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Messages - brtech

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General Mach Discussion / Re: Wiring Limit & Home Switch
« on: February 07, 2011, 09:47:56 PM »
All 8 shields go to ground

General Mach Discussion / Re: Wiring Limit & Home Switch
« on: January 21, 2011, 10:03:52 AM »
How many inputs will you use?  1 or 3?

General Mach Discussion / Re: Wiring Limit & Home Switch
« on: January 19, 2011, 02:10:38 PM »
How many inputs will you use.  Let's assume 3, one each for X, Y and Z.

Wire the "far" end to the two wires.  Wire the "near end" by breaking into the outer cable, grab one of the wires, cut it, and attach the two cut ends to the switch.  Doesn't matter which wire.  This is for a Normally Closed (NC) switch.  At the SS, wire one side of each of the 3 cables to ground, and the other wire to the SS input.

General Mach Discussion / Re: Wiring Limit & Home Switch
« on: January 19, 2011, 09:42:45 AM »
I will admit to still getting myself accustomed to this new strategy, but a very good buddy of mine has been telling me that it's now the only way to achieve FCC B in modern computer systems or even embedded systems, which he works on.

One interesting read is:

chapter 6 I believe.

The old problem with grounding both ends was that if you didn't correctly tie earth ground to the frame of the enclosure, and have a proper star ground inside the frame, then you would get a current in the shield due to unequal potential between the two ground points.  The new advice is to make sure you do tie the frames to good earth ground, so that there is no possibility of current flow through the shields.

While "earth" and "ground" are different, the advice is to make sure they are at the same potential everywhere.  If you do, you don't have to treat them as separate.

General Mach Discussion / Re: Wiring Limit & Home Switch
« on: January 18, 2011, 06:35:19 PM »
Sure.  Looks fine.  Why wouldn't you put 2 switches on Y?  It's probably overkill for A, but if you are taking the trouble, put one on the "far" (opposite of home) on Y.

General Mach Discussion / Re: limits triggered randomly no display
« on: January 18, 2011, 01:28:35 PM »
You can change the settings in Mach to ignore the noise.  It's in General config, debounce.  A setting of 1000 is often good.  The pullup resistor is a very good idea.  Do this first.

HiymeKabibble, I've worked on computer systems for 30 years and the shield ground on one end only has always been the way it's done.  These days, much to my surprise, they advise grounding both ends, and making sure all frame earths are tied together well.  It turns out that at the Ghz frequencies that we have noise problems with today, single ended shielding isn't effective, and tying frame grounds together so that you don't get any current through the shield when grounded on both ends gives better results.  I have to keep repeating this, or I will forget it myself.  It's so weird to change something as fundamental as this, but you know, a Ghz here and a GHz there, and pretty soon you are talking high frequency noise.  Ghz signals don't behave all that well with conventional wiring, so we shouldn't expect the noise to behave the same.

General Mach Discussion / Re: Wiring Limit & Home Switch
« on: January 18, 2011, 01:18:15 PM »
I think you want separate switches for the home operation of Y and A.  Depends on how rigid your system is, and how little noise you get, but generally, you home A separately from Y.

You can, if you want to, wire all the limit switches for X, Y and Z into one input, and even include the opposite (from home) A in that loop, and have one input for A, a total of 2 inputs on your BoB.  A more conventional setup is 4 inputs, one each for X, Y, Z and A. 

You really, really want to use shielded cable as Tweakie says.  It used to be that the recommendation for shield grounding was one end only.  Today, the recommendation is earth all metal really well and ground both ends of the shield.

Your basic wiring  idea is sound.  If you want to use 2 inputs, you can use a single conductor shielded cable running all the way around the machine, or you can use the 2 conductor shielded running per axis, and series them close to the BoB.  If you use 4 inputs, then your basic idea works. 

To put them in series, on the "near" switch, you cut one of the wires and put the switch on the two ends of, say, black, leaving the other intact and not connected.  On the "far" switch you connect the two wires to the switch.   

I had some installation trouble, but my router is now running Mach3 on W7 on an older computer.  You really need to make sure that the DVD you get is a 32 bit version; the normal retail or OEM DVD you find around is 64 bit.  While you can run Mach on 512MB, W7 is a pig with that little memory, although 1G seems to be enough.

Newegg does have a 32 bit version OEM 1 pack for $99 with free shipping.

Did you ask the shop if they could sell you a licensed version of XP with the machine?  They may be able to do that for less than $100.

Well, since it wasn't anything "normal", I wiped the install (uninstall and deleted the Mach3 folder after saving my mill file).  I installed the stable release with zero options, and it worked.  So, somehow, the original install was screwed up.  I had trying just re-installing, which didn't fix anything.

Oh well, it seems to work now.  I'll try upgrading to the development version, but I bet that is going to work now too.

They are in the bitmaps folder.  So, for example C:\Mach3\Bitmaps\MillBitmaps\BackgroundJog.  I looked at them with a bitmap viewer and they appear to be fine

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