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Author Topic: cnc screwcutting???  (Read 19702 times)

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Offline Hood

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Re: cnc screwcutting???
« Reply #20 on: January 22, 2011, 09:08:22 AM »
You may already be doing this but if powering externally you will likely need to connect the 0v of your supply to your BOBs 0V.
Hood
Re: cnc screwcutting???
« Reply #21 on: January 22, 2011, 01:30:27 PM »
Hi Hood, Got machine back up and running again, found blown fuse's on my drives, BOB is working okay. Just tried running mach with index sensor on, but no input signal on mach's diagnostic page. thanks for the heads up on the 0v common on my BOB I'll give that a try tomorrow.

Kind regards

Dale gribble

Offline Hood

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Re: cnc screwcutting???
« Reply #22 on: January 22, 2011, 02:06:37 PM »
You remembered to set the correct pin and port for the Index and also enable it?
Hood
Re: cnc screwcutting???
« Reply #23 on: January 22, 2011, 02:52:34 PM »
Hi, yes I entered in the correct pin and port number. I'll have another go tomorrow with the 0v common on the BOB.

Regards

Dale gribble

Offline rcaffin

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Re: cnc screwcutting???
« Reply #24 on: January 22, 2011, 06:51:56 PM »
Hi Dale

We really need a bit more information than you have provided so far. I see that the BOB uses pull-DOWN resistors on the inputs: the optical interrupter circuit you have may be designed for pull-UP resistors. They are not really compatible without some little interface or redesign. Perfectly possible to do; but more info needed.

Cheers
Re: cnc screwcutting???
« Reply #25 on: January 23, 2011, 07:01:39 AM »
Hi, Ok I've had another go this morning, I'm getting strange results, I've tried using an external power supply which give the same result as the on board power, which is when connecting the 0v to common on BOB volts drop on my input wire (blue) pin 10 from 5v to 1v. I have no ideal what going on any help would be gratefully received

Regards

Dale gribble

Offline Hood

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Re: cnc screwcutting???
« Reply #26 on: January 23, 2011, 08:40:28 AM »
It could well be as rcaffin has said, I am not an electronics guy so I will leave that up to others. One thing though is if you have a second parallel port you could easily connect via that, take the power from a USB socket or a 5v molex in the computer and just put the input direct to the port, thats the way I did it on my first mill.
Hood
Re: cnc screwcutting???
« Reply #27 on: January 23, 2011, 11:36:18 AM »
Hi,

Hood I don't have a 2nd port so that option is not available to me.

Rcaffin what info do you need?  As you can tell I have limit knowedge of electronics's. do i need an additional circuit to maybe switch to and  from 0v - 5v using the output wire from the sensor.

Kind regards

Dale gribble

Offline Hood

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Re: cnc screwcutting???
« Reply #28 on: January 23, 2011, 11:43:05 AM »
Might be worth looking at another port if other methods dont work. As long as you have a PCI slot free then the ports are cheap enough, heres one
http://cgi.ebay.co.uk/High-IEEE-1284-Parallel-Port-PCI-Printer-I-O-Card-UK-/270695334553?pt=UK_Computing_ComputerComponents_InterfaceCards&hash=item3f06b30299

Hood
Re: cnc screwcutting???
« Reply #29 on: January 23, 2011, 03:25:08 PM »
Hi,

Thanks hood for the info and maybe I might need to go down that route of a second parallel port. But I have been doing a bit more research and think I might have found a solution, it is to use a transistor as a switch. Here's what I thinking. I'll power the sensor with it's own 5v supply, I will use the blue output wire from the sensor and connect this to the base to switch the transistor on and off. I'll connect the 5v from my BOB to the collector and then connect the emitter to input pin 10 on BOB. I've uploaded a image of the circuit i found online. If anybody can confirm I'm moving in the right direction I would much appreciate your input.

Kind regards

Dale gribble