Drilling on lathe and blank size

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Woodchipper

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After watching the video on another thread, I had stated that I drilled some hardwood on the lathe. The label said 3/4X3/4X36. However, the blanks were a bit loose in the jaws. This is a Supernova 2 lathe with the long pen jaws. As a result, the holes were oversize. :mad: I marked them as 7 mm+ for future use. I got curious and tried some acrylic blanks that were drilled and had the tube inserted. These were from Woodcraft- I have a store close to my home. The jaws were turned down as far as they would go. A couple of blanks slid in with no trouble, indicating a loose fit. Others did not fit and would have required loosening the jaws a bit for the blank to fit snug. Obviously, not all blanks are what is indicated. What is your experience here? What can be done besides drilling on the drill press? I have concluded that when I cut my own blanks, the dimensions will be over 3/4 square to fit the chuck jaws.
Thanks in advance.
 
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I can tell you this... I have made some beautiful pens with some itsy bitty blanks. When I buy expensive wood I try to make it last and turn as little as possible into sawdust. For me the answer would be to find a better way to hold them on the lathe rather than require larger blanks for everything. I've gotten to where I'll cut some wood just over the bushing size because I'm confident I'll drill it straight. Of course, I'm a neanderthal and still use my drill press and a square... :eek:
 

Woodchipper

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The pen jaw number is 6034, l isted as the Nova Pen Plus Accessory Jaw. It seems that all my acrylic blanks are not exactly 3/4x3/4. The chuck is a Supernova2 chuck, not lathe as I stated earlier.
 

KenV

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Checked mine on a SN2 and the calipers reads 0.470 flat to flat with the jaws closed. Have used 1/2 inch blanks with success (corian).

Sounds like a opportunity to take the SN2 apart and check the gear and slides.
 

Woodchipper

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KenV, I just checked the chuck and this is what I saw. I'm going to call the part that screws to the chuck body the base. The edges of the four jaws/bases are touching adn can't tighten down anymore. I sent Teknova an email to see what the minimum size of a square would be. Hope I hear from them.
 

Marcros

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you have something wrong there. the spec states:

Sizes:

Square (Contracting) Grip : From 0.3937” up to over 1”. Length of turnings from jaws up to 9”

Rounds (Contracting ) Grip: From under ½” (actual: 0.4561”) up to over ¾”. Length of turnings from jaws up to 10”

Rounds (Expanding) Grip: From 1.37” up to over 2.5”. Length of turnings from jaws, up to 10”

do you have a pic of the jaws on your chuck?
 

Woodchipper

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I'll have to get one later.
Here is what I got from CS-
"No worries, then your jaw range is going to be at 0.394-1.220 when contracting. I have attached our jaw range specification table for future reference as they do differ between different chucks. Please contact us back if you have any additional questions or concerns and we will be more than happy to assist you."
Will print off the chart.
 
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KenV

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John, I have 2 jaws set opposite of each other for Pen Jaws

I have 4 piece PIN jaws.

Do you have two sets of Pen Jaws mounted??
 

tomas

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One of the first things I bought was PSI's Dedicated Pen Blank Drilling Chuck, and I've been very happy with it. It'll handle blanks up to 1 inch. Just out of curiosity, what is the model number of the Nova jaw set?

I first bought a Super Nova chuck set and ran into the same issues. However, I concluded that the problem was using a 4 jawed chuck when what I really needed was two jaws. I, too, purchased the PSI Dedicated Pen Blank Drilling chuck and will not use anything else. I experiment with the blanks to see which end spins the truest. This works regardless of the dimensions of the blank.

Tomas
 

KenV

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John, the metal pieces with hole that the jaws screw to are called "slides".

They should come together with the pointed ends nested together when the jaws are closed. With both screws into the slide for each jaw there should be no gaps beyond about 1/64th of an inch. The space between flats of jaws should be less than 1/2 inch.

Are the points of the slides together fully closed?
 

Woodchipper

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Ken, they don't meet. Would I need to change the position of the jaws? Might that be the problem? I'll be in Chattanooga this Thursday- grandson is taking a pen turning class at Woodcraft. I'll take the chuck with me and let them look at it. Thanks to all for your replies.
 
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Woodchipper

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Pen jaws

It shows the jaws completely closed. Do I need to take out the pieces between the jaws? Just noticed this. Duh!!!! And to think I stayed at a Holiday Inn Express once!
IMG_20171031_071444373.jpg
 
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Woodchipper

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I answered my own question. I removed the two jaws and the pen jaws snug down to within a 1/16 inch of each other. Measuring between the flats reads about 1/2 inch. Believe it or not, after I removed the two jaws, I got curious and read the instructions for the pen jaw installation. There was no mention of removing the two jaws to allow the pen jaws to close. Live and learn. Now I can make drill smaller blanks as we all know that some pens like the Slimline turn down to a very small diameter part. Seems a shame to start out with a 3/4x3/4 blank and turn off most of it to land on the floor of the shop.
Again, many thanks for all the replies from the forum folks. :bananen_smilies051:
 
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