4 jaw self centering chuck

[durhambuilder]

I've finally had enough of my fairly well worn 3 jaw chuck and rather than replace like for like I bought a 4 jaw instead. Holding power and accuracy on round stock up to fairly large diameters is far better and machining angle iron etc to length for buffer beams is a doddle. This is definitely going to be the chuck of choice for 95% of the time now.



The three jaw will still be used for making the odd bolt and nut and I can live with the inaccuracy for these, rarely to the hexagon heads and shanks need to be truly concentric.

Treat yourselves, christmas is coming

[teakfreak]

I have one as well, use it a lot for square stock, but it isn't much good for hexagon, which is used for a great deal of my work! I still prefer my Burned 3-jaw for most purposes, so much so that I'm looking to have another, so I can have one with the outside jaws fitted and the other with the inside ones, as it's a bit of a pain swapping them.

[miken]

I too used a 4j self centering chuck on the Boxford lathe that I used to have for many years.Im surprised you say hex bar doesn't run true for you.
I used to use it on hexagon all the time because it always ran true on mine.
Square bar was different because I always seemed to have one jaw that was loose. Obviously because the "square" bare isn't exactly sq.
Have you actually tried it with hex?
Mike

[teakfreak]

I have to admit that I haven't, but I'll give it a go some time. I suppose that if it is gripping on the four opposing flats it would be ok, I'd been thinking in terms of two faces and two edges, which obviously wouldn't work.

[abby]

Several years ago I was given a 4 jaw s/c chuck , it was in the stores of a company I worked for and had never been used.
In addition to having a scroll , each jaw also had screw adjustment like an ordinary 4 jaw independant chuck.
This was amazingly useful for machining batches of odd shaped components.
I was obliged to dispose of most of my model engineering assets but would like to replace this chuck now.
I have found nothing online so does any member know of such chucks.
Mine was if I recall correctly "Original Knopfer" and probably German or Swiss made.

[tomol409]

I bought a 4-jaw self centering chuck many years ago for my Boxford Aud, because of the large amount of cross drilling required on models. For shorter lengths it has been a boon. In over 50 years I have lost count of the number of different cross-drilling jigs published, all requiring extensive machining. But my chuck does the trick and is multi purpose, also being used for the multiplicity of square yoke ends on locos. If drilling close to one end, a longer piece of packing strip can be placed behind for support across the bore of the chuck. I also use a lot of say 1/4in hexagon brass and can always get it to run true, as others have. I am still using it to produce square bodied throttles for model diesel engines, and it can be used to drill a1/16thin hole through 1/8th in rod with accuracy and ease.