Messages

1321

General Mach Discussion / Re: Opinions on use of ancient computers to run Mach3

« on: December 21, 2008, 01:51:43 PM »

Sooner or later, all CPUs, even low level ones suitable for running Mach (if indeed it stays in its current incarnation) will be 'green' as will probably everything that runs on electrons.

The question is not the stupidity of buying a fast compter for Mach, although I suspect that many (including myself) use the same computer for CAD/CAM and then also run the output thru LazyCam, or some post processor and then test the resulting Gcode on a copy of Mach running on the same machine.

I only send the finished and tested Gcode to whatever computer is actually running the machine tool.

It is not a matter of power supplies, component cost or anyone's definition of stupidity. I used Core 2 only as an example of the new 'green' technology that is finding its way into processors. The question is if the new CPUs 'throttle' and if so do they do it internally? Do they do it automatically? In such an instance, would it disrupt a running low level Mach process? If this feature is built in, can it be externally controlled or disabled?

Anyone with the knowledge to shed light on those questions could make a useful contribution to the community.

1322

General Mach Discussion / Re: Opinions on use of ancient computers to run Mach3

« on: December 21, 2008, 10:36:06 AM »

I think the comparison between older high quality hardware vs more 'modern' cheap stuff is a valid one. C64 is old AND cheap, so it does not qualify for consideration     

This old server was overclocked to 1ghz and ran that way 24/7 for many thousands of hours in a rendering farm with both processors pegged at 100% hour after hour, day after day, week after week, year after year. I honestly have to wonder if todays super hot running computers can match that.

From what I've been reading the new Core 2 chips are not nearly as self destructively hot as my current Pentium D and its cousins.

However, the point at issue here is if the new 'green' chips throttle back to save energy. Again I don't know much about that yet, but based on my experience with my laptop similarly slowing itself and the consequences for the timing sensitive Mach processes, I think it would be worth looking into to see if the new processors might not be suitable for Mach for that reason.

It is just a point of curiosity as I have no plans on building a Core 2 Quad with 16 gigs of DDR3 to run Mach   

1323

General Mach Discussion / Re: Random stop at x axis

« on: December 20, 2008, 08:16:06 AM »

From the FWIW department:

Besides the obvious: accelleration set too high, wrong pulse width, etc., I've had the steppers stall for three non-Mach related causes:

1) ways too tight  . .  i.e. el cheapo X2 with el crappo machinging has tight spots in the travel. Set the ways at the 'loose' point and it will jamb at the 'tight' point.

2) laptop/notebook with 'energy save feature' active. Slows down the CPU when battery gets low, or when it 'predicts' it is going to get low  . . uh . .  'soon', . . . . or because it's Thursday, or for no reason at all.  Causes instant stepper stall. Mine could be disabled in the bios and I removed the battery altogether and run off the charger. No more problems with it.

Some desktop processors also have forms of 'throttling' so look for that and disable it if possible. I would not swear to it as I am just now doing some homework on Intels 'Core' series architecture, but I think they have the ability to throttle. I don't know enough about that to be helpful, but it's worth a look in troubleshooting problems if these processors are used, methinks.

3) wrong (too high) resistor on a Gecko stepper driver. I hooked up a 4 amp motor to a Gecko 203V that still had the resistor on it for a 6 amp motor. The 4 amp would squeal and move in apoplectic spasms. Calculated and installed the correct resistor and it runs smooth as silk.

1324

General Mach Discussion / Re: Opinions on use of ancient computers to run Mach3

« on: December 20, 2008, 07:47:29 AM »

Thanks to everyone for the valuable comments!

The old server has Windows2000 pro and is definitely set up for the two processors. The task manager shows the load on each processor separately. This machine was never actually used as a server, but as an animation machine for 3ds MAX. Expensive servers had the only dual processor boards at the time. The 850mghz processors were an upgrade from the previous P3's. I don;t recall the speed of the original CPUs, but I do remember upgrading the two to 850s was something like $800 (the price had dropped all the way to that tiny cost . . LOL!!)

Anyway, using my actual XML, I ran my most complicated .tap with backlash, CV, tool comp, etc and it didn't come near maxing either processor. I can actually dedicate one processor to Mach and have the other do everything else, but that does not seem necessary at all.

When I get my goofy silicon keyboard, I'll move the beast to the garage and run the mill with it and post back the results.

Does anyone know what parts of Mach are multi threaded?

1325

General Mach Discussion / Re: Limit Switch Problems

« on: December 19, 2008, 07:42:27 AM »

Just FYI, the info I came across said that the drive is the source of the noise.

The metal box is to keep the drive from bothering the other electronics. It seems to work . . although I made several changes at the same time so I can;t say which was the effective cure. I can say that it is a plus for convenience and safety to have the spindle control in a box on the bench right next to me (and the computer) rather than on the mill head where it originally was mounted.

