Messages

1151

General Mach Discussion / Re: Spindle motor control problem

« on: June 06, 2009, 04:47:28 AM »

If I understand you correctly, you have some sort on safety intelock on your spindle controller.

My X2 had something similar. You had to turn the speed dial (rheostat with integral switch) all the way past zero to reset the controller befor it woudl start again, making it basically incompatible with Mach.

Your switch is separate, but the function seems similar.

On the X2, the switch energized a relay on the controller board that activated the controller. Once energized, the relay stayed latched unless a fault kiled the power holding it closed. Then it would stay open until energized again by the switch. Hope that made sense.

What I did was follow the wires from the speed dial and then the traces on the contoller board to find the relay and I simply figured out which pins energized the coil and put a jumper across the pins so that is was always on.

I don't use that controller any more so I can't give you specifics,  fried it . . . twice . . . long story . . .  but not related to the above mentioned modification, which solved the reset issue.  

 

1152

Show"N"Tell ( Your Machines) / Re: Success! Mini Machining Center under Mach3 control - Video link

« on: June 06, 2009, 04:18:49 AM »

Coolfox, You're not pestering me. I enjoy conversations and debates on topics that interest me. There is always something new to learn. That's one of the enjoyable aspects, second only to actually designing and building stuff.

Thanks for the spindle offer, but I want something that is reproducible . .  i.e. something that someone could make for themselves if they chose to follow the project and duplicate it.

Coolfox and Bloy, I'm definitely interested in starting a thread on the programming/control aspects of an combination indexer/spindle.

The macros I've written so far are just the basics to get things working.  I'm going to want to talk to the Viper drive thru the serial port, and get Mach to adapt based on the data  . . . . . that should be an interesting challenge. Hopfully enough to lure Hood and Vmax or some of the other Mach programming gurus into the discussion.


Question is, where to start the thread. General Mach Discussion, Mach Programming, or Show and tell.

1153

General Mach Discussion / Re: Has anyone used Viper Servo drivers?

« on: June 06, 2009, 03:59:28 AM »

  I'm using the G320's on a slaved axis and the motors are 1000rpm/60Vdc-max 3000rpm, so basically the motors are 180VDC.   

This is interesting. What is the proper way to interpret motor specs? From your example, it would seem that the relationship of voltage to RPM is linear? Which of the numbers you quoted are the published motor specs, and which are you extrapolating?

Increased voltage increases the RPM, so what property actually causes the real world limit on RPM?

Same question on voltage. What property dictates the practical limit?

1154

General Mach Discussion / Re: Has anyone used Viper Servo drivers?

« on: June 06, 2009, 03:50:37 AM »

Agreed:

1) 80Volt Limit.  This alone makes it harder to find a transformer that is just less than 2:1 when making a DC Power Supply.

I'm at 'Electronics for Dummies' level. Can you elaborate on what 2:1 means relative to transformer design?

2) Fault limit of 147 (I thought it was 128) that is not scalable.  This is a real pain when you use the pulse multiplier feature because the fault limit does not scale with multiplier, to get things to move without faulting your acceleration / deceleration profiles have to be slow (ie: takes longer to reach the MAX IPM during rapids)
Thanks for the info

The Gecko manual says both 120 and 128. The 147 figure comes from forum discussions that I was reading. Whatever the number, it is far to tiny to be useful in my application, and as you pointed out it does not scale with the multipier. I had not thought of it in those terms, but that is the perfect way to describe it, methinks. The Viper I think can be programmed out to 2000. More important to me is the 'soft fault' and the motor load warnings. The Gecko would be useable if it didn't "hard fault" (if that's actually a real term ).

Mostly I am inrigued by the Viper's RS232 real time communications capbility. I know of a USB Oscilloscope/Signal generator that is programmable in real time also. The conbination could make for an interesting spindle control.
 

1155

General Mach Discussion / Re: Has anyone used Viper Servo drivers?

« on: June 06, 2009, 03:35:43 AM »

I have these drives in a couple of machines.They work great.
I have called Larry Kenny a few times with some minor issues and
he is great to deal with.If you have some specific questions post them.

Good info,thanks. Calling Kenny might be what I need to do. You can't order from his web site and I sent him an e-mail order on Thursday morning asking for the paypal account he wants the payment sent to and I have not had a response back.

On the Viper questions: So far, I have read that there is no facility for connecting a scope, but one fellow has written a scrpit that reads the drive via RS232 and feed the data into Excell to create a chart that shows the 'waveform' that a scope would show. Very slick! Have you tried this?

In general, I'm interested in how you got along with the RS232 tuning/programming? Do you use more than one setup? Can the setups be swapped in real time? I am contemplating the possibility of having two setups; one optimised for indexing and one optimised for turning.

I have more Qs, but these are the ones I am most interested in at the moment.

THANKS!

1156

Show"N"Tell ( Your Machines) / Re: Success! Mini Machining Center under Mach3 control - Video link

« on: June 05, 2009, 09:16:35 AM »

Coolfox,
I agree with you completely, but you are on a different level. Many moons ago I had my own machine shop to develop prototypes and am familiar with the construction of machine tool spindles. 

I would love to use specific purpose machine spindle bearings, but the cost is way out of line with a hobby level toy sized machine. Even angular contact bearings would be a bit of overkill for the amount of stress I can actually put on them with the miniscule power that I have available. I also know that preloading deep groove ball bearings is not proper, but that's how these little mills are set up and installing some decent ABC3 sealed bearings ($100 worth of spindle bearings in a $500 machine) is as far as I think is reasonable for an upgrade. I have to stick with what I can fit in my very crowded garage with my wife's classic Vette (which is not going outside), and what I can spend on a hobby and not end up living in said garage (we have no dog house). I've already passed double what I said I was going to spend on the CNC conversion. This is not a good strategy for getting my favorite cookies.   

