chattering skew

[nev]

I thought I'd got the hang of this skew lark, I use it most turning days, I dont get catches anymore and i get a smooth finish. however today whilst 'skewing' a pen blank (in walnut ) I was getting a lot of 'chattering', which i could see as well as hear and feel. resharpened - still the same :?
I thought maybe I was going against the grain but it was same when i changed direction.
I haven't changed anything that i normally do, Any ideas anyone?

 

[Doug B]

Are you keeping the bevel in contact, rubbing it on the piece as you cut?

 

[Richard Findley]

Hi Nev

Could be one (or more) of a few things...

Could be the wood, rarely is but worth a look. Walnut is pretty soft and friendly though so very unlikely. Try another piece and see.

Most likely is too much pressure on the wood, this makes the wood flex and the tool bounce. Ease back, relax and let the wood come to the tool. If you want to put pressure anywhere put it tool to tool rest and not tool to wood!

Could be not enough bevel contact although this usually is accompanied by a loss of control.

If you have recently re-sharpened you may have slightly changed the angle of your bevel, go back to basics and rub the bevel and lift until it cuts.

The other thing you could try is grinding off the heel, much like my bowl gouge grind, this will soften the harsh edge of the heel which can also cause too much contact.

Hope this is of some help.

Cheers

Richard

 

[Harlequin]

too much of a concavity on the bevel ? have you worn down your grinding wheel ?

 

[Jonzjob]

I'll go with too much pressure too. It could also be that you are just getting the resonance of the wood which will amplify the chatter. Try a slightly lower speed if you can.

Failing that make it a feature :mrgreen: or sand it out..

 

[nev]

cheers guys, too much pressure! sort of ...
The wood was flexing even with the lightest of touches, it stopped when i put me finger on the opposite side whilst turning.
the wood tapered from 8mm up to 15mm down to 6mm over the length of 125mm, but it didnt do it with the london plane the same size. obviously walnut is more flexible #-o

 

[L2wis]

I had the exact same thing and I believe it was caused as mentioned above by either too much pressure or the tailstock applying too much pressure to the mandrel.

Probably the tool against the wood though.

*edit, ah glad you got it sorted

 

[nev]

I had the exact same thing and I believe it was caused as mentioned above by either too much pressure or the tailstock applying too much pressure to the mandrel.

Probably the tool against the wood though.

*edit, ah glad you got it sorted

Not using a mandrel for this job and I think thats where my problem/ confusion arose. not had a problem with walnut before but theres always been a rod of steel up the middle. remove that from the equation and it becomes a tad flexible #-o