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IndustryArena Forum > CAM Software > BobCad-Cam > Setting Rapid Feed and Maximum Cutting Feedrate when Z rapid is different than X & Y
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  1. #1
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    Setting Rapid Feed and Maximum Cutting Feedrate when Z rapid is different than X & Y

    My machine has a different rapid traverse rate on the Z axis than the X and Y. How do I accommodate this in BobCAD-CAM v27?
    X is 250 IPM
    Y is 250 IPM
    Z is 150 IPM

    All axis are original rated at 100 IPM cutting

    This machine can run faster than this because I have retrofitted it with AC servos and Teco drives, but for now I just want to use BobCAD, and I set Mach3 to run at the original specs above

    There is no breakdown per axis in BobCAD, just two settings of Rapid Feed and Maximum Cutting Feedrate

    Not sure what I should so. If I make the rapid feed 150, then it will be moving Z correctly, but X and Y will be 40% slower than they are capable.

    What to do?

    Should I just set the rapid at 250? I assume Mach3 will just say no and run Z at 150 max anyway?

  2. #2
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    Dec 2014
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    Re: Setting Rapid Feed and Maximum Cutting Feedrate when Z rapid is different than X

    Hi Jevs, I'm a newbe with cnc and bc but I'le take a stab at the question. By no means take this as anything I just figured I'd see if I have learned anything.... top end rapid speeds generally set in mach3 engine tuning to accommodate your equipment and they don't have to match each axis..... cutting feed rate is determined by the material, cut depth and cutter with the ball park speed automatically calculated in bc when creating features and tool paths!!! Z is a different speed most the time... Hope I'm close ...Enjoy the weekend

    Dave

  3. #3
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    Re: Setting Rapid Feed and Maximum Cutting Feedrate when Z rapid is different than X

    Yeah, I am in the machine setup of BobCAD. It has nothing to do with the materials or feeds and speeds used during cutting other than I assume it sets the limits to top speeds within what your machine can do. I think it just sets the max parameters that BobCAD will try to use when it generates the rapid moves and cutting moves. You cannot set for each axis though. I set it at 250 IPM max rapids so it would not limit X and Y rapids. This is too fast for Z, but I believe mach will slow it to the max anyway and I doubt it will get any where near any of this for cutting speeds. Not sure there is anything else I can do since BobCAD has no independent axis parameters for these in the machine setup as far as I can see. My Z can actually move that fast and faster, but that is beyond what it could do when they spec'd it in 1978. I don't want to hurt it

  4. #4
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    Re: Setting Rapid Feed and Maximum Cutting Feedrate when Z rapid is different than X

    Rapid moves (G0) don't have a feedrate, so I'm not sure what BobCAD is doing with them.

    If BobCAD is exporting G0 for rapids, then Mach3 will handle the rapid feedrates.
    Gerry

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

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

    JointCAM - CNC Dovetails & Box Joints
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    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  5. #5
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    Re: Setting Rapid Feed and Maximum Cutting Feedrate when Z rapid is different than X

    I have no idea either. I just know I am setting up the software following the tutorials and in the machine setup "Machine Parameters" you have to enter Max # of tools, Max Spindle Speed, Rapid Feed, & Maximum Cutting Feedrate.

    I am just getting into this, so I don't know all the G codes or how they are used.

  6. #6
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    Re: Setting Rapid Feed and Maximum Cutting Feedrate when Z rapid is different than X

    On Edit,,
    after dinking around a bunch,I have found the rapid feed is used to help the simulation come up with a total machine time on its clock.
    So whatever your controller is set at,that would be what you would set this.
    To the OP,,,pick a number you think is an average from the 3 different axis
    Simulation Time Clocks are not usually highly accurate anyhow.

    G code back plot like Preditor Editor level 2 is better for real machining times.

