Drilling center holes for small projects

[AJ]

There has to be an easy way to drill centred straight holes for small turned projects such as bottle stoppers, cheese knives etc. Is it better to predrill the hole before turning or after. I've tried various methods but haven't found one that works every time. Heeeelllppppp!!!!:?
AJ

[Skew ChiDAMN!!]

For me, I drill first. I find it's easier to centre around an existing hole than it is to drill an existing form to dead-centre. Especially if it's a hole of any length, as drill bits tend to wander. :(

Once drilled, I either centre the hole on my tailstock or, if maximum precision is of major importance, fit an appropriately sized dowel in the hole and use pin-jaws to hold the dowel.

One thing I do intend to make for myself, one day, is a jacob's chuck mounted on a bearing... so I can fit small dowels/plugs, etc into the jacob's chuck and mount it on my tailstock as a live centre. :thyel:

[hughie]

One thing I do intend to make for myself, one day, is a jacob's chuck mounted on a bearing... so I can fit small dowels/plugs, etc into the jacob's chuck and mount it on my tailstock as a live centre. :thyel:
[/QUOTE]

Skew my MC1100 came with a semi detachable end on the live centre. I have often thought of doing a mod much like you suggest. I reckon It would be far cheaper and far easier to do this than a mod on a jacobs chuck.

For me on my handles for turning tools. I drill afterwood via a jig and then do the final straighten at the gluing stage......when the mod is done I would not be doing it this way.

[TTIT]

Skew my MC1100 came with a semi detachable end on the live centre. I have often thought of doing a mod much like you suggest. I found that the shaft of my old Makita battery drill was an exact fit for the live centre that came with my old MC900 - just had to shorten the shaft a little so it would replace the point and Bob's yer uncle. - - but now I'm wondering why I let that go with the MC900 :doh::doh::doh:

Just remembered why! The bearing kept moving offline - thought I'd be better without it but haven't got around to replacing it.

[joe greiner]

One thing I do intend to make for myself, one day, is a jacob's chuck mounted on a bearing... so I can fit small dowels/plugs, etc into the jacob's chuck and mount it on my tailstock as a live centre.

If your live centre has a removable point, you could make an accessory to fit directly into it; different accessory for each application. Take a piece of same-size metal shaft, drill a hole in the timber blank to match, glue the shaft into the timber and attach to the live centre. Turn the accessory between centres, leaving a small nubbin until last to drive the turning. Then cut off the nubbin; similar to final cutoff of a goblet bottom. I doubt you could turn the whole thing from a single piece of timber because the smaller dowel probably wouldn't stay centred in the live centre, or would get beat up by the grub screw. Example accessories could be a set of ball chucks for final shaping, large cone centre for steadying the tailstock end of a hollow piece, and who knows what else.

[If same-size shaft is hard to find, and/or doesn't match your available drill bits, you can turn from a larger brass, copper, or aluminium shaft on a wood lathe, using a surplus file or HSS cutter with the end ground to shape; micrometer or dial caliper to check diameter.]

Use of the Jacobs chuck on timber dowelling is likely best as a one-off application; accurate re-mounting would be quite questionable, owing to crushing by the jaws.

Joe

[Skew ChiDAMN!!]

Ah, but you see there is method to my madness. :wink:

The point of my live centre is only a smallish diameter and any dowels inserted would have to be sized to suit that and not the hole I've bored, else there is problems with centering. Of course, I could use size a dowel that fits the centre nicely and hold it in the pin jaws to turn it down to fit the bore (or vice-versa) but then you're increasing the odds of screwing up by adding intermediary steps.

It'd also mean that when using cole jaws and vac plates, I could simply whack any convenient length of dowel into it as a "safety retainer" (I'm sure you know what I mean... using the dowel to hold the form in place, while keeping the tailstock far enough away that I can swing a chisel for cleaning up the foot) without having to worry about sizing accurately first.

Even the above reasons are actually incidental to why I want a free-spinning jacob's... it's so I can turn plugs or "lids" for my goblets and hollow forms and mount them fairly securely at the tailstock end. Using a jacob's to hold the tenon/stub end of the plug means I can make the tenon thicker than one for the live centre, hence increasing rigidity a bit.

(I've also considered mounting a small chuck, maybe a precision midi, or a small faceplate on a bearing at the tailstock end. :- I still might, too. One day.)


Use of the Jacobs chuck on timber dowelling is likely best as a one-off application; accurate re-mounting would be quite questionable, owing to crushing by the jaws.

I definitely agree with that... I guess I should've mentioned that I only do it on a one-off basis.



BTW, sorry for the minor hijack AJ. Back to you... :D

[OGYT]

AJ, For drilling holes in handles, I use a Jacobs chuck in my tailstock. Drill a small hole (1/4" - 6.35mm) with a brad point bit. For accuracy, turn the speed of the lathe up to about 12-1500 rpm, and very slowly advance the bit into the wood. I'd back it out quite often, to clear the shavings which should help to reduce the heat somewhat, and drill to the length of the bit. Then put in a 3/8 bit. Do it again. By then, the size bit you want to use will follow the hole, and not veer off course. JMO.

