Jaw question

[Burt Alcantara]

I'm going to begin turning boxes using 2", 3" & 4" square stock. I'm also turning 8-12" bowls which are wobbling on my G3. I'm thinking SN2 with something like the 75mm bowl jaws or Powergrip. I can buy either already installed in place of the standard 2" jaw set since I already have that on the G3.

Will any of the above mentioned jaws work with the stock that I've described? If not what would your suggestion be? Funding limits me to only one set of jaws at this time.

Thanks,
Burt

[Jim Ketron]

Burt sounds like something is going on with your tenon or your chuck.
I have turned some nice size bowls with the #2 jaws on my Talon and I have the G3 chuck also, and I would see no reason to turn any that you describe with what you already have.
here is a little checklist to help solve what may be your trouble.
1Check your chuck for run-out.

2 make sure the threaded spindle adapter is seated good on your chuck body

3 make sure your tenon has straight sides.

4 make sure your tenon is not too long, the bottom of the bowl/shoulder of the tenon should meet the face of the jaws on all 4 jaws.
I think it should be under 1/2" to do this with the #2 jaws.

[Burt Alcantara]

While I haven't measure the runout, the chuck feels and looks like an unmoving piece of metal while it runs. As far as tenons, never had a problem with small bowls but since they are getting into the poundage area the problems arise.

On my G3, the depth is 10mm which is smaller then 1/2". I'd like to go deeper and wider. I mount all of these blanks on the faceplate that came with the 1624. Once I get them trued then reverse they are out of slightly out of round. That's probably where a lot of the problem lies. I can't bear down much when hollowing because the bowl will usually pop out of the chuck.

Then there is still the issue of square stock...

Burt

[Gordon Seto]

Burt,

Since your chuck body seems to run true, then you don't have to worry about the chuck insert. There may have been some debris between your chuck slides and jaws preventing the jaws to seat properly.

Nova chucks use dovetail tenons. The keys to good gripping is the tenons not bottoming out (as Jim suggests) and a good fitting shoulder against the top of the jaw.

A picture of your tenon would help.

When making boxes, using the chuck to grip the square stock is just one option. You can turn the square stock between centers and make tenons on both ends for the chuck to grip. Using the standard jaws to grip square stock is not the preferred chucking method. It is very difficult to re-chuck a square stock to the same axis.

Gordon

[Bill Blasic]

Burt,
As Gordon states Nova uses a dovetail jaw. Your piece needs that dovetail to match. With your procedure of using the faceplate to rough out the bowl and the tenon you should not have a problem of knocking the bowl out of the jaw if you are using the dovetail on the tenon to match the dovetail of the chuck. A couple of face cuts across the face of bowl and any out of balance situation should be taken care of. I believe thr G3 can be used up to 14" bowls, I have two and they hold very well.

[Burt Alcantara]

Looking at my "problem" bowls, I see that the tenons are much too short. probably around 5-6 mm. Regarding the square stock, I must have had one of the fade outs not thinking about turning between centers.

Guess I really don't need another chuck at this point, just better technique, and perhaps, stronger coffee.

Thanks guys,
Burt

[Kurt Whitley]

I agree with others, the chuck should be good for the projects you describe. As you set it up, stay attentive of how everything seats (jaws and blanks) be sure that the flat of the jaws that faces the tailstock is seated in full contact with the wood.

Cheers,
Kurt

[Burt Alcantara]

Just to make sure, I broke out my dial indicator and measured the outside and insides of the chuck. Outside one jaw was .0300 out of alignment but inside the entire face was only .0020. No change on the chuck, measured from a few different spots.

Measured the faceplate on the spindle. Nothing.

I made some tenons 10mm deep with a slight dovetail. Bowls did not fly off the chuck. However, with these larger bowls I'm having problems getting them true round. When I do the outside I keep getting a tock-tock sound as the gouge cuts across. I'll take off a few inches and still get that out of round sound.

When I reverse the bowl it is way out of round. If I begin the hollowing process (with a 1/2" gouge) I can't seem to find center and get a lot of vibration. I've ended up resorting to my giant scraper to get the bowls hollowed. While this works easily and quickly, it is hiding the overall problem.

Never had this problem with my small turnings but then "the bigger they are, the harder they fall," so to speak.

Burt

[Steven Wilson]

I turn the outside with a face plate, turn the area for a chuck, mount the chuck on the tailstock, and then seat the chuck onto the tenon. When I then take off the faceplate and mount the chuck onto the drive all is usually well (not out of round enough to be an issue).

[Gordon Seto]

Does the headstock and tailstock line up on your lathe? Are you using the tailstock after you mount the bowl blank in your chuck?

Gordon

[Jamie Donaldson]

... the faceplate, and rough out the outside and make the chuck tenon between centers. The piece should then reverse in the chuck jaws with very good balance, bring up the tailstock to true the outside, then hollow the inside. Piece of cake!

[Burt Alcantara]

I measured the centers. The vertical offset is 1/64", the horizontal is 1/32." The margin of error is my ability to hold a piece of paper in one hand and a pencil in the other and making marks. Not sure how else to measure. Or for that matter how to adjust this to be dead on. Lathe is Nova 1624.

As far as turning between centers, the blank weighs about 17 lbs. I thought this might be too heavy to turn between centers so I mounted it on a 3 1/2" face plate using 2" brass screws.

Burt

[Bernie Weishapl]

As far as turning between centers, the blank weighs about 17 lbs. I thought this might be too heavy to turn between centers so I mounted it on a 3 1/2" face plate using 2" brass screws.

Burt

Burt I definately would not use brass screws. When I first started turning with a faceplate I used some of the brass screws because I had bins full of them. The second bowl I turned I had a catch and it went sailing across the room after it bounced off my shoulder because all four screws snapped. Now I only use Stainless Steel screws. Just my humble opinion.

[Gordon Seto]

The 1624 has a pivoting head, the horizontal offset can be adjusted. The size and weight should not be a problem with your lathe or G3 chuck.
You didn't say whether you are using the tailstock while you are using the chuck. When you are using both, any mis-alignment would cause you vibration.

But if you do as Jamie says, even your chuck has obvious off-set, once you get the blank true up; your blank doesn't know it is not running true to the lathe bed. You can even pivot the headstock, as long as you are not using the tailstock at the same time, you should not have problem turning the outside or inside of your bowl.

BTW, did you match up the number of dots on the jaws to the numbers on the chuck slides?

Gordon