chuck and tenon size for hollow form

[Martin Rock]

Hi all

I have been hollowing hf with my talon chuck with #3 jaws. the max opening of these jaws are about 4". So I thought that the bigger the tenon better as far as holding power. On a few occasions when I got catches, The piece did moved a bit in the jaws, making the thing running untrue. I do take care that the tenon does not bottom in the jaws and make a crisp 90 degrees shoulder.

I currently make HF up to 10" tall but eventually would like to go a little taller

My question are:

Is the talon strong enough for such hollowing? and should the tenon be sized close to the minimim jaw capacity?

thanks

Martin

[Scott Hackler]

Martin,

The tenon should be of a size that allows for the jaws to "almost" be completely closed. This maximizes the surface contact of the tenon to the jaws and makes for a very strong attachment. I am not familiar with the Talon #3 jaws so I don't know what the "closed" dimension is, but on my SuperNova 2 the basic jaws are 50mm (about 2" closed) I use these jaws for almost everything up to 10" diameter. I have another SN2 with 75mm jaws that I will use for larger diameter stock.

Of course a long / tall HF that isn't super large in diameter, will be less likely to catch with a steady rest attached. I wouldn't even think of turning a piece taller than 8" without my Nicol's steady rest. Even with a small catch, it can't move because of the support of the steady rest.

[Bill Wyko]

I'm with Scott, a steady rest is the key to successful stabilization of a tall vessel. Do a search here and you'll find members that have made SR's out of ply wood and roller blade wheels and those of us that bought them as well. I use a Keith Clark model.

[Tim Rinehart]

My question are:

Is the talon strong enough for such hollowing? and should the tenon be sized close to the minimim jaw capacity?

thanks

Martin
I don't think there is a problem with the Talon being strong enough. As for the jaws, the normal response offered is correct that the design diameter (near closed) is ideal...however, if you have the Talon with profiled jaws...you can grip well all the way thru the diameter range it offers due to the design of the grip profile, vs smooth jaws. Take a look here... http://www.oneway.ca/chucks/accessories/no4_jaws.htm

[Steve Schlumpf]

Martin - I use the Talon with the #2 jaws for just about everything I hollow. Every now and then when I turn something really large... then I will use the #3 jaws. Like Scott mentioned - if you are extending the wood 10" from the chuck - seriously check into either buying or making a steady rest. Makes a huge difference in stability!

[Baxter Smith]

Another possibility is to use the tower jaws. I used the #3 tower jaws today with my stronghold to rough out a 10" tall endgrain HF. I have a steady but didn't use it.

[Jack Mincey]

I use a stronghold chuck with #4 jaws for all my larger hollow forms and when coring large blanks. The only time I ever had a problem with this technique is when I did a demo on coring last summer for the brasstown woodturning club. The tenon cracked a touch when I cored my first small bowl out of the blank even with the tailstock firmly in place. The blank must have had a small flaw, but it did give me a chance to show the club how to remount a blank turn the old tenon off and put a new one one the blank and finish coring the set of bowls.
Jack Mincey

[Alan Trout]

I have done some pretty big hollow forms with the #2 jaws. The key is having a steady rest as already mentioned. I generally try to use the smallest jaws possible as it aids me in clearly seeing the shape of the piece. Driving the piece does not take a big tenon. Plus I always rough my pieces between centers so tenon size is much less of an issue. Now if you do not have a steady rest, size does matter. For the Talon chuck I would go with the #3 tower jaws in that case. But I would not be scared of using the Talon chuck. The largest hollow form I ever made was with my G3 chuck and it performed flawlessly.

Good Luck

Alan

[Roger Chandler]

My go to jaws for my SN2 and regular SuperNova on a larger HF is the "Power Grip" jaws......they are slightly over 3" when closed, but have room for a deep tenon and has serrated rings on the inside for even more gripping power. These are beefy jaws for the Nova Chuck line up........real holding power.

