Flush cutter v Spiral cutter

[inferno6688]

hey guys,

Which bit would be better for flush cutting/pattern following work? Ie using a straight flush cutting bit with bearing guide, or the spiral bit with bearing guide?
From the decriptions in catelogues the spiral bit sounds like it will give a better finish.

Also is it better to use a small diameter or large diamter cutter? assuming there are no tight internal radius to cut.

Cheers guys :)

[doug the slug]

What material are we cutting?

[inferno6688]

Well i was cutting MDF, when i thought of this question.

But i guess this is more of a general question, as a wanna buy a good quality bit. just not sure which to buy

[Auld Bassoon]

hey guys,

From the decriptions in catelogues the spiral bit sounds like it will give a better finish.

Cheers guys :)

For outside edges, I generally prefer to run a hand plane over the routed edge as it leaves a much smoother finish - but obviously this wouldn't apply to MDF or such.

[ozwinner]

- but obviously this wouldn't apply to MDF or such.

Whats wrong with MDF? :confused:
Its solid timber, or so they say.

Al :p

[Toolin Around]

Whats wrong with MDF? :confused:
Its solid timber, or so they say.

Al :p

Nothings wrong with it if used in the right circumstances. It's very stable and has consistent density, but very heavy. Excellent for making patterns and such. I've seen it used as flooring; proved to be very high wearing and actually didn't look bad. Good for making stuff that will be painted... Has a million and one uses. Hard on the lungs though, hell of a lot of dust is produced when machined.

[bloggs1968]

Hi Inferno,

I've done a fair bit of this work recently and use a carbatec spiral bit 1/2" x 1 1/4" in the trusty old triton router table and it does a good job. Last job was cutting 2 pieces of 17mm ply tacked together with an MDF template on top and it ate it up. Stay away from the smaller carbatec spiral flush trim bits - mine fell apart on first use ( the bearing is only held on with glue and when it heats up it flies off and then a large carbide chip flew off). Carbatec were aware of this when I called them and gave me a credit towards a nice CMT bit.

regards,

AD

[Harry72]

The spirals do cut very smooth... but they dont cut no where near as fast and it pays to rough cut you piece as close as posible to the line.

You dont need a bearing either(on a router table!)with spirals... just grab a drill bit the same dia and securely suspend it just above the cutter on the fence... ala pin routering!(can be done with normal bits too... if you got a pin/drill bit big enough)

[QldWoodie]

For my money:

1 - always trim with bandsaw as close to the line as possible
2 - use largest diameter bit you have (must follow any inside curves of course)
3 - spiral cutter preferred over straight cutter every time. Hold firm onto table.

Only one problem. Almost all bearing-guided flush trim bits are straight cutters. CMT make a cutter that shears a bit. Amana make a spiral flush trim bit but I've never used one. Not sure if anyone else make one.

Qw

[inferno6688]

thanks for the replies guys.
I saw in the Cabatec categloue that they have a spiral bit with a bearing, which is how i came up with this question!
:)