Woodworm Screw

[Linda Jarvis]

I am a fairly new turner, and have yet to successfully use a woodworm screw to mount anything to my lathe. I have a Nove G-3 chuck. No matter where on the scriew I try to clamp with the chuck, it never stays. Help!

 

[George Stratton]

The end of the screw should stick out about 13/16 of an inch past the jaws. In that position, it will interlock in place and not rotate when tightened down to the flats. I have the same chuck Linda.
Geo.

 

[hockenbery]

Like George says the nova screw has flats that should face the points of the chuck jaws underneath the auxiliary jaw plates you screw to them. The jaws usually center themselves into the middle of the flat. When the chuck is tightened they lock in well.

The ONEWAY screw is the best it has a little groove that the points of the jaws fit into.
So it locks in perfectly every time.

The other part of getting the screw to work welll is the blank preparation.
Screws work on face grain. An endgrain blank won’t hold screws well if at all.
The blank should have a fairly flat surface and the pilot hole for the screw should be close to perpendicular.
The drive force is from the tops of the jaws pressing against the wood.
The hole needs to be the right size and for soft woods it can be a little undersized.

 

[Richard Coers]

It would be helpful if we knew how you were installing it. Like is the face of the blank flat? Do you install the screw in the chuck and then screw on the blank? What size drill do you use for the pilot hole, how much engagement, and finally what do you mean by "it never stays"? Ideally, the screw pulls the blank tight to the face of the jaws. The friction from the jaws is a critical point of making the screw work.

 

[Don C Davis]

What Richard said is important--you need jaws on your chuck for the piece to be 'threaded' up against--I also like a square flat piece to put my hole into for the screw chuck--I typically use a large forstner bit to drill a flat in my blanks if they aren't already flat.
Lastly, the best method I have found is to drill your pilot hole and then lock the woodworm screw into your chuck and lock the spindle then screw your blank onto the woodworm screw until it is firmly up against the jaws on your chuck.

Good luck!!

 

[Mike Johnson]

Depending on your lathe and the length of thread on the spindle, a washer is required on some lathes to allow the chuck to tighten down correctly onto the worm-screw head. If your lathe has a longer spindle thread when the chuck is mounted onto the spindle and bottomed out against the spindle thread shoulder the end of the spindle thread jams up against the jaw mechanism in the chuck preventing it from closing all of the way onto the worm-screw. A washer about an 3/16" thick placed on the spindle usually solves this problem if that is the issue. I use a hard plastic washer on several of my lathes which makes it easier to remove the adjustable chuck. A hard steel washer will make it difficult at times to remove the chuck if the threads get over tightened.

 

[William Rogers]

Linda

I had done the same thing. I didn’t realize there were flats, so now when I install it I wiggle it as I tighten the chuck. I have learned how much gap between the jaws to tell me I have it correct.

 

[Linda Jarvis]

Well, I got it to work, but here's where I was:

I drilled a hole the size recommended in the Nova instructions. I guess my basic question is: do the flats face the open space between the jaws, or the rounded parts of the jaws? I screw the wood on with the screw already in the chuck. Otherwise, I think I would lose my mind.

 

[Mike Johnson]

You normally want to have a flat surface on the wood billet to contact the entire surface of the chuck jaws to prevent movement while using the worm screw. Without the entire 360 degree circumference of the jaws bracing the wood the centrifugal forces of the billet will loosen the hold of the worm screw. Centrifugal forces will easily overcome the mechanical forces of the chuck jaws if the wood billet is not braced evenly against the jaws.

 

[hockenbery]

Well, I got it to work, but here's where I was:

View attachment 26098 I drilled a hole the size recommended in the Nova instructions. I guess my basic question is: do the flats face the open space between the jaws, or the rounded parts of the jaws? I screw the wood on with the screw already in the chuck. Otherwise, I think I would lose my mind.

The flats on the screw head face the points of the jaw. The round parts of the screw head face the openings.
And as you said the screw needs to the locked tight in the chuck before mounting the work.

What you show in the photo won’t work. As mike said - With only two small contacts spots on the jaw tops the piece will rock an pull loose from the screw. You need a near flat for the jaws to rest against when the screw is tight.
Chain saw flat works fine.

This could work as long as the tailstock is used to hold it tight and keep it from rocking but
As soon as the tailstock is pulled away it will,come loose from the screw.

I use a spur drive to drive natural edge bowls.

 

[Bill Blasic]

If you take a large forstner bit and drill a flat that the jaws would fit into your problem would be solved.

 

[Richard Coers]

Here's a cutting direction tip. On a natural edge, it's tough to cut all the way from the bottom to the rim. You'll get that chip out on the rim like you are getting here. Cut from the rim down until you get to the continuous contact, then cut from the bottom up. It takes a lighter cut to get a good finish going the opposite direction on the interrupted cut, BUT you maintain a quality rim.

 

[Randy Heinemann]

I have the same chuck and woodworm screw.

I just barely tighten the jaws on the screw and try to twist it with my hand before completely tightening it. Then, when threading the blank on the screw, if it is not seated properly, it will move just from the force of tightening the blank down. If that happens, the jaws must be retightened on the woodworm screw. It isn't the most straightforward, easy process, as even if it seems like it's seated properly, it sometimes isn't.

 

[Linda Jarvis]

It was a steep learning curve, but I managed to make this small piece from a large hunk of wood. Thanks for all your input.

 

[Mark Jundanian]

Strong work! Very nice bowl form and beautiful grain pattern.

 

[Michael Mills]

As other said, the flats on the screw mates with the flats on the jaw slides.
The easiest way to me is to turn any jaw top center, you can see a flat on the screw (also top center) to align it as you install it.

 

[Gerald Lawrence]

In addition to the flats on a Nova there is a double ring creating a slight recess where the flats are. I think this adds extra safety as "if" the jaws loosen to hold the screw in position while action is taken.

 

[Emiliano Achaval]

If you take a large forstner bit and drill a flat that the jaws would fit into your problem would be solved.

That would be an expensive solution, not sure how wide her jaws are but I'm guessing it's a $30 plus bit...

 

[John Torchick]

Lina, my complements on the bowl. We h ad a demo at our chapter last night. The fellow had a piece of plywood as a "washer" or "spacer" on the woodworm screw. I'm guessing the plywood would have a bit of give when tightening the piece on the screw. Plus, it would be easier to remove the piece.
Nylon would be good, as mentioned earlier. I have a large piece of plastic/nylon/whatever I rescued from the recycling center.

 

[Randy Heinemann]

I have found that the woodworm screw on my Nova holds the blank very securely. a "washer" of plywood or a nylon material would, I think make it much easier to remove the blank when done turning the outside of the bowl and would lessen the depth to which the screw is embedded in the blank, but I'm not sure it would accomplish much else. Since the screw only goes in about 7/8", the depth inside the blank hasn't really been a problem for me. Plus, I like the mental security of knowing the screw is solidly secured inside the blank. It is hard to unscrew sometimes, depending on the type of wood and how much I've tightened the blank onto the screw.

 

[hockenbery]

I use plywood or MDF as a spacer to shorten the length of the screw.
I don’t think they make it easier remove the piece from the screw.

I use these twice in the seed jar demo I do. There is a video in the techniques section.
http://www.aawforum.org/community/index.php?threads/turning-a-seed-jar-split-hollow-form.13584/