#1
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5-axis control, G100 (GeckoRex), and Rabbits - it's a zoo!
Spun out of another thread:
This may be a dumb question (but then again, I was always told that the dumb question is the one that you don't ask), but, if you are planning on building a 5 axis machine like Rainnea, do you just purchase another PMDX-122 and tie it to another parallel port? Or can two PMDX-122's talk to each other? Or do you suggest another solution? |
#2
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Guys building genuine 5 axis machines (not just router table plus indexer) have bigger budgets and more guts - they probably are using things like the G100Rex from Geckodrive on ports other than parallel ports (LAN or USB).
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#3
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using two breakout boards is the most common. it also doubles the number of switches and relays you can use.
Dave |
#4
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Dave, that's what I wanted to say, but then I realised that I don't know true 5-axis machines that well and actually didn't know of a single such machine running Mach3 on parallel ports. By "true" 5-axis I mean where the spindle motor body "pans" and "tilts".
I hear that Mach runs rough when it has to move too many axes simultaneously. Most of the so-called 5-axis machines are actully 5-motor machines with at least one pair of motors synch'ed together, and even then the remaining 4-axes seldom profile simultaneously. |
#5
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I doubt that I would use all of the axis simultaneously - though you never know. I would like to build/purchase a BC axis because I have quite a few uses for it.
Would you classify Rainnea's machine as a "true" 5-axis machine? Of course, either way you go - two PMDX-122 ($88 ea) or the G100 ($399) the difference is "only" about $200. IF "money was no object" would you go the G100? |
#6
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From http://www.rainnea.com/cnc.htm
Yes, all these motors run simultaneously: 1. x-axis, the gantry is rolling along the table (2 motors) 2. y-axis, the y-car is moving along the top of the gantry 3. the z-slide is going up and down 4. the spindle head swivels in the horizontal plane (c-axis) 5. the spindle head swivels in the vertical plane (b-axis) ==== 5 Axes total (6 motors) If money was no object I wouldn't be trying to build my own machine! |
#7
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True, but you (we) wouldn't be having half as much fun
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#8
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Hi All,
I am not sure if people realise this but Mach is really a 7 axis control (just look at 'motor outputs' under 'ports and pins'. It will run 6 axes quite happily if you spend some time setting the PC up correctly. The real challenge is creating the tool paths, there are no 'low cost' 5 axis CAM packages around, rainnea is good but requires a little bit of effort to work correctly. You could run all 5 axes and 2 outputs off a single break out board quite easily, a second port is not necessary. Regards, Greg |
#9
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Quote:
NO, there are serious problems with the Rabit microcontroller. seems that they fail way too often and Mariss is after the manufacturer to figure it out. But, in my work, I rarely use 3 axis at a time. In fact, I usually move X and Y, then park them and run the Z. 5 full axis all moving at the same time does require more of everything. Dave Dave |
#10
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As I understand it, the problem with the G100 is that the Rabbit controller must initialize all I/O lines so that they don't 'float'. Mariss has no control of how Mach 3 initializes the Rabbit module. Z-World has no control of how Mach 3 initializes the Rabbit module. Please be aware that I'm NOT pointing fingers at Art and Mach 3 because there may be other quality control issues that Z-World should address. However, those of us who've been in the process control business for several decades know that sometimes a few lines of computer code can fix a bunch of hardware problems. What I do know is that the G101/G102 module that I bought when Mariss first offered them for sale is still running strong after about two years. The G100 module is also working perfectly. I bought it somewhere around February or March of this year.
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#11
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Quote:
If you need a tool, by all means get the tool. but some tools wear out. I have more than one milling cutter and more than one router bit that has worn out thru no fault of my own. I think some of you might have a box of dull router bits that might be more expensive than all the electronics on the machine. Cost of doing business. Keep it cool and shut off all the electronics when not in use overnight and weekends. As Gerald says, the MechMate is to be used to make money. Make money and if your only problem is that every couple years you have to replace a chip or a board, you can laugh about it while driving to work in your brand new car. Dave Last edited by driller; Sat 27 October 2007 at 06:40.. |
#12
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Quote:
here is the update: http://finance.groups.yahoo.com/grou.../message/13762 Re: G100 Something keeps killing the rabbit! Yes, and it's good news. Rabbit Semiconductor has identified the cause of the RCM3720 modules failures. They have sent me an internal corrective action report that details the problem, its cause and their solution to prevent it from reoccurring. Their analysis shows 6% of shipped units being affected which meshes reasonably with our measured rate of 8%. Unsurprisingly it is ROHS related. I am satisfied with their handling of the situation and I am confident the problem has been solved. Mariss |
#13
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Now that is good news!
Next MM I will certainly use the G100 controller - maybe even upgrade the existing unit for fun if I have the time. Many Thanks to Mariss for his continued support and great Gecko's. |
#14
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By Mariss last night:
The G-Rex has been a huge disappointment for me. The development time took 5 years and untold $$$. By comparison, the G203V drive took less than a year and only $25,000 in direct expenses to develop. It is an idea I probably loved too much and I loved it for too long. It is expensive to build, expensive to test and very expensive to support. In a word, it is nearly unprofitable. The mistake was misapprehending what our strengths and weaknesses are. We design good hardware, we are not so good at firmware. The G-Rex needed both. Second, the G-Rex is being squeezed by improving PC-only solution step pulse rates at one end and me-too, less expensive similar products from the other end. I cannot justify investing any more effort and expense into further development, hardware or firmware, of the G-Rex given its past market performance and future potential. Instead, that effort and expense is going into new motor drives. The Rabbit fiasco was the last nail driven into an already expensive coffin. We will always have the G-Rex available. We ordered 500 more G100 boards yesterday. We just aren't going to develop it any further. |
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