Instructables

How To Cut A Straight Line Using A Skill Saw Or Jig Saw

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Picture of How To Cut A Straight Line Using A Skill Saw Or Jig Saw
This instructable will teach you how you can cut straight lines using an electric skill saw, circular saw or jig saw. This is very handy when cutting long boards like a piece of ply wood. The ideal thing to use would be a table saw, but like me, some people can't afford one.
 
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Step 1: What You Will Need

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The things you will need to do this are: - a pencil - to mark your cut line. - a square- to assist in making a straight pencil mark. - a straight piece of wood- this is to act as your saws guide so it should be free of big bumps or warping. - 2 clamps- these need to be able to tighten as they will hold your guide. If they move your cut won't be straight. - a measuring tape- to set your guide in the proper place. -of course you'll need a saw and a board you want to cut.

Step 2: Measure Your Blade To Shoe Distance

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Measure the distance from your blade to to edge of your saws shoe. The shoe is the bottom piece of metal that rests on you wood when cutting. measure the shorter side of your saw for a smaller more manageable measurement. Look at the photo above to see what this measurement should look like looks like.

Step 3: Put The Guide Onto Your Lumber

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Draw the line onto your board where you would like to make your cut. This line really only needs to be on the first and last 6 inches of your wood but I like it all the way across as a visual guide. Put your guide onto the wood your going to cut and get your clamps ready. Measure from your pencil line the same distance you measured on your saw and make a pencil mark. Do this to both sides then clamp your guide onto these marks. Measure again and adjust till its as perfect as you want. I like to get my saw ready as if I'm going to start the cut and make sure the blade lines up with my line when the saws she edge is against the guide.
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the batman10 months ago
Really usefull
mbecks (author)  the batman7 months ago
holy crap batman has instructables. I tip my hat to you.
dimtick10 months ago
sorry if i came across negatively
your way of cutting is fine.
just one thing. always always always cut with the wide part of the circular saw base on the save side. instead of measuring from the blade to the outside (the 1 3/8") , measure from the blade to the inside face of the plate (+/- 3 1/2"). use that measurement to set your fence board. the blade thickness (1/8") will be to the waste side of the cut so your measurement will stay accurate.
much safer and much cleaner cut.
mbecks (author) 10 months ago
Thanks for the comments. It brings up a question though, why do so many people search for an instructable on something they already know how to do
dimtick10 months ago
the way that you're cutting with the circular saw, you'll get an uneven cut. you've got the narrow part of the saw guide supported while the wide part is on the waste side. when you start the cut, the saw will be flat but as you got and the waste wood sags, the saw will lean and you wont get a square cut.
what I do is lay several 2x4's perpindicular to the cut line and lay the plywood on that. set the saw depth to be just a little deeper than the plywood and then cut. I also use some guides that i made rather than a board. the guides work well because the edge of the guide is the cut line so you place the guide on the save side of the plywood and align the edge with the line. that way the blade thickness will be to the waste side. the guides are really easy to make and i'm pretty sure there are instructables for some.
also always lay the plywood with the good side face down. all the tear out and rough edge will be on the top. I also recommend getting a plywood circular saw blade. has a lot more teeth and makes a much cleaner cut. well worth the 20 bucks and 10 minutes it takes to swap blades.
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mbecks (author) 10 months ago
My grandpa taught it to me, he uses metal guides and all the great stuff an old man has, and it opens a new world of wood working.
paqrat10 months ago
I have not yet tried this but it looks like something I, a fledgling woodworker, could use.
mbecks (author) 10 months ago
Haha I'm not safety supervised, poeple will do what they want.
mbecks (author) 10 months ago
Good advice all around. Mind mapper make a instructable for your template so I can copy it.
wilwrk4tls mbecks10 months ago
I have an instructable for a jig-I'll try and post a link to it when i get to my computer or figure out how to from my phone
Mindmapper110 months ago
I made a template that is exactly the right width from the outside of the teeth to the edge of the fence to save measuring everytime, far more accurate.
I have an instructable on making a jig like you're describing, and if you cut the edge that follows the line after it's attached to the straight edge (guide), it's extremely accurate-just put the cut edge on the line you're cutting and that's exactly where the saw should cut if it's held against the guide.
tim_n Mindmapper110 months ago
I'd like to see that, just a stick with a line on it? Would probably have saved me hours on the last project if I'd thought about it. I spent ages lining everything up!
Mindmapper1 tim_n10 months ago
Just a piece of plastic cut to the right with, marked up what it is for, keep it with the saw and yes it saves loads of time
Eh Lie Us!10 months ago
"...and blah blah blah."
Laugh out loud!
Nice Instructable! One thing I've found helpful with using a jigsaw is to find a metal rule (or simply a straight strip of metal) that's as wide as the distance from the edge of the shoe to the blade. (I found a metal ruler that happened to be the right width for my jigsaw.) I then use the ruler to measure the distance from the cut line to the fence. I also recommend a metal fence for accuracy.
mbecks (author) 10 months ago
There is no pink to nails though not sure we're that came from
mbecks (author) 10 months ago
Haha I was wondering if anyone would see that. Don't do as I.
klee27x10 months ago
You'd be very lucky to get this to work with a jigsaw. I have had 2 Bosch, made-in-Switzerland jigsaws. Neither cut straight to the shoe. When I tried using a rip fence, the results were horrible, no matter the feed rate. When the blade is forced against it's natural inclination, the unsupported free end of the blade starts to twist and bend until your blade is not only going off line, but it's also cutting at an angle. My cheap bandsaw will cut along a fence no problem, even with the fence off by several degrees. So I think it's partly due to the single point of support on the jigsaw blade. Now, if the shoe angle were adjustable, this might work.
Agreed, jigsaw blades are not very good for straight line fence ripping. One thing I found that helped, but did NOT eliminate the blade heat warp was an extremely light but sticky silicone spray I used to have. Could rip 5x the distance before the heat started warping the blade. So, I'd respray before it happened. If you are going for those rip lengths, a circular saw would be preferred.
klee27x klee27x10 months ago
...Might work, but I doubt it. Because the end is free, a jigsaw has to be sorta "driven" when cutting anything with significant thickness. Any slight bend of the blade, whether caused by feed alignment or even just a knot in the wood, has to be corrected for, or it just gets worse. In other words, when your cut line starts going left, you have to angle the saw to the right, but you simultaneiously need to allow the saw to move laterally to the left to straighten the blade.
GonzoDuke10 months ago
Skill is a brand, it's a circular saw.
The brand name is actually Skil, But Skil Saws are genericized trademarks for circular saws, like Kleenex tissues. And Kleenex don't cut through plywood very well, at least not fresh out of the box... :)
Miro_B10 months ago
Step 3:nice shoes on picture, ... for safety work
snoopindaweb10 months ago
Thank You looks definitely worth the bit of effort..
snoopindaweb10 months ago
Pink toenails..? Yuk-Yuk.
chuckyd10 months ago
You should actually measure from the teeth, not the blade.
marshall p10 months ago
Try one of these out you will be really impressed -- good for ripping eight foot sheets very accurately and the saw can't jump out of the track very easily .
http://www.leevalley.com/en/wood/page.aspx?cat=1,240,45313&p=41707
papagun10 months ago
While this works for this particular saw and blade combination, it will not work for ALL Jig saws. Jig saw blades do not always follow the base plate like circ saws do.

