Patriot Jaws - Ideal Spigot & Recess sizes?

[wizer]

I finally bit the bullet and went for a Patriot chuck recently. It comes with 50mm Jaws and I'm trying to work out the ideal sizes for both recess and spigot? I found thispage, But I don't think it's telling me what I need to know. Just the min and max capacity of the jaw.

Is there a formula to work out the 'perfect circle'?

 

[stevebuk]

IMO i would say the nearer to 50mm you are the more true the circle would be, but there will be others 'in the know' along soon.

 

[loz]

"

The standard jaws supplied with the Patriot chuck are the nominal 50 mm jaws (referred to by the nominal size of spigot onto which they will compress when set at their "perfect circle" diameter). These standard jaws will expand into a dovetail recess sized from 50 mm (2") to 75 mm (3"). In compression mode, these jaws will close onto a spigot, or bowl "foot", with a diameter from 42 mm (1.33") to 67 mm (2.33"). "

Not a great help - as most will actually tell you the circle dia !!

But i'd agree with Steve, the closer to the fully closed ( but giving allowance for the curf from when the block was cut ) .

Regs

Loz

 

[wizer]

I've been using 50mm for both but I'm getting marking even with light pressure. I've have to play with it.

 

[loz]

I've been using 50mm for both but I'm getting marking even with light pressure. I've have to play with it.

It'll be close to 50 ( maybe 52 or 53 ) in expanstion mode - ie in a recess.

and close to 42 ( maybe 43 or 44 ) in compression - arround a spigot.

which mode did you get marks at 50 mil on your work ?

 

[wizer]

Both.

I want to make a marking tool so I don't have to set the dividers\callipers each time.

 

[Dalboy]

Have the same problem Wizer so made one of these https://www.ukworkshop.co.uk/forums/view ... hp?t=31524[/url]

 

[Bodrighy]

Ideally you need your spigot to be as close as possible to the minimum measurement which is when the jaws are slightly open. If you are getting marks then try, carefully, not tightening up so much. Alternativelly put some tissue paper or paper towel in between the chuck and the wood. If you tighten too much you are in danger of crushing the wood and the tenon will possibly weaken and snap. This is especially true of softer woods. If the jaws are the same as on the supanova the inside is angled so that the tenon needs to be a dovetail dominishing from the outside to the inside.

Pete

 

[CHJ]

Tom, have a look at the Nova Manual Page 20.

http://www.teknatool.com/products/Chuck_Accessories/General/downloads/Accessory Jaw Manual_Nov07.pdf

The Patriot is marketed as compatible so dimensions may be relevant. I can only see an optimum for recess but at lest this would alow you to check and measure true round etc.

There is some useful guidelines in there as well regarding sizes of work and recommended loads etc. for different jaw sizes.

 

[Old Dave]

I have heard it said - but don't know how true it is - to allow 1/8th inch opening between the jaws. This should give a perfect circle of grip.

If you have a 1/8th parting tool just slot this in the gap and then measure the inside or outside diameters.

Other than that - trial & error seems a good method.

 

[big soft moose]

I dont think some marking is avoidable to be honst tom - as any pressure sufficient to hold onto a fast spinning piece is bound to also mark the timber where the jaw contacts.

what you need is a way of rechucking the tother way up so you can clean up the recess or turn away a spiggott.

 

[wizer]

Cheers Pete. I was mainly wondering if there was a published or accepted way of working out the 'perfect circle'. You're right, I need to sort out a reverse chucking solution soon. I'm thinking home made cole jaws. Add that to the tuit list.

 

[boysie39]

Tom .Ihave some Andy Lodge DVDs abd his suggestion is as Old Dave said a 1/8"blade is used to cut steel into four sections and the nearer you can get to that the less markings. their is also a dovetail involved which makes a big differance IMO. REgards Boysie.

 

[CHJ]

Cheers Pete. I was mainly wondering if there was a published or accepted way of working out the 'perfect circle'. You're right, I need to sort out a reverse chucking solution soon. I'm thinking home made cole jaws. Add that to the tuit list.

Tom I take it you do not have any vernier calipers, if you can borrow some it's just a case of adjusting the jaws until you have a true circle (same dimension all round) and then noting the internal and external dimensions.

 

[wizer]

I do have a set of digital callipers and will try your advise, thanks Chas.

 

[Woodmagnet]

Have the same problem Wizer so made one of these https://www.ukworkshop.co.uk/forums/view ... hp?t=31524[/url]

Great idea. 8) 8) 8)