Carving smooth surfaces

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dtorney
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Carving smooth surfaces

Post by dtorney »

When I carve hardwood bowls, parts of the surface are smooth and other
parts are furry, due to the grain. Some woods, like hard maple, yield less furring.
I could reduce the stepover or change the rpm or select a different bit.

What would you recommend for obtaining uniformly smooth carved surfaces?

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Adrian
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Re: Carving smooth surfaces

Post by Adrian »

I don't do a lot of 3D but when I do I use the raster rather than offset finishing strategy with the raster angle set to the same direction as the grain of the wood. That helps a lot but for some woods the age of the bit has the biggest effect.

LittleGreyMan
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Re: Carving smooth surfaces

Post by LittleGreyMan »

I don't have cut a lot of wood, but I have machined several different parts in small quantities.

For each part, the raw material was carefully selected by the customer (a luthier). So the wood quality is not the issue.

The different parts were made of different woods (soft and hard).

2D parts were cut with Aspire, 3D parts with a CAM software allowing advanced toolpath control.

The result is: there is no magical recipe. Wood is a natural material and its mechanical parameters have a great variability.

Some parts were absolutely perfect, others had many flaws (from my point of view. The customer was satisfied as he always performs a manual finishing) with the same tool and the same parameters for toolpaths. The results were the same with soft and hard wood parts. More than this, you can have a mix of bad and good finishing in the same part as you already noticed. Even with the CAM with all bells and whistles.

I ended with this simple general rules:
-use the biggest finishing tool you can use
-always use sharp new tools of the best quality
-select the cutting parameters that seem to give the best result on an homogeneous wood and avoid changing them
-make tests to select the best cutting direction depending on the wood and the type of operation (roughing, cutting, 3D finishing)

HTH
Best regards

Didier

W7 - Aspire 8.517

ger21
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Re: Carving smooth surfaces

Post by ger21 »

The wood can play a part, but you'll usually get fuzzy finishes with climb cuts, and smoother finishes with conventional cuts.
Gerry - http://www.thecncwoodworker.com

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scottp55
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Re: Carving smooth surfaces

Post by scottp55 »

What size/type/manufacturer of bit are you currently using?
How big are the majority of bowls?
3D or fluting toolpath?
Virtually no bowls here, but lots of dishing and pocketing cuts.
Pics are very good to show,as well as the file or a shot of the toolpath settings the bit setting for us to give better info.
scott
I've learned my lesson well. You can't please everyone,so you have to please yourself
R.N.

potzmannwoodshop
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Re: Carving smooth surfaces

Post by potzmannwoodshop »

dtorney wrote:When I carve hardwood bowls, parts of the surface are smooth and other
parts are furry, due to the grain. Some woods, like hard maple, yield less furring.
I could reduce the stepover or change the rpm or select a different bit.

What would you recommend for obtaining uniformly smooth carved surfaces?
This is a more involved process and works much better with machines with Auto Tool changers, but having a full set of Right hand(traditional) and left hand cutting bits and using each one where needed, switching between the two when necessary will solve your problems. Also having really sharp bits helps

LittleGreyMan
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Re: Carving smooth surfaces

Post by LittleGreyMan »

potzmannwoodshop is right, I forgot that one: switch between upcut and downcut bits as often as needed.

And yes, it's easier with an ATC.
Best regards

Didier

W7 - Aspire 8.517

potzmannwoodshop
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Re: Carving smooth surfaces

Post by potzmannwoodshop »

LittleGreyMan wrote:potzmannwoodshop is right, I forgot that one: switch between upcut and downcut bits as often as needed.

And yes, it's easier with an ATC.
Yup up cut and down cut, not forgetting compression when needed, in both left hand and right hand varieties. Thanks for adding up and down cuts. :)

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scottp55
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Re: Carving smooth surfaces

Post by scottp55 »

Don't forget Bowl and Tray straight bits guys :D
scott
I've learned my lesson well. You can't please everyone,so you have to please yourself
R.N.

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