Carvex - Circle cutter | How to start a (ventilation) hole?

[threesixright]

Hi All,

I need to cut a ventilation hole in a piece of plywood (200 mm diameter). Seems like a great opportunity to use the Carvex (PS 420) circle cutter.

Dumb as I may be. What is the smart way to start the hole?
a) Pre dill a (forstner?) hole against the circle and then use the cutter? The cutter attachment is pretty rigid.
b) Doing it with a plunge cut?  [blink]
c) Something better?

Checked out a few videos, but what I found, cuts where made from the "outside" of the workpiece.
I'm sure sone of you smart fellas already got did covered  [big grin]

Some help appreciated, thanks!

 

[six-point socket II]

Hi!

Yes, drill a hole against the circle, fitting the jigsaw blade.

Given that it is a ventilation hole, the cutline will be covered, right? In this case I would simply draw the circle, cut on the line without the circle cutter.

Kind regards,
Oliver

 

[AlexThePalex]

A or B will both do. But not a forstner, just an 8 mm bit.

 

[Sparktrician]

You can also use the Festool Circle Cutter that's made to use with the Carvex.  [smile]

 

[threesixright]

[member=61712]six-point socket II[/member] yeah, it will be covered, but its more about using the jig.  I never tried the cutter and this is was a great opportunity to test it.

[member=5277]Alex[/member] yeah so I tried and that, and lo and behold it didn't work great.

[member=7493]Sparktrician[/member] I have the cutter, and wanted to use it 

What I did was the following.

1. Mark the center and drill a 4mm hole, CHECK

2. Set the radius of the cutter to 100 mm (200 mm dia), CHECK

3. With the CARVEX, stick the pin in the cutting jig, and with a pencil draw a line around. CHECK (looks great). There is a small notch on the base of cutter jig, that can guide your pencil.

4. Drill a 10mm hole (as suggested by FT instruction video) against the circle, CHECK.

And now there is a problem, since the hole is against the circle, yet the blade because if the geometry is not perfectly aligned.

Forgot to make pictures, but this drawing illustrates the problem I think (and the FT cutter I have).

So I'm thinking, should I just cut the 1st part free-hand (~ 20mm), and then align use the cutter?

Thanks all!

// update
I update the drawing. What I first tried was to drill the blue hole, but then I couldn't position the blade on the line. So, I ended up doing the green hole, but it took a "bite" out of the circle. Not a big deal, this ventilator has atleast a 50mm cover all around it, so you see nothing. But for me it's more about the jig and future cuts where it could be important.

 

[Svar]

If you want clean look use larger forstner bit to start (blue circle on your picture), not 10mm that Festool recommends. That way you can have the blade almost flush with the large circle. You can also flatten one side of the starter hole with a file.

 

[threesixright]

If you want clean look use larger forstner bit to start (blue circle on your picture), not 10mm that Festool recommends. That way you can have the blade almost flush with the large circle. You can also flatten one side of the starter hole with a file.

Thanks, good tip. I will give that a try  [tongue]

 

[Euclid]

To get the smallest possible 'notch' in the finished hole, I'd just drill a few small 'joined up' holes centred on the circumference line, to give a slot just wide enough and long enough to get the jigsaw blade in and begin cutting from a tangential position. (Harder to describe than imagine, I think...)

 

[DeformedTree]

I have to ask, why a jig saw verses using a router (unless you have no router)?  I gather it's rough construction, but still.  Jig saws don't make good cuts/perpendicular cuts on good days in straight lines, in a circle it's just going to be wonky.  I'm also assuming this is plywood, which jigsaws like to make a mess of.

Is this in part a case of "it may not turn out nice, but it's ok this time and I get to try this once?"

 

[threesixright]

[member=42852]Euclid[/member]
I'll give that a try 

[member=68063]DeformedTree[/member]
Yeah, I have a router. Yet, I also have the Carvex and their "circle cutter". By no means a "cheap" jig, and it should kind of work. Normally I would just freehand (since its covered and only temporally). Just looked like a quick and easy way to make a nice hole  .  Merely curious how you (jigsaw) guys would use this jig for this type of a hole.

Is this in part a case of "it may not turn out nice, but it's ok this time and I get to try this once?"

Kind of. Besides the notch visible, I apparently also didn't tighten the knob enough  [embarassed], which made it drift slightly.

 

[DeformedTree]

[member=68063]DeformedTree[/member]
Yeah, I have a router. Yet, I also have the Carvex and their "circle cutter". By no means a "cheap" jig, and it should kind of work. Normally I would just freehand (since its covered and only temporally). Just looked like a quick and easy way to make a nice hole  .  Merely curious how you (jigsaw) guys would use this jig for this type of a hole.

Is this in part a case of "it may not turn out nice, but it's ok this time and I get to try this once?"

Kind of. Besides the notch visible, I apparently also didn't tighten the knob enough  [embarassed], which made it drift slightly.

Makes sense to try.  I'd probably do the same. Sometimes we have add ons and such and never use them and miss chances to try them.    I have to use jigsaws in plywood a lot, I hate it and in general hate jig saws, try to avoid as much as i can, holes never come out nice, messy, need other tools (drill).  You can be cutting stuff up with barely any mess with the track saw, then soon as jig saw is needed, big old mess of saw dust, etc.

I keep telling myself to make templates for router for common cutouts.

 

[HiCal]

Drill the starter hole inboard of the cut line, then freehand from the hole to the line, then use the circle cutter jig to finish the cut. Personally I would not ever use a circle cutter for a jigsaw. If you need clean holes then a router with a circle cutting jig is vastly better. If the holes don't need to be perfect then just freehand with the jigsaw.