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Messages - comet

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General Mach Discussion / Re: Breakout Boards
« on: November 18, 2007, 10:02:19 AM »
 if you look on Ebay you should be able to pick one up for about 10-15 £ 0r double that for dollars.
heres one:


If your not an ebay member join up,as most of us buy the bulk of our gear from there!! Also open yourself a paypal account.
its the best and safest way to transfer monies via the net.
    The shielding is usually grounded at the driver end,I ground every thing ie computer/machine/drivers and the ground is linked to 0volts andI use servo's so there's loads more wiring.
  hope that helps?

General Mach Discussion / Re: Breakout Boards
« on: November 18, 2007, 05:25:11 AM »
  yes I use passive breakout boards.
and good quality shielded data cable(twisted pairs)
be sure to only ground the cable at one end. Not sure why, but
its  apparantly good  practice?

General Mach Discussion / Re: Breakout Boards
« on: November 17, 2007, 05:00:39 PM »
 for my two-pence worth, I would not use a break out board,and thats nothing to do with cost cutting.
firstly, practically all stepper/servo drives have optoisolation built in.so it is purely to safeguard against bunging
more than 5 volt back down the port by mistake.Treat your port with respect!
 Alternativly use a pci card,best to use them +5volt common though (as a laptop) taken from a spare usb port.
Secondly,if the optoisolater or its wiring isnt quite right,that can be a bitch to trace,giving you mis-steps, and
hours of fun! Some drivers,aparantly dont like being fed through secondary opto's.
Just my opinion!

General Mach Discussion / Re: high count servo encoders
« on: October 28, 2007, 06:07:07 AM »
  USB smoothstepper board? whats that all about then?

General Mach Discussion / high count servo encoders
« on: October 28, 2007, 02:26:51 AM »
  for my next project I want to retrofit a bridgeport mill,max feedrates on rapid will be about 3-4mpm
I am using 500 watt servo's with 2048 count encoders ( 8193 pulses to deal with)
I would like to use gecko 340's with 10 x dividers. My problem is going to be lost steps on direction
changes.I figure if I use exact stop rather than CV that will go some way to helping.
  I appreciate that I could use a higher kernal speed,but for the sake of reliability with the computer I'm
using I dont want to go above 45khz.
  What I really need to do is make mach3 pause for 1/4  second between direction changes especially rapids
Is this possible? I have bought Mach so can I get into the code somehow and do this?
I really dont want to have to put a G4 between every move,as a toolmaker I do alot of programing
and that would be very tiring!

General Mach Discussion / Re: glass scales and servo's
« on: October 14, 2007, 10:25:30 PM »
 I was hoping for a more constructive reply,
 perhaps you could quantify yours as your obviously an expert on the subject.

General Mach Discussion / glass scales and servo's
« on: October 13, 2007, 12:02:58 PM »
  I would like to fit linear encoders onto my smalll ballscrewed servoed
miller. I have already got motor encoders and gecko 340's.
I was wondering could a piece of electronics be designed that would instantly sence
a movement pulse streem and switch from the rotary encoders to linear for positional accuracy?
then once the pulse stream stops switches (maybe 1/4 sec pause)back to the rotary motor mounted encoders
to stop them from hunting.Even though I only have .002" backlash I think the machine
will burn its servo's out sharpish without this type of system. I would think it might be possible to do this
in hardware rather than delving into Mach.
  Any thoughts?

Mach Screens / try this screen set
« on: September 22, 2007, 07:56:03 AM »
  I have been working on this screenset for a couple of months now,its for a four axis mill
and gives you everything you need on the mainscreen.
try it out and let me know what you think.

General Mach Discussion / Re: New Computer w/ no parallel port
« on: September 13, 2007, 04:36:27 PM »
I always use a PCI card on a mach machine, as I figure if I accidently do something silly
with the wiring then it will most likely only blow the pci card and not the mother board.
plus a pci card from ebay is a fraction of the price of an opto isolated breakout board.

General Mach Discussion / Re: How to use Mach3 outputs?
« on: September 10, 2007, 04:38:53 PM »
  dont know if its any use but I use the m07 comand (I only use flood coolant)
to operate a Quill lock. obviously you have to manually put that code in if your using a cam package.

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