I use a cheap Bosch jigsaw that I bought for a few pounds from a car boot sale but i buy the best blades i can, if a blade is blunt it will not cut straight often cheap blades will nor cut from new. if you push hard it will not cut straight also look at the blade and not the machine

You are using some cutting oil/3 in 1 /WD40? Just find the optimum blade speed/ feed pressure and it might come right. In theory the blade should be doing 200 Ft/min (milling cutters). So at .5"/rev this works out to 4800 RPM, seems too high. On the other hand manual hacksawing is 50 strokes per min of a 10" blade , is 500 ins/min or 40 Ft/min, which would be 4800/5 = 1000RPM.

Frank

One of Myfordboys video's shows him cutting 1/4 steel neatly with one of these, building a furnace series.

**LINK**

I would have thought it would handle a good deal more on aluminium with the correct blade.

John

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I use an ancient Bosch jigsaw (their first pendulum model) and have used it on 6 and 10mm thick ali plate. I get the best results using freshly made wood powder (sawdust) as a lubricant.

To clarify, when cutting metal I mark out where I want to cut on a thin piece of plywood or hardboard and clamp or tape it to the metal. The jigsaw blade cuts through the meat and the wood creating the 'fresh' sawdust (at the right time and at the right point) and seems to act as a lubricant. It certainly stops aluminium 'sticking' to the blade.

I used to frequently cut apertures in already painted or anodised enclosures and regardless of how much masking up or surface protection I applied the sole plate of the jigsaw always marked the finished surface because trapped swarf particles got hammered into the surface. Masking tape or any liquid lubricant just made this worse by holding the swarf in (the wrong) place. A layer of hardboard totally eliminates this problem.

The only way to cut a dead straight or accurately with a jigsaw is to proceed very slowly. Let the saw do the work and only use light pressure in the cutting direction.

Ian P

David,

Have you got this Bosch "pendulum motion" set right. Iv'e never experienced it but the claim is that it eases cutting forces on thick sections. According to the Bosch spec your'e good for 25mm alum or 15 mm steel so you are well inside the limit
Speed wise you are on a 25mm stroke up and down so 1 rev = 50mm 2" or 1ft in 6 reolutions. Therefore to get 200ft/min youwould be looking at 1200rpm not counting the fact that its a sinusoidal motion so the average velocity is probably half that.
Read more about pendulum motion at <http://www.toolstop.co.uk/the-importance-of-pendulum-action-what-it-is-and-why-you-should-have-it-a1119&gt;

Bob D

Not using the pendulum when cutting metal is something I would agree with, I should have mentioned it earlier.

Using Bosch blades I have always found their life quite acceptable although in steel I have only cut 3mm thick (plus wood thickness)

Ian P

Ok, I’ll hold my hands up and take the shame. Some years ago I bought a JML Exact Saw, a small handheld 2” circular saw that’s more like a Jigsaw really.

Quite a clever little design except for the spring loaded trigger switch and the spring loaded blade guard, which are both really s%*t pieces of design. Any way, I use this to cut up to ¼” thick Aluminium plate which won’t fit in my Bandsaw, and it breezes through this like butter. However, if you don’t modify the sprung switch and guard, you would be cursing the awkwardness of that bit of design to high heaven.