Strange problem with Carvex cutting foam board, bending the blade

[Stan Tillinghast]

I am trying to cut 2 inch styrofoam insulation board using my Carvex, purchased as a reconditioned tool within the year.
I was using the base with the rail and a Bosch blade made for soft materials. Earlier I had cut one edge of the board at an angle, using the angle base, without problems.

With this newer setup, after a short length of about 10 inches of normal cutting, I saw sparks coming from the blade; on removing the saw, the blade was bent at about a 45 degree angle, and the cut had been at an angle--basically, a mess.

I was not using a splinter guard; had adjusted the blade guide to a little loose but not a lot; pendulum stroke set to zero.

I'm going to finish the job using my TS55, but would like to know if this is a problem with this blade; my settings; or possibly a problem with the saw itself, since it's still under warranty.

 

[Stone Message]

Hi Stan

Did you do the correct adjustment on the blade guide? If it is too tight it will cause very rapid overheating and it may also cause problems if really loose.

Peter

 

[Crazyraceguy]

The sparks coming from the blade are because of the blade guide system of rubbing blocks, instead of the more common roller wheel with a groove in it.  The blocks are far more supportive and stable and I have seen many of the rollers fail. They lock up and the blade wears a flat spot in the groove. This causes them to overheat and it just gets worse.
The blade going crooked is likely from the blade itself. If the set of the teeth is worn more on one side that the other, it will not track very well. You can compensate for this when sawing free-hand by hedging the saw slightly but when it is constrained by a guiderail, not so much. The saw body is forced int a straight line and the blade does what it wants, based on the wear of the teeth.
If you had started with a new blade, rather than one which had cut at an angle, this may not have happened, but we can't be sure.
That said, I have never had good luck with a jigsaw (of any brand) when trying to make guided cuts. IMHO, a jigsaw is a free-hand tool and works best in that way.

 

[rst]

I've cut quite a bit of 2" foam with my Carvex using Festool's foam blade and never had an issue.

 

[mino]

...

100% to above

One note to add:
When used with a rail, or any other guiding, it is critical not to push the saw - you must allow it to make the cut itself. It can be very unforgiving when pushed.

For that setting it to the lowest pendulum stroke (i.e. not zero) to allow it to take the material better is usually needed. Basically, with a jigsaw guided by something, if you need to push, you are doing it wrong.

 

[ScotF]

You can also check the shoe of the saw to make sure it is square to the saw body. If you swap bases you can install them at a slight angle and this will cause an issue using the guide rail. From what you describe the saw wants to go in one direction and the blade is tracking differently and this causes deflection. I always push the base forward when I tighten the lever and that helps keep it square.

 

[Cheese]

The problem comes with using the saw on a rail. Once the blade gets a little off track it just keeps getting worse because the guide rail is prohibiting any sideways movement of the jigsaw. When using it freehand or even guided next to some 2x material, the body can move a little bit and reposition itself which brings the blade back (almost) to where it should be.

Having said that though, I'm surprised that you're having these issues when cutting soft foam. I'd expect the kerf to just get a little wider which would bring the saw blade back to being perpendicular.

One final note, Mafell recommends that when using their jigsaw on a guide rail, you install their W1 jigsaw blade which is twice the thickness of the average blade, this limits blade bending.

W1 on left side, Festool blade on right side.

[attachimg=1]

 

[Stan Tillinghast]

Many thanks to all for your advice.

As I said earlier, I will finish this project with the TS55, but will keep in mind your advice regarding not pushing, using the lowest pendulum setting ( not zero), and checking adjustment of the blade guide.