position.
Screw the angle iron to the crosspieces, checking for accuracy as you go. Also check your countersunk hole is deep enough that none of the screw head is proud.
Step 5: Positioning the Other Rail of Your ‘railroad Track’
Now grab your circular saw and place it so the right side of its base plate rests on the angle iron, then slide the other angle iron into position. What you’re effectively making is a ‘train track’ that the saw will run along. Top tip... use an old playing card to create a tiny tolerance between the saw and the angle iron.... you’re looking for a set up where the rails aren’t too tight that the saw won’t slide, nor too sloppy that the saw can wander left or right.
I also polished up my angle iron with wire wool and waxed it, for an even smoother ride! Now have a well earned tea break and let all the glue dry
Step 6: Marking Where Saw Will Cut
The final stage of the main build is to set the depth of your circular saw so that it just cuts into the plywood base by 1/16”, and run the saw all the way along the track. This will cut right through your crosspieces, but just cut an indicator line on the main base.
Step 7: Making a Stop Block (optional)
Cut a piece of thin ply approx 2” x 6”, plus two blocks ¾” x 1” x 2”. On one of the blocks use a spade bit or forstner bit to drill a small rebate. Then on the opposite face drill a suitable hole to take a threaded insert nut. Finally drill a ¼” hole right through which allows you to thread your bolt into the block, from the side with the rebate.
Now you can glue and pin the pieces together, effectively making a square u shape, which will slide left or right on the crosspiece.
Once the wood glue is dry, use a hot glue gun to fix an old cabinet knob to the bare threaded end on the bolt.
The stop block means that once you’ve set it in your chosen position, you can cut several pieces to the same size, without measuring each one.
Step 8: Bonus Content - Handy Tips & Hints
Read all the instructions all the way through, then assemble everything loose with no glue or screws. That way you can, for example, figure out where the saw will cut, so you don’t put a screw through your crosspiece there!
Because it can be cold & damp here in the uk, ordinary steel tools can rust, so I also used some leftover clear spray lacquer to protect the steel (before waxing) and also varnished the ¾ ply.
You can vary the sizes, but this works for me as it...
*Only uses a half sheet of 8’ x 4’ ply
*Is manageable single handed.... any bigger would mean more steel, and wood, and more weight.
*can cut a whole 8 x 4 sheet across the middle (since the gap between the crosspieces is well over 4’.).
Step 9: Using the SAW ‘O’ MATIC
Simply mark up your timber, then position the mark against the saw line scribed into the base/crosspiece.
Let’s say you want to reduce a 18” sheet down to 17”, you put your 17” mark to the LEFT of the saw line.
But let’s say you wanted to cut a 6” strip to use for a project, and you needed to cut it from a bigger sheet, you would put your 6” Mark to the RIGHT of the saw line.
Obviously because I made the crosspieces ¾” thick, that holds the ‘train track’ ¾” above the base board, so ¾” is the thickest sheet you can cut. But there’s nothing to stop you using deeper crosspieces if you like.
Thanks for reading, and if you have any questions, I’ll try to help.
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