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Messages - simpson36

1141
General Mach Discussion / Re: Has anyone used Viper Servo drivers?
« on: June 08, 2009, 11:30:43 AM »
But .  what does the ratio refer too? Primary to secondary? So far the Torroids I have found are listed as to output voltage. The ratio spec is something new to me. 

I'll take a stab:

120V 2:1 nets 60V secondary multiplied by 1.4  yields  84V . . . . is that pretty much how it goes?

What it the purpose of the resistor across the CAP?

1142
General Mach Discussion / Re: First Post - Help with setup issue?
« on: June 08, 2009, 11:03:03 AM »
Rich, your 'direction change' analogy and physics reference do nothing to explain Machs real world behavior.

It would be useful if had an explanation for what Mach is actually doing:

If I run with CV on and make a circle, the machine runs smoothly past the direction changes . . . . therefore . . .  obviously long pauses at direction changes are not intrinsic and unavoidable.

If I use backlash comp, even at tiny numbers like .002 there is a definite pause at each quadrant.

Cutting at 40ipm, the .002 movement should take .003 seconds, i.e. imperceptible. That actual pause is many, many times that and is very noticeable . . . . thefore . . . . obviously Mach is occupied doing something that takes far longer than .003 seconds while the machine sits waiting for that operation to complete.

In addition, CV even without backlash comp, does not seem to be able to reach thru A axis movements, but that's another discussion.

I'm not saying Mach is bad, but it does what it does and facts are facts. Mach has some room to improve in some of its functions. 








1143
General Mach Discussion / Re: XY zero
« on: June 07, 2009, 10:39:39 PM »
Zero at the bottom was just a suggested solution that I think Himy made for you. That IS a solution, but it is not a rule. There are lots of ways to skin a cat, and you have not invented a new problem. We all have the same issue to deal with. You seem to have become impaled on the 're-zeroing issue, so my suggestion is to simply walk around that obstacle and not re-zero at all.

I'll just give you a quick example of the best way to solve your problem and you'll need to do your homework from there. You need to study the tool offset feature of Mach and get yourself a couple of end mill holders for whatever spindle taper you have.

Example: you have one endmill holder with your roughing endmill. You have another end mill holder with your ball end finishing mill. You LEAVE these items together so that you change the holder/endmill together as if it were one solid piece.

Now, since the holder/endmill combination has a fixed length, you simply need to tell Mach what the difference is and it will AUTOMATICALLY compensate for you when you change tools and you do NOT have to re-zero.  For simplicity, lets say the holder/roughing mill is zero, but when you switch to the holder/finishing mill and place the end on the same surface, the DRO now reads positive .25". No problemo, just tell Mach that your finishing mill is .25" longer than your roughing mill and when you change the tool, you tell Mach "changing to tool number 2 now" and Mach will automatically adjust for the longer tool.

That's all I have time for right now, but Mach has these features that are designed for exactly the situation you have, and it is invisible to the CAM program.   





1144
General Mach Discussion / Re: Has anyone used Viper Servo drivers?
« on: June 07, 2009, 11:47:23 AM »
jeep,

My issues have nothing to do with the size of the motor. The Gecko340 is 'big' enough, and it ran the same motor with a 300 line encoder just fine. But a 300 line encoder is not adequate in this application.

It does not seem like it would be a huge problem to have the fault steps scale with the multipier, or have it be separately settable via jumper, or be programmable.

If none of that is feasible, then a socketed eprom where a customer could swap to a chip with different parameters would be a solution. That would not be blazing new trails for Gecko as they already sell the multiplier board sparately and you remove a chip and plug in the daughter card in it's place.
 
I may well be severely underestimating what would be involved, but never the less, hopefully the Viper will do the trick in my application, if I can get the thing ordered.

1145
General Mach Discussion / Re: XY zero
« on: June 07, 2009, 08:48:49 AM »
Kak,

It's not complicated, instead of starting at the top surface and using negative coordinates, you simply start at the bottom and all coordinates are positive, which is actually more intuitive, in my experience.

'Zero' is used as a noun and also as a verb in machining, so those darn semantics get in the way again . .  i.e. 'zeroing' (verb) is  just a term used for the process of telling the CNC machine where stuff is and it does not necessarily involve the number zero (noun) at all.

Example: Let's say your stock is .75"  . . grab your PC board and do the the tool height thing with the Himy stuff and what do you have? You have the end of the tool .75" (material thickness) plus .125" (the PC board) above the bottom of the stock. All you need to do is tell Mach3 where the tool currently is. There is no rule that says you MUST get the tool to 0.000 and then tell Mach it is at 0.0000. Mach just needs to know the coordinate of the CURRENT position and it will know where everything else it from there. 

In the example, if you want the bottom of the material to be zero, then the tool is currently sitting .875" above that, so you simply tell Mach where it is by typing positive .875 in the DRO and your good to go. You do not have to have the tool physically at zero on any axis. 'Zero' (the noun) is simply a reference plane from which the coordinates are all taken. It could be on the roof or 100 feet underground.The only caveat is to remember that you physically hit something at positive .875 in our example, so don't get absent minder (like me) and pick up the tool to say .5" for a rapid move or  :'(

 







1146
General Mach Discussion / Re: XY zero
« on: June 06, 2009, 02:33:07 PM »
Thanks, Hood!

Got it!

1147
General Mach Discussion / Re: XY zero
« on: June 06, 2009, 12:32:22 PM »
Thx, had to join that group. Waitiing to be 'approved'  ::)

1148
General Mach Discussion / Re: setting up a 5th axis
« on: June 06, 2009, 11:37:43 AM »
I didn't think the X4 had an option for a 5th axis on the head.

If that's correct, then the OP must have something else in mind. 

1149
General Mach Discussion / Re: XY zero
« on: June 06, 2009, 06:17:39 AM »
Himy,

Your probing stuff looks really handy.

Where does one find the 'Files' section of the group. I'm sure it's in front of my face, but I can't find anything.

Thanks,



1150
General Mach Discussion / Re: setting up a 5th axis
« on: June 06, 2009, 04:54:40 AM »
Mach has three additional axis, so that should not be a problem.

More than likely you will need a second parallel port to run 5 axis, but that's easy to accomplish.

You will need an appropriate drive for whatever motor you plan to use unless the machine has a drive that can handle multiple motors and it still has a spot open.

A 5th axis can be a lot of different things. Can you describe further exatly what yuor 5th axis is? 'Gantry' is not making sense to me relative to a mill.