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1st March 2019, 04:42 PM #1
Long Thin Spindles - pulling not pushing
I'm a bowl turner and don't really enjoy spindle turning. The longer the spindle and the smaller the diameter, the less I enjoy it.
From the bit of spindle turning I do, it seems to me that thin long pieces of wood don't like to be put into compression between centres; they naturally want to deflect sideway. It's like trying to move a piece of string by pushing on the end! String is much more manageable when pulled and not pushed.
If I could pull a thin spindle blank (ie put it into tension), instead of pushing it between the centres, I expect the turning experience would be better.
I've been looking for an off-the-shelf piece of kit that can do this for me. I'm aware of steadies (roller, string, etc), but I'm looking at a different approach here or at least one that is complementary to those methods.
The solution I'm after needs to provide both a holding and rotating grip at the tailstock end of the spindle.
My thinking is that I need:
- A morse taper that is already threaded internally to take a draw bar. This will prevent the MT from being pulled away from the tailstock taper.
- The MT needs to have a live centre that will work under tension. ie. not come apart when being pulled rather than pushed.
- Some form of chuck attach to the live centre to grip and pull the spindle blank.
I have found the following that will do this for me provided they already have the internal thread ready for a draw bar. I'm yet to check with the suppliers about that. I'm also not sure that all of the international sellers will ship to Australia. Apologies if some of the following links have expired by the time later readers get to this post; if so, use the descriptor to search for new or similar listings.
Ready to go complete solutions:
Soba 2 MT Live Centre with 3 Jaw Chuck
50MM 3 JAW LATHE CHUCK ON A 2MT MORSE TAPER . M12 UNIMAT SL THREAD
MT2 3 Jaw Self Centering Lathe Chuck 50mm Morse Taper Shank
2MT Shank Revolving Live Center M14x 1 with 50 mm 3 Jaw Self Centering Chuck
This one doesn't ship to Australia
High Precision MT2 Shank Revolving Live Center M14x 1 with 65 mm 3 Jaws Self Centering Chuck
And, this one is already here in Australia, but looks like one of the above with a hefty mark-up.
2MT / 65mm Revolving Live Centre With 3 Jaw Chuck
There is also the option of adding an adaptor to a live centre to attach one of my existing
chucks.
Hurricane Turning Tools, Live Tailstock Chuck Adapter, 1" x 8 TPI, 2MT
PSI Woodworking Products LTCA18 Live Tailstock Chuck Adapter 1-Inch by 8TPI Male Thread Mounting to a 2 MT
Does anyone know of any other off-the-shelf piece of kit for doing this?
Of course, putting the spindle blank into tension won't eliminate sideways deflection if too much sideways pressure is applied. Of course, all musical instruments that have their strings under tension do vibrate when struck or plucked, but I'm hoping with reasonable technique that turning thin section spindles might be a little more enjoyable (and less fiddly) when done under tension.
Do any of you have any experience to share on any of this?Stay sharp and stay safe!
Neil
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5th March 2019, 06:42 PM #2
OK, all of those suppliers got back, but none of their Morse Tapers come with a pre-threaded bore to take a draw bar from the rear of the tailstock.
A further search found only one assembly available that provides:
- a chuck that attaches to
- a live centre, with..... EDIT: I GOT THAT WRONG, IT DOESN'T!!
- a MT that is pre-threaded to take a draw bar.
This one;
MT2 3 Jaw Self Centering Lathe Chuck 50mm Morse Taper Shank for CNC Drilling
AS IT TURNED OUT, IT WAS THREADED TO TAKE A DRAW BAR, BUT DID NOT HAVE A LIVE CENTRE.
As always....Stay sharp and stay safe!
Neil
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5th March 2019, 07:21 PM #3
Are you sure that's on a live centre?
You may have more luck with locating such a chuck mounted on MT1 and a live centre that takes the MT1 mounted on a hollow MT2. (So you can use the draw bar.)
And even them you'd need some sort of bearing on the draw bar end to stop it unthreading itself.
- Andy Mc
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5th March 2019, 07:47 PM #4
Hi Neil , why not have a chuck on both ends ?
Get yourself one of these for the tailstock end .....Cheers smiife
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5th March 2019, 08:03 PM #5SENIOR MEMBER
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6th March 2019, 01:27 AM #6SENIOR MEMBER
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Neil, what are your diameters of these spindles, and how long would they be when completed?? Also, how many are you looking to do? ............ Jerry (in Tucson)USA
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6th March 2019, 09:51 AM #7
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6th March 2019, 10:24 AM #8
Vermec do a live centre with a thread of which I’m sure if you ask, he could drill and tap for a drawbar.
Threaded Live Centres MT2 Revolving
Maybe he could make you one to your specs?Cheers
DJ
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6th March 2019, 10:32 AM #9
Smiife, that would be the ideal solution if the thread adaptor will not pull out of the live centre and the Morse Taper is already internally threaded to take a draw bar?
How is the thread adaptor held in that live centre that you have posted, Smiife?
So far, I haven't been able to find a MT2 with a live centre that is already threaded ready to take a draw bar. Then there is the issue with the thread adaptor being secured in the live centre so that it will not pull out under tension.
I have considered how I could drill and tap a MT that is not already threaded, but the challenge there is how do you hold and accurately drill the morse taper once it is attached to the live centre?Stay sharp and stay safe!
Neil
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6th March 2019, 10:44 AM #10
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6th March 2019, 01:31 PM #11SENIOR MEMBER
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I have a threaded live centre with the same thread as the spindle. With a vicmarc chuck on the tailstock there is a lot of force transmitted through the piece of turned wood to bring that chuck up to speed at startup. A soft start with a gentle ramp up would help.
TonyYou can't use up creativity. The more you use, the more you have. ~Oscar Wilde
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6th March 2019, 01:35 PM #12
Hi Jerry - Spindle turning is something that I only do occasionally as small jobs for family and fiends. eg, I recently turned some yarn spindles (abt. 8mm diam) for my daughter-in-law, just half a dozen of them, so not production turning.
My next job is some drum sticks for a friend. I anticipate they will benefit from being turned under tension.
Even less occasionally I add small finials to lidded forms, but they are normally short enough to be turned between centres without any much trouble.
This forum thread is really just me playing with the idea of how I can put a spindle blank into tension to see if it improves the spindle turning experience. If it works I will share that on the forum. After that I'm unlikely to use it very often myself, that is until the next grandchild's birthday comes around, etc, etc.
As always, I'm trying to...Stay sharp and stay safe!
Neil
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6th March 2019, 01:45 PM #13
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6th March 2019, 02:26 PM #14
OK, I have since spoken to Enzo at Vermec.
He will do a one-off for me with an M8 thread added to rear of MT2 and also add Loctite when he presses the bearings into the live centre to keep it in place under tension. As a once-off that will cost me an additional $20, so $119 all up + postage. Should there be enough interest and he were to do a batch of them he said he would setup the CNC machine to do a run and the additional unit cost would come down.
So, thanks again Acco for your suggestion.
If it proves its worth I'll explore a group buy, but that is getting a bit ahead of myself. It may just 'turn' out be a white elephant!
As always...Stay sharp and stay safe!
Neil
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6th March 2019, 03:51 PM #15GOLD MEMBER
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You can buy a transfer mandril from Mcjings for about $50 .This has an M2 taper and an m30x3.5 male thread .This will enable you to mount a chuck on your tailstock .It should not be a big job to drill and tap a thread in the end of the morse taper for a drawbar , after all it doesn't need to be dead acurate . Once you have a transfer mandril you will be suprised how many uses you find for it
Ted
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