Re: [CAD_CAM_EDM_DRO] Re: Bobcad scores

A good post processor will (for a G00 move) do a Z-up move before the X & Y
moves, if the Z-move is in the positive direction (i.e., UP) and it will do
a Z-down move only after the X & Y moves, if it's a Z-down move. This, to
prevent a crash, if working in a pocket, or alongside of a profile. If you
have the ability to write your own 'post', I'd strongly suggest you employ
that technique. My SHARNOA (1980's vintage) uses this technique, although, I
think the software is Bendix.

RayHex

-----Original Message-----
Date: Saturday, June 17, 2006 5:34 AM
Subject: [CAD_CAM_EDM_DRO] Re: Bobcad scores

>R Rogers <rogersmach@...> wrote:
>>
>> You mentioned that Bobcad was telling your machine to take off
>while it was making a Z axis move. From a G-code standpoint, this is
>impossible. To issue a move and issue another while the original is
>being carried out. It can't be done. It must complete the first.
>>
>> The only way this can happen is a machine that is lagging way
>behind it's commanded position. It's issuing new commands before the
>present one is fully carried out.
>
>I'm not a G-Code expert but I do know it's possible to write a G-Code
>such as G0 X0Y0Z0 then write another like G0 X1Y1Z1 which on the
>MaxNC machine results in movement in all three axes at once. The
>problem as you've stated is taking off or moving in XY while moving Z
>can cause unwanted impact to flat stock material (depending on the
>situation). Unfortunately Bobcad 18 does generate G-codes with this
>error which must be manually converted to a sequence like:
>G0 X0Y0Z0
>G0 X0Y0Z1
>G0 X1Y1
>
>(Simplified for illustration purposes, the actual program may require
>use of minus sign.)
>
>Now is there a setting on Bobcad to automatically eliminate these
>manual program corrections? If so, I'd also appreciate a quick
>lesson or tip on how to get it to automatically repeat in 3D with
>increments in Z since my desktop machine tends to skate at anything
>more than a 0.025" depth of cut. Repeating the program manually
>writing in the Z increments is annoying. Thank you.
>
>Kirk