Drilling holes in stocks for the centres

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Drilling holes in stocks for the centres

Postby tmb24wh » Tue Jan 31, 2012 3:27 pm

I am about ready to make the poppets/stocks for my MKII pole lathe and wanted to ask for some advice...
One of the flaws I have noticed on my current lathe is that the adjustable centre in the tailstock does not run exactly level (when the stocks are located in the lathe bed/plumb if you are drilling the hole), and that this makes the workpiece want to wobble eccentrically. Bearing in mind that the timber I have earmarked for the stocks is 6"x2" Iroko, and I do not own a pillar drill - is there a recommended technique for ensuring that the hole ends up true or do I just wing it and take a great deal of care?
Hints.tricks and comments appreciated!

Tom
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Re: Drilling holes in stocks for the centres

Postby bulldawg_65 » Tue Jan 31, 2012 4:09 pm

Never built a pole lathe but anytime you are building anything that has to line up precisely, you cut and drill them together as one piece so if your bed is level they will line up exactly. Hope this helps.
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Re: Drilling holes in stocks for the centres

Postby Ian S » Tue Jan 31, 2012 8:43 pm

Drill the centre mounting hole in one poppet.

Mount the centre in the drilled poppet.

Mount the poppet in the lathe.

Mount the second poppet in the lathe, as close as possible to the first poppet.

Use the mounted centre in the first poppet to mark the second poppet (gently tap the second poppet towards the first poppet, keeping both poppets firmly in contact with the lathe bed).

Unmount the second poppet.

Carefully drill the second poppet and mount the second centre.

With much care both centres will be in line, or close enough to work well.

Cheers
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Re: Drilling holes in stocks for the centres

Postby SeanHellman » Tue Jan 31, 2012 9:39 pm

As Ian says. Do you have a long enough drill for drilling through 6 inches. Even if you have you only need to be a degree off over 6 inches to have a rather offline hole. I would project a pencil line around the poppets and drill from both sides. You should more or less meet in the middle if not no one will ever see or know!
Try it out on a bit of scrap first.
If the thread ever becomes loose unwind it and put a thin shaving in the hole and wind back in
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Re: Drilling holes in stocks for the centres

Postby jrccaim » Wed Feb 01, 2012 5:36 am

Difficult to drill any long hole square and level! The way I do it is according to Drew Langsner and Jennie Alexander: Drill the poppet in the bed. I assume you are drilling the tailstock. The headstock need not go through all the way. Tape a short level to the drill bit. I assume a hand drill! Put a big square on the bed to keep you square. . Drill slowly. Each turn check level and square. Once it is well and truly started it is easier. You can drill 300mm long holes that way with a millimeter error. I find a brace and bit is much better than an eggbeater drill because the bits are longer and I can tape a level to them. They are so cheap used over here that I own seven! Saves having to change bits, as Mike Abbot says in his book. There are two axes, square and level and you must be on both of them.
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Re: Drilling holes in stocks for the centres

Postby gavin » Wed Feb 01, 2012 8:23 am

These images from an earlier tutorial may help. viewtopic.php?f=14&t=863&p=4925&hilit=drill#p4925
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Re: Drilling holes in stocks for the centres

Postby Paul Thornton 2sheds » Wed Feb 01, 2012 9:24 am

i clamp the 2 peices together and mark out my square & level then drill through as one using a buddy to sight me on my lines.
this works well enough but the flex in a 12" long 12mm auger bit does mean the centres do not always line up perfectly.
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Re: Drilling holes in stocks for the centres

Postby simon » Wed Feb 01, 2012 6:30 pm

I have made two lathes and on neither of them do the centres quite line up. Close but not perfect. Both lathes work fine. If you are just a little out you can try tapping the non adjusable centre with a hammer to get it closer to where it should be, depending on what the centre is made of and how much is sticking out of the poppet.
A bit off seems to work ok, especially if you do not need to turn the workpiece around.
Make it, mend it, wear it out,
Make it do or do without.
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Re: Drilling holes in stocks for the centres

Postby trollwumple » Wed Feb 01, 2012 9:24 pm

Hi,

Take a piece of wood, "12 x 2", drill a hole in it, then cut this piece of wood down the middle, hey presto, you will have 2 pieces of wood a little under 6 x 2 with a hole in each.

These holes in theory should match up perfectly, just depends on how carefully you have drilled the original hole.
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Re: Drilling holes in stocks for the centres

Postby tmb24wh » Wed Feb 01, 2012 10:59 pm

Thanks folks - it seems there's more than one way to skin a cat. Will try some methods on scrap first and let you know how it goes...
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Re: Drilling holes in stocks for the centres

Postby gavin » Thu Feb 02, 2012 5:17 am

tmb24wh wrote: Will try some methods on scrap first and let you know how it goes...

That is very useful idea. Saves you lots of time and materials.
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What size hole?

Postby voodooalpaca » Sat May 26, 2012 8:50 am

I've got a nice 60deg point on some 12mm rod, but what size hole should I drill?

Do you treat this as you would metal, and tap out the hole? Or just go for 11mm hole and self tap, by winding in the screw thread?

Thanks

Phill
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Re: Drilling holes in stocks for the centres

Postby SeanHellman » Sat May 26, 2012 6:30 pm

I would go for 10 mm, I am sure the thread is greater than 0.05 mm in depth. you may need a 10.5mm in hardwood, give it a go and try on a scrap bit. I have also had great success with when the thread strips taking out the thread and putting a thin shaving in the hole and doing the thread up again.
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Re: What size hole?

Postby gavin » Sat May 26, 2012 6:35 pm

voodooalpaca wrote:I've got a nice 60deg point on some 12mm rod, but what size hole should I drill?

Do you treat this as you would metal, and tap out the hole? Or just go for 11mm hole and self tap, by winding in the screw thread?

Thanks

Phill

Self-tap.
To be confident of the hole-size, drill holes of varying size in a scrap of the same species, ideally from the same tree. Try the sizing in the scrap and decide which diameter suits you best.
Last edited by gavin on Sat May 26, 2012 11:01 pm, edited 1 time in total.
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Re: Drilling holes in stocks for the centres

Postby Bob_Fleet » Sat May 26, 2012 10:52 pm

Putting two through the new poppets at Wooplaw tomorrow.
12mm threaded stainless and we'll drill 10mm or 3/8".
Grease it well then use it to self tap. Even use a branch or handle as a lever to force it through.
Similarly at the fixed end. Use 2 lock nuts and self tap with the point then remove and reverse it and screw it in with the lock nuts.
Grease is part of the answer.

At the other end of their lives when they get slack, remove and pull two bits of string through the hole then put it back in tight.
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