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IndustryArena Forum > Community Club House > Answers Needed Should I Search Or Should I Post? How To Get The Best From The Cnczone
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  1. #1
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    Answers Needed Should I Search Or Should I Post? How To Get The Best From The Cnczone

    I’m new to the CNC ZONE and need information on a particular subject what is the best way to find the information I need?


    Why should I try to find the information first rather then just asking in a forum?


    Could some one give me good advice on the best way to use the search engines available on this site?


    If I find information but am still unsure how to use it should I post for more help?


    If I post in a forum and get no replies should I post my question in a different forum?


    Any other good advice will be welcome.

  2. #2
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    Quote Originally Posted by Oldmanandhistoy View Post
    If I post in a forum and get no replies should I post my question in a different forum?
    No, duplicate posts get deleted. If you don't get any replies, reply to your own thread with more info if posible. There are a lot of posts here, and it's easy to get overlooked. Bumping it with a reply will usually get it noticed.
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  3. #3
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    I’m new to the CNC ZONE and need information on a particular subject what is the best way to find the information I need?

    Advanced search.

    Why should I try to find the information first rather then just asking in a forum?

    Honestly, because it's good internet etiquette to try and do a little work of your own first, by searching, if you can't find what you are looking for then ask. If you do find what you are looking for it and it isn't exactly what you need you can refer people to other postings, develop other questions that you wouldn't have thought of and basically learn a little.

    I try to do searches first, but sometimes they just don't work for what you need or you can't remember where you saw something or what it was called.

    People tend to help those that help themselves as well.


    Could some one give me good advice on the best way to use the search engines available on this site?

    Learn to use the search feature. I use the advanced mode so I can search on titles first then if I can't find what I am looking for I do a search on the bodies. Also, learn how to do searches in general, example: "vee bearing" is different than the words: vee bearing

    Using quotes forces the search to find the two words next to each other with a space in the middle, whereas the second one will find the word: vee and the word: bearing in the body and the thread may actually be about something totally different.


    If I find information but am still unsure how to use it should I post for more help?

    The more information you can give, the better. Sometimes you just need general information, sometimes a little more. In short, yes, post. I usually tell people what I found through the search engine and why it's different or not exactly what I am looking for, this helps them understand what you are trying to do.

    If I post in a forum and get no replies should I post my question in a different forum?

    No, this is considered cross posting and is looked down on in certain areas of the internet. Besides it is probably rare that a question can fit more than one category. If it's a general question trust me there will be an answer somewhere. And what Gerry said, It get's deleted.

    Any other good advice will be welcome.

    If you are building a machine start a log in the work log section people seem to like these, I know I do. I get a kick out of seeing other people's machines and will usually have a question or two about techniques. There are so many ways of building a machine that it isn't even funny.

    Certain things usually have their own support groups off cnczone as well. For example, Mach3 has a yahoogroup. It might be better to ask a question there. Or if it's directly related to the product email the company directly. I have emailed Mariss from Gecko, directly, sent him a pm here and have even asked questions about Gecko in the forum.

    Look at the importance or vitality(if that's a word) of the question, when I emailed Mariss directly it was questions about length of wire for gecko drives and how this affected voltage across the resistance of the wire. It was something very specific that I needed a very "correct" answer for.

    I've PMed quite a few members as well, about their machines. I'm sure I'm not alone, but we all love bragging about the work we did


    -Sorry about all the red

    Hope this helps,

    Matt

  4. #4
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    You could change it to green. or blue? lol

    Thank you for your time and input.

    John

  5. #5
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    Matt:

    Very nice reply and in a very readable format.

    Should be required reading for 'newbies'. A lot of the "generic" inquiries get asked over and over and the replies really don't/won't/can't change. Your "how to search" info might help them get answers quicker and in a more complete fashion.

    I must say that your reply was much less acerbic than my frustration laced reply that addressed data searching as displayed in post #15 regarding of the following thread:

    http://www.cnczone.com/forums/showth...9&page=1&pp=15

  6. #6
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    One more question; how would I know if a question I have needs expert advice, so would need to be posted here instead of the relevant forum.

