My Carvex 420 sometimes cuts perpendicular

[NH-Engineering]

Hi
I have seen that this topic has been discussed before. And as the subject says I have mixed experience with the Carvex about this issue. In genereal it does not cut perpendicular but the amount of inaccuracy varies a lot and changes along the cut, this makes the Carvex my most unpredictable Festool.

Today I did a little research on how my Carvex performed and took some pictures to show how it looked.
First some facts:
I used an almost new FSG blade. (FSG are recomended for true pependicular cuts)
I followed the correct procedure for inserting the blade and adjusting the saw blade guide. (As described in the manual)
The pendulum action was set to 1.
Wood: Pine three (CU impregnated).

The job was quite simple: Remove wood from both sides of a 2"x8" plank. I did cut 2 planks for this test.
1st attempt: (Image 01 to 18)  As you can see from the images the cut is not perpendicular and has opposite angle on each side of the plank even if the cuts are done in the same direction.

2nd attempt: (Image27 to 31): The cut starts out perfectly perpendicular, but is changing along the cut (only right side is shown in the images)
For the left side the cut was perfect perpendicular all the way!

However this has been the same over many FSG blades I have used. And is not effected by the cutting direction in the wood (along or perpendicular to the anual rings).

Does anyone have Comments?

 

[MGB]

I am no carvex expert.

But I would think it's due to speed at entry of the cut or maybe a little too much pressure as well?

I noticed with the blade guides, the blade can "flop" around prior to the blade being pushed against the guide while cutting.

 

[semenza]

    I can see a slight cup in the board. It is most noticeable I the first picture. I think that the cut may be more square than it appears due to the Square being tilted towards the outside at the top of the cut when checking. Though the saw base/ blade would be tilted as well , the tilt would be much less due to the shorter span of the saw base than the Square.

    I suggest testing the saw on a thick layer of something really flat. Maybe MDF.

    I would also think that framing lumber would cause the cut to vary along the length due to lots of variable in the surface to edge relationship.

Seth

 

[MrToolJunkie]

I prefer the FS blades - just as thick, but no set to the teeth so it is smoother. Also, what orbital setting were you on?

 

[NH-Engineering]

Thanks for replies!

The orbital (pendulum) setting was set to 1.
I have tried different things:
1. Slow entry at the beginning of the cut (the longest  blades seems to wobble a bit)
2. Different pressures when pushing the Carvex
3. Different FSG blades
4. All 4 settings of the orbital/pendulum action.

BUT I have to admit that my "research" have one weakness:
I have only being cutting in one type of material and think that the structure of the wood is deflecting the blade along the cut.

As SRSemenza is mentioning: Maybe a true flat, and more random structure material like plywood and MDF will give better results.
Unfortunately I have not many materials to test with here at my construction site at the moment. If I do some more testing I will report it here.

 

[ear3]

Until you try a cut under optimal conditions, using a straight board, it's impossible to know if it's the machine.  The fact that the left and right cuts on that board look like they are mirrored in terms of their angle suggests the cut might actually be square.  You could always try a cross-cut on a portion of the wood that is flat.

Are you using a splinterguard?

If you still find that there are problems, check the base as well.  What happened with my Carvex -- which required that I send it in for service -- is that there was a small amount of play in the base.  So when I would cut into a new splinterguard, the applied pressure would skew the blade slightly out of square, and it would remain in that position because it was locked in place by the splinterguard.

Even after that problem was fixed, though, I discovered another one, due to one of the base inserts that came with the accessory kit having too loose a fit.  I can't use that base insert anymore with a splinterguard, because the same blade deflection that was happening with the defective base is now happening with this base insert.