Quick question

[hawkeyefxr]

As you know i am have a go a bowl turning.
On my chuck they say when making an external clamp NOT to make it a dovetail shape but leave it square so the jaws can bite into the wood. I have just seen a video where the guy said it's best to make a dovetail, who's right or are they both right.

 

[Phil Dart]

It depends on your jaws Ken. The ideal situation is the make your spigot the same diameter and profile of your jaws when they are closed in to the point that they are a perfect circle. Most jaws would therefore require a dovetail profile spigot, but some "gripper" type jaws are parallel, requiring a squared spigot.

The problem with using a squared spigot with dovetail jaws is that the point of the jaws can dig in too much to the wood and fracture the fibers, which can ( I said can - not does) lead to the spigot shearing off. The rule of thumb is that the more contact between metal and wood, the more secure the hold, so try to marry the two as far as possible. With a bit of practice, you can just cut a dovetail by eye, using a skew as a scraper.

 

[Dalboy]

As Phil stated, remember that some of the u tube video's are made when there was only dovetailed jaws available or it is the type the poster uses. So follow the chuck guide and you can't go far wrong

 

[Penpal]

Let your instructions be your guide too many other ifs what type of chuck , how wide an opening. Explanations given so far are valid.

Peter.

 

[Woody]

Phil gave you the perfect answer there are some dodge ideas out there that people show just to be different or its people who dont really know what they are talking about and give advice that can be very dangerous dovetail jaws should never be tightened to the extent that the jaws dig into the wood it is the best way to damage the surrounding and have a bowl go airborne now gripper jaws are another ball game they are designed to gig into a larger spiggot of wood and on end grain not side grain the people who made your chuck also know what they are talking about but you have done the right thing in asking

 

[wm460]

What Phil said.

 

[hawkeyefxr]

Well i made a visit to the shed and my jaws are a true dovetail on the outside. On the inside they are parallel most of the way but just at the end they have are kind of have a small dovetail . Perhaps i should say i have a record SC4 chuck, it will mean more to you than my description i would think.
The instructions definitely say a parallel tenon. I do understand about crushing the wood and destroying the wood structure.

 

[Phil Dart]

In which case, as they are parallel (the small dovetail you refer to is just to prevent interference where the jaw meets the register), cut your spigot parallel.

 

[hawkeyefxr]

Thanks one and all.
Walter, i think you should write an encyclopaedia of your vast knowledge, i would buy one for sure. I can even tell you where to make the book lol.

All i need now is a 10 degree rise in temperature so i can spend a few hours in the shed without turning blue. Summers coming.

 

[Phil Dart]

Who's Walter?? He managed to give you all that advice without even moving his lips. Hopefully I'll get some of his royalties.

 

[Vic Perrin]

Who's Walter?? He managed to give you all that advice without even moving his lips. Hopefully I'll get some of his royalties.

How about The Compleate Woodtuner by Walter Dart & Phil Hall

 

[hawkeyefxr]

You beat me to it. Sorry Phil no knock intended.
How about all you turning guys collaborating, it would be one extremely interesting read that for sure.

I avidly read all you words of wisdom here and in the pen section. I feel like a sponge soaking up all this wisdom, unfortunately at my time of life some now leaks away so i have to keep coming back. :-)

 

[Phil Dart]

No knock taken I assure you Ken. I know what you meant - I was just teasing.

If there's a book collaboration, bagsy I write the chapter on friction polish. It will be brief.

 

[Walter]

Who is Phil Dart anyway?

Seriously, it is good to see that people appreciate the sensible advice of people who know from experience what they are talking about and don't just listen to the snake oil salesmen and self promoters.

As Woody said earlier "there are some dodgy ideas out there that people show just to be different or its people who dont really know what they are talking about and give advice that can be very dangerous"

 

[Dalboy]

No knock taken I assure you Ken. I know what you meant - I was just teasing.

If there's a book collaboration, bagsy I write the chapter on friction polish. It will be brief.

Who is going to write the chapter on how to apply hair restorer then

 

[Penpal]

Well with Walter the Sage of Amble and Phil the Prince of Spean, Woody the Sherrif of Sherwood Forest this forum has a bright New Year. HAPPY NEW YEAR EVERYONE> Happens tomorrow here.

Peter.

 

[Winemaker]

What Woody says