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Messages - comet

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211
General Mach Discussion / Re: Encoder pull up resistors
« on: February 18, 2009, 03:32:42 AM »
Ray,
  interesting stuff,I dont need to run the cables that long I was just experimenting I will try the
cap method and see if that works.
  regards
  Tony

212
General Mach Discussion / Encoder pull up resistors
« on: February 17, 2009, 02:40:49 PM »
Hi,
  Does anyone have experience of using pull up resistors on encoders?
The story is:
 While "playing" with a G340 and a servo (heds 5500 encoder) I noticed I had erratic movement
with cables 12 foot long.
  I swapped each cable out and found that it was the 5volt feed line,and if I shortened it to below
4foot it would work fine,even though the main power and a-b channel (screened) were 12ft long.
 I then put a seperate psu to feed the encoder,this made no differance same problem.
  I remember reading somewhere about putting pullup resistors on long a-b cablles, would this work on
the 5v line? if so what sort of value and series or parallel? which end encoder or drive?
     Cheers

213
General Mach Discussion / Re: My First Mill and first CNC upgrade
« on: February 12, 2009, 04:20:33 PM »
Andy,
   I have been seriously considering one of those machines,they have excellent travel,and
are more sophisticated than the rf45 types available from:
http://www.engineerstoolroom.co.uk

The only objections I have to it is that it has a MT3 taper which is not really the best for milling,R8
would have been better.Plus he has put the cost up by £200 since the last batch,which takes it over my budget!
 As to stepper/servo's do a bit more research before you commit I have built a few systems now and I find
that the advantages of servo's far outweigh there (small) price differance.
Whatever you do you will need a Z axis motor of twice the size of the X&Y because of drilling etc.
  Where abouts in the UK are you based?
      Tony

214
General Mach Discussion / Re: step-analog board,CNT 803
« on: January 10, 2009, 12:24:26 PM »
Hood,
   chers thats very informative.
Resolvers is another ofthose things I have heard mention but I dont know what they are and how they
interface with encoders? Can you advise on any books or websites I could read?
  cheers
       Tony

215
General Mach Discussion / Re: step-analog board,CNT 803
« on: January 10, 2009, 04:26:32 AM »
Chip,
  thanks for that,can you elaborate on the index pulse?
I am still a bit fuzzy with resolvers,etc. as I have only dealt with simple gecko 340 systems.


cheers
   Tony

216
General Mach Discussion / step-analog board,CNT 803
« on: January 08, 2009, 05:34:50 AM »
Hi,
  What is the curant state of play with available step-analog conveters?
I have found these,but they are quite expensive:

http://www.vigproducts.com/html/an2step.htm

 Also while Im here does anybody have any information on the Ctek CNT Controller?
I cant get any information out of the manufacturers regarding the servo drives.
I am thinking of retro fitting to Mach3
   Hope someone can help
   Tony

217
General Mach Discussion / Re: cat 5
« on: December 22, 2008, 04:21:16 AM »
Vince,
 I too am on my 5th servo conversion!,I have generally used twisted pair shielded data cable for a&B
But I supose its not data,so maybe the best would be individual/single coax like audio link up cable?
plus its cheap and readily available.
    Tony

218
General Mach Discussion / Re: cat 5
« on: December 21, 2008, 04:54:57 PM »
Vince,
   should the other twist be earth/zero volts? I've used two core twisted shielded data cable
a&b together and never had a problem.
   Tony

219
General Mach Discussion / cat 5
« on: December 20, 2008, 12:26:38 PM »
Hi,
  would cat5 network cable be ok for the wiring to the encoders on a servo system?
     Tony

220
General Mach Discussion / Re: RF-45 conversion
« on: October 07, 2008, 11:08:03 AM »
Ray,
  it seems mostly not working or under construction.
Thanks for the reply all the same.

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