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Messages - BluePinnacle

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I've got a program spread across two fixtures for making a large waveguide flange. The start point is at G54 X100 Y130 (left hand fixture), and the whole cycle finishes there, returning from a similar position on the right hand (G55) fixture. This normally executes well, using a 3-axis movement to clear the fixtures and a fast return to the start point. I've done about 40 flanges so far, and they're all good, but today Mach3 has run away twice. The first time it drove the cutter up (Y+) without any provocation, shredding the jig and snapping the cutter. Secondly, without any warning, it was returning to the start point when it seemed to hop to a subroutine I'd written for boring a 10mm clearance hole. Again, the cutter broke as Z fed down and stubbed it into the part.

This isn't funny, I've trashed over £60 of carbide cutters and aluminium blanks today and we're going to be in trouble if I can't sort this out. Any clues?

General Mach Discussion / Re: random e stop error
« on: November 20, 2008, 12:02:30 PM »
could be earth leakage, that held me up for a while. It takes very little current to ground a pin. Use a seperate supply like a 'phone charger, feeding your estop and limits, and use it to hold a relay closed. Wire the relay contacts to your logic pins.

General Mach Discussion / Re: Deleting spammers
« on: October 09, 2008, 04:48:22 PM »
it's a possibility. This isn't usually an inflammatory board and there are lots of responsible adults.

General Mach Discussion / Re: Home and/or limit switch
« on: September 12, 2008, 07:42:12 AM »
Jim - good call, mine uses DIP16 packaged darlington phototransistors (ISP845X). Four isolation channels per chip and 5KV isolation. nice sharp switch-on with very little forward current required, ideal for a first stage from one's LPT. And like you say, very cheap :)

General Mach Discussion / Re: Home and/or limit switch
« on: September 11, 2008, 11:31:09 AM »
Spindle control is pretty easy and by implication so is coolant control. Of course the cheaty way is to have the coolant pump in series with your spindle motor (if you don't use reverse) and switch it out if you want to cut dry. I didn't think of this, put in software control and the computer runs the whole thing.

A quick opto-isolator circuit will drive a small 5v coil relay, and the relay, if selected for its contact properties and isolation values, will drive a hefty 3-phase contactor with no gripes. While we're here, mobile phone chargers power relays and opto circuits very nicely :)

General Mach Discussion / Re: Fried 2nd Computer (Newbie)
« on: June 06, 2008, 07:15:05 AM »
Words to the wise, if you want a quick 5v supply, an old Nokia phone charger does very well. Almost everybody i know has old Nokia chargers kicking about somewhere.

General Mach Discussion / Re: PCI port card addressing woes
« on: June 06, 2008, 07:11:49 AM »
Who doesn't need an emergency stop? I don't like the sound of that one bit.

This has been solved anyway, thanks for the help, i think we've established that MosChip boards are the way to go and not the cheapy triangular ones. :)

General Mach Discussion / Re: PCI port card addressing woes
« on: April 02, 2008, 05:51:25 AM »
This has been resolved, I just used a different PCI card. Vista? not using Vista, and won't be for some time. Thanks anyway. :)

General Mach Discussion / Re: Home switches
« on: March 28, 2008, 09:00:59 AM »
this is the same way I had my limits wired up, and they triggered occasionally for no good reason. I fixed the problem by using a relay interface, ie feed 12v into your series switches, series switches to relay coil, relay coil to 12v ground. Then fix the n/o contacts across pin 18 and 12. This gives you some isolation from the long wires and damp switches you normally find on NC machines. Computer pins have a high output impedance and will happily trigger if they so much as smell a path to ground.

mount the relay close to the computer with short wires to the socket and remember to fit a diode backwards across the coil to absorb the flyback pulse.

Suggestion: find an old mobile phone charger which outputs 5v (nokia, usually) as they make great little power supplies for small stuff like this, and use 5v relays. use 12v and a bigger supply if you would like to run 12v hardware like low-voltage lamps.

General Mach Discussion / Re: EStop problem/question
« on: March 18, 2008, 09:27:23 AM »
np :) cost came into it, i could have bought much smaller relays but these Tyco ones were the cheapest that would do the job. As it is they'll carry 10 amps so they're well overrated, and another benefit is around 1,000 volts worth of isolation between the coil side and the contacts. happy wiring!

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