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Author Topic: Opinion and advice - explain relationship of encoder to kernel speed  (Read 17013 times)

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Offline simpson36

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Re: Opinion and advice - explain relationship of encoder to kernel speed
« Reply #50 on: April 18, 2009, 06:10:43 AM »
I did a quick perusal of the CNC brain site and I have do disagree with what's been said in this thread about it thus far.

First off, it is not exspensive. In fact, it is the opposite if one considers what is included in it's price. The CNC Brain @ $500 cost less than my 4 Gecko Drives ($600), and the CNC Brain is 6 axis. Also the 'GUI' appears to be the control software and is included. Mach is now $175. The CNC Brain also includes the functionality of the smooth stepper.

Just combining the cost of Mach and a smooth stepper together gets you a long way toward the CNC brain cost, and the functionality of both is included in the CNC Brain. I don't know at this point what kind of 'dumb' amplifiers one would need to handle the motor current, but unless they are $150 each, like a Gecko 203v, you can subtract the delta from the CNC Bain system's actual cost.

Second, it doesn't work with Mach, but there would be virtually no point to using it with Mach. IF the thing works as they claim, Mach would be a major step backward, and as I mentioned, the CNC Brain already has it's own control sofware, so it does not need Mach.

Third, there seems to be a very active forum assiciated with the device, so more than a couple of people are using it. There woud logically be little disussion about it in a dedicated Mach forum.

Lastly, anyone who can compete in the DARPA robotic challenge is cutting edge, so in my opinion, that resume' entry alone deserves respect.

I am definately going to look into this further, but from the descrition, it does exactly, precisely the kind of functions I was referring to that Mach cannot do.

Of course, there remains the question . . . does it actually work . . . but here again, in fairness, I read in the Mach forum about the relatively new smooth stepper's current limitations and what is 'planned' for the future, and nobody seems uncomfortable with that concept. This demonstrates some acknowledgement within the Mach community that new technologies need time to mature.

Obviously, I need to do a lot more homework on the CNC Brain to make an intelligent assessment, but it seems to me that the negative comments here are perhaps a rush to judgement.





Offline Hood

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Re: Opinion and advice - explain relationship of encoder to kernel speed
« Reply #51 on: April 18, 2009, 07:17:29 AM »
Please do purchase one and let us know how you are getting on with it, also there is a section on CNC Zone dedicated to the CNC Brain, you can check that out as well, here is a link.
http://www.cnczone.com/forums/forumdisplay.php?s=4a6d3e5452581e230452df2e300b2ef6&f=432

Hood
Re: Opinion and advice - explain relationship of encoder to kernel speed
« Reply #52 on: April 18, 2009, 07:46:20 AM »
YES !  Please do.
   I am anxious to see your results as well.
 
Clip:

You will need TTL output encoders or linear scales to feed back the position. Newall linear scales with differential TTL output levels should plugh straight in. You can check the pinout of the encoder input on the brain from the CNC Brain control panel. Just download it and run the trial version.
If you haven't bought any steppers yet then don't. Have a look at Gecko DC servo drives before you make up your mind or Sureservo if your budget is big enough.

Keep in touch,
RC
« Last Edit: April 18, 2009, 07:51:22 AM by Overloaded »

Offline simpson36

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Re: Opinion and advice - explain relationship of encoder to kernel speed
« Reply #53 on: April 19, 2009, 06:41:10 AM »
Overloaded; My first DC servo and Gecko 320 arrive on Tuesday, so sayeth Brown.

CNC Brain, however is not on the menu at this point, although I do plan to follow it's progress if I have the time to do so.

As I said, I only did a quick scan of the CNC Brain site and I was not aware it used linear scales, but linear scales are nothing new. I had them on my little el-cheapo Mini mill before I converted it to CNC. I had not considered getting feedback from a linear scale, but it makes a lot of sense. Absolute is always going to be more reliable than relative positioning.

Hood; I am not interested in blazing new trails in home grown retro CNC. An engineer is, by definition conservative, skeptical, anal, and only interested in facts. The CNC Brain may not be ready for prime time, but the idea is very valid and the apporoach, if it is developed fully, would solve the issues I was pointing to, and at an entry level price point. AS I have already said several times, these capabilities we have been discussing are not new. Machining centers incorporate ths technology and have for some time.

Getting anything remotely  similar for $500 or $600 would definately be something new, as are servo motors under $100 and $30 encoders, apparently.

It appears that the CNC Brain is being developed by a very small outfit, so, like most of the other suppliers to the CNC retrofit community , including Artsoft, it takes a while to get things accomplished.


I just feel strongly that discounting new technology simply because it is not fully developed or based on the cost of a single component is not a good strategy. If one were to evaluate, for example, the Gecko 540 on price alone, it would look expensive, but it has 4 drives in it. The smooth stepper has a way to go before everything is implimented the way people (including yourself) want. The only way to look at a CNC retrofit, in my opinion, it to set your criteria and then compare the total system cost of the alternatives that meet the criteria.

One of those criteria, of course can be that certain features must be fully functional right now, today. Mach has been around for quite a while and it seems they are just now getting threading to work right. I don't know of any bug free software that is under active development. I also know of no software that does not have a wish list associated with it.

There is a saying . .  'it is what it is'.

I'll say this, if I made my living off my CNC machines, I would definately be following CNC Brain and any other promising technology, unless I had the cash to plunk down on a machining center.

Lastly, were I to purchase CNC Brain, which actually would make sense in some ways as I am very interested in new technologies and at my hobby level, I don't need to make money with the machines or have tight production dealines, so beta products are not a critical issue for me . .  hell, I've had the Windoes 7 beta runing since day one availability . .  8) but in any event, I would not be posting the progress of CNC Brain on a Mach forum . . that would make no sense.
« Last Edit: April 19, 2009, 06:53:18 AM by simpson36 »

Offline Hood

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Re: Opinion and advice - explain relationship of encoder to kernel speed
« Reply #54 on: April 19, 2009, 07:24:20 AM »
No need to post here, I religiously follow the CNC Zone and the SR forum re the CNC Brain as I too am very interested to see if this can work.
Hood

Offline simpson36

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Re: Opinion and advice - explain relationship of encoder to kernel speed
« Reply #55 on: April 20, 2009, 10:05:10 AM »
Excellent!

Retrofitting this little mill was my first foray into home grown CNC and it has been a lot of fun. Some setbacks, but overall not nearly as difficult as I envisioned.

I have some other commitments that will take me away from my toys for a few months and I'm thinking about selling this little mill complete. I've pretty much taken it to it's limits. When I get time to play again, I would be doing up the larger X3 with servos. Maybe the CNC Brain, or equivalent, will be working by then.

I'll look you up when that times comes and see what you think of the progress.