Chuck-_jaw_modification.jpgI am considering buying a set of 35mm Bowl jaws for my Supernova 2 chuck. My problem is that the jaws have an external dovetail but no internal dovetail for holding a small spigot in contraction mode. This is illustrated in the image of my 25mm jaws wich are essentially the same profile.
There is a 35mm Spigot jaw set, but this only has a serated internal profile and is not suitable for holding a 3 -4 mm deep spigot on the bottom of small boxes. Since the proposed box diameters are approximately 40 - 45mm, IMO the external dovetails are too large to use in contraction mode without wasting valuable wood. My problem with the smooth parallel internal profile on these jaws is the lack of clamping force on the small spigot: 1 twitch and I have an instant UFO.
I am proposing to have the internal profile of the new jaws modified to provide an internal dovetail as indicated in the above image. This raises 2 questions (at least) -
1. Is my technique wrong and I don't need to modify the jaws? I am ready to be educated if this is the case.
2. The existing jaws have a 15mm thick "leg". Can I safely reduce this to 10mm?
Theory suggests that the proposed modification is practical - the remaining thickness of the leg at its thinnest point will still be almost double the thickness of the 25mm jaws and also of the 50mm jaws. I want to increase the minimum capacity in contraction mode from 9mm to about 20mm as this will increase the area of the jaws which are in contact with the 30 mm spigot.
I spent about an hour at Carba-Tec yesterday and we checked every version of the Nova range and found nothing which matched the design I was looking for - which suggests my technique might be the problem.
I would appreciate any advice. I don't want to spend money needlessly on new jaws and machining if there is a better solution.
Bob
PS. Many thanks to Robbo for his videos on chuck maintenance. The Bonhan chuck now looks presentable:2tsup::2tsup:
There is a 35mm Spigot jaw set, but this only has a serated internal profile and is not suitable for holding a 3 -4 mm deep spigot on the bottom of small boxes. Since the proposed box diameters are approximately 40 - 45mm, IMO the external dovetails are too large to use in contraction mode without wasting valuable wood. My problem with the smooth parallel internal profile on these jaws is the lack of clamping force on the small spigot: 1 twitch and I have an instant UFO.
I am proposing to have the internal profile of the new jaws modified to provide an internal dovetail as indicated in the above image. This raises 2 questions (at least) -
1. Is my technique wrong and I don't need to modify the jaws? I am ready to be educated if this is the case.
2. The existing jaws have a 15mm thick "leg". Can I safely reduce this to 10mm?
Theory suggests that the proposed modification is practical - the remaining thickness of the leg at its thinnest point will still be almost double the thickness of the 25mm jaws and also of the 50mm jaws. I want to increase the minimum capacity in contraction mode from 9mm to about 20mm as this will increase the area of the jaws which are in contact with the 30 mm spigot.
I spent about an hour at Carba-Tec yesterday and we checked every version of the Nova range and found nothing which matched the design I was looking for - which suggests my technique might be the problem.
I would appreciate any advice. I don't want to spend money needlessly on new jaws and machining if there is a better solution.
Bob
PS. Many thanks to Robbo for his videos on chuck maintenance. The Bonhan chuck now looks presentable:2tsup::2tsup:
0 commentaires:
Enregistrer un commentaire