I have Mach turning the spindle on and off, but I still control the speed manually because I find I need to vary the speed during a run sometimes to eliminate chatter. Having the knob nearby is extremely helpful in this regard.

1326

General Mach Discussion / Opinions on use of ancient computers to run Mach3

« on: December 19, 2008, 07:33:37 AM »

My little notebook computer is getting destroyed, so I have resurrected an old server that has been gathering dust and plan to use it for Mach3. It is a dual processor P3 pushing 850mghz each. These were the days then 'dual' meant two separate processors. The motherboard is a very expensive SuperMicro server board and running the mach 3 tests show a dead flat line and 'excellent' grades up to 65khz where it fluctuates. There are certainly faster computers, but I don't think any higher quality than this old beast.

I read somewhere that mach3 is multi threaded at least in some processes, but now I can't find that info again.

Anyway, I was just interested in opinions on the wisdom of using such a 'slow' machine for mach. It appears, surprisingly, that this machine is doing a far better job than the new notebook I am currently using.

Incidentally, I bought a completely sealed silicon keyboard that actually can be rolled up!  I don't care about rolling it into a ball, but the 'completely sealed' part is appealing. 'Food service' keyboards or keyboard covers were fairly common at one time. Apparently no longer as I could find none.

1327

General Mach Discussion / Re: Where do I get my 5 volts from?

« on: December 19, 2008, 07:23:00 AM »

Seconding everything Hood said and adding that USB power caps at something like 500ma (per port).

I can't speak for all computers, but my laptop's reaction to drawing too much power was to simply SHUT OFF the juice to the port!  Not pretty.

PC power supplies are regulated very well, methinks and they are dirt cheap. I'm using an old one that can no longer run a motherboard, but still puts out a nice steady 5v and 12v. You can just jumper the 'ready' or 'power good' (per Hood's post) pins on the motherboard plug and the power supply will switch on a and run by itself.

1328

General Mach Discussion / Re: Backlash - very slow movement with every change of direction - Normal?

« on: December 19, 2008, 07:07:40 AM »

The backlash thing and some CV issues and threading problems are things I am watching to see if they get sorted out before I take 'the plunge' and commit to Mach 3. I already have a fairly big investment in time into Mach 3 and so I would want to use the same control software for both mill and lathe.

The backlash, as noted in the documentation, is really only good for things like increasing the precision of drilled holes or things like that. The implementation currently in mach is not useful in my opinion for general machining because of the pauses when the slack is taken up. I simply cannot use it for milling.

I watched a youtube video from Hossmachine where he has to use backlash compensation just to get a round hole. I'm not nearly that bad off, but I did have .005 on both x and y and a good deal more on Z.

My solution has been to buy oversized balls for the leadscrews. I located .0009" oversize balls on ebay and they have taken the lash to less than .0005" on the X a little under .002" on Y (my problem axis) and I designed and built an entirely new mechanism for the Z and it now has only .005 and I am waiting on the new oversize ballscrew bearings for that axis to get that number down . . I am hoping for .002" or better.

For my purposes, this will be accurate enough so long as it can hold or a while.

I am no expert in CNC control programming by any means, but it does seem to me that adding the backlash amount to the distance of first movement after a change of direction (per axis) would not be a difficult thing to accomplish. While that would not be as accurate as stopping and taking out the lash and then proceeding (with jerky, tool burning pauses), it certainly would increase the accuracy of the machine while maintaingin a smooth CV. That would not be a perfect solutio, but in my opinion it would a logical and valuable compromise between the current 'useful for drilling, useless for milling' gap.

You mentioned that there is a change in the backlash comp behavior  in your software that is version dependent. Can you elaborate on that please?

1329

General Mach Discussion / Re: Rigid tapping with servo spindle

« on: December 18, 2008, 10:21:55 AM »

I recenntly aquired a Tapmatic head. The SPD series is specifically designed for use on a mill and uses a standard boring cycle (it self reverses).  No clutch, so make sure you know the depth you need.

Works fantastic!

Anothe approach is to fab up a simple slip joint with a retun spring so you just down Z less than the thread pitch until the tap touches the hole and then stop Z movement and keep the spindle turning. The tap will draw itself into the hole and all you need to do then is reverse the spindle at the 'bottom'.

I know this is a bit of a red-neck approach, but it does work and it doesn't ruin good parts by ripping the threads out as with an uncoordinated rigid attempt.

1330

General Mach Discussion / Re: Limit Switch Problems

« on: December 18, 2008, 10:07:54 AM »

From your post, it seems you are getting power from the computer. I had two problems with limit switches; one was when metal chips were getting on the exposed switch terminals . . easily remedied.

The other was a host of random spooky occurences . .  false e-stops, motors randomely bumping a step here and there. Occational motor stalls for no apparent reason . . etc. I was drawing power from a laptop USB port. All of those issues went away when I set up a separate clean regulated source (and old PC power supply) for the 5v and 12v power to the electronics, and moved the DC variable speed drive into its own metal box away from the other electronics and the steppers.