That being said, try this (It's what most carpenters that I know use when they use a fence at all): Attach a piece of 1/4" or 1/8" plywood to the bottom of the fence with glue and fasteners. Cut 'That'. Now you have a gauged fence that shows EXACTLY where the blade will cut. Measure your work piece in two places, one at either end of the propose cut. Place the cut edge of the plywood base of the gauged fence of those marks. Clamp or screw the gauged fence to the work piece and cut.
esoolo papagun10 months ago
When you try to use a jigsaw against a single fence like this, one side of the sawblade will rub more against the material, so this one side heats up and causes the sawblade to curve. The process is self-amplifying because the more the blade is bent away from the fence, the harder you presses it back against the fence, and the more the fence-side of the blade heats up.

To cut straight with a jigsaw, the guide needs to have two fences to keep the loads on the saw symmetrical. I have made a sawing guide with two fences and used it successfully for straight cuts into 12mm birch plywood.

When cutting more dense materials, like 16mm melamine-coated chipboard, the blade still starts to go awry at some point. When that happens, the saw has to be backed off and let to cool down completely before continuing the cut.
klee27x esoolo10 months ago
Can you explain what difference having 2 fences makes? Do you leave a slight gap so the jigsaw can move around a little between the two fences?
glorybe10 months ago
I can help you a bit. First get a metal straight edge instead of wood. Wood changes shape with the weather and temperature. Next you need a board that is only as wide as the offset of the blade from the saws edge. Lay that board against the pencil line. Then put your guide board in place and lock it down and then remove the narrow board. When you start the saw the blade should not touch the wood. On some saws the blade will move sideways a bit when it starts spinning. You want to start the cut with the blade at full speed. The skill type saw is actually safer than cutting large sheets on a table saw. Keep both hands on the saw handles and you can not cut your hands or arms. Safety glasses, a dust mask as well as a heavy bid apron can save you some suffering. Many skilled workers have had to dig carbide teeth out of their wounds. Better safe that sorry.
mbecks (author) 10 months ago
Thanks for all the feed back and extra info. It's always helpful
hzmtrsq10 months ago
Great instructable!
This works well for cutting down large sections of plywood so they can be handled better on the table saw.
A note on measuring - remember that the teeth of the blade are wider than the side of the blade. So if you are needing an exact cut, measure from the side of the teeth that are angled towards the short side of the shoe.
onemoroni110 months ago
This is a good tip. I've been doing it for years. However instead of using clamps I'm lazy and just secure the fence with drywall screws.
tim_n10 months ago
I had to work out how to use my circular saw by trial and error.

Most have a depth gauge. If you don't set it properly, the safety guard can catch causing the guide to lift, the blade to angle off and either grind to a halt or rip your stock up.

Ditto to neo71665. I can't think of a time that I'd be cutting down the middle of a line, I'd only be cutting to one side of it for accuracy. Otherwise I'd probably not bother to measure!

Just my 2c.
mbecks (author) 10 months ago
thank you. I was wondering about that. I'm going to keep it in the name though because lots of people call it that so it will help people in there search.
bradk310 months ago
Great instructable. This is a good trick to know.

My measuring skills are not the best, so instead of using a tape measure to position my board everytime, I cut a guide out of wood as wide as the distance from the edge of the shoe to the blade. I find this easier than using a tape measure everytime.
mats-notes10 months ago
This is the method I use, even though I have a table saw. I use it for cutting plywood and it works better then trying to get it through my small table saw. Make sure you support the piece underneath. I will put it on the edge of my workbench or sandwich the piece with another board under my guide. If you don't support it I have found the middle can sag throw the cut off.
mbecks (author) 10 months ago
No because I wanted the centre of my blade to cut the centre of the line. If I wanted to cut on one side of the line I'd measure from the kerf.
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