Tool rest vibration

[Tiger]

While doing some spindle turning, I noticed a large amount of vibration and noise particularly in the middle of the spindle which was about 1 1/2 foot long. When I pressed the skew chisel down hard on the tool rest the noise disappeared as well as most of the vibration but it feels unnatural to have to press down so hard on the tool rest. The tool rest is well seated and is a tight fit, any explanations or suggestions?

[Toolin Around]

Whip that's what it's called. The wood is flexing as you try to tear fibre off. It's trying to climb up the edge of your tool but springs back about 1000 times a minute (your mileage may very). The act of pushing down harder on the spinning spindle is a technique used to load the wood so it pushes back harder reducing the whip. Sometimes playing with the rpms can help or using your forward hand to absorb the vibration of the spinning material works well. Or if you want to get really carried away you could build/buy a steady

[Tiger]

Changing speed and using my hand as a steady made no difference to the vibration or noise. Didn't think that I'd have to use a steady for such a short spindle.

[joe greiner]

Depends on the diameter. It doesn't take much slenderness to produce vibration. (Varies with hardness of timber.) Also, tailstock might be too tight, thus preloading the blank to encourage buckling.

Joe

[Skew ChiDAMN!!]

:whs:

[Baz]

As a rule you can turn a piece 10x the diameter without flexing, you said your piece was about 450mm long, so if it is 45mm or greater you should not experience any flexing. Other that that wot the others said.
Cheers
Barry

[Tiger]

<TABLE id=HB_Mail_Container height="100%" cellSpacing=0 cellPadding=0 width="100%" border=0 UNSELECTABLE="on"><TBODY><TR height="100%" UNSELECTABLE="on" width="100%"><TD id=HB_Focus_Element vAlign=top width="100%" background="" height=250 UNSELECTABLE="off">Thanks guys, the rule connecting diameter of spindle to length will be useful. D'ya reckon that the vibration will always be much greater with the skew chisel?
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[joe greiner]

D'ya reckon that the vibration will always be much greater with the skew chisel?

That element of vibration is a different critter. More flexible tools can be subject to chatter. To minimize, set the toolrest as close as possible to the work. Some folk deliberately use flexible tools and longer span to create chatter patterns.

Joe

[RETIRED]

Gooday Tiger. A couple of things spring to mind.

What sort of timber is it? Hardwood or softwood?

The problem may be that the chisel is not sharp enough, is being presented to the work at the wrong angle, trying to remove too much timber, the timber is not being held rigidly enough between centres, or the timber itself is causing the problem.

1:chisel is not sharp enough. A blunt chisel will have to forced and can create "lumps" in the work which get worse as you proceed, like corrugations on a dirt road.

2: presented to the work at the wrong angle. There is a fine line between not enough angle and too much angle between the wood and the cutting edge. Too fine and you are not getting good support from the bevel behind the cut and the same results as in 1.
Too much and you run the risk of catching with the long point or gouging out a bit of timber with the short point. If either happens the work is generally ruined.

3: trying to remove too much timber. The skew is basically the woodturners finishing plane. Whilst some of us use the skew to rough down it is better suited to taking the last couple of cuts to smooth out the lumps left by a gouge or other tools.

4:the timber is not being held rigidly enough between centres. You can overtighten the tailstock which can "bow" the timber but conversely you can have the tailstock too loose and the timber will vibrate. Wear in headstock bearings and wear in the quill of the tailstock can have the same results.

5:the timber itself is causing the problem. Some hardwoods do not like a skew chisel no matter how sharp or what angle you have. Vic Ash ( as distinct from proper Tassie Oak) is one that can "ripple" with a skew because of its open grain, but with practice this can be achieved. Pine (yes it is a timber) does the same thing but more so because of the varying hardness between the grain.

[Tiger]

<TABLE id=HB_Mail_Container height="100%" cellSpacing=0 cellPadding=0 width="100%" border=0 UNSELECTABLE="on"><TBODY><TR height="100%" UNSELECTABLE="on" width="100%"><TD id=HB_Focus_Element vAlign=top width="100%" background="" height=250 UNSELECTABLE="off">Thanks, . The timber is radiata pine and the tool is pretty sharp but I will try some of your suggestions.
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[RETIRED]

Tiger. I love turning pine probably because it gives a lot of people the irrits and because I have made a lot of money from turning it.:wink: :D

This is what I do: Set your tool rest a little below centre.

Chisel has to be sharp.

Make sure that where you start is round to start with and start your cut there.

With the cutting edge at about 30-45 degrees to the horizontal of the timber, rub the bevel first.

Twist handle until a shaving appears.

Do not apply a lot of pressure to the cutting edge but maintain pressure on the rest.

Raise a little more shaving and start to traverse the tool rest without applying more pressure to the cutting edge. Maintain this angle by doing "the lathe tango".

The trap is not to let the cutting edge "fall" into the soft spots between the grain. The bevel must rub on the cut timber, it is the only support it has.

Hasten slowly until you get the knack then you can really get into it.

[Skew ChiDAMN!!]

And double-check that your tool-rest hasn't any nicks/dings. They can cause serious trouble when using a skew, 'specially if you're not proficient with one.

(I start my newbies off with Tas Oak or Redgum, then move 'em on to Radiata once they start getting cocky. Might get rid of some of my Paulownia that way soon... :D)

[bosco555]

Hi everyone, I have been turning (wood that is) for a couple of months so please excuse my ignorance, but i found that radiata pine, oregon pine they all produce vibrations. in my case I found that I was too eager with the tightening of the tailstock. Relaxing the grip a bit, alleviated the tendency. By the way, go the skew...now that I managed to show it who's the boss. regards to all

gb

[rodent]

now you've done it bosco a terminal catch is coming your way shortly . Its not the digins I hate it's the wood bouncing off my head that ticks me off .

[RETIRED]

now you've done it bosco a terminal catch is coming your way shortly . Its not the digins I hate it's the wood bouncing off my head that ticks me off .
That explains a lot.:wink: :D

[Hickory]

First thing that came to mind was that you had a crack in your tool restholder (have seen that happen) but then I remembered the chatter I got from my old Lathe (had bushings rather than bearings) when the bushings were worn out. Replaced the bushing and it quit. If you have bearings in stead, it may be the harmonics tied to a loose or worn bearing... I would check both the Toolrest, and toolrest holder and the bearings/bushings...

[Tiger]

<TABLE id=HB_Mail_Container height="100%" cellSpacing=0 cellPadding=0 width="100%" border=0 UNSELECTABLE="on"><TBODY><TR height="100%" UNSELECTABLE="on" width="100%"><TD id=HB_Focus_Element vAlign=top width="100%" background="" height=250 UNSELECTABLE="off">, I use radiata pine because it's readily available and if I stuff something up, I say, oh well it's only pine and it's no great loss.

Some interesting thoughts, tool rest is filed down regularly to remove nicks, bearings well not sure, have to investigate further.
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