Screwchuck question

[Dancie]

At the weekend I turned a small bowl from seasoned Yew, I used a 10mm screw chuck, screwed into an 8mm pre-drilled hole. I've had problems getting the wood off the screw chuck in the past but this time it was a real bugger. Whats the best thing to place between the screwchuck plate and the timber? is it something simple like a disc of card or something more sophisticated?  Any views or suggestions please.

[APH]

I find waxing the screw first often helps. Just an old candle stub works fine.

[David Buskell]

I put an old CD or the plastic top off of a spindle of DVD's there. Works a treat.

[Bryan Milham]

I've never had a problem with screw chucks, as long as you can lock the headstock.

The ones I always had a problem with was the Pin Chuck. Once that pin rolled it seemed to be there forever.

[Dancie]

Many thanks for the replies, I'll use a combination of the 2 suggestions - However viewed 68 times but only 3 replies is a bit disappointing, does that mean that no one uses screw chucks or does it mean that no one has problems with them.

[Lazurus]

Bit of waxed paper pinched from the cooking drawer works for me...... As stated locking the headstock is the main problem for some lathes.

S.

[bodrighywood]

I hve never found a problem with screw chucks finding that locking the headstock is sufficient to get a good grip to unscrew. If you don't have a lock I can see that it might be more difficult though. Is there any way you can fix it somehow?

Pete

[Dancie]

Hello Pete, yes my lathe does have a lock and thats been ok in the past but this time it wouldn't budge, in the end I had to chisel it away from the blank ! Extreme I know ! Many thanks for all the suggestions. Hopefully I'll be ok in the future. All the best.

[fuzzyturns]

I don 't use my screw chuck very often, but never had a real problem with it. I think you need to be a little flexible when it comes to the hole for the screw. A softer wood will require a smaller hole, as otherwise the fibres will just give way, but on a hard wood like yew you might be better off with something slightly larger. For hardwoods I would measure the actual diameter of the core of the screw and drill a hole slightly larger than that.

[Derwent Woodturning club]

I don 't use my screw chuck very often, but never had a real problem with it. I think you need to be a little flexible when it comes to the hole for the screw. A softer wood will require a smaller hole, as otherwise the fibres will just give way, but on a hard wood like yew you might be better off with something slightly larger. For hardwoods I would measure the actual diameter of the core of the screw and drill a hole slightly larger than that.

Hi Dancie, I raised this very question with Record Power who recommend a 9.5mm dia. hole for using a screwchuck, in one of their DVDs, which seemed quite large. I use a Supernova chuck with their 'woodworm' screw, which has an 8mm core but has an overall diameter of 10mm, so I drill an 8mm hole. I've never had a problem getting anything off it, large or small, in any wood.  Apparently Record, and I know Oneway use a thicker screw, so I would concur with Fuzzyturns and measure your screw core then drill an appropriate hole.
I would be wary of using anything as a spacer/washer, as that could cause wobble of the piece as you are turning.

[rick_dobney]

Hi Dancie
A couple more things to consider further to the advice from Fuzzy and Paul is to look at the profile of the threads on your screw chuck.

If you look at the Oneway woodworm chuck the threads are thin blades that cut into the wood. Some screw chucks have a more conventional pyramidal screw thread, these will cause more compression of the wood and consequently make the piece harder to unscrew if used in the same size hole. You need to adjust the size of the pilot hole accordingly.

As for spacers to shorten the exposed length of the screw, I use MDF as it is usually uniform thickness and density, this reduces the risk of vibration and wobble providing you have a sound flat surface on your blank as well and you seat it firmly.

Cheers
Rick

[Dancie]

Many thanks to everyone for their help and suggestions its very much appreciated.

[Les Symonds]

There's a host of good info here....but one thing to add. There is no magical rule of thumb about what size hole to drill for your screw chuck. The fact that you were turning a piece of yew suggests to me that you may possibly have drilled the hole too small. You state that you use an 8mm hole for a 10mm screw, but you might benefit from re-thinking this strategy. An 8mm hole in a soft, low density wood like lime or alder might well result in the wood slipping, but in a dense, close-grained wood like yew, it might well be too small a hole. OK....you'll get the wood mounted onto the screw without too much effort, but the forces involved in turning are constantly tightening the wood onto the screw, so it becomes a nightmare to get it off again.

These are my thoughts....Les

[The Bowler Hatted Turner]

Dancie, I lock the chuck in place against the tool rest and put a pair of heavy duty rubber gloves on to give me a grip, works a treat.

[ken rodgers]

Like Bryan stated I never have a problem with screw chucks but pin chucks always causes me a problem.
Ken