  7. #7
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    Re: Setting Rapid Feed and Maximum Cutting Feedrate when Z rapid is different than X

    Yes, I am not sure how that helps? Z still has a slower rapid than X and Y. That is the main concern I had. Don't want to over speed Z, but don't want to slow down X and Y. If you only get one setting for all 3, I have to assume you pick the fastest.
    However if as ger21 says all G00 code rapid moves have no actual setting for the speed when used and the machine decides, then I am not sure what it uses this for. Maybe it only uses the Rapid Feed setting for simulation?? So it shows you in the real speed you might expect your machine to move.
    I would assume it uses the Max Feedrate so it knows the actual limit it can ask a tool to cut.

  8. #8
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    Re: Setting Rapid Feed and Maximum Cutting Feedrate when Z rapid is different than X

    Quote Originally Posted by jevs View Post
    Yes, I am not sure how that helps? Z still has a slower rapid than X and Y. That is the main concern I had. Don't want to over speed Z, but don't want to slow down X and Y. If you only get one setting for all 3, I have to assume you pick the fastest.
    However if as ger21 says all G00 code rapid moves have no actual setting for the speed when used and the machine decides, then I am not sure what it uses this for. Maybe it only uses the Rapid Feed setting for simulation?? So it shows you in the real speed you might expect your machine to move.
    I would assume it uses the Max Feedrate so it knows the actual limit it can ask a tool to cut.
    jevs

    Follow what ger_21 is saying and then pause and think backwards :-

    1) The maximum speed setting for the rapid moves are in BobCAD for the simulation timings and should be set the same as your maximum velocity setting under the Mach3 motor tuning , if not then the estimated run times will be quite a way out.If the X,Y and Z have different settings then the actual machining time will be a little out when compared to the BobCAD times but won`t be too far out. They will also stop BobCAD outputting feed rates that are higher than the machine settings.
    The max feedrate is there as you have rightly surmised is to limit the feed rate any tool can run at, actual feed rates for individual tools can be set at the tool in the tool library.

    2) ger_21 is correct, the actual speeds of the axis of your machine are controlled by Mach3 not BobCAD. A G0 command is just a command to the machine to run at the maximum setting at the machine, has no relation to a rapid setting in BobCAD, BobCAD does not output a rapid speed, ony a G0 command.

    3) BobCAD only outputs the cutting speeds, plunge feeds etc that are generated either automatically (System feeds/speeds) from the information in the cutting conditions and tool libraries or from information that you enter manually either in the Tool area at the Feature or alternatively in the tool setup, you can set each tool to cut at a specific rpm and feed under each tool parameters.
    If you aren`t able to spend the time setting up your materials and cutting conditions the you can create a couple of tools the same size say a 0.5 inch for Aluminium, one for Steel, one for Stainless etc and set feeds/speeds at the tool in the tool library, that way you will always have the correct speeds/feeds being output by BobCAD for your tooling/machine capabilities to suit the material

    Hope that helps

    Regards
    Rob
    :rainfro: :rainfro: :rainfro:

  9. #9
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    Re: Setting Rapid Feed and Maximum Cutting Feedrate when Z rapid is different than X

    Rob,I just figured it out and edited above as you were posting

    I know rapids only started being used in V26

  10. #10
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    Re: Setting Rapid Feed and Maximum Cutting Feedrate when Z rapid is different than X

    Quote Originally Posted by jrmach View Post
    Rob,I just figured it out and edited above as you were posting

    I know rapids only started being used in V26
    Yes, V26 was when BC started with the generated setup sheets so rapids were needed for generation of the timings, as are the X,Y and Z distance limits

    All good stuff

    Regards
    Rob
    :rainfro: :rainfro: :rainfro:

  11. #11
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    Re: Setting Rapid Feed and Maximum Cutting Feedrate when Z rapid is different than X

    I would assume it uses the Max Feedrate so it knows the actual limit it can ask a tool to cut.



