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Life Meter (No, Not Mario Bros)
« on: May 14, 2011, 12:20:09 PM »
As I do more and more work with Mach 3 and my little Taig Mill I become more aware of the fact that I really need some better kind of life meter for parts of the mill.  Spindle, lead nut adjustment, etc.  In a conversation about air flow from the internal fan on a Bosch Colt Router (my current choice in high speed spindles) over on news:rec.crafts.metalworking somebody said they thought Mach3 had a spindle life counter or something like that.  Now I am no expert on Mach 3, but I have never seen it if there is. 

Is there something like that in Mach?  If there isn't would that be a good candidate for a future feature addition?  Maybe an option to add and name a life counters to a list with resettable values and triggers? Spindle triggers by S words.  Nuts triggers by code file start and stop.  Etc. 

Offline Hood

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Re: Life Meter (No, Not Mario Bros)
« Reply #1 on: May 14, 2011, 04:11:06 PM »
Operator menu then Maintenance Hours may be what you are looking for.
Hood

Offline DAlgie

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Re: Life Meter (No, Not Mario Bros)
« Reply #2 on: May 14, 2011, 06:41:34 PM »
Been my experience that you can never predict when mechanical devices will wear out or break down. After a lot of wear cycles you will get a better idea, but you just never know. Leadscrews for example, never get used at a constant rate, lot of rapids, hard cutting, slow movement.
Re: Life Meter (No, Not Mario Bros)
« Reply #3 on: May 15, 2011, 12:08:36 AM »
Operator menu then Maintenance Hours may be what you are looking for.
Hood

Thanks Hood.  Not as comprehensive as I hoped, but much better than I expected.  

Been my experience that you can never predict when mechanical devices will wear out or break down. After a lot of wear cycles you will get a better idea, but you just never know. Leadscrews for example, never get used at a constant rate, lot of rapids, hard cutting, slow movement.

Well, yes and no.  If you always try to push things to the last possible instant before it fails it is going to be hard to predict, but I have talked to a lot of people in manufacturing who use automated systems of various types including building size 5 and 6 axis CNC machines to make jet engine parts and most of them have told me there is a fairly predictable wear to limit of tolerance life for most moving components.  No not precise failure prediction, but it should be good for atleast this long limits.  

My brother in law is a manager for a company that makes major engine components for Boeing, my uncle was the head of R&D at Don Products and headed several departments after they were bought out by USG, and my Grandfather retired from NASA as a research mechanic, amoung others I have had the opportunity to talk with.

While the exact moment of failure is going to be difficult to predict, it will not be so hard to establish a base for, "it will pretty much always be within tolerance for X many hours," or, "you need to increase tolerance testing starting at about X hours or inches of travel."  
« Last Edit: May 15, 2011, 12:12:24 AM by Bob La Londe »

Offline DAlgie

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Re: Life Meter (No, Not Mario Bros)
« Reply #4 on: May 15, 2011, 12:22:09 AM »
Well, if you use your Taig mill to do thousands of repetitive part runs like Boeing then you might just be able to predict something. Remember, the mills that Boeing use also have programmed oiling and real ballscrews, so that makes a huge difference to the wear. I hardly think you can apply an example of a massive company's machine experience over dozens of years, with top quality machinery, to your Taig mill making one or ten off part runs.
Re: Life Meter (No, Not Mario Bros)
« Reply #5 on: May 15, 2011, 01:17:15 AM »
So you don't think it is possible to establish a base of something like, "Gee I can be pretty much sure its not going to be out of acceptable spec for 5000 inches of travel," or "since the bearings in the spindle have never gone out of acceptable spec in less than 500 hours I should never have to worry about bearings if I change them every 500 hours"?

???  

I think my brother in law would disagree with you.   I certainly disagree with you.  

OT:  As far as I know Boeing doesn't make any of those parts except design and prototypes.  They contract them out to companies like the one where my brother in law works.  Even a lot of the prototype stuff they send out to job shops.  If you wonder why I said this reread what I actually wrote.  

Back on topic.  Like I said.  If you want to predict the exact moment of failure you will fail.  In this small and very narrow precise definition I agree with you.  That is not MY definition or goal.  

