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IndustryArena Forum > CAM Software > BobCad-Cam > Simulation Pro - Setting up the Machine Definition
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  1. #21
    Join Date
    Dec 2015
    Posts
    20
    Well, more than 7 months on and I've finally got a 5 axis mill up and almost running ! We have a 5 axis Bridgeport with a 350mm dia integrated table.

    I'm currently trying to figure out my post processor with a local support company, but its hard going due to the heidenhain control.

    I've roughed out my vice spacer and mounted my 5th axis vice on top. Then it has been clocked to the middle of the table (10-15 microns in x & y and 3 microns parrellism). I've done a basic 4th axis program to check the alignment and I'm suitably impressed how accurate the machine is.

    I'm hoping to try a 5th axis job on the machine next week (machine is cool that it stops at anything it doesn't like and the help file explains what it doesn't like).

    The biggest question I have is how do I properly show the vice jaws in the machine clamping the part ? Also I need to add them into my collision detection and I'm not completely sure how.

    Shaun

  2. #22
    Join Date
    Apr 2008
    Posts
    1577

    Re: Simulation Pro - Setting up the Machine Definition

    Hey Shaun, I'm replying a bit late on this of course and I hope you got it figured out. I interpreted your question about the vise jaws to mean how do I open and close the jaws for a more accurate simulation. Then set a collision pair between the tool and the jaws so that you get a nice big red warning when the tool collides with your jaws!

    There are quite a few ways to do this. The documentation is a bit skimpy but after playing around with this for a quite a while I think I've got the hang of it enough to answer properly. The Machine Definition takes a bit of care to setup but if you've made it this far this may not be much more difficult than what you've already done.

    In this example I've got a Haas VF2 with a Kurt D675 bolted to the center slot and centered on the table. By default the Work Offset values in the Machine Setup dialog will be 0,0,0 and the machining Origin will place the Top of Part in the sample file flush with the surface of the table (Kurt vise hidden for clarity). This is pretty well the standard setup used in the BC_3x_Mill machine that BobCAD comes with on installation but substituted with models for the Haas VF2.

    Attachment 417212

    This isn't particularly helpful because most parