Outboard turning piece pieces procedure?

[Acharya Kumarswami]

I posted a question about outboard turning big pieces and got some good advice. I haven't gotten the lathe bed extension for the powermatic that will allow for this, but I'm thinking through the process. Those who are adept at this: do you follow the usual procedure of fastening the rough blank to a faceplate (in this case I'm going to get a 6" faceplate), to turn the outside of the bowl and put a tenon on it, and then mounting it in a chuck to turn the inside? I guess my question is this: is a Vicmarc 5-1/2 chuck adequate to hold a large piece for turning?

[Dave Ogren]

Every thing that I turn is similar to outboard turning as I do not have a tailstock, bed or ways. I usually use a 6" face plate with 6 #14 screws. The hex shaped blanks are 28 to 30" corner to corner and weigh I am guessing close to 100 pounds. I have never used a tennion but always cut in a dovetail recess about 2 3/4" in diameter for a Vicmarc 120 chuck which is 5" in diameter. I have never lost a part and I think that I take a lot of agressive cuts. I don't think that you will have any problems.

Good Luck and happy turning,

Dave

[Acharya Kumarswami]

Thank you so much! That is a brilliant way to work. I have the Vicmarc 100 chuck. Do you think it is adequate for big pieces using the 2-3/4" recess? I can see with this system, you don't have to worry about turning the bowl around when you come to do the final turning after the pieces dries: just put it back on the recess and finish the inside and the outside. Am I right? It seems that this system could be used for any size bowl, eliminating the need for soft jaws and jamb-chucks.

[Dave Ogren]

I am not familiar with the Vicmarc 100 except that I know that it is smaller, and would require a smaller dia. recess, I think. The Vicmarc 120 jaws are about 2 5/8" dia. when closed. Here is the problem....When the bowl dries everything warps including the recess. I turn some what larger because of that, ( 2 3/4" or more) if I turned just over 2 5/8" dia. most of the time rhe recess is too warped to re-chuck. Having said that I always finish turn when green and let it warp, and only sand when dry. I have never re-turned. You are right, no soft jaws, no jam chucks, no vacuum. When I was getting into turning and was trying to figure out the easy way etc. I picked two masters to read a lot of their posts so I could learn. They are Leo Van Der Loo and Reed Gray AKA Robo Hippy. I think that these two guys are primarily bowl turners and that is what I wanted to learn about. They probably forgot more than I will ever know.
Good luck and happy turning,

Dave

[Bob Bergstrom]

Roughing a big bowl is probably the easier part of big bowls. Wood is wet and turns easier, warpage is too bad yet, and wet wood also dampens some of the vibrations. when finishing a 20+ inch bowls some of those problems can raise some real problems. If you try to finish relatively thin, the harden wood can start to change shape and warp. Get the rim turn and don't try to go back. If the rim has some thickness and the belly of the bowl is thinner it can set up a resonance and vibrate like a drum leaving some bad looking groves(light cuts and lot of patience usually are in order). Then if you are lucky and it didn't change shape too much you should be able to jam chuck in some kind of capture chuck and duct tape to hold in as a safety belt to turn the bottom. I have a Oneway Stronghold Chuck and a use about a 5" tenon. I wouldn't even try to hold it on a smaller one.:eek:

[Acharya Kumarswami]

I will look for those posts as well. So am I right that your finished pieces would maintain the natural warpage? How does it go when you are sanding one of those after it dries, if it is not trued-up?

[Bob Bergstrom]

When I sand any dried bowl it is a slow speed (under 100). Warpage is dependent on reactionary forces in the wood. If bad, I power sand with the lathe off. I use a close quarter Milwaukee drill. On a big platter that has some tool marks on the inside I once got out my 5 inch orbital. Whatever works.

[Dave Ogren]

I agree with Bob. I sand as slow as the lathe will go, also run the sander at a real low speed. I don't have the Milwaukee-Souix drill . I have the much cheaper copy cats...$30 to $50 price range.

Dave

[Neil Strong]

I posted a question about outboard turning big pieces and got some good advice. I haven't gotten the lathe bed extension for the powermatic that will allow for this, but I'm thinking through the process. Those who are adept at this: do you follow the usual procedure of fastening the rough blank to a faceplate (in this case I'm going to get a 6" faceplate), to turn the outside of the bowl and put a tenon on it, and then mounting it in a chuck to turn the inside? I guess my question is this: is a Vicmarc 5-1/2 chuck adequate to hold a large piece for turning?

Acharya - I work this way almost all the time. I have that bigger Vicmarc chuck (along with many others) and readily hold pieces up to 750mm/30" diameter in them. I use the larger diameter jaws for the larger pieces. Any of the following jaw sets will fit on the larger Vicmarc chucks.

Dovetail 128mm (http://www.vicmarc.com/default.asp?contentID=576)
Dovetail 148mm (http://www.vicmarc.com/default.asp?contentID=707)
Dovetail 173mm (http://www.vicmarc.com/default.asp?contentID=708)
Dovetail 198mm (http://www.vicmarc.com/default.asp?contentID=709)
Dovetail 223mm (http://www.vicmarc.com/default.asp?contentID=710)

I find turning bowls outboard in this way the most pleasant way to work.

[Acharya Kumarswami]

Sounds great. So simple. I'm wondering if my Vicmarc 100 would be sufficient to turn large pieces. I have the 5" jaws, which is the largest it takes.

Also, Dave mentioned that he uses a 2-3/4 recess to fit the stock jaws. They differ from the other dovetail jaws in that they have that platform around the jaws. I wonder if Dave uses this jaw set because of that feature. In other words, would that steel base give more stability than the jaws that don't have that flat surface around the jaws? I hope that is clear.

[Neil Strong]

Sounds great. So simple. I'm wondering if my Vicmarc 100 would be sufficient to turn large pieces. I have the 5" jaws, which is the largest it takes.

Also, Dave mentioned that he uses a 2-3/4 recess to fit the stock jaws. They differ from the other dovetail jaws in that they have that platform around the jaws. I wonder if Dave uses this jaw set because of that feature. In other words, would that steel base give more stability than the jaws that don't have that flat surface around the jaws? I hope that is clear.

I wouldn't push the VM100 much beyond about 24" diameter. Anything above that you should be thinking about a bigger chuck.

That platform on the outside of the standard jaws is just there to reach the outer screw holes and has nothing to do with the strength of the actual jaws.

[Dave Ogren]

Neil is right. I bottom out the jaws on the inside of the recess. Meaning I cut the dovetail recess only about 3/16" deep. I hope that makes sense.

Dave

[Acharya Kumarswami]

Thanks so much, Dave and Neil, for sharing this info!
Soooo helpful.