> Tachs are not without their own problems. Brushes, noise, belts,
> couplings, etc.
Right, the less to go wrong the better!
> I didn't know that hostmot2 could output velocity, that is pretty
> slick. That would certainly be a low cost solution and that should be
> very reliable.
I didn't know that either. Where can I find info on it?
> But lets face it. That machine you have is probably worth an easy $40K
> or more if it is running right.
>
> What is $195 x 3 for a $40K machine. Insignificant.
Actually we bought this machine for over $700K about ten or 15 years ago but
for the type of work we do the machine is fairly priceless! The only bad
thing about it is the Fanuc 11M is pretty weak on keeping up. An example
would be a programmed feed of 80ipm while cutting complex arcs in point to
point programming slows down to 4 to 8 ipm during some portions of the
program. The control only has 3 lines of look ahead. A program that ran in
55 minutes runs on EMC in 24 minutes! Big difference.
Thanks to all for the input given today and hopefully we can revisit this
subject again soon.
Best wishes and good night world,
Dave
----- Original Message -----
From: "Dave" <e...@dc9.tzo.com>
To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net>
Sent: Saturday, March 20, 2010 8:26 PM
Subject: Re: [Emc-users] G52 and Fanuc conversion to EMC
>I wouldn't waste my time adding tachs on an existing system.
>
> Tachs are not without their own problems. Brushes, noise, belts,
> couplings, etc.
>
> Tachs were used because there was no way to determine velocity off of a
> position resolver way back when.
>
> No one is installing tachs these days. The standard is to derrive the
> velocity from an encoder. Heck, even Fanuc did that in your existing
> control, which you are ripping out.
>
> Adding tachs is just adding possible mechanical issues and going
> backwards.
>
> I didn't know that hostmot2 could output velocity, that is pretty
> slick. That would certainly be a low cost solution and that should be
> very reliable.
>
> But lets face it. That machine you have is probably worth an easy $40K
> or more if it is running right.
>
> What is $195 x 3 for a $40K machine. Insignificant.
>
> Dave
>
>
>
> On 3/20/2010 5:33 PM, Paul Keeton wrote:
>> I agree with you Chris. The drive can be setup for either a 3v/1000 or
>> 7v/1000 tach signal. This might be the simplest way to to do it. Servotek
>> makes really good tachs, May be just what I need.
>>
>> Dave
>>
>> ----- Original Message -----
>> From: "Chris Radek"<ch...@timeguy.com>
>> To: "Enhanced Machine Controller (EMC)"<emc-users@lists.sourceforge.net>
>> Sent: Saturday, March 20, 2010 5:19 PM
>> Subject: Re: [Emc-users] G52 and Fanuc conversion to EMC
>>
>>
>>
>>> On Sat, Mar 20, 2010 at 03:57:02PM -0500, Jon Elson wrote:
>>>
>>>
>>>> If you look further, I think you will find there is NO tachometer in
>>>> the
>>>> machine. The Fanuc controls synthesize this from the encoder signals.
>>>>
>>> The mesa hostmot2 driver has a good encoder velocity output that
>>> considers the time stamp of the last encoder event to give smoother
>>> output than d(counts)/dt. I'd just send that to a dac and see if it's
>>> good enough to keep the amp happy. If it is, you have a pretty
>>> cheap solution (just the cost of another 7i33).
>>>
>>> If that didn't just work, I'd quickly give up and fit real tachometers
>>> like some others have suggested, because I bet in the long run that
>>> is the best configuration.
>>>
>>> Chris
>>>
>>> ------------------------------------------------------------------------------
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>>
>>
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>
>
> ------------------------------------------------------------------------------
> Download Intel® Parallel Studio Eval
> Try the new software tools for yourself. Speed compiling, find bugs
> proactively, and fine-tune applications for parallel performance.
> See why Intel Parallel Studio got high marks during beta.
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> https://lists.sourceforge.net/lists/listinfo/emc-users
>
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proactively, and fine-tune applications for parallel performance.
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