This is all the motor I have to work with for the 4th axis power:
http://www.homeshopcnc.com/servo2.html

This equipment will never see production levels nor will it be called upon for precision work (.0005 and closer). Those are the parameters for the project.

Yes, I would share the macros and other stuff, but it would not be useful unless you had the same setup as I have.

1157

Show"N"Tell ( Your Machines) / Re: Success! Mini Machining Center under Mach3 control - Video link

« on: June 05, 2009, 08:52:02 AM »

Hood,

I don't need to read the speed since there is an encoder on the motor. The issue is homing te axis. There are some symantics do deal with . .  the 'index pulse' is an ADDITIONAL once per rev pulse built into the encoder. I can't use that with the gearing , because Mach has no way to know the position of the spindle from the position of the motor. i.e. index pulse from the motor can mean the spindle is at 0, or 120, or 240 degrees. Mach would no know which, so I have to have a n index on the spindle itself (as far as I know, but you've enlightened me before).

You are correct about the form of the index pulse. It is not something that can be connected to the BOB in any simple fashion (I don't think) as it is a tiny ampitude square wave or something like that. If I could have used it, I would have already been pestering the electron guys for a how-to.

 

1158

Show"N"Tell ( Your Machines) / Re: Success! Mini Machining Center under Mach3 control - Video link

« on: June 05, 2009, 05:53:57 AM »

Coolfox,

Some encoders have a separate 'index pulse' in addition to the regular incremental quadrature. My encoder has this, but the motor is geared down to the spindle, so I can't use it for indexing and therefor I added a separate photointerruptor to the degree wheel.

It is not neccessary to zero the machine after homing unless you are recutting a part that has already had indexed operations done to it, or if you want to use absolute azimuth locations. Another reason would be to have the DRO numbers be meaningful for monotoring purposes. The Mach manual describes the A axis as 'infinate', and I have taken it to the tens of millions, so I don't see a practical limit there, and if your Gcode utilizes only relative (incremental) moves, and a DRO showing rediculously huge numbers is not a problem, then you would not need to zero the A axis.

Fixture offset is unaffected by the A axis shenanigans . .  so far anyway.

My objective is to make a sort of 'mini machining center' and emulate as many of those funcitions as time and budget (and Mach3) allow. A combined spindle/indexer is, I think, the first and most important step, and I have that pretty much worked out. I've just been prototyping to test feasibility up to this point, but I'm satisfied now that the concept is proven out sufficiently to start designing a sturdy permanent head with reasonable quality ball bearings and alignment pins and table mounting. I'm going to have two gear ratios 3:1 and 2:1 to accomodate different materials and stock diameters.


EDIT: checked out your site. That is some seriously unique and beautiful jewelry!  I pray my wife never discovers your site . . .
 

1159

General Mach Discussion / Re: Has anyone used Viper Servo drivers?

« on: June 05, 2009, 05:22:00 AM »

The 80V max is not a problem for me. Since I was buying new motors, I simply bought 72V. I read that anything over 80V is lethal, so I'd just assume stay under that anyway.

My issues with the Gecko Servo drive are several. Prior to buying the Gecko and the 1,800 line encoder, Gecko tech support assured me that their 340 would not limit my speed with an 1800 line encoder, and that drive's 250khz pulse rate "can easily handle anything Mach3 can throw at it".

Well, it turns out that the 250khz limit is not only on the input side, but also on the encoder side, so even though you can multiply the inputs by an order of magnitude, you still hit a wall on the motor side. With the 1,800 line encoder, the Gecko limits my speed to about 2,080 RPM. The motor is capable of over 4,000RPM. The Viper can read encoder pulses at 625khz, which is over 5,000 RPM with an 1,800 line encoder.

The Gecko faults at a fixed rate of 147 steps. On a 300 line encoder, that's plenty, but on an 1,800 line encoder used on a spindle, the Gecko faults constantly on harmless tiny following errors. And the Gecko has no 'soft fault' It just shuts down the motor and does not recover which is a huge PIA, and the Gecko is not configurable in any way, so it is not possible to correct these issues.  The Viper, by contrast, can have the fault steps programmed wherever you need them to be and it has a 'soft fault' where it will just issue a warning.

There are other annoying characteristics of the Gecko, but those are the two critical problems that make the Gecko unuseable in my application. The Viper has a lot of other very useful features, not the least of which is reporting back to a host via RS232 port. You can read the following erroe, and the mortor load in real time. With a VB macro or more likely a 'Brain' monitoring the servo, Mach3 could actually approach something like t a true closed loop system.

I've ordered the Viper, so we'll see how it goes. Incidentally, I have several of the Gecko 203V stepper drives and I am happy with those.

1160

General Mach Discussion / Re: Xbox 360 controller USB cable

« on: June 04, 2009, 12:25:05 PM »

You might consider buying a wired controller.

I had problems with the wireless interferign with the machine electronics. Others have had no problems.

The entire genuine microsoft xbox 360 wired controller cost me 16 bucks on ebay . . brand new . . and it works fine in Mach . . . provided I use an old computer.

The wireless controllers are actually for my step-son's Xbox360, but I'll be happy to sell you my PC USB adapter if you want it . .