Skew: (I've also considered mounting a small chuck, maybe a precision midi, or a small faceplate on a bearing at the tailstock end. :- I still might, too. One day.)

Oneway's Live Center comes with an adapter to mount a chuck on it. It would be ideal for what you want. A mite costly, though. :)

[rsser]

Brad point's a good idea for the first foray but not for the second IMHO Al.

[reeves]

There has to be an easy way to drill centred straight holes for small turned projects such as bottle stoppers, cheese knives etc. Is it better to predrill the hole before turning or after. I've tried various methods but haven't found one that works every time. Heeeelllppppp!!!!:?
AJ

Its probably been answered already but a standard $50 drill chuck 2MT into t he tailstock usually does the trick. Always drill on the lathe with the work in the headtsock chuck and you cant go wrong, works for me everytime.

If you want total accuracy (who doesnt) just add the drill process to the rest of yr processes without moving the work at all.

I use those carbatec wood drills with the little point bit out front so it centers itself. General forstener bits also work fine for bigger holes, get a boring bar attachment for longer holes..The general advice is to drill at slow speed but i have used high and its find, less likely to drag or burn.

happy drilling

cheeeeeers
john

[scooter]

I made some wood heater handles & knobs a little while back & did the following.

Used the method described here (http://www.woodworkforums.ubeaut.com.au/showthread.php?p=464620&highlight=drill+press#post464620)to drill accurately point to point in my handle blanks.

I turned a spigots on a couple of pieces of scrap, one went on a screw chuck on the drive end, & the other fit over the live centre. These spigots were sized to suit the holes bored in the blanks.

Each blank was then mounted between the spigot centres, (driven by friction) & turned to shape.

This ensured that the outside was turned concentric to the hole up the guts.

It could be adapted to cater for blanks only drilled from one end.


HTH...........cheers.................Sean

[soundman]

What you do realy depends a lot on how the the type of work and how it will be held and why the hole has to be there.

I will often pilot drill and use the drill hole for the tail centre.
I will often turn the use the tail centre dimple as a start point.

If the work is short and firmly held in a chuck you can drill any time you like.

you realy have to think process management.

A lot depends on how and where the centre reference will be set.
there is no point drill a criticaly central hole If a later process causes the hole to shift in a remount and become " not centre"
So you need to drill your hole ( or at least the pilot) either after the centrr has be established or as a means of defining the centre.

So there is no point drilling a central hole in square stock unless that hole defines the centre.
If you want to drill a central hole in a blank for a rear mounting hole for a knob or such, you probaly need to do that before you chuck it up but you need to be sure it will stay central.

Every siuation is different, and forethaugt is your friend.

cheers

[OGYT]

RSSR:
Brad point's a good idea for the first foray but not for the second IMHO Al.
<!-- / message --><!-- sig -->Of course you're right there, Ern. :)

[rsser]

... recently went to fit a gouge shaft to a turned handle. Had just assumed it was half inch diam. Nope. 5/8. Biggest twist drill was half. Late at night, wanting to get the job done so I had a go at reaming out the half inch hole with a 5/8 spade bit.

Not pretty. Thank heavens for epoxy ;-}

[joe greiner]

Even with a drill chuck in the tailstock, and even with a steady rest, enlarging a hole can be iffy. The spade bit in particular is long enough to flex off-centre as guided by the wood grain. For counterbores, drill the counterbore first (Forstner bit preferred), and use the dimple to start the smaller drill.

Joe

[Skew ChiDAMN!!]

Not pretty. Thank heavens for epoxy ;-}

So I'm not the only one? [phew!] I've found that the biggest problem when enlarging a hole with a spade bit is getting it started in the first place. With no centre support, when the spurs start to bite it tends to do a maypole dance around the hole as the shaft flexes, leaving an 'orrible, 'orrible mess.

One way around it is to use a small scraper or the toe of a skew and enlarge the first few mm of the mouth of the bore to the appropriate size, so the cutting edges are constrained by the rim of the bore. Still not a "nice" cut but it does save a bit of cussin'. :rolleyes:

[scooter]

One way around it is to use a small scraper or the toe of a skew and enlarge the first few mm of the mouth of the bore to the appropriate size, so the cutting edges are constrained by the rim of the bore.


Good idea, thanks Andy :)

[RETIRED]

or, put a dowel in the hole and redrill.

[AJ]

Thanks for all of your replies, you're all awesome.:2tsup: I really appreciate your help and look forward to trying the various methods next weekend

AJ:roll:

[Skew ChiDAMN!!]

or, put a dowel in the hole and redrill.

And where's the challenge in that? :D