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Messages - BluePinnacle

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261
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. :)

262
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.

263
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!

264
General Mach Discussion / Re: EStop problem/question
« on: March 17, 2008, 07:07:29 AM »
That's about the strength of it, my 9v supply feeds the coils of several relays. One has its coil in series with the limit switches, the other in series with the Estop mushroom. Hitting a limit or punching the mushroom cuts the current through the coil and allows the NC contact of the relay to snap shut and short out a pin. (10 for estop iirc).

The relays areTyco T7S S5E6-12 single pole changeovers, about sugar-cube sized, 57pp from RS, part number 616-8714. They're 12v rated but run fine on 9v.

265
General Mach Discussion / Re: EStop problem/question
« on: March 16, 2008, 07:46:14 PM »
I had a similar problem with Estops in particular. Slightly leaky circuits, long wires in particular, can trigger a pin. All my estops and limits feed into relays, which short the PC pins via a short length of printer cable. The relays run off my 9v control circuit that also powers the hall effect home switches. i used to suffer all the time from false Estops, now life is easy with relayed signal inputs. Why, i liked it so much i bought the company*

[/victor kyam]
* more relays, anyway

266
General Mach Discussion / Re: Thread Milling hardware requirements?
« on: March 14, 2008, 07:00:14 AM »
Maybe worth clarifying a few differences here, I thought we were talking of rigid tapping which is a different ball game altogether. That would require a very well controlled spindle.

267
i had some thoughts about the wire - it would be prone to expansion and creep if the temperature changed. I saw a heater with a length of wire as a thermostat today, it's not a new idea but it got me thinking. Of course if your workshop is blessed with a steady temperature you may well be ok. Best way is to try it out :)

268
General Mach Discussion / Re: Power Supply Question / Problem
« on: March 13, 2008, 09:39:10 AM »


That's the way! nice and simple. use a rather slow relay for best results.

269
General Mach Discussion / Re: Power Supply Question / Problem
« on: March 13, 2008, 05:53:32 AM »
You may need a different breaker type instead of a different rating. Over here at least they are to be found in B, C and D flavours. So a B60 would protect a 60A (running current) circuit, and have close protection, tripping instantaneously at 5x the rated current for fault protection. So you'd use it for resistive loads like heaters, boilers etc. A C type breaker allows its magnetic trip to operate at 10x its rated current value for motors and fluorescent lamps, and a D type at 20x for induction heaters and transformers. The thermal response curves are the same, but the magnetic fault protection differs.

A microwave oven transformer - hefty kit - tramsformers often suck in 10 to 15x their maximum running current as inrush so do consider some current limiting measures. Even a series resistor shorted out by a delayed contactor will help, allowing the core to saturate then giving it full power. You will need a high power, low value resistor. incidentally, a lot of the high-voltage guys use microwave oven magnetron transformers to drive the primary tank circuits of Tesla coils and other insane devices... 4hv.org will tell all. Summary: bonkers ;D

270
General Mach Discussion / Re: Steppers DEAD!
« on: March 12, 2008, 11:32:19 AM »
silly, I know, but i saw the headline "stepper motors dead!" and the sticker "very hot!" and thought there was an electrical fire issue... i think I've been up too long

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