Problem with bowl turning

[stewart]

Hello all

Have had a go at making a bowl tonight - unfortunately I'm not sure what wood it is - it looks like maple but feels too light. It was a blank I got from the person I bought my lathe off. The problem was tearout - lots of it, much like the small oak bowl/pot I made last weekend.

The tearout was restricted to the areas of end grain on both the inside of the bowl and the outside. Is this due to poor sharpening skills?? Or is it technique? I cut the outside shape of the bowl from the headstock end to the bottom of the bowl, then when I'd rechucked the bowl I cut from the outside to the inside of the bowl, deepening the cut and depth of the bowl each time. (Not mentioning that I then got carried away and cut right through the bottom ). Have I made the cuts in the right way?

 

[CHJ]

Stewart it can depend on the grain orientation of the wood blank.

But normally on the outside curve you cut from the centre of the bowl to the outside (chuck end) and from the outside to the centre on the inside.

Think in terms of the grain direction as if you were trying to plane the piece of wood, if you go against the grain it will tear, if you go with the grain it will slice. Another way to think of it is to go downhill from the highest layer (the tailstock end) to the lowest.

Tear out is due to the tool pulling the fibres instead of slicing, primarily down to sharpness of cutting edge but influenced by the presentation of tool, rubbing bevel and angle of attack, try to aim for a slicing cut as opposed to a 90deg chopping approach as you traverse the problem area.

If the wood is soft try moistening it with water, finishing oil, or apply sanding sealer for the last few cuts.


See this diagram from Turning tools.co.uk chap.7.2

Note: this is for Bowls spindle work is different as shown in the e-book Turning tools.co.uk chap.7.2

 

[stewart]

Thanks, Chas
I was definitely cutting it the wrong way on the outside!
Nice link too - added to favourites.
Have to have another go and see how I get on.

 

[PaulH]

Stewart,

I had a similar problem - some more suggestions here.

Paul.

 

[Scrums]

(Not mentioning that I then got carried away and cut right through the bottom Embarassed Embarassed )

hehehe.......been there done that.......!!.....an excellent way to ruin what could have been a nice bowl.

Chris.