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I made some Canexican saw horses for a friend. I liked the design feature that made it so the 2x4 sat in a perfect recess and could be changed out easily.

Saw horses in my shop

I was cutting the angles with the jigsaw, using a 3 inch blade, and every cut I made was not straight. I measured some of the angles at 10 degrees which is awful.

If I just run my jigsaw in the air I can see the blade at the end move about 2 cms. I would have expected that to be normal since nothing is support it out that far. Not sure if that is a factor. The blade I was using was not a fine tooth (8 teeth per inch) so there should have been enough space for dust to get out. I really don't think that is the issue since the problem starts at the initial cut as supposed to starting straight and getting progressively worse. Speed didn't seem to matter. I started slow and fast (to attempt to prove a point) and the results were the same.

My jigsaw is a cheap Jobmate one that has served me well for sheet goods but I just cant use it for this reliably.

What I am doing wrong or it is possible my tool or blade are at fault here?

Matt
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    Perfect job of sawing by hand IMO :-) Mark out accurately, if desired cut your marked lines for cleaner surfaces and saw, if needed using a square cutting guide clamped in place to help saw at 90° to the board face. You could go a little further with the cut lines and create what Paul Sellers calls a "knife wall" for the saw blade to track in. – Graphus Sep 25 '15 at 08:36
  • @Graphus Speed was of the essence for this project. I just needed it done. the cuts were not that big so hand sawing would have been perfectly fine. – Matt Sep 25 '15 at 12:25

4 Answers4

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Really, jigsaws are not the best tool for this job. They are far better at cutting through thinner board materials, though even then you may struggle to get a fully straight cut.

As you say, nothing supports the blade at the end so it can easily wander off of its intended course.

A more expensive jigsaw may have better rollers/support for the blade though so that might help, but if you're going to be buying a new tool for this kind of job then I'd probably recommend a skillsaw or a chopsaw / mitresaw.

WhatEvil
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If the blade is not exactly in line and you move the saw exactly in line it might wander off.

Try it like this: Take a piece of plywood or other cheap material, between half a meter and a meter in length. ( 2 feet plus/minus however many centimetres you like ). Then clamp a straight piece of something to said wooden piece.
Run the jigsay against the straight piece and saw away.
If the blade is out of line it will bend and wander to the side.

LosManos
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I was thinking about LosManos's answer and my comments about my wandering blade.

A better variation of his idea for a fence would be to make a "track board" (small piece of plywood or sheet good) and cut a straight line through it. It does not have to be long just enough to get the cut started.

Use that on the bottom, with clamps, of the piece that is actually being cut. Have it stick out at least the blades width so that it will guide while the cut is being made. Assuming the blade is long enough it should get the cut started vertically without bouncing of the guide track / board. Once the cut is started then it should remain straight.

I think my jigsaw is just cheap. Like Graphus said I could have just used a saw but maybe this and LosManos's answer can make my jigsaw just a little more useful.

Community
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Matt
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  • Interesting, I trust that you will reveal how this scheme works out for you. – Ast Pace Sep 26 '15 at 03:08
  • @ASTPace I plan on trying this weekend for sure – Matt Sep 26 '15 at 03:13
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    A track board might help. And while I don't want to badmouth your jigsaw, I don't think you can expect stellar results from it. (Even my fancy bosch wanders a bit.) – Aloysius Defenestrate Sep 29 '15 at 02:25
  • @AloysiusDefenestrate No offence taken. It's a 20$ tool. Can't expect too much from it. I guess I just find it funny they make longer blades even though they cant cut 90 degrees to save their lives. – Matt Sep 29 '15 at 03:11
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Ya cutting 2x material with a jig saw requires a good powerful jig and a nice long blade . Good rule of thumb is 3 teeth of your saw blade cutting the wood at all times, so to do this your best bet is to use a circular saw, jigsaw is best for your sheet goods. Circular saw is by far the most versitile saw u can own. u can even cut curves in sheet goods with a circular saw. With a circ and a jig you wont run into many projects you cant figure out.

Adam McKenzie
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