    Yes.
    Many machines are not capable of the crazy speeds and feeds that small carbide tools ideally run at.So yes,it keeps the speed and feed at a usable amount.

  12. #12
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    Re: Setting Rapid Feed and Maximum Cutting Feedrate when Z rapid is different than X

    I am sure I don't need it at this stage and maybe never. I just want to make a part here and there for myself for other projects, so the time it takes is not critical. I won't be paying myself by the hour unfortunately

    I am going to post another thread. My head is spinning on setting up tools. I am starting some coffee, so maybe I will get focused soon. I feel like it is taking way too long just to getting to cut a part....

    I need to make this...
    Attached Thumbnails Attached Thumbnails Capture2.jpg   Capture.jpg   20150227_235118.jpg  

  13. #13
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    Re: Setting Rapid Feed and Maximum Cutting Feedrate when Z rapid is different than X

    Quote Originally Posted by jevs View Post
    My head is spinning on setting up tools. I am starting some coffee, so maybe I will get focused soon. I feel like it is taking way too long just to getting to cut a part...
    Quite often I can make a part faster just by doing it manually. I have a couple small mill drills I'll probably never get rid of for exactly that reason. Although, I have gotten familiar enough with the g-codes that I often will "manually" cut a part on one of the CNC mills by using the midi mode and just typing in the instructions. A pendant doesn't hurt either.
    Bob La Londe
    http://www.YumaBassMan.com

  14. #14
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    Re: Setting Rapid Feed and Maximum Cutting Feedrate when Z rapid is different than X

    Personally,I would quit worrying about your rapids.
    There is a lot of software to learn here.
    If you have Preditor Editor level 2 ,,, here you go ,,you think your mind is spinning now,take a look at this..

  15. #15
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    Re: Setting Rapid Feed and Maximum Cutting Feedrate when Z rapid is different than X

    Yeah, I move past the rapids thing yesterday. It was a good exercise though, because I found I had them set too slow on the X & Y and too fast on the Z in mach. So it did some good....

    So, what would you do next if you were me?
    My machine is working with Mach3 fine.
    My machine parameters and post are setup in BobCAD
    I have not cut anything though.
    I have nothing setup anything with tooling in software or actual tools. I am not sure what I have to do as far as measuring the tools in the tool holders and stuff?
    My part is designed.
    I do not have my touch probe or touch plate wired in (not sure how to have both those hooked up?)

  16. #16
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    Re: Setting Rapid Feed and Maximum Cutting Feedrate when Z rapid is different than X

    So, what would you do next if you were me?

    Spend a lot of time here https://www.youtube.com/user/Depoalo...view=0&sort=dd

    Also the Mach forum should be of big help.I know nothing about Mach,so I hesitate on telling you how to set-up your offsets.
    You do not need a tool probe and touch plate though.There again I hesitate giving you information on how I do it because my machine is Worlds different than yours,but there are other ways involving a piece of paper and an edge finder.That is how I do it.
    Engine Guy is a whiz with Mach,maybe he can explain way to do it in Mach the way I just described.It will get you going faster,which is what you want,right?

  17. #17
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    Re: Setting Rapid Feed and Maximum Cutting Feedrate when Z rapid is different than X

    Mach isn`t any different for tool setting, I use a slip guage (More accurate than jrmach piece of paper although that works fine as well).

    Normal way I do it is I have a tool holder with a piece of ground bar in it (You can use any tool though) and touch it off on either the bed or the workpiece, doesn`t really matter which, that tool num ber is set to 0.00 for tool length in Mach and is set as your MASTER tool, after that all your tools can be touched off to the same point as the master and they will all be either longer or shorter when set in Mach, so in the tool library in Mach what you will see is the difference between each tool and the master, not the actual length of each tool.

    Don`t worry about the tool lengths in BobCAD too much, it`s nice to have them accurate as you have a better simulation but they don`t affect your code in Mach, all you will get for tool height will be a line of code something like this :-

    G43 H1 Z0.1

    That would bring your Tool #1 to 0.1 inch above your job, the G43 tells Mach to go get a tool length and the H# tells it which one to go get.

