Single screw chucks.

[robert baccus]

I recently broke my fourth Nova single screw chuck. Just work hardened i think. For 23 usage years this may be average--I use them a lot in glueblocks glued to mostly vases and urns to 10 to 20" long. This is a lot of grunt for the screws. Has any one else had this problem with any screw chucks.

[Brian Kent]

I would tend to think that 23 years out of 4 chucks is really good congratulations and go buy yourself another one. Maybe 2. And may they last 5+ usage years each. Congratulations.

[Bill Blasic]

I have never had a Nova screw break and usually I have to take the wood with the screw attached out of the chuck and turn out the screw with water pump pliers. I did have a Oneway Stronghold chuck screw break the first time I used it and the Vicmarc just does not look strong enough so I never even used the one that came with it.

[Richard Casey]

I recently broke my fourth Nova single screw chuck. Just work hardened i think. For 23 usage years this may be average--I use them a lot in glueblocks glued to mostly vases and urns to 10 to 20" long. This is a lot of grunt for the screws. Has any one else had this problem with any screw chucks.

Robert, are you supporting your turnings with a steady? That sounds like a lot of stress for that little screw. I only have Vicmark chucks, and broke the screw early on, it did not seem to be very good steel, so I only use dovetails now, turned to match whichever jaws are the best fit.
Rgds,
Richard.

[Aaron Craven]

I would imagine that screw takes a lot of stress, so 5+ years is probably more than respectable. I've been really impressed with the Nova screw. I was initially worried about mounting with only the single hold, but I've come to trust it almost as much as a faceplate mount.

[Michael Mills]

I haven't had one break but I don't turn items as deep as you do either.
You probably know but Nova has a longer woodworm screw which fits the powergrip jaws.
Having a 4" base surface rather than a 2" base may help reduce stress on the wormwood.

[Scott Ticknor]

If you are using a glue block why not use a face plate? A steadyrest will help with the lateral pressure But at 23 years of turning you know all this. I would like to see the finished product or one in progress . It seems to work for you but it seems a bit scary turning that size of vessel with only a single screw. Please educate me.

[robert baccus]

I use a glueblock/screw because a green endgrain has no strength even with a faceplate and screws. I also turn my bases down to 3" or so limits which limits a faceplate and 20 screws. Also CA thick glue has 5-6000 psi strength on a green endgrain vase blank. Also the outside is turned using the tailstock and hollowed with a oneway stabilizer. Single screws are limited in strength only by the wood used for screwing into. I prefere dogwood-beech ect. Michael, I was unaware of a Nove larger screw--have looked extensively and called around. Any info is appreciated. They need one for softer woods like sweetgum ect.

[John K Jordan]

I use a glueblock/screw because a green endgrain has no strength even with a faceplate and screws. I also turn my bases down to 3" or so limits which limits a faceplate and 20 screws. Also CA thick glue has 5-6000 psi strength on a green endgrain vase blank. Also the outside is turned using the tailstock and hollowed with a oneway stabilizer. Single screws are limited in strength only by the wood used for screwing into. I prefere dogwood-beech ect. Michael, I was unaware of a Nove larger screw--have looked extensively and called around. Any info is appreciated. They need one for softer woods like sweetgum ect.

In sorting through my SN jaws and wormwood screws the other day I found several different styles and lengths. As Michael said, one was much longer than the others and must have come with one of the chucks or jaw sets. (Can't remember which, I think I have 14 Tecknatool chucks now.) This thread indicates the long one may have come with a special edition of the SN2:
http://www.sawmillcreek.org/showthre...uck-evaluation

BTW, I've used the Glaser screw chuck for years on almost every face turning - it uses a 1/4" hole and holds very well. I like it better than the Technatool wormwood screws. I haven't tried it on a turning as big as you do.

I don't know exactly what I would do to turn such a thing but I would not try to hold it with any kind of screw in end grain, especially green end grain. The fact that you broke even one screw should be a clue. My first idea would be to hold it it in dovetail compression with the biggest jaws of the strongest chuck I could afford. I like the SuperNova chucks but there are bigger and stronger and better quality chucks and jaws available from other companies.