However for example, if I keep track of how long it is before spindle bearings start to increase runout beyond what I am willing to settle for, and wear out four sets of spindle bearings with a life of:

(Purely for illustration purposes)
750 Hours
1000 Hours
680 Hours
1100 Hours

I can establish a baseline that I should never have any problems unless there is a major crash to cause them in less than 500 hours.  I don't care if its a $99 Bosch Colt Router or a $10K 10 Kw water cooled 3 phase spindle.  If in my example I replace bearings every 500 hours I should never have a problem with bearings under "normal" use.  I should of course note and log any major crashes or replace any components that I feel may be negatively impacted.  The figures 500 hours and 5000 inches are used purely for illustrative purposes.  

I can also use this to establish "value" to determine over time if a stock bearing, hybrid sealed bearing, or full ceramic bearing is a better long term value when comparing cost to life expectancy.  Two sealed full ceramic bearings for a Bosch Colt router cost almost 2 and a half times the price of the router, but if my "safe" limit is 10K hours out of them and get a "safe" limit of 500 hours out of the stock bearings they're more than worth it.  

While lead screws and nuts like the crappy V leads and pinch nuts on the Taig might seem harder predict the same data gathering can be performed over time.  I may not be able to predict that it will go bad at a particular time, I can certainly find a life/inches of travel where it almost never goes beyond my acceptable tolerance, and use that as the baseline to adjust the pinch nuts, gibbs, and bearings per axis.    

I might add that I have already established a "feel" for some of this.  The Taig has been on 3 different computers now so I can't give you the total number of hours its been powered up, but after Hood pointed me in the right direction I discovered that this computer has been running Mach 3 for over 2300 hours. I estimate that is about 87-90% actual running time.  I do not leave Mach open when I am not running a job.  It was on its previous computer for a substantially longer calendar period, so its probably got around 4000 hours of actual run time on it.  

In the past when I was just using the machine to play and learn it was no big deal, but now I am more and more concerned with preventable crashes and failures as I run it longer at a time and much more often.  Its just a matter of whether trying to push it to the longer limits is worth more than the wasted time when it fails and destroys a work piece VS changing the components and making adjustments within the established "safe" period.    

I'll continue to try not to destroy work pieces if I can prevent it in my way.  I think that this type of data and record keeping can help work to establish a tolerance life with a Taig, a Haas, a Hurco, or a building size custom built machine.  It does require some diligence and recording keeping.  As a hobbyist being miserly with my time I may not want to do that, but I firmly believe it can be done and its is a useful tool.  If I start making money and find a niche business then it becomes much more important.  

If you still disagree so be it, then we are just going to have to disagree then.  Mach 3 does have a time and distance log.  Somebody besides me must have thought it was useful.  
« Last Edit: May 15, 2011, 01:22:56 AM by Bob La Londe »

Offline DAlgie

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Re: Life Meter (No, Not Mario Bros)
« Reply #6 on: May 15, 2011, 01:37:37 AM »
Well, good luck with that. I prefer to do regular maintainence and instead of spending my time replacing parts that are still working, use that time to actually make parts.

Offline RICH

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Re: Life Meter (No, Not Mario Bros)
« Reply #7 on: May 15, 2011, 08:18:29 AM »
A clock which turns on when a device is activated will record in a  most simplistic way and can be done in a more complex fashion if one so desires. Most parts have a predictable life and manufactures provide engineering info but certainly does not reflect exact
time line. That  provides an initial baselline which one can use and then refine based on experience and good engineering judgement and knowledge of the factors used in the guidelines.

The above is only one input for forecasting  and additional  criteria is required. Manny industiral places are  totaly automated 
and use actual measurements in real time. The data provides for collection, analysis, level of alarm and applied action based on
engineered logic. In some cases corrective action is implemented.

The right level of data acquisition, monitoring, and logic  is required for meaningfull  application to a task.
The time and distance is useful but certainly not complete for what you want to do. All i use the time and distance log is to get an idea of machining time.  ;)

RICH 

Offline BR549

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Re: Life Meter (No, Not Mario Bros)
« Reply #8 on: May 15, 2011, 10:43:38 AM »
SO other than the Spindle hours do not seem to work what about the manitanance page does not work for you?

(;-) TP
Re: Life Meter (No, Not Mario Bros)
« Reply #9 on: May 16, 2011, 01:23:40 PM »
SO other than the Spindle hours do not seem to work what about the manitanance page does not work for you?

(;-) TP

Since I just found aout about it I don't know, but I'll do some tests.  I'm doing a tear down on the Taig right now and making some major changes to it, but as soon as its back up I'll find out.  Should be pretty easy to test distance with some test code.