Vibration

[Bigbud78]

When I started my first bigger bowl (12") I found a was getting a lot of vibration, so much so that even when round and flat front and back I was still betting chatter on the tool.

Once it was hollowed out it was better but still there, I do have a new chuck as well, I wondered if it could be that.

The bearings feel smooth and I can't detect any movement except for the spindle which moves slightly in and out.

The lathe is bolted down to a piece of kitchen work surface and I'm wondering if this is heavy enough or should I be looking at changing the bearings?

Any thoughts?

Jim

 

[Woodmonkey]

Bigger, heavier lathe!

 

[Rhossydd]

It's unlikely to be the bearings if you can't feel any play in them.
Does the worktop move much when you're turning these bigger blanks ? If so, that's an issue you may be able to resolve with a more rigid mounting.

If you wanted to test the chuck you could try making up a big disc of MDF(or similar man made material that's of consistent density) and seeing if there's still vibration once you've turned it true.
Timber being a natural material will never be 100% even density throughout, so some vibration will always be there. A stonking big lathe will dampen most out, but smaller lathes like yours(ours?) can get a bit 'lary' when pushing their design limits.

 

[yorkshirepudding]

What timber are you turning? I've had ash which is still well out of balance even when i've finished.

 

[RogerP]

try making up a big disc of MDF(or similar man made material that's of consistent density) and seeing if there's still vibration once you've turned it true.

I agree - give it a try.

 

[woodfarmer]

Very likely the wood is denser one side than the other.

see if the wood turns when you place it in various positions as you move it by hand monted in the spindle. If it is out of balance enough you can often rebalance it by screwing a weight to the back plate. I Have in the past screwed a bit of board to the back plate and then moved the weight along ( using screws) to get a good balance. If you do this
BE VERY CAREFUL YOU DON'T TRAP YOU HAND OR SOMETHING IN THE BALANCE WEIGHT AS IT SPINS

This photo might give you an idea, the weight is the dark wood held by the light coloured runners either side.

download/file.php?id=22975&mode=view

 

[Bigbud78]

What are these like ? http://www.ebay.co.uk/itm/Union-Jubilee ... 35ee0de8eb

Got to admit I am looking at a bigger lathe, was also looking at this http://www.yandles.co.uk/record-power-d ... eed/p18129

Will try the ideas above, the lathe seems to have more vibration when turned through 90 degrees into the large bowl mode. The chatter wasn't nice

 

[Rhossydd]

What are these like ? http://www.ebay.co.uk/itm/Union-Jubilee ... 35ee0de8eb

Certainly a step up from what you have now. Very heavy, but will need new chucks etc and not very 'domestic friendly'

was also looking at this http://www.yandles.co.uk/record-power-d ... eed/p18129

That's not much of a step forward from what you have now.

the lathe seems to have more vibration when turned through 90 degrees into the large bowl mode.

That's when you turn the big bits though. The larger the piece, the greater the effect of any timber variation in density and the less chance of it being balanced before you start to true it up.
Another factor is that when rotated the axis of vibration is along the shortest base line (the width of the mounting rather than the length), so there's less inherent support from the mountings.

 

[dickm]

Another factor is that when rotated the axis of vibration is along the shortest base line (the width of the mounting rather than the length), so there's less inherent support from the mountings.

i wonder if that is actually the case? On the Mystro, the base of the head is actually square, so there's no difference in rigidity of the head mounting due to rotating. But what does differ is the effective length of the mounting to the baseboard (a piece of 2" thick chipboard in my case). In spindle mode, the feet are about 12" apart in the plane of vibration, but rotated, the feet are spaced apart by the 4 feet length of yhe bed in the vibration plane. OK, thr Mystro bed isn't that rigid along its length, but it seems to me that the whole system of bench plus lathe might even resist vibration better when the head is rotated for bowl turning. Just a thought.