I can't see it being much use for smaller work as the 4 blocks won't go much closer than 40mm x40mm by the looks of it. It would be a useful tool for things that won't easily mount in a 4 jaw but I would say not a replacement for a 4 jaw.

J

David C – the adverts on the right are blocking this thread for me!

ChrisH

The adverts were fine for me but I altered the long link which may have been causing the problem.

regards david

I have delayed replying to Pekka's questions as being the originator of the design I felt it better to first give others the chance to comment. However, I would like now to attempt an unbiased reply.

Whilst I may have inferred that it could be used in place of a four jaw chuck, which it can, I do believe that unless the user has a reasonably frequent need for its use outside what a similar sized chuck can perform then a standard chuck is to be preferred. This because, within these limits the chuck is likely to be a little easier to use in many cases. What then are its benefits?

This is mainly to work with much larger workpieces that can be done with a similar sized chuck. Typically, compared to my similar sized 150mm chuck, it can hold rounds and squares up to 83mm compared to 58mm for my chuck. This also with an available jaw depth 35mm compared to only 20 for my chuck.

In addition to rounds and squares, this capacity permits it to hold larger and more irregular shaped parts with ease.

With it being possible to add support pieces it can deal with thin parts much more easily, even on top of the jaws making 150mm diameter/square being perfectly possible.

The following three pictures show some example some of which have only been taken as mock ups rather than an actual processes. however, they should give some idea of its capability.

Pictures, one,

two,

three.

A fourth picture shows it being used as a two jaw chuck and using support pieces as mentioned above.

Without the jaws it makes an excellent faceplate, having the advantage that one only needs to use one spanner as one is not required on the rear, yes I do know tee nuts can be used on the rear of a faceplate but wonder how many do. This gives a free hand to support the workpiece.

Having a much greater mass, small errors in the balance of the workpiece and its clamps becomes less significant resulting in less frequent need to balance an assembly. This picture show a typical example of it being used as a faceplate.

In a nutshell then.

1. If a four jaw chuck already exists, the alternative is only worthwhile if its additional capacity will find sufficient use to make it worthwhile making.

2. If a chuck is not available but the need for one can be mostly met with a purchased item, then this is the way to go unless it is seen as an interesting project.

3. If a 150mm chuck is available but the additional capacity and adaptability will find a use, then making the device will be better than purchasing a 200mm chuck which still will not perform everything that that being discussed will.

For more details regarding the device see here.

You mention Pekka that you do not have a tee slot cutter. When the surface of cast iron has been machined removing any hardspots that there may be then machining it is very easy. This can easily be done using a shop made tee slot cutter, see here for suggestions.

Harold

Edited By Harold Hall 1 on 29/04/2012 21:57:51

For more details regarding the device see here.

I wasn't sure whether to mention it but there are no pictures on that page or any of the others

The plans downloaded fine tho