On 17.01.14 16:34, andy pugh wrote:
> My milling machine has a swinging table. This is excellent for gear
> hobbing, as I can set the table to the hob helix angle.
>
> If I forget to put it back I can make trapezoidal boxes. DAMHIK.
>
> I am wondering how to be sure that the table is properly square. I guess
> that the critical thing it needs to be square to is the Y slides.
Mine is 195mm across the Z dovetail, and I'd try the front face of that
first, if it's perpendicular to Y. The flats of the Z ways are nearly
300 mm across. It might be advantageous to be able to swing the DTI out
of the way when crossing the dovetail, though.
If they're not perpendicular to Y, then it's hopefully not an unfounded
assumption that the Y slides are parallel to the axis of the horizontal
spindle, so that a very slightly concave disc, turned in situ (cutter
running only one way from the centre), fitted to a toolholder in the
horizontal spindle, should give two widely spaced points of reference
parallel to X. (The DTI doesn't need to run on the centreline, either.)
My horizontal spindle has nigh on 250 mm radius for a disc, giving
reference points about half a metre apart, if needed. I'd just have to
build a table-mounted toolpost, to turn a disc on an INT30 holder.
OK, the bottom half of the disc would need to be cut off, to allow the
table near the centreline, or the toolpost would also have to be used
for tramming, I figure.
Why bother?: Set-up has to be twice as quick as setting up two ways with
a square.
If the horizontal spindle and Y slides are not parallel, I'd be tempted
to add a shim to one side of the disc.
My swing table has big degree graduations, but even they'd be pretty
rough, and I wouldn't rely on them.
A last-minute notion: A ground parallel, clamped in the horizontal plane,
by gripping the Z dovetails, could be set with its front edge good for
X. It should be close enough that it could be shimmed to suit if off a
whisker.
Erik
P.S. Woulda bought some of all that ice in USA at any price yesterday.
It was 44°C (111°F) here, the 4th successive day over 41°C (106°F)
--
For the month of December 2013, 57.4% of all the electricity consumed in Denmark
was generated by wind turbines. Over the whole year, it was 33.8%, and on 21st
December, the wind turbines produced over 100% of Denmark's electricity
consumption.
-
http://epn.dk/brancher/energi/alternativ/ECE6403277/danske-vindmoeller-skriver-verdenshistorie/
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