black walnut

[SteveF]

i am trying to turn a small bowl

i have sharpened bowl gouge 3 times and am struggling to get a clean cut
lathe running the correct direction
speed around 1500
it is "bouncing" as i try to shape the outside
it is definitely a hard piece of timber with grain running all directions
any thoughts on what i may do? just keep going ?

Steve

 

[Dalboy]

Have you got a fingernail grind gouge now Steve as this is what I find is the best to cut the outside, by doing the pull and then reverting to the push cut.

 

[Random Orbital Bob]

It sounds like the blank is sufficiently out of true that you're turning air half the time and then wood the other. hence the chatter of the tool as it hits wood intermittently.

Just keep the speed fairly slow, 1500 sounds a bit fast to me but if the blank is safe then OK. Tools must be really sharp as any walnut is a brittle abrasive wood. Take very fine cuts starting at the bottom and working towards the headstock. Angle the flute in the direction of travel and keep the toolrest at around centre or slightly above. Once you're true you should be able to run the bevel a little more and it'll sweeten up.

If you're feeling slightly more bold angle the toolrest so it would take the corner off the imaginary base. In other words so its neither at 90 deg to the base nor parallel to the axis of the lathe spindle but exactly in between ie 45 deg to what will become the bottom. Holding the tool very firmly you can make a deeper cut which causes the bevel to rub straight away. Because you're on the corner the mass of wood isn't as great and I find that's often a quick way to get the gouge really stuck into the job without all the more prissy knocking the tops off type cuts. But I'm not sure I should advise that because it requires a fair bit of confidence which if you get wrong will cause a severe catch. And that's a pull cut by the way ie from the centre of the base out towards the sides. That will eventually create a step which when you follow up the sides will keep the bevel rubbing and is a much more pleasant cut than knocking the tips off which sounds like what you're doing now.

I stress however, the knocking the tips off cut which feels and sounds horrible is the safest way to go at the beginning. Slow lathe speed and light cuts with a sharp tool is the generic advice. Keep sharpening every few minutes if you're getting a lot of tearout and experiment with holding the bevel at slightly different angles as you go to see where the sweetest spot is.

 

[Richard Findley]

Walnut is lovely timber but I have experienced this bevel bounce using it. It's not that it's a hard timber because it is actually relatively soft timber. The main problem is too much pressure tool to timber. You need to ease back and let the tool and let the wood come to the sharp tool. Bevel bounce is a problem that can occur with a push cut, if you are still struggling, try a pull/draw cut, although this is less good as a finishing cut. Alternatively a shear cut with the wing of the bowl gouge should sort it out for you. I'm sure a google search would bring up a video of shear cutting with a bowl gouge.

Good luck

Richard

 

[SteveF]

Have you got a fingernail grind gouge now Steve as this is what I find is the best to cut the outside, by doing the pull and then reverting to the push cut.

i dont have a fingernail grind just the usual 45% ish
i am tempted to get a fingernail as that is what i was taught with

Steve

 

[SteveF]

It sounds like the blank is sufficiently out of true that you're turning air half the time and then wood the other. hence the chatter of the tool as it hits wood intermittently.

blank is now round but still getting tearout and chatter

Steve

 

[SteveF]

Walnut is lovely timber but I have experienced this bevel bounce using it. It's not that it's a hard timber because it is actually relatively soft timber. The main problem is too much pressure tool to timber. You need to ease back and let the tool and let the wood come to the sharp tool. Bevel bounce is a problem that can occur with a push cut, if you are still struggling, try a pull/draw cut, although this is less good as a finishing cut. Alternatively a shear cut with the wing of the bowl gouge should sort it out for you. I'm sure a google search would bring up a video of shear cutting with a bowl gouge.

Good luck

Richard

google time for me

Steve

 

[Phil Pascoe]

Join a club.

 

[Grahamshed]

Join a club.

and hit the wood with it

 

[JimB]

Join a club.

and hit the wood with it

Ok but what glue to use.

 

[Spindle]

Hi

If you are bouncing on the bevel take very fine cuts and or cut from the opposite direction until the surface is uniform.

Or be a heretic and true up with a scraper before going back to the gouge :wink:

Regards Mick

 

[JimB]

Some good advice above. One point that hasn't been mentioned is whether you have been doing this in one hit or over a period of time. Every time you leave it the shape could change sufficiently to make it out of round and cause the problem.
The only time I've used black walnut was to make a small tilt-top table top and it was well worth the effort. Sharp tools and gentle cuts seem to be the way to go.

 

[SteveF]

this was one hit
blank has been dry for 15yrs so i would have thought it was stable

not had the chance to try again
thankyou for all for assistance

i will report back

Steve

 

[Richard Findley]

Steve

I'm demonstrating at Garden of England Woodturners a week on Saturday. I will be covering bowl work and tool sharpening there if you are interested.

http://www.gardenofenglandwoodturners.org

Richard