Centres, what size ?

discussion of the niceties of turning on a bow, bungee or pole lathe.

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Centres, what size ?

Postby NorfolkNige » Sat Nov 20, 2010 10:57 pm

I've been thinking about the centres for the new poppets under construction. Without giving it too much thought I had decided on 12mm studding for the centres but have suddenly thought that 10mm may be better.
Any thoughts and experiences gratefully received :)

Nige
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Re: Centres, what size ?

Postby Mark Allery » Sun Nov 21, 2010 10:24 am

My first centres were 10mm studding but now I tend to use 12mm as standard, the 10mm just seems a bit on the skinny side especially for larger turning - I still use my first lathe for demos and courses , but prefer the 12mm centres. If you wind the centre in a lot (say 2 or 3 inches), the 12mm is noticeably stiffer than the 10mm No big deal, especially if you are intending on spindle turning,

cheers

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Re: Centres, what size ?

Postby Donald Todd » Sun Nov 21, 2010 2:30 pm

I use 8 mm studding, but mainly do spindles and small things: no bowls of any size.
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Re: Centres, what size ?

Postby NorfolkNige » Sun Nov 21, 2010 3:05 pm

Thanks Mark and Donald. I'll go for 12mm and can always make reduced sized points if necessary.

Again thanks

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Re: Centres, what size ?

Postby jrccaim » Tue Nov 23, 2010 3:35 am

When dealing with lathes, my experience is the bigger the better. Go 12mm. Be careful when you grind the 60 deg angle, it's probably more important than the difference in diameter (10 vs 12mm). I posted on that before; too sharp and it's a drill; too broad and it pops off.
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Re: Centres, what size ?

Postby jrccaim » Tue Nov 23, 2010 3:39 am

When dealing with lathes, my experience is the bigger the better. Go 12mm. Be careful when you grind the 60 deg angle, it's probably more important than the difference in diameter (10 vs 12mm). I posted on that before; too sharp and it's a drill; too broad and it pops off. You can, as you say, make reduced size centers; but you will have to make new poppets for them. Ain't no way a 10mm center will fit tight in a 12mm hole! Unless, of course, you have a machinist's lathe and can turn 12 mm down to 10 :)
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Re: Centres, what size ?

Postby ulfhedinn » Mon Dec 06, 2010 5:30 am

NorfolkNige wrote:I've been thinking about the centres for the new poppets under construction. Without giving it too much thought I had decided on 12mm studding for the centres but have suddenly thought that 10mm may be better.
Any thoughts and experiences gratefully received :)


Those diameters seem reasonable, but please, for the benefit of a dumb Yank, what's "studding"?

Over here, metal "studs" are headless bolts with each end threaded, used in auto engines and the like.

A "stud" in wood is an upright in the wall of a balloon-framed house, or the (low) quality grade of lumber (timber) used for such.

Looking forward to learning what it means in British....

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Re: Centres, what size ?

Postby Mark Allery » Mon Dec 06, 2010 9:55 am

Ulf,

I understand that there is also a 'studding' sail - sometime abbreviated to Studsail on our square riggers, which, now we don't have an aircraft carrier will shortly be reentering the Royal Navy as a part of our attempt to reduce carbon footprint (perhaps it should be renamed the Austerity Footprint :D ).

But you are on the right track, it's loose terminology for threaded rod which is sold by the metre (since we're talking M10 or M12) or other standard lengths and then cut to length for use as studs,

cheers

Mark
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Re: Centres, what size ?

Postby ulfhedinn » Fri Jan 14, 2011 8:08 am

OK--so "studding" is what Americans know as "all-thread". Thank you.

Has anyone ever made a crafts dictionary for British, American and perhaps other English dialects?

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Re: Centres, what size ?

Postby ulfhedinn » Fri Jan 14, 2011 8:12 am

Mark Allery wrote:Ulf,
I understand that there is also a 'studding' sail - sometime abbreviated to Studsail on our square riggers, which, now we don't have an aircraft carrier will shortly be reentering the Royal Navy as a part of our attempt to reduce carbon footprint (perhaps it should be renamed the Austerity Footprint :D ).

Hey, who are we to knock traditional technology? And don't forget, when she used that technology at sea, Britannia really did wave the rules...

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Re: Centres, what size ?

Postby RichardLaw » Sat Jan 15, 2011 5:25 pm

And there was me just thinking that studs were the things that hold your collar on!
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Re: Centres, what size ?

Postby robgorrell » Fri Jan 04, 2013 9:08 pm

Ahhhhhh, all-thread, not that makes more sense here in WV also.
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Re: Centres, what size ?

Postby Davie Crockett » Fri Jan 04, 2013 11:54 pm

I've used 12mm gate eye bolts, about £3.00 each (from countrywide farmers) Very successful when pointed and screwed into a 10mm hole. The eye provides excellent leverage with a 12" bar to turn it.
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Re: Centres, what size ?

Postby jrccaim » Sat Jan 05, 2013 6:21 am

Nice thing about pole lathes: they are really insensitive to what the sizes are, and they don't really care about metric or Imperial, either. My only comment is this: if you you use too small a center, say 6mm, it will act just like a drill. It will work itself into the turning. Then it is too loose. Of course you are busy turning and don't notice it until your piece flies off the lathe accompanied with much bad language on your part. Ask me how I know :). I think 12 mm is fine for an average-size pole lathe but I am beginning to think that bigger is better and if I can get it I will use M15x1 or M16x1 on my next pole lathe, now I use 3/8" threaded rod (about 10mm) and I think it is too small. I use this barbarian measure because I find metric threaded rod only on the Internet; then I pay for shipping. Expensive. I think the angle of the tip is important and the time-hallowed 60 deg point is what you want. Less than that and it's a drill. More than that and it will fly off. I turn dead centers these days on my metal-working lathe but you can do it with a drill and a file; that's the way I do it for the threaded end (tailstock) because my metal lathe will not pass a 3/8" rod through the spindle. So I stick it in the drill press (pillar drill) and apply a file. I suppose you could use a battery-powered drill too. And yes, if you can find a long enough bolt at your supplier, you can use that too; although I find that bolts are most inconvenient to point -- can't chuck the bolt end into my lathe or the drill press. I like threaded rod. (AKA "all-thread".) Moral. It ain't just the diameter. The cone angle of the points is very important. And apply lots of oil to them. Any old oil. And keep tightening up on the tailstock, especially at the start of the turning.
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