HELP ! too much chatter

[thefixer]

G'day forumers

I'm getting a lot of awful chatter from the lathe when trying to hollow out goblets etc in hardwood. Anything longer than 100 mm is really hard to turn and the constant chatter of course causes many big digs and heavy tearout, not to mention the messy undies. lathe is Carbatec MC100 G3 chuck with standard jaws using spindle or bowl gouges.
Do i need different jaws, should I sharpen the gouges at a different angle, is the banjo and tool rest too flexible or is it purely technique?
BTW. I am cack handed and too old to change so I do all my hollowing from the back side of the lathe.

Cheers
Shorty

[ss_11000]

i had the same problem today using the supernova 2 chuck with the spigot jaws on a 11" piece of timber ( 11" long not diameter:) ).

[thefixer]

i had the same problem today using the supernova 2 chuck with the spigot jaws on a 11" piece of timber ( 11" long not diameter:) ).


So, just how deep were you gunna hollow out that 11" of timber? I don't even have chisel that long.

Cheers
Shorty

[DJ’s Timber]

The standard jaws are not really the right ones for what you're trying here. What chuck are you using?

[thefixer]

The standard jaws are not really the right ones for what you're trying here. What chuck are you using?

Hi DJ

I'm using the Teknatool G3 chuck


Cheers
Shorty

[DJ’s Timber]

In that case you need these (http://www.teknatool.com/products/Chuck_Accessories/Spigot.htm), made specifically for long stock with spigots

[scooter]

I was getting a lot of chatter recently, fixed by replacing the headstock bearings & flanges. About $50 from Phil at Bearing & Industrial in Cranbourne - great service.

Not saying that is the cause of yours, just one of the possibilities.


Cheers.....................Sean

[joe greiner]

G'day Shorty and mates.

Some other things that might help:

Tool rest as close as possible to the work, to reduce tool chatter.

Tool post directly under the cutting location, to reduce tool rest flex.

Long handle on the gouge for better leverage and control.

Largest available shank on the cutter. Deepest I can go with a 1/2-inch shank Oland tool is about 6 1/2 inches (165mm).

An 11-inch-long cantilever is likely too great for almost any chuck. Only a light nudge will induce wobble. Best use a steady rest.

Once the workpiece is adequately stabilised, higher speed can give a smoother surface.

Joe

[Skew ChiDAMN!!]

Joe has pretty well nailed it, but I'll add one more cause of chatter...

Flex in the MC-x00 headstock swivel arrangement. (MC-900s are more prone to this) It doesn't need much flex at all to translate into significant movement on the tailstock end of a long goblet blank, especially when you're end-grain hollowing.

It has a side benefit though - sometimes, if I hold my tongue just right, I can get a lovely spiral texture running up the inside of my goblet bowls without needing to invest in a texture tool... :roll:

[artme]

Joe is right. A heavier tool helps a lot.
Do you hollow out the inside of the goblet first and then moove onto the outside shaping ?

[OGYT]

If your chatter is coming from the headstock movement, and not the tool, I can't add anything to what's already been posted. Hope you get the problem solved. Please post your answer to the problem... it might help someone else. :)

[Frank&Earnest]

I'm not sure whether what I am talking about is the same problem Shorty has (the symptoms are the same, though:wink:). So far I have assumed that it was only my poor technique, but now I have noticed that there is a slight defect in the alignment of my SN2 chuck, i.e. it runs maybe .2 mm off centre at the jaw edge. Using supergrip jaws solves the holding problem, but 300mm out on a thin rim the unevenness becomes quite noticeable. I have read the instructions carefully and there seems to be little I can do differently, can the problem be fixed or will it always be a matter of tolerances?

[OGYT]

F&E, sometimes the runout problem can be almost totally cured by re-seating the insert. You might pull the insert, check the shoulder it seats against for burrs, clean the threads really clean and re-seat it. The insert threads are purposely made to fit tightly in the chuck, which makes 'em hard to screw in. In order to get mine to seat properly, I clamped a 1/2" thick piece of steel in my vise, opened the jaws 'til they would slip down over the steel (between the jaws, not clamped in them), and then tightened the insert with a 12" adjustable wrench, until I couldn't possibly turn it anymore. It worked. Zero runout on the little Vic.
Another thing, you might check the spindle, without the chuck mounted, and see if there is any runout on that.

[Frank&Earnest]

The insert threads are purposely made to fit tightly in the chuck, which makes 'em hard to screw in.

That might be it, I think the insert thread was not at all hard to screw in. In any case, I'll give it another overhaul as you suggested.
Thanks Al, much appreciated.

[rsser]

Another issue may be jaw alignment F&E.

Screw the jaws down but not tight, tighten the chuck til closed, then cinch the jaw screws up.

[thefixer]

Thanks for all the words of wisdom and experience everyone. Plenty of ideas to try there. Now that I think back it is possible that the chuck is off centre or it is my technique or maybe both.:rolleyes: I'll still take you up on that offer though . Thanks again.

Cheers
Shorty

[Frank&Earnest]

Another issue may be jaw alignment F&E.

Screw the jaws down but not tight, tighten the chuck til closed, then cinch the jaw screws up.

Thanks Ern, that was in the instructions...:wink:

[RETIRED]

Thanks Ern, that was in the instructions...:wink:Still surprising how many that don't do it.

[thefixer]

Still surprising how many that don't do it.


GUILTY!!!:((:((:((

[Frank&Earnest]

Still surprising how many that don't do it.

OK, OK, code violation. My apologies!:D

[rsser]

Same here.

[joe greiner]

Instructions? Ya got instructions with it? Oh . . . here they are; in the bottom of the box, safely ensconced in a widdle pwastic baggie. Even so, nothing about Ern's suggestion for the Grizzly, and not as directly for the Nova Compac. Thanks, Ern.

In any event, even when properly aligned, some manufacturing and assembly tolerance may creep in. So, if ever un-mounted, mark the tenon with jaw numbers to assure accurate re-mounting. I find this helpful with the spur drive too; just scratch an identifying mark on one of the spurs and pencil an asterisk on the timber at that location.

Joe