Bulldog Chuck

[Paul Gilbert]

I bought a Bulldog BD 550 (5 1/2") with the standard set of jaws which are dovetailed. The main selling point of these chucks is that the jaws are plated and will never rust. Well, I think that the polished jaws are too slick to grip tightly. I have tried in vain to exactly match the shape of the dovetail on the tenon on my bowls, but this chuck just keeps launching bowls across the shop.

I broke a tenon off of a bowl once, but have never lost a bowl with my Strong hold chucks. Am I doing something wrong, or does a polished set of jaws not hold well?

I have ground a 3/8" square HSS blank into a bedan shape that is angled to match the dove tail jaws and use it to shape the tenon. I turn the tenon to 1/4" - 1/2" greater than the closed diameter of the chuck jaws. I make sure that I have a good flat where the tenon meets the bowl blank. I still get flying bowls during my rough out phase.

[Roger Chandler]

I just took a look at some pics of the Bulldog chucks...........they look okay in the pics as far as configuration of the jaws, but what you refer to as "polished jaws" may be an issue?

I have SuperNova2 chucks and Hurricane chucks and do not have flying bowl problems. That being said, the standard 50 mm jaws on the supernova2 chucks are not the best for bowl blanks, although they can be used. I like a mechanical fit like with dovetail jaw configurations, or serrated jaws to grip better.

Another good thing to do is to periodically check the hold as you progress in the turning.........I usually tighten the jaws about 3 times during a project.........just to make sure they are tight, but I do not crush the tenon, just want to make sure vibration has not allowed the hold to back off a smidgen.

[Thom Sturgill]

Personally, I do not think the plating would be an issue. The geometry is much more important. The optimum size for a tenon or recess is based on the jaws being open about 1/8". They are generally machined from a single piece of stock and cut apart and that 1/8" is the saw kerf. I have heard that some companies are starting to go to cast jaws, but have not seen anything definitive on that.

1/2" larger than closed means you are only gripping in the center of each jaw in expansion and only on the corners in compression. Clamp down on a tenon and then remove the piece from the chuck and examine the depressions caused by the jaws crushing wood. When sized correctly the dovetail should contact all the way around. In contrast, the stronghold serrated jaws are designed to grip on two spaces on each jaw regardless of tenon size.

[Steve Mellott]

I'm not sure what is causing the problem, but I don't think it is the polished surface of the jaws. Can you post a picture of the piece in the chuck?

[Shawn Pachlhofer]

I've got 2 Bulldogs - the "VM100" sized, and the VM120 sized - and a variety of jaws to go on each.

I also have Vicmarc chucks.

I've never had an issue with the BD letting go of anything.