I can't comment specifically on the Compaq, but I think it would be fairer if you said that most green woods are poor on chucks:) Like you discovered, green wood is soft, and also weak. It is very easy to break the wood around the chuck. You may need to use a wider and deeper recess, leaving plenty of material around it, and make more sympathetic cuts.
The wood is spongier than dry wood. I use the external tenon method and tighten the chuck well. I try to make the tenon larger than smaller. My present chuck is a Oneway Stronghold and it is very good but I have used a no-name cheapie as well with the external tenon. A trick you can try is to put CA glue around the area the chuck will grip. The CA glue will firm up the wood. Billh
Because the wood is soft I find it impossible to get a really good grip.Guess the wood acts like a sponge. Is this chuck unique or is it a fact that most chucks are poor on green wood.
Its your chuck. I only use Oneway Stronghold chucks and I never have a problem holding green wood (which is 95% of what I turn). I've used the Compaq chuck and promptly returned it. I found its grip extremely weak.
The CA trick is good. It penetrates well into the end grain, but hardly at all into the face. Makes it more of an improvement in recesses or small tenons where it can get some percentage distance. Problem is, small tenons can fall on the natural fault lines of annual rings!
Try to use the tailstock until your piece is at its best balance or least weight, so as not to put unwanted stresses on your mount. Don't think "grip" so much as "mount," and you're conceptually better off. The grip only has to keep the piece from rotating under tool pressure, which shouldn't be much at all if you're letting the wood come to the edge rather than stuffing the edge into the wood.
If you've got a dovetail, inner or outer, it's the key to your mount. It needs to wedge the nose of the jaws into a flat created for that purpose on the piece Needn't be tight, just snug, because as long as there is no gap, the only way it slips is if you deform one side of the mating surface or other. Which you don't do, because you keep your tailstock in play until late, and you let the wood come to the edge to be cut, right?
I have a Nova Compac Chuck that I have used on green wood. It's a decent little chuck. (Pay particular attention to the word "little") It's a decent chuck when you observe it's limitations of capacity. It's grip is acceptable when used on smaller blanks, but when you try to grip green wood blanks approaching the size limits of a mini lathe, you're gonna throw a blank or two. If you intend to turn larger blanks, get a larger chuck. Either a Talon or a Supernova with spigot jaws.
InspirePoint website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.