Messages

631

General Mach Discussion / Re: limits triggered randomly no display

« on: January 16, 2011, 12:28:41 PM »

Put a good, stiff pull-up resistor, like 220 ohms, between pin 11 and your +5V source.  Use only shielded cable, with the shields tied to your ground bus ONLY at the BOB.  NEVER connect the shield at the machine end.

Regards,
Ray L.

632

General Mach Discussion / Re: Power Supply Unit

« on: January 16, 2011, 12:12:58 PM »

Your schematic looks fine.  Personally, I would connect the DC and AC grounds together at a single point.  Better to have them tied together at one point intentionally, than to have a connection occur later on it's own, and create all kinds of flaky problems.  It will save you some grief down the road.

When you get around to wiring up E-Stops, limits, etc. always use shielded cables, and connect the shield to that same ground point ONLY at the electronics box, NEVER at the far end, and NEVER at both ends of the cable.

BTW - It would also be wise to wire in a relay for E-Stop, that cuts the AC power to the transformer.  There are many ways to wire an E-stop, but the most direct, and certain is best.  You NEVER want to depend on the software working properly for your E-stop to work, and it's best not to depend on the BOB either.  The simpler the better when safety is concerned, as it reduces the number of potential failure modes.

Regards,
Ray L.

633

General Mach Discussion / Re: Locating question

« on: January 16, 2011, 10:28:30 AM »

And, if you put the code to cut the rectangle in a subroutine, you don't need to repeat the code, just call the subroutine after applying each offset.

Regards,
Ray L.

634

General Mach Discussion / Re: Power Supply Unit

« on: January 15, 2011, 04:54:47 PM »

http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Delectronics&field-keywords=3AG+Slow+Blow+Fuse&x=14&y=17

635

General Mach Discussion / Re: Power Supply Unit

« on: January 15, 2011, 04:10:35 PM »

Thank you Ray, it shows how much I know about power supply units LOL.

So I will only install a fuse on the incoming AC (black wire). Since this is 110VAC, 15A circuit should I put a 15A fuse? perhaps less?

And how you install a fuse on the 110VAC? with the same fuse holder they sell for the DC circuits? or perhaps a 15A breaker?

Richard thanks for the tip but we have settled the bridge rectifier; Hood suggested earlier a 400PIV, 25A which I will purchase from mpja.com at $2.70 (item #5248 BR)

The primary power will be roughly equal to the secondary power.  Since the secondary is 24V/10A, that's 240W.  Since the input is 120V, the input current will be roughly 240W/120V = 2A.  You want to use a larger fuse, for some safety margin, so I'd go with something in the 3-5A range.  You'll also NEED a slow-blow fuse, to prevent it from blowing due to the turn on transient caused by the large capacitors.  Use a 3AG style fuse, and any style holder that will accomodate it, and is rated for >120V AC, will be fine.

Regards,
Ray L.

636

General Mach Discussion / Re: Power Supply Unit

« on: January 15, 2011, 10:24:04 AM »

I’m planning this weekend to order the transformer and rectifier online and at the same time I would like to order the fuse and fuse holder

I think I will not install a fuse on the 110VAC incoming line but definitely I will have a fuse on the outgoing DC line.

Since my transformer has an output of 24VDC @ 10A (12V-0V-12V) should I get a 10A fuse or 15A or 20A?

Thanks

That is completely backwards.  Put the fuse on the AC input, NOT on the DC output.  If the fuse on the DC blows while the machien is moving, the back EMF frpm the motors can blow the stepper drivers.  Plus, with no fuse on the input side, if the transformer develops an internal short, you'll be completely unprotected, and could havd a fire.

Regards,
Ray L.

637

General Mach Discussion / Re: Bridgeport Series 1 boss 6.1 Please Help!!

« on: January 14, 2011, 10:19:49 AM »

My impression is most BP Boss conversions are handled in one of two ways:

1) Toss all the electronics, AND the motors.  Proper drivers for the original high-voltage steppers are hard to come by and expensive.  The motors can be replaced with modern ones for much less money.  If you go this route, you also have the option of using servos instead of steppers, for little additional cost.

2) Toss all the electronics, but keep the motors.  But, performance will suffer, as the modern drivers (like Geckos) will not be able to drive them to full power, due to voltage limitations.  This will, however, give a perfectly useable, though perhaps not fast, machine.

Go to CNCZone.com, and peruse the Bridgeport Mill forum.  You'll see every possible option,with pictures, and have plenty of people to ask for advice.

Regards,
Ray L.

638

General Mach Discussion / Re: Announcement: MachStdMill (MSM) Released

« on: January 13, 2011, 09:51:01 PM »

Dave,

Excellent news, and an excellent product!  Thanks for all your hard work.  This is a major upgrade for Mach3!

Regards,
Ray L.

639

General Mach Discussion / Re: Power Supply Unit

« on: January 08, 2011, 08:51:43 PM »

You get what you pay for.  Those E-Bay supplies are switching power supplies., which are not the best thing for steppers.  They are also brand X Chinese-made power supplies, and a number of people have had problems with other such supplies.  Don't be surprised if it doesn't work well, or goes up in smoke.  Saving pennies by buying cheap motor drivers, and cheap power supplies is what leads to flaky machines, and supports the old myths about steppers being inherently unreliable....

Regards,
Ray L.

640

General Mach Discussion / Re: Power Supply Unit

« on: January 08, 2011, 07:32:30 PM »

This would work perfectly: http://www.antekinc.com/details.php?p=170

Regards,
Ray L.