'flycutter' (?) style wood bit for surfacing on a cnc machine?

[julianf]

I've got a job here that's too wide for my toy planer/thickenesser.

I realise i could just bolt it down to the cnc table, and run a surfacing program over it.

But i have little idea as to what bit to use?

Any recommendations?


(for reference, we are talking about 24 x 12 inches - not dining table size!)

Thank you.

 

[MattH]

I use these to skim cut my spoilboards on my CNC’s.
they are great because they are both up and down cutting:

https://www.completecnc.co.uk/cnc-router-tooling/router-accessories/bed-skimming-tools

 

[mtt.tr]

Very sharp HSS does work, whatever you do will leave a degree of tear out but nothing salvagable.

how much do you need to remove?

 

[julianf]

Ive got a "plank" thats like those kitchen work tops, made of all seperate blocks. Im not talking end grain - evreything is in the same direction, but i need to skim the thing to make it flat.

...then flip it to normalise the thickness.

I mean its a 5 min job on the planer, thickeneser, but i think mine is 10" max. Whatever, this one is too large for it.

(and ive got another comming up that will be the same dimensions, but with the grain the other way - so that would be way too large to run through the right way)

 

[MattH]

With the correct bit you shouldn’t get any tear out.

 

[MattH]

Example:

 

[julianf]

This is the part -

I did not normalise the thickness of the parts prior, as you always have to after anyway, and id rather maintain as much thickness as possible until the finishing passes. The lower side, of course, turns out fairly flat, but still not perfect.

 

[mtt.tr]

Personally if its just to flatten id go for a power plane, then no.7 plane

 

[MattH]

I'd throw that on the CNC and skim cut it without a second thought.

 

[mtt.tr]

With the correct bit you shouldn’t get any tear out.

im not talking serious tear out just wont be as decent as a planer, although having seen the block and grain being in all manner of direction skimming top of will likely end better

 

[julianf]

Its got to go on the cnc for the parts to be cut from it anyway, so there's no advantage in using hand tools from that perspective.

 

[julianf]

Ive also found this recommended (on someone else's thread) on a wood working forum -


https://www.wealdentool.com/acatalog/Online_Catalogue_Surface_Trim_225.html

 

[MattH]

I think you’d be much better off with the bit I linked to as it has both positive and negative rack cutting faces.
I have three that I use on all my CNC routers.

I settled on these after using much more expensive Amana tool carbide insert cutters.

 

[MattH]

Remember that the wider the tool the more any tram error will show on you cuts.
I find the smaller surfacing bits to be better because of this.

 

[mtt.tr]

Ive also found this recommended (on someone else's thread) on a wood working forum -


https://www.wealdentool.com/acatalog/Online_Catalogue_Surface_Trim_225.html

They make good cutters wealden

 

[julianf]

Not by any of the mentioned methods.

A small bit of tear out at one of the joints, bit not bad at all.

Thank you for all the suggestions.