[Joe Meirhaeghe]

I have done some pretty big hollow forms with the #2 jaws. The key is having a steady rest as already mentioned. I generally try to use the smallest jaws possible as it aids me in clearly seeing the shape of the piece. Driving the piece does not take a big tenon. Plus I always rough my pieces between centers so tenon size is much less of an issue. Now if you do not have a steady rest, size does matter. For the Talon chuck I would go with the #3 tower jaws in that case. But I would not be scared of using the Talon chuck. The largest hollow form I ever made was with my G3 chuck and it performed flawlessly.

Good Luck

Alan
I'm in the same camp as Alan. I've turned a number of 300 to 450 lb logs into vessels, hollowing them up to 32" deep. I use either a Oneway strong hold or a Vicmarc V120 chuck with the standard # 2 jaws & a tenon of about 2 1/2 " on them. But I do always use a steady rest,so the tenon is just driving the piece Not Supporting it.

[Jake Helmboldt]

I'm in the same camp as Alan. I've turned a number of 300 to 450 lb logs into vessels, hollowing them up to 32" deep. I use either a Oneway strong hold or a Vicmarc V120 chuck with the standard # 2 jaws & a tenon of about 2 1/2 " on them. But I do always use a steady rest,so the tenon is just driving the piece Not Supporting it.
Joe, when you say you use standard #2 jaws on the Oneway, are you saying you don't use their patented profiled jaws? I personally don't feel like they offer an advantage (and perhaps are not as good as regular jaws), but I'm curious to hear from someone like yourself turning big pieces and using different brand chucks.

[Alan Trout]

Joe, when you say you use standard #2 jaws on the Oneway, are you saying you don't use their patented profiled jaws? I personally don't feel like they offer an advantage (and perhaps are not as good as regular jaws), but I'm curious to hear from someone like yourself turning big pieces and using different brand chucks.

Jake,

The #2 jaws are the standard profile jaws. I don't know if they have an advantage but I do know I kind of like that they function with a lot larger range of tenon size than a dovetail jaw. I call them my lazy jaws as I do not have to be so precise on the tenon size. With that being said I have never had a problem with any jaws holding my work. Dovetail, spigot, profile, they all work well if used properly.

Alan

[Bernie Weishapl]

I use the #3 jaws on my oneway chuck and make the tenon just a little larger than the diameter of the chuck fully closed. I do agree with Steve that if you have a large HF extending from the chuck a good steady rest is a must.

[Joe Meirhaeghe]

Joe, when you say you use standard #2 jaws on the Oneway, are you saying you don't use their patented profiled jaws? I personally don't feel like they offer an advantage (and perhaps are not as good as regular jaws), but I'm curious to hear from someone like yourself turning big pieces and using different brand chucks.
Jake I do use dovetail jaws on my Oneway strong hold chuck. I may take a piece on and off the lathe 3 or 4 times before I finish it. The dovetail jaws allow me to do this with ease. The serrated jaws that come with the Oneway would destroy a tenon trying to remount that many times.

[Martin Rock]

thanks all for you comments, I am sure learning stuff here. But there is one point I would like to clarify. What makes the strong hold to have a stronger grip on the tenon than the talon (does it really?). My guess is the amount of surface area of the tenon, the jaws comes in contact with. The greater the surface area in contact, the better grib.

If It is the case, for the same surface area in contact, does the stronghold have a stronger grib. and if so why.

Martin

[Curt Fuller]

One other consideration is the wood you're holding. End grain usually makes a stronger tenon than face grain. But regardless, if the wood isn't very hard then you can have trouble holding either. I do two things that seem to work for me. First I apply a liberal dose of thin CA glue to the tenon to help fortify it and then I tighten the jaws (I'm talking the standard #2 talon jaws with the teeth) until they bite into the wood. But once they start leaving visible bite marks if you go beyond that sometimes you're just crushing the wood which might actually weaken the hold.