    For this to work right you will also need to have set up your workpiece offsets, particularly the Z one, again you can use your master tool to touch off in the X and Y for positioning although this will depend to some extent on what type of fixture/vise you are using.

    When doing a shape like you have I would always draw it with the centre of the job at X and Y zero, that way it is very easy to machine the shape from your stock slightly deeper than the thickness of the part.
    That can be done as an advanced pocket operation for both the outside shape and the inner shape.
    Then after you have done the desired shape machine out some soft jaws in the vise and machine off the excess material from the back of the part, if you are going to run a small chamfer to the part for de-burr/cosmetics then that is why you would do the soft jaws, if you are finishing it off by hand de-burr then the machined soft jaws are not required.

    I see you have some nice solids there for your part for a simple 2D job like your part there is no need for all that, a simple 2D outline is all that is needed to be able to generate the toolpaths.

    If you need any help with getting the Features done and tool path generated quickly then Zip up your solid and upload to the thread here and someone will take a look at it for you

    Regards
    Rob
    :rainfro: :rainfro: :rainfro:

  18. #18
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    Re: Setting Rapid Feed and Maximum Cutting Feedrate when Z rapid is different than X

    I use a slip guage (More accurate than jrmach piece of paper although that works fine as well).


    I take it another step further by subtracting the paper thickness too
    If I need perfection on an EM,I start her up and put on my bionic goggles and touch off the surface that I marked with marking pen.
    Using an edge finder to precision,is a skill all of its own,,,


    Yes,start a new thread with your solid attached,,,I am sure we can get you so confused you will wanna quit,,,
    Kidding,the collective knowledge on this forum will surpass anything you will need to know.

  19. #19
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    Re: Setting Rapid Feed and Maximum Cutting Feedrate when Z rapid is different than X

    I drew the part for the design to make sure it would all fit the real application. I have to machine from that. I don't plan on using the CAD in bobCAD, it is not as good as mine. I can do a lot more including assemblies and all that stuff...

    This is all starting to make sense. I guess what I should do is go ahead and try to generate the tool paths and just use the generic tools in there that match what I plan to use.

    I am curious about this:
    "When doing a shape like you have I would always draw it with the centre of the job at X and Y zero, that way it is very easy to machine the shape from your stock slightly deeper than the thickness of the part.
    That can be done as an advanced pocket operation for both the outside shape and the inner shape.
    Then after you have done the desired shape machine out some soft jaws in the vise and machine off the excess material from the back of the part, if you are going to run a small chamfer to the part for de-burr/cosmetics then that is why you would do the soft jaws, if you are finishing it off by hand de-burr then the machined soft jaws are not required."

    This does not make complete sense to me. Not sure why it would have to be in the middle of X and Y rather than the whole thing being positive X and Y (how I drew it in my CAD). How does that keep you from milling deeper than the part (3/8" by the way). My material is the thickness I need. There will be no face milling or cleaning.

  20. #20
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    Re: Setting Rapid Feed and Maximum Cutting Feedrate when Z rapid is different than X

    Doesn`t keep you from milling deeper, keeps the part in the exact position if it needs to be turned over for example other operations that may need to be machined from side two.

    Looking at your part there is no need in this particular instance but IMHO it is a good habit to get into right from the start.

    If your material is the same thickness as the part then I assume you will be leaving a small amount and then knocking out the part, either that or doing the holes and bolting it to a sacrificial plate

    It will all come with time, I have various vises that I have set keys into the bases so that it will always be in the same location on the machine bed every time I put it on, along with some pre-set end stops I have no need to position the vise or the workpiece, a simple bit of math will tell me where material centre or corner is every time

    Regards
    Rob
    :rainfro: :rainfro: :rainfro:

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