JKJ

[Michael Mills]

[QUOTE=robert baccus;2548313] Michael, I was unaware of a Nove larger screw--have looked extensively and called around. Any info is appreciated. They need one for softer woods like sweetgum ect.

If you scroll down to the "Standard Equipment" to the Titan Chuck... Safe Lock™ Woodworm Screw (Extra Long)
http://www.teknatool.com/products/Ch...itan_chuck.htm
I have one that came with a SN Premier chuck (back before the SN2 was released). If you phone the service center they should have it since they still list it. It is the same diameter I believe, just longer, but you have a larger mating surface for the top of the jaws to seat against.

[Dick Strauss]

Agreed JKJ...a longer screw will not help prevent you from breaking it in the future (if anything the screws will break FASTER because you have a longer lever in the turned piece!)

You may want to rethink faceplate limitations. I don't know what size screws you use where you can put 20 screws in a 3" diameter piece but I would guess they are too small for this purpose. There is no reason you can't leave the bottom 5-6" in diameter, do your shaping on the upper 75% of the outside of the HF, do your hollowing, finish turning the bottom 25%, and finally part off the piece from the sacrifical remains. Faceplate screws for can be driven at slight angles to better grab in endgrain HFs. Also, the bottom of the blank shold be every so slightly concave so that the force gets transferred to the outside diameter for best support (kind of like trying to tip a 4x4 versus a 4x6 placed flat on its longer 4" and 6" (3.5" and 5.5" actual) dimension).

If you insist on a single screw, find a much larger and more robust option!

[Michael Mills]

Robert,
Here is a link to the current Nova USA site where you order items/service.
They list what I assume to be the same thing with the Titan.... "Safe Lock™ Woodworm Screw and 4" Powergrip Jaws"
http://novatoolsusa.com/NOVA-Titan-C...List-13055.htm
I would think you could order just the screw if you think it may work for you and if you have the Powergrip jaws.
Mine came with chuck and powergrip jaws with a Supernova (prior to 2004 because that is when then switched to Supernova2)
I can't say if it is stronger or not, just longer. It seems to me there would be less side force against it because the width of the jaws providing support are twice as much. I leave that analysis to engineers or as Dick states above "the force gets transferred to the outside diameter for best support".
You probably will not be able to use it anyway since you want to turn down to a 3" base and it is made for the 4" PG jaws.

[robert baccus]

John, I have had no problem with the strength or holding with the Nova 2's I use. Years ago I tried Bigger faceplates and many screws and found my attempts unreliable. I almost never use a tenon grip on large stuff especially green. Green has a lubricating and crushing habit. Dick, good words but I often use expensive woods and to lose any length just kills me. The single screw is plenty strong but I have to realize any metal can work harden. Each of these screws have turned 50+ heavy pieces-like sandpaper I need to replace them on some schedule. Michael, I will contact the factory and beg one more time. I found out the hard way that Other brands do not fit. I have been astounded how well thick CA holds on green wood-just use fresh glue and if in doubt test it.- 5 minutes maybe. I might mention I also use and love Expand into screw on faceplates for starting bowls and glueblocks. I had my own made locally twenty years ago and have bought two of the new Nova versions. Really speed mounting and dismounting especially when finishing on the lathe. Just checked the Nova site(thanks) and still no listing for a longer screw.

[Dick Strauss]

Robert,
Is there is a way to widen your base with a waste block glued to the good stuff? Maybe you could turn the good stuff between centers to get a small tenon on one end...then turn a recess in a waste block and glue the good wood tenon into the waste block recess. If so, you would only waste 1/4-3/8" of tenon from the good stuff and have a much larger base of support. If the wood you regularly turn is wider than your current jaw set, you can also get the largest jaws possible to provide a wider base of support when you use the screw for mounting. I apologize if I'm stating the obvious here...

I think I've seen larger dedicated screw chucks but can't seem to find them now?

[Michael Mills]

. Just checked the Nova site(thanks) and still no listing for a longer screw.

I had looked also but... they also don't list parts for the Nova Live Center. I wanted an additional "threaded insert" and phoned them, no problem at all.
I imagine it would be the same for the powergrip woodworm screw; just not something they have a lot of request for separately. Just on my experience I would not bother with an email but a phone call seems to get good result for me so far.