    For instance I recently posted this (after doing a search of course) http://www.cnczone.com/forums/showth...313#post214313 did I post this in the correct forum or should I have posted it in this forum for the experts to answer?


    John

  7. #7
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    OK, NC Cams, I have a question..Just how in heck do you "remember" all of your posts ? ? , you have almost 2000 posts since Dec. 2005...Thats a lot !
    Do you have a" magic" cross referance system ? Or just a very very good memory ? I ask because sometimes I have trouble remembering my childrens birthdays ( some days, names ) and their are only 7 of them..Will you reveal your secret ?

    Adobe (old as dirt )

  8. #8
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    The reason I posted this thread in the “ask the expert” forum was, if I were a new comer to this website and needed questions answer and was not the kind of person to make the effort to do some searching and reading of relevant threads, then I would go straight to the “ask the expert” forum (we would all like our questions answered by an expert if we had the choice) and post my question there. So in the hope new comers would see this thread and think twice about asking a question that had been asked too many times before I thought where better to post it then there. If I was the already described new comer I would be very unlikely to look here before asking a question.

    Just letting you know why I posted it there

  9. #9
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    Quote Originally Posted by Adobe Machine View Post
    I ask because sometimes I have trouble remembering my childrens birthdays ( some days, names ) and their are only 7 of them..Will you reveal your secret ?

    Adobe (old as dirt )
    7 Children !!!

    Did you never get around to buying a TV ?

    I guess looking at both sides of the problem, yes some questions get asked all the time, power supplies are up there, but that isn't necessarily the fault of the person asking the question for the first time, I would think a begginners link would solve a lot of problems (as I have mentioned before), simply an overview of a basic setup and requirements, maybe with a few hot links to more detailed information.

    Something at the top of the main page that is easy to spot.

    Russell.

  10. #10
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    No on TV, never had time..

    Adobe (old as dirt)

  11. #11
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    how would I know if a question I have needs expert advice

    I'm going to take a guess and say that this is one of the new forums as before this week I never saw, but haven't been on the zone for about a month.

    I'm not sure, to be honest, what the main scope of the forum is either. Possibly expert type questions like something to do with engineering in order to understand them.

    What would be nice is to have a single thread on each major subject. The rack and pinion vs lead screw vs ball screw gets asked a lot. I even made a posting about it some time ago. But I think that subject is covered under the linear motion category.

    Wikipedia type posts for these things would be great, then people could simply edit in what they know, or give tips about.

  12. #12
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    Quote Originally Posted by Oldmanandhistoy View Post
    One more question; how would I know if a question I have needs expert advice, so would need to be posted here instead of the relevant forum.

    For instance I recently posted this (after doing a search of course) http://www.cnczone.com/forums/showth...313#post214313 did I post this in the correct forum or should I have posted it in this forum for the experts to answer?


    John
    John,

    For something like that I would have emailed that company directly. I read that thread and what you want to know seems fairly technical. I would tend to agree with Gerry, though, steppers can't stop on a dime unless you cut power. I have steppers from Bob Campbell and have been messing with them all week in Mach3 if I jog them one direction then immediately jog in the other the motors don't immediately reverse. Keep in mind this is just an observation and may only apply to what I am doing.

  13. #13
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    Adobe: Some people have a mind for figures, some have a head for cards, some know drill sizes and fractions by heart (some I do, most I don't), while some folks brains are filled with minutae - mine tends to be cluttered to extremes with technical minutae of ungodly proportions.

    When that fails, I refer to a cheat sheet. In it, I copied and pasted links on the website to the commonly asked/replied to inquiries that I or someone else posted. Also pasted links to "important neat stuff" that needed to be remembered that unless written down, would soon be forgotten. Comes in real handy....

    It is one thing to know the answer to stuff, but I learned from a neat old college prof that you don't need to know the answer. Rather, only the key "trick" on how to figure it out or locate the answer.

    It also helps to know where to FIND answers to questions/problems. This was something that I learned during the creation of college research papers and in my formative years as an automotive engineer - namely, how to research technical stuff. The fact that I did this sort of research at my last employer in the auto industry should not be that much of a surprise...

    It used to be hard to find information because you had to go to the library and use books - now it is a veritible cinch to do research due to the volumes of info available on the internet. PDF's take up so much less space than catalogs but I still keep my well worn catalogs.

    Being single, I can pretty much focus on what I want to and let the other stuff slide - I can search for stuff on the net day or nite or whenever the urge suits me. Sort of became an information junkie.

    I do recall certain VERY critical birthdays and which florist to call who can send flowers when I forget to send birthday cards.

    The technical memory comes in handy as an engineer - it enables me to solve a lot of my own problems and get involved with a plethora of things. Besides it is fun to generate a "how did he know THAT????" reply.... It also enables you to prevent competitors from taking unfair advantage of you and/or your capabilities....

    What was the question????? grin

  14. #14
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    NC Cams..Thanks, I also remember obscure facts, tolerances, numbers, torgue values, interferance fits, slide fits etc..but I do think that even with indexing, and the computor you have a real talent and ability to concentrate, KUDOS my friend, you have tained your mind well, a lot of us appreciate your knowledge.

    Adobe (old as dirt )

  15. #15
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    In reference to post #12 concerning direction changing issues, I offer the following background information:

    A couple pieces of dynamics information will be of assistance.

    When something is moved, the displacement is measured in some scalar quantity (inches, feet, mm, etc).

    The rate of change of displacement is considered velocity (ft/sec, in/ft, mm/sec, etc).

    The rate of change of velocity is acceleration. THis gets a bit tougher as now you relate a change in velocity in a unit of time. The terms now are "ft/sec per sec" or ft/sec-sec. Acceleration is a byproduct of the external force that was applied to change the velocity of a body at rest or in motion.

    There is also a rate of change of acceleration and this is referred to as "jerk" or the terms of "ft/sec-sec-sec". Jerk is also a quantificatio of the RATE AT WHICH FORCE IS APPLIED TO A BODY. Example: slow gentle poke versus sharp poke in the ribs - same force but the rate of application makes a big difference in the "feel".

    These factors determine/quantify not only the force required to do stuff but also how fast the force is/has to be applied.

    To move something a foot can be fairly easy if you take your time and don't work up a sweat. However, if you want/need to move something a foot REAL REAL FAST, you'd better input a lot more force. The faster you want to do it, you also need to apply more of it faster.

    How does this pertain to steppers or servos?

    Simple.

    The faster you try to do something, the more force it will take to do it. Whether it be to accelerate it or decelerate it - faster activity (given the same mass), simply requires more force.

    While experiementing with our servos on the Eztrak, we ran circular cutter traces - these force the motors to simultaneously accel/decel thru min and max velocities repeatedly thru the whole trace path.

    Well tuned motors with minimal backlash, regardless of type, will cut round circles and have minimal "flats" at the 4 direction change points IF YOU RUN THEM SLOWLY.

    As soon as you start to speed them up, we found more and more issues with "follower error" (electromechanical gremlins) and other issues more related to inertia and dynamics. THe faster we went, the circle got less round and more irregular and vice versa.

    Essentially, whatever power you input to get something moving, you have to put an equal amount in to slow it back down IF YOU WANT IT TO FOLLOW THE SAME VELOCITY PROFILE in both directions.

    IF you want it to stop FASTER than you sped it up, you'd better find a way to externally apply a braking force. Otherwise, the mass in motion (inertia) will overcome the braking force available from the motor/geartrain.

    It all comes down to F=MA where

    F= the force applied to speed up or slow it down
    M= the masss of the system in motion or at rest.
    A= the ACCELERATION force input by the motor or the DECELEREATION force applied by the motor or brake to slow it down/stop it.

    The velocity, acceleration and jerk are purely byproducts of what the motor is capable of doing as it acts or is acted upon by the mass being moved or trying to be stopped.

    If guys would look at their CNC'd whatevers as cars that someone is trying to drive around a course, they'd SEE that you need varying amounts of control forces to affect the motion path that they are trying to generate. The faster you want to do it, the more horsepower (wattage) you need - period. BTW, the braking system in most cars generates WAY more horsepower than the engines - the cars stop WAY faster than they can accelerate.

    Why would servo or stepper motors act/react any different? They have to follow the same laws of physics, no?

    Hope this helps...

  16. #16
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    Fricton ? Gravity ? formulas ?

    Adobe (old as dirt)

  17. #17
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    Adobe: as you well know, the devil is in the details.

    Basically, the novice comes up with a "spec" whereing they want to cut whatzits at 100"/min and ask what size motor. To REALLY answer that question, you need to know the mass of the devices being moved (so as to find the equivalent inertia), the coefficient of friction between the moving member and the supporting member (to find out frictional resistance) as well as gear ratios, motor inertias and a bunch of other minutae that add up in the equations.

    Having worked as a bearing applications engineer, I can tell you that professional machine tool designers can't answer all the questions needed to "do the math" - it stands to reason that "I dunno" will be uttered more often than not by the DIY'er.

    Unfortunately, "I dunno" is an input value that results in too many unknowns in an equation thus making it unsoleable.

    Ok, make some assumptions. By, as an experienced business many, you already know that when you assume something, you make an "a$$ out of u and me".

    THere is a lot of charm in actually measuring the force needed to turn a mill or lathe handle - this will give you a NET force that takes all the friction and inertia into relative consideration. You can then turn that into a motor requirement spec and proceed with a form of calculation.

    HOWEVER, when you add heretofore unspecified acceleration factors into the mix, the calculations become MUCH more complex. Bigger motors WILL accelerate things faster BUT the larger motor will also have more inertia thus they will be harder to slow down - see prior post about power versus rate of velocity change.

    Formulas????: Mariss gave a neat disseratation regarding the "basics" on that very subject here:

    http://www.cnczone.com/forums/showth...078#post214078, see post #15

  18. #18
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    Everything NC says is right on the money but my experience from the first (and only) CNC machine I built over 20 years ago combined with more recent reading is that you can shortcut a lot of stuff.
    Jump straight to this step: "when you add heretofore unspecified acceleration factors into the mix, the calculations become MUCH more complex. Bigger motors WILL accelerate things faster BUT the larger motor will also have more inertia thus they will be harder to slow down..."
    If your machine is stiff enough and your motors big enough to handle the acceleration loads and give acceptable rapids it is almost certainly stiff enough and powerful enough to handle any cutting load.

  19. #19
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    Geof: the issue I see is the guys come up with some "vaporware" speed at which they want to move the axis, irrespective of whether or not you can cut the material at that rate.

    Perhaps with routers or the like you can go zooming right along but when you cut metal you can more oftern than not easily exceed the ability of the cutter with regard to the axis speed that you can jog at.

    From what we learned via experiementation, if you want to reduce follower error, SLOW THE FEED RATE DOWN. Both cut accuracy and finish (when cutting metal) are usually improved.

  20. #20
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    Quote Originally Posted by NC Cams View Post
    Geof: the issue I see is the guys come up with some "vaporware" speed at which they want to move the axis, irrespective of whether or not you can cut the material at that rate.

    Perhaps with routers or the like you can go zooming right along but when you cut metal you can more oftern than not easily exceed the ability of the cutter with regard to the axis speed that you can jog at.

    From what we learned via experiementation, if you want to reduce follower error, SLOW THE FEED RATE DOWN. Both cut accuracy and finish (when cutting metal) are usually improved.
    You are correct slow is more precise but with modern machines it is sometimes surprising how fast things can be pushed and still keep with better than a thou tolerance and when this is acceptable for the part and time is money that is the way to go.

    However, really what I was getting at is that the biggest load your structure and servos will ever see is during acceleration so design for that and then you are sure you can handle the cutting. Also you can always back down the oomph on an overdesigned and built system but the reverse is not possible.

    EDIT: I forgot this: http://www.cnczone.com/forums/showthread.php?t=22589

    I had a good example of the follower error a while back.

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