RE: [CAD_CAM_EDM_DRO] EMC, ISA and other Questions...

Hi Art,

I'll try that tonight, maybe if it is not too cold in the shop, and see what
EMC does with a compound move as you describe. My problem with EMC and the
angular (rotary) axis is that when it is configured to have 1 degree = 80
steps it makes almost no visible motions on a command of G1a360f20 which
should move the table at a rate of 20 degrees per minute but in fact moves
the table at more like 20 degrees per hour. There are times that I only
want to move the rotary table and no other axis in conjunction with it, such
as drilling a bolt circle.

John Guenther
'Ye Olde Pen Maker'
Sterling, Virginia

> -----Original Message-----
> From: Art [mailto:fenerty@...]
> Sent: Wednesday, January 22, 2003 16:46 PM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: Re: [CAD_CAM_EDM_DRO] EMC, ISA and other Questions...
>
>
> Hi:
>
> I just noticed some questions on the rotary capabilities of EMC
> and Mach1.
> In EMC, the rotary axis is designed to follow the X,Y Z axis in their time
> frame. That is to say a move like G1X1A360 will try to "fit" the
> A move into
> the time necessary to move the X 1 unit at the present Feedrate.
> This causes
> a runaway rotary axis and usually lost pulses. If you try a
> G1X.1A360 you'll
> find it races away in the A axis.
>
> I have redesigned that section to recalculate the feedrates for the
> rotary move by applying a ratio of feedrate necessary to maintain the feed
> at the proper speed. This is done by setting the diameter of the rotary
> stock. The feedrate is then calculated as a function of the
> circumference of
> the item beingn machined taking into account the movement in the
> Z axis for
> the move.
> It can be used 2 ways. Either tell the machine the diameter is zero( or
> close to zero) .0001 or so in diamter in which case the Z must be
> set to the
> distance from the center, or tell the system the actual diamter
> of the stock
> and set the Z to zero as it touches the stock. The circumference
> is adjusted
> on each move to be an average of the Z position during that move. The
> feedrate is then recalculated onh each move to take these varibales into
> account. Internally, the feedrate of an F60 move may be changed
> to F.034 for
> example to allow the X to complete its move in the time frame of
> the rotary
> axis instead of the other way around. The recalculations are not very
> complicated but do necessitate adding new information inputs such as
> diameter of stock to the input screens.
>
> The rotary axis center is assumed to be from the Z axis in
> both the A and
> B and no correction is yet applied to the C, but in the end it will be
> corrected as a function of the X,Y offset from center. The A and B are
> designed to be XZ and YZ axis while the C is rotational in the XY plane.
> Ideally, a selection will be aded to allow for reconfiguration of the axis
> planes in a per session basis.
>
> Hope this information helps,
> Art
> www.artofcnc.ca
>
>
>
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