when is a precision vice not a precision vice>?

Hi, I think the word precision alone in a statement has a certain amount of ambiguity, as precision is allowed a tolerance just as anything else has. e. g. precision is not the same as high precision. When deciding on anything, you need to know all the factors that you expect of it, so the precision description alone, does not lead it to be of a high accuracy. To claim that something is not fit for purpose, you need to have written documentation of all it's parameters, word of mouth does not cut it.

Regards Nick.

Precision, is probably, like beauty, in the eye of the beholder, or determined by your needs, and the equipment available.

James Watt would not have believed that it was possible to produce, consistently, cylinders and pistons to within 0.001"

Maudslay's invention of the Micrometer started us down the path of greater precision.

Aiming an arrow at a target, calls for precision of the order of an inch (25mm) or so to be within the Gold or whatever band you seek to hit. A darts player has to be more precise in order to place a dart within a band barely 3/8 inch (10mm) wide, to score a double or a triple.

If you are making vehicle engines the cylinder bores need to be within a 0.001" (0.0254mm) tolerance of nominal size.

If you are making the fuel injection equipment for that engine, the plunger and barrels, or Injector needles and Nozzle bodies will be sized to within a micron or two, and then each lapped to its partner.

If you are thinking of the track separation within an Integrated circuit, think in terms of a micron, or maybe now, of less.

Similarly with machine vices; to drill clearance holes for nuts and bolts, if it holds the work within 1mm, it will probably suffice. If you are looking to ream a cylinder, to match a plunger, or to position dowel holes, then you need a much better piece of equipment, i.e. of greater precision.

Which is why a cheap vice will have rattling good fits, and a consistently accurate one will be expensive.

A Box Brownie could never do what a Leica 111f did in terms of capability or resolution, but what would you expect for £2/10/0 (£2.50) against £168?

Howard

Some useful feedback on what vices other people are using, where they bought them from and how they have found them to operate, very helpful for myself and hopefully anyone else thinking of buying a vice within the constraints I mentioned.

Thank you everyone,

Ian

Posted by Neil Wyatt on 19/08/2018 17:36:48:

The only downside is I need to sort some M14(!) fixings to match both vice and drill press table.

Thanks for the information, Neil.

Yes, M14 fasteners will be a little difficult to come by, I imagine. Even M12 can be hard to source in some things, as I found recently when I wanted some M12 Tee nuts to make a new work bench with adjustable feet.

Edited By Bill Phinn on 19/08/2018 20:08:49

I think I would go with M12 and a couple of custom made thick washers or flange nuts, even on the Axi website they show the biggest one with M12 fixings though the flanged nuts do look a bit small for the slots.

Hi, M14 bolts are available **LINK** Most places that sell bolts to industry should be able to supply them.

Regards Nick.

M12 will do if it has a decent flange, that's what I have at the moment - using washers rather than flanges - but the fit in the slots is sloppy and the washers can fall into the slots.

For the smaller press I made a couple of top hat washers for a smaller screw with a wing nut underneath for rapid movements, I'll probably make something similar using M10 or 12 screws.