minferror parameter

["Till Franitza" <xfa-at-isw.uni-stuttgart.de>]

Hallo!
Fred and Will,
Please add to your documentation what is the meaning of minferroer in the
ini-files! What emcmot does here is quite difficult to understand and i tend
to say that it is a bit confusing.
The "simple" ferror is - as i understand it - somehow used as
velocity-dependant while if this boundary becomes smaller than minferror,
minferror is used as boundary. I found that out by looking into the source
code.
The documentation emcsoft.html is not up to date in this case.
Till
-----Ursprüngliche Nachricht-----
Von: Jon Elson <jmelson-at-artsci.wustl.edu>
An: Multiple recipients of list <emc-at-nist.gov>
Datum: Dienstag, 5. September 2000 08:09
Betreff: Re: Look Ahead


>
>
>
>Scott Stephens wrote:
>
>> -----Original Message-----
>> From: Jon Elson <jmelson-at-artsci.wustl.edu>
>> To: Multiple recipients of list <emc-at-nist.gov>
>> Date: Monday, September 04, 2000 2:07 AM
>> Subject: Re: Look Ahead
>>
>> >I use this when drilling PC boards with tiny drills, to make sure the XY
>> >position has settled completely before starting to plunge the drill in,
and
>> that
>> >the drill is fully retracted before moving X & Y to the next hole.
>>
>> Could you tell me what speeds you use to plunge the drill in and out? Do
you
>> ramp?
>
>The inverter I'm using right now goes up to 400 Hz, which allows me to
>get up to about 24000 RPM.  It is actually desirable to go faster, but
>until I build a custom inverter, that is my max RPM.  You use about .001"
>per revolution plunge on the bigger drills, around .035" and up.
>Too fast a plunge will stall the drill motor with really large drills, so
you
>have to take that into account.  You get down to around .0002" / rev
>on the very small ones, in the .021 to .018" range.  So, that works out
>to 24 IPM for the larger drills, and down to about 5 IPM for the tiny ones.
>It depends a bit on whether you are using entry and exit materials (and
what
>types), the board material, how thick the board stack is, etc.  I
occasionally
>use a stack of 3 .062" thick boards with larger drills only, .035" and up.
>For drills down to .025" or so, you can do 2-high stacks.  With the smaller
>drills, .021, .018 and down (if you dare) the chip binding is so bad that
>you will likely break drills if you try to do a 2-high stack.  So, if there
>will be small holes, I do a single board at a time.
>
>I generally retract the drill at the same rate as the plunge.  You can go
>twice as fast, but don't go faster.  Some experts say too rapid extraction
>traps the chips that are often wrapped around the bit above the board
>and jams it, breaking the bit.
>
>I don't understand the ramp question.  Do you mean an acceleration ramp
>of the spindle when plunging?  Yes, the machine ALWAYS ramps up and
>down, but the way I set up the clearance plane .1" above the board, it
>does the ramp up/down at the top of the stroke outside the board.
>There is another ramp down/up at the bottom of the stroke, that is mostly
>done in the exit material.  I use a piece of PCB scrap under the board
>to keep from raising an edge around the bottom hole.  I have been
>experimenting with using .010" aluminum for entry and exit material
>with pretty good results.
>
>Jon
>
>