Rotary Tables?

Hi all, Im looking at buying a rotary table and wondered if anyone here has experiance of the Shoba tables from Chronos? The 6" one with dividing plates and tailstock looks quite reasonably priced at 140ukp?. Or any recommendations for what to get? my budget is less than 150ukp, and I think a 6" RT would be most useful.

thanks

Dave

There have been some reasonably priced ones on ebay recently, could save yourself a few pounds by holding on for a while and seeing what comes along. Also put a post on the model engineering sales/wants site, that often brings something nice along :-))

Peter

-- Peter & Rita Forbes Email: snipped-for-privacy@easynet.co.uk Web:

Think about the size. My 150 mm RT is often enough too small. You need room for clamping.

Nick

I agree entirely, a 6 inch rt doesn't give much room for mounting things like a vice etc. My problem is the opposite though - I have one of the 6" Shoba tables from Chronos and it is a bit big for the 6" table on a VMC. If you have a wider table though then I'd follow Nick's advice.

Hth,

Currently I dont have a mill, so it wont fit on any table... and the boring table to center height on my harrison is ~57mm, so even a 4" table is to big for that, and i think a 4" is to small to be very useful. currently I plan to use it for things like drilling the cylinder head bolt circles, dividing and such like,hence a set with all the bits seems like a good idea. One concern was what the quality is like, as I would be mail ordering, so wont be able to play with it until it gets here so to speak.

Dave

On a drill-press!? How will you find the center and move to the bolt circle?

Nick

well, the plan was to use a pointy scriber in the lathe to mark the pitch circle and then set this on the drill center, and then turn the handle to index round. what obvious flaw have I missed? I thnk that will work, though it's less conveniant than winding the table across on a mill. I have sucessfully divided for a 6 spoke flywheel using the 3 jaw chuck and a spirit level to make out both the rim and the hub and then carefully drilling the holes. it all lined up ok, but was less than easy ;) hence the interest in an easier dividing method...

Dave

No, that works, if you get the pitch circle precisely. If! But then, you could also use a compass (pair of compasses?) to divide it into 6 or 3 equal parts or a "center finder"*) to get 4 points.

Nick

I am aware of these sort of dividing methods, but they dont do odd numbers or fine divisions easily....ie With the cylinders the current engine has 5 bolts.... But once I have set the table to do the cylinder head as long as I dont move it the cylinder will end up on the same pitch circle and so the parts will mate? There is some (small) room for error in the absolute dia of the pitch circle. I plan to get a mill soon, just not this year, the garage is still in a state of disorganisation from absorbing Tim's Surface table (think it must have brought some disorganisation with it ;)

Dave

Could be done with a compass too. You also could drill the mating part off.

My point is: Don't buy an RT before you have a mill. Or maybe you discover that it doesn't match. Too big, too small, not enough room RT - spindle nose, mill has no tiltable table so you want an RT with a tiltable base, whatever.

Nick

How do you divide by 5 accurately with compasses? Last time I tried drilling through one into the other I scrapped both parts, however that was a long time ago, before i improved my drill and its clamps.

Ok, I understand what you are geting at now...

Dave

If you know the PCD or circumference of the circle, divide by 5 and mark off with dividers.

Get a copy of the Zeus tables book, there are formulae in there for this sort of stuff.

Peter

-- Peter A Forbes Prepair Ltd, Luton, UK snipped-for-privacy@easynet.co.uk

Ah, Its been a while, but I do wonder if I covered that in school, I dont remember it...

Dave