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Theory of screw chucks

John Kelsey

John Kelsey

Joined
May 22, 2017
Messages
101
Likes
132
Location
Lancaster, PA
Kai Koethe, our good friend from Frankfurt, Germany, led a terrific discussion of screw chucks for woodturning, how and why they hold, and how to get the most out of them. Here's the video, from Lancaster Woodturners Weekly Coffee Hour. BTW our coffee hour is free and open to all woodturners, it's a brisk hour entirely devoted to woodturning and woodturners. Message me if you'd like a link.
View: https://youtu.be/8HpenD9nQc0
 
Early on when I bought one of my first chucks, I had the screw break off and a piece went flying. I'm quite sure my technique was at fault, not sure if there is a limit to the size of the blank or was it my chuck face was not perpendicular to the screw, but at this time, the two new screws that came with the last two Vicmarc chucks I bought have never been used. I hope this video can be added to the tips and tricks section or remains available. I will be watching it soon. It will really have to be convincing to make me try this method again as that was the only time I had a piece come completely off the lathe, and scared me bad enough to almost have a runaway with my legs......
 
I just watched the video, I think my problem was I was not drilling and mounting the screw on a piece that I had made sure there was a perpendicular plane for the jaws of the chuck that held the screw to ride on. I think as I tightened the screw the last little bit where the piece hit the jaws, it was stressing the screw to the point it finally broke. The second thing I was doing wrong and he mentioned it in the video was the piece I was mounting was large enough to screw on a faceplate and most of my work is. As I said, this was very early in my turning and my learning curve was at it's greatest.
 
Marvin Jones said:
I just watched the video, I think my problem was I was not drilling and mounting the screw on a piece that I had made sure there was a perpendicular plane for the jaws of the chuck that held the screw to ride on. I think as I tightened the screw the last little bit where the piece hit the jaws, it was stressing the screw to the point it finally broke. The second thing I was doing wrong and he mentioned it in the video was the piece I was mounting was large enough to screw on a faceplate and most of my work is. As I said, this was very early in my turning and my learning curve was at it's greatest.
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Was it a Vicmarc screw that broke? I can't imagine the force it would take to break the Vic screw I got with my VM120. It's a beast. It works great for me.

Now the screws that come with the Nova chucks are a bit smaller and a lot shorter. I've had those let go of the wood a few times. Now, I will only use the Novas on rare occasion where needed on something not too big.
 
It was a Vicmarc that came with my first 120. I was using the big jaws that came with the chuck so the piece was pretty good size, like I said, I was trying to turn a natural edge bowl so the surface was not flat so it's no telling the stress put on the screw when the first part of the wood started pressing on the edge of the jaws, then I really twisted hard to seat it. It broke after a couple of cuts with a gouge. I usually turn bowls so I got into the habit of using the face plate and have not looked back. I'm not a big guy but if an anvil can be broken, I would be the one......
 
John Kelsey said:
Thanks for asking, I don't know any way to post a video to the AAWForum besides linking to it this way, maybe the mods will see this and help out. But this video will remain up on our club website, lancasterareawoodturners.org and also on my YouTube channel, https://www.youtube.com/c/JohnKelseyArtisan
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That's the only way John, we do not have enough room to store videos, a link to where the video is, YouTube, Vimeo, etc.
 
Tom, I know of three cases of a broken Vic woodworm screw.
Same guy that broke them though... Never happened to me.
I prefer the one made by Oneway. The screw thread seems to work better.
 
Marvin Jones said:
... I hope this video can be added to the tips and tricks section or remains available. I will be watching it soon...
Click to expand...

You may only post original content created by you in the Tips & Tutorials forum. This doesn't mean that you are necessarily the first person to have ever had the same idea. It just means that you aren't plagiarizing someone else. Your tip or tutorial could also be a novel approach for accomplishing a familiar task. In addition to what Emiliano said about "attaching" videos (or images or any other digital content) for which you aren't the copyright owner is a violation of the Digital Millennium Copyright Act of 1998. So, embedding a link to the file on YouTube or Vimeo etc as John Kelsey did is the correct and only way allowed.

Regarding your concern about content disappearing, we have no control over what happens on other websites such as YouTube. However, content created on the AAW forum has been remarkably permanent in the nearly eighteen years since the forum's first post in April 2004. You can bookmark posts so that they will be easier to find later.
 
Bill Boehme said:
You may only post original content created by you in the Tips & Tutorials forum. This doesn't mean that you are necessarily the first person to have ever had the same idea. It just means that you aren't plagiarizing someone else. Your tip or tutorial could also be a novel approach for accomplishing a familiar task. In addition to what Emiliano said about "attaching" videos (or images or any other digital content) for which you aren't the copyright owner is a violation of the Digital Millennium Copyright Act of 1998. So, embedding a link to the file on YouTube or Vimeo etc as John Kelsey did is the correct and only way allowed.

Regarding your concern about content disappearing, we have no control over what happens on other websites such as YouTube. However, content created on the AAW forum has been remarkably permanent in the nearly eighteen years since the forum's first post in April 2004. You can bookmark posts so that they will be easier to find later.
Click to expand...
I will certainly keep this in mind regarding requests of this nature, my apologies to all.
 
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