What Size Jaws for Larger Bowls for SN2

[Mike Peace]

CSUSA is running a sale now on Nova jaws.

I have a PM3520b and a Supernova2 chuck. Which set of larger jaws would you consider the most versatile and why?
3"
4"
5"
or Powergrip

I am beginning to turn some 12 -14" bowls that are approaching or outside of Tecknatools recommended size for the 50mm jaws. I have not done any hollow vessels yet but probably will eventually. I already have 35mm bowl jaws, 35 mm spigot jaws, 50mm bowl jaws and the long nose jaws since I got them all used with my first lathe, a Jet mini.

[Bob Hallowell]

I only have a psi barracuda 2 but I turn alot of 12"-14" bowls and have only used the 2" jaws.

Bob

[curtis rosche]

if its a good sale i would say get one of each, you never know when you light need a different one.

some people have only a few, then there are some like Scott H., who have about 6 chucks if not more and have one jaw on each so that he never has to change the jaws, just the chucks.

it all depends on what you want to spend

[Jim Becker]

Unless you are turning extraordinarily large pieces (and they may need special handling anyway), I don't see much reason to go beyond about 4" for a tenon. What is most important is to match the tenon size to the "ideal" sweet spot for the particular jaws you are using and be sure that 1) your tenon is not bottoming out in the chuck and 2) you have a small shoulder on the workpiece that can rest on top of the jaws for maximum support.

[Jason Clark2]

I also have the 3520B and a pair of Supernova2 chucks. One has the standard 50mm jaws and the other has a pair of Powergrip jaws.

I do quite a bit of coring, usually Mesquite in the 14-18" range and the Powergrip jaws are more than up to the task.

I'm much less concerned about matching the dovetail shape of the jaws or matching the size of the tenon to the closed size of the jaws. I'm looking to make the tenon as large as possible to prevent it from shearing off.

Jason

[Jim Becker]

I'm much less concerned about matching the dovetail shape of the jaws or matching the size of the tenon to the closed size of the jaws. I'm looking to make the tenon as large as possible to prevent it from shearing off.

These two things can be opposed to each other. You get the best solid grip when the tenon is sized to match the "sweet spot" of the jaws...more contact = stronger grip & and better support. The tenon will be less prone to shearing off during a catch that way. The shoulder I mentioned in my previous post is also important in this respect. The tenon is more at risk if the workpiece gets knocked out of plane and that's more likely to happen during a catch, etc., if the grip and support is not solid.

[Richard Madison]

Ditto everything Jim said, and 4". Why 4"? Well, 3" not much bigger than the 50 mm that you have. And 5" is really overkill for most projects.

[Reed Gray]

I use a recess, and core. I do bowls up to 18 inches this way with my big Vicmark with jaws that are 2 5/8 inches wide. I do match the angle of the dove tail and the angle as close as possible. Plain and simple, you get a better grip. I did turn one that was 21 inches, and used the big jaws which are 5 inches across. Not a bit of wobble. 3 inch tenon on a 12 inch bowl is doable, but minimal. 3 inch tenon on a 15 inch bowl might work if you don't core, and never have a catch. Matching the dove tail angle and size give more metal on the wood and better holding power.
robo hippy

[Mike Peace]

So I am hearing recommendations for a 4" jaw set. On the SN2 this will hold a spigot 3 - 3.9" with closer to 3" being the "sweet spot". The Powergrip jaws have about the same spigot and recess capacity but seem to be advertised as more for gripping end grain spigots for hollow forms.

Anyone with the Powergrip and the 4" bowl set have a recommendation as to the most versatile? At this point I am leaning toward the Powergrip jaws since it appears that they would probably do ok for bowls in the 12 - 14" range and probably better than the 4" jaws for hollow forms. Though it may be a while before I tackle hollow forms.

Unfortunately, Curtis, but "get one of each" is a little outside of my budget.

[Gary Max]

I agree-----SN-2 and 4 inch------if you really need big ----Titan and 5 inch jaws are a nice match.

[Mike Peace]

I agree-----SN-2 and 4 inch------

Gary, I said I am leaning toward the Powergrip vs. the 4" jaws. Just so I understand, are you saying you like the 4" jaws better than the Powergrip? If so, help me understand why.

Anyone else got an opinion on which would be more versatile?

[Gary Max]

Really don't know about the power grip jaws-----I have two SN-2's-----my thought is nothing bigger than 4 inch. When you move up to 5 inch jaws you are really going to give the chuck body and lathe a work out. The only lathe I run 5 inch jaws on is my big Powermatic.
I looked up the Powergrip jaws and they look like a good match to the SN-2

[Chip Sutherland]

Unless I just missed it, I didn't see anyone mention the 75mm bowl jaws for the SN2. I use them a ton. My 50mm are gathering dust. The 75mm bowl have a bigger flatter top making it easier to mount a bowl. I also use the spigot jaws...which I think are identical to the bowl jaws but for whatever reason have a different name. What I like about both is they can grip a tenon wonderfully...especially for HF work. The spigot jaws will even grip up to 1 3/4 square stock so I don't have to hunt down my spindle chuck so so I can round-up some square stock like for finials.

I have the 4in and only use them for platters and occasionally bowls that I know will have a wide foot which are usually 12 or greater.

That's my 2 cents.

[Steve Kubien]

I'm with Chris on the 75mm bowl jaws. I have those, #2, 50mm jaws and #1 jaws mounted on my 3 chucks (SN2's for the bigger sets and a Nova Midi for the #1's). I love 'em.

Steve

[Mike Peace]

Chris, from the pictures at the Teknatool site and description it appears that the 3" would be a better bowl jaw set than the 50mm for many bowls I do. It just seems that if I was only looking to get one set of jaws for larger bowls (and platters and perhaps HFs in the future), skipping over the 3" to a 4" or Powergrip would seem to make more sense. But, I don't know so that is why I am asking for folks that have experience with the various larger jaws. Except for platters I tend to use the contracting method and part-off the tenon. It appears to me from the Teknatool literature that they favor the recess method for bowls so perhaps I should explore that more.

I see CSUSA has a simple chart for SN2 jaw size to max bowl size:
2" up to 8" bowl,
3" up to 12" bowl,
4" = 16, &
5" >16
I do not think I will be doing bowls larger than 16".
Teknatools info on the Powergrip says it is good for up to a 16"x6" bowl in recess mode and an 8X12 in spigot mode for a HF. It just looks to me like the Powergrip would be the most versatile. But this is based on reviewing and trying to understand the confusing specs and not on experience. I am sure there is some compromise but it is not clear exactly what the tradeoffs are.

[Harvey Schneider]

Mike,
I have been through the same decision making process, and want to offer a couple of thoughts.
The size of the chuck will influence the size of the base on you work. A four inch chuck really doesn't work with anything smaller than about a 13" bowl. I say that because the foot should only be about 1/3 the max diameter of the bowl and you need some wall thickness for the chuck to bear against if you mortise the chuck into the bottom of the bowl. Even if you use a tenon, the jaws will be in the way when you are defining the shape of the bowl. You should, if possible, have a few choices of chuck size in order to not have the chuck dictate the aesthetics of the work.
IMHO, a too small foot usually looks better than a too large foot.
The three inch jaws have tremendous holding power, I have a done 13" bowl on the three inch, and a 15.5" on the four inch jaws. I never felt that there was any danger of their losing their grip on the work.

I hope this helps,
Harvey