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Got a Screw Loose

Dave Fritz

Dave Fritz

Joined
Jul 24, 2008
Messages
729
Likes
203
Location
Montfort, Wisconsin
Ok, my wife tells me this all the time - anyway -

I'm using a Super Nova 2 chuck with 50 mm jaws. When I use the screw drive in the chuck it comes loose. I've looked at the Nova tech sheet and am using it as directed.

I have the tail stock up against the blank and can tell the screw is coming loose by feeling a slight wobble in the blank. when I stop the lathe, sure enough the screw is loose.

Is this a common problem with the Super Nova or is there a fix I'm missing?

Thanks,

Dave F.
 
I have the smaller G3 and I have this issue when I don't line up the flats on the screw with the jaw slider bars on the chuck, that could be your issue
 
Greg, thanks for the reply. I've made sure I'm following the directions supplied by Nova but someone suggested I may have trouble if the blank isn't made round on the band saw. Actually that may well be the problem as I use the screw chuck to rough out the bottom and cut in a tenon. I'll really true up a blank and see if that makes a difference.

What size hole do you drill for the screw threads?

Dave F.
 
Dave, I had problems initially with the woodworm coming loose in the chuck and I discovered I was not pulling the wormwood screw forward and then tightening it. There is a little forward/backward slop. As the manual says BEFORE FINAL TIGHTENING MAKE SURE THAT THE FRONT OF THE BOSS SECTION OF THE SCREW IS SEATED BEHIND AND AGAINST THE 50mm (2 INCHES) JAWS.

Properly installed it should not come loose in the chuck. You should be drilling a 5/16" hole. This is not a good chucking method for punky wood.
 
Last edited:
Hi i use 8.5 drill and make sure the screw is on the flats by loosening a little after it is tight giving it a wriggle to make sure it is lined up then retighten if the wood is soft i use 8mm bit and they never come lose even if a little out of ballence
 
Dave F. said:
Greg, thanks for the reply. I've made sure I'm following the directions supplied by Nova but someone suggested I may have trouble if the blank isn't made round on the band saw. Actually that may well be the problem as I use the screw chuck to rough out the bottom and cut in a tenon. I'll really true up a blank and see if that makes a difference.
Click to expand...

Couldn't tell from your initial, and still in some doubt as to whether the screw is loosening in the blank, or the screw/blank loosening in the chuck.

It's a real good idea to have a flat area on the blank at least as broad as the 50mm jaws for them to register against. One easy way to do it is to make overlapping Forstner bores on a DP, with the depth stop set. Resists racking just as a good shoulder on a tenon will do. That'll also protect you from dismounting on some minor catches. http://i35.photobucket.com/albums/d160/GoodOnesGone/Forstner-Flat.jpg

Proper size hole is critical with soft, wet wood. It'll pull loose with just minor catches unless you're shouldered and you've got plenty of thread in the wood.

The remark about not cutting to round is troubling. I'm hoping you know that making things round comes from cutting from the bottom toward the lip, not with the nose of the tool into the rotation. Start out far from the center, swinging the properly anchored tool through the ghost image that lumps make. Starting far from center improves balance rapidly. As the piece becomes more regular, you can guide the bevel of the tool on the nearly regular surface to refine the shape. You don't need perfect circularity, but it really does help if you take off the two thick ends to approximate the slope on the sides of a center up piece.

http://i35.photobucket.com/albums/d160/GoodOnesGone/Trim-for-balance-1.jpg

Unless, of course, you're making something deliberately non-round. Close to circular is nice. Undercut is more important for balance. Most important is a proper tool presentation.
 
Another cause of the problem with loosening wood worm screw (even if you're using a stronghold chuck) is that, when you're putting the screw in the chuck, just before final tightening, you're not pulling it out. I know it sounds weird, but, when you place the wood worm screw, you'd have to pull it out (this way you assure that during the turning, the screw wont surprise you by pulling itself out.)

The way I do this task is:

open the chuck jaws,
place the screw,
tightening the jaws (not too tight)
pull the screw away from the headstock until it reaches it's maximum distance,
finally tighten the jaws.


Also, look at Michael's note. The hole in the wood plays a big role too---if the wood is not completely facing the chuck jaws, then you'll definitely have problems with loosening screw...

Cheers
 
Mike Peace said:
Dave, I had problems initially with the woodworm coming loose in the chuck and I discovered I was not pulling the wormwood screw forward and then tightening it. There is a little forward/backward slop. As the manual says BEFORE FINAL TIGHTENING MAKE SURE THAT THE FRONT OF THE BOSS SECTION OF THE SCREW IS SEATED BEHIND AND AGAINST THE 50mm (2 INCHES) JAWS.

Properly installed it should not come loose in the chuck. You should be drilling a 5/16" hole. This is not a good chucking method for punky wood.
Click to expand...

I just submitted a reply, and then realized that Mike has made this statements well 🙂

Mike, I completely agree with you and I think it's one of the causes of the problem.

Cheers
 
Thanks everyone, I turned a white oak bowl last evening. The blank was as round as I could make it on the band saw before I began. Things went really well and when I took it off to turn around the screw drive was still engaged in the chuck tightly.

I think my problems we a combination of all the things mentioned, improper mounting in the chuck, too big of a hole, and too many catches and bumps on an irregular blank to start.

Thanks again,

Dave F.
 
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