Vic Marc mega dovetail jaws

[Breck Whitworth]

I would like to hear from someone who like me cores large green blanks around 18 to 19" in diameter. I recently bought the oneway easy bowl coring system. Up until now I have always used a 1"+ power grip jaws to grip green blanks for coring, but would like to switch to the vic marc mega dovetail jaws to save a little depth for coring purposes, Here is what I need to know, what size dove tail jaws do I need for 18 to 19" massive wet blanks the 5" 6" or 7" jaw set. I am thinking the 6" set of jaws will work safely, but I really want other turners experience and advice as to size of jaws to order for my vic marc 120 chuck. Thanks I have always relied on a longer tenon that was not very wide so I have never really had to grip a extremely wet and heavy blank with a wider and narrow tenon. Thanks for any help you can give me.

 

[robo hippy]

Breck,
I cored a 22 by 7 inch diameter Madrone bowl with a 5 inch wide recess. No problems. I used the McNaughton, and had to break off a 2 inch tenon at the bottom of the biggest core. Going deeper than 1 inch with either a tenon or recess doesn't gain you any strength advantages that I can tell. To me it is more about fit than about depth.

robo hippy

 

[JeffSmith]

Breck - I’ve got a set of 4” vicmark jaws that I use for all blanks larger than 12 inches or so, up to 22” when coring using the Macnaughtom. They haven’t failed me yet with the wettest maple and madrone blanks. Tenon usually about 5/16s...good step turned to mate with the jaw faces; lathe is Robust AB 3 hp. Can’t see needing anything larger. Used the same setup with a 24-1/2” platter without issues.

 

[olaf Vogel]

Oneway 4" is all I ever needed. Just crank them down hard

View media item 14718

 

[Breck Whitworth]

ok thanks for all the input guys

 

[Bill Boehme]

Personally, at my early stage of coring I prefer much larger jaws. For something that is 20 inches in diameter I would probably use the 223 mm jaws (I think that Craft Supplies calls them 9" jaws). I have a large piece of box elder that I plan to core when I am sufficiently recovered from back surgery. The largest core will be about 20 inches and I just bought the 223 mm jaws specifically for holding that piece.

 

[John Spitters]

I’ve done a lot of coring and have never felt that I need to go larger than 5” on my tenon.
This would be for a maximum 23” block to be cored.
I have a Vicmarc VL300 with slightly less than 24” of swing and I use the OneWay coring system.
What is of the utmost importance is the quality of the tenon, both in wood structure and how it is shaped to fit the jaws of your chuck.
For coring the large blanks I will generally use a V150 chuck. The 5” dovetail jaws in their closed position are at 4 1/2” so generally I’ll make the tenon slightly less than 5”, you don’t want to have your jaws opened to much because you will have less positive contact with the tenon.
So form your tenon with clean shoulders, the depth of my tenons are only about 3/8”-1/2”, and you need to make certain that the face of your chuck jaws have positive contact with the base of your blank next to the tenon.
If I had an exceptionall deep blank of 23” x 9” or more then I would use the same jaws but with a recess rather than a tenon.

 

[Paul M. Kaplowitz]

I turn bowls that are 19 to 24", and core them with the Oneway system. Many of the blanks weigh over 100lbs and require a shop crane to lift them. The largest jaw set for my vic 150 gives me a max grip of 91/2". Although I have never had a problem with using the third set which gives me a grip of 63/4", with real large blanks I prefer the biggest set. These jaws fit the 120. I just finished a 33" bowl using the # 4 set.

 

[Paul M. Kaplowitz]

The only difference between the 120 and the 150 is that you can unlock the back ring from the jaws and instead of twisting the key to tighten or loosen, you can put the key into the hole and rotate the entire ring which moves the jaws very quickly.

 

[John Spitters]

Yes I can fit the same jaws on the V120 as what I have on the V150, and there is no doubt that I could be using the V120. However I have the 5” jaws set up on the V150 plus my V150 is a direct thread to the spindle (no thread adapter insert) as a side note I also have jaws that go up to more than 7” in their closed position for this chuck but have never seen the need to use them.

 

[Bill Boehme]

I presume that it is preferable to size the tenon so that it is close to the perfect circle diameter of whatever jaws you are using?

 

[John Spitters]

The only difference between the 120 and the 150 is that you can unlock the back ring from the jaws and instead of twisting the key to tighten or loosen, you can put the key into the hole and rotate the entire ring which moves the jaws very quickly.

The V150 is a larger and much heavier and more robust chuck probably an additional 3 lbs+ in weight. Weighs 5 kg without the jaws, it’s one heavy chuck.

 

[Breck Whitworth]

Since I will be using my new easy core system to core many bowls in the future. I am gaining as much good advice and proper techniques I can that will help me. Our forum here is a gold mine of information from fellow turners with hands on experience for so many, especially me. John since you and many other turners use the one way easy core system please tell me what is the best way to put a tenon on these cored bowls if you don't have a vacuum chuck. When ever I used the wood cut I would put a tenon on the inside face of the bowl to be cored, then it was easy to chuck it and then form a tenon on the reverse side. I really don't want to spend more money on a vacuum system.

 

[hockenbery]

An easy way to put tenons on is do the small core first.
Reverse chuck it in the opening it came out of turn the tenon
Do the next core reverse it where it came out of. And so on.

This works more efficiently if you are coring 3-4 blanks then you can put tenons on all the small ones at one time.
Maybe the two smallest fit nicely in the opening from the second smallest.
I want the tenon area i’m Turning to be proud of the opening it is jammed into.

It is easy to center a core in the space it came out of you just have the kerf difference so it will be close to the rim and eye ball it even.
Also the center where it breaks free can be used to line it up too

 

[Breck Whitworth]

One more question gentlemen, what size threaded rod do I need to buy so I can replace the ones that come in the easy core knife sets? adjusted all the way out, I am still a little over a 1/2" short of dead center with my American Beauty which is 25-1/2 + from bed to center! I need the size of threaded rod to buy that will fit the nut they provide or I can buy new nuts to fit whatever the threaded rod is that will screw into the knife sets

 

[Bill Boehme]

..... I am still a little over a 1/2" short of dead center with my American Beauty which is 25-1/2 + from bed to center! .....

Maybe 12¼" from bed to center.

 

[Paul M. Kaplowitz]

I just drop some washers into the tubes that hold the support finger and the one that holds the knife until I'm on center.

 

[John Spitters]

Inset into the bottom of the support tubes are short lengths of cold rolled rod, just purchase a 12”length of this rod and cut new pieces to replace the ones already in there, you will need to make the new ones 1/4” - 3/8” longer.

 

[John Spitters]

Since I will be using my new easy core system to core many bowls in the future. I am gaining as much good advice and proper techniques I can that will help me. Our forum here is a gold mine of information from fellow turners with hands on experience for so many, especially me. John since you and many other turners use the one way easy core system please tell me what is the best way to put a tenon on these cored bowls if you don't have a vacuum chuck. When ever I used the wood cut I would put a tenon on the inside face of the bowl to be cored, then it was easy to chuck it and then form a tenon on the reverse side. I really don't want to spend more money on a vacuum system.

Nothing wrong with the way you are currently doing it.

Generally when I do coring I’ll do several blocks at the same time, it’s seldom a one block setup.
I’ll first rough turn the outside profile of all my blocks first set up between centers and put on my tenon.
Then I will mount each block and do a recess in the face of each before I setup for coring.
Once all the blocks have been prepped I’ll begin coring doing the largest core first, once I’ve taken the largest core out of each block I’ll pull back my knife setup and mount these core outs with my jaws expanding into the recess on the face of the core outs and put tenons on each of the core outs. I’ll then set the knives up again for the next core outs to come out of these then repeat the process till I’ve finished with the smallest coreout.

 

[Breck Whitworth]

Maybe 12¼" from bed to center.

oops, thanks for the correction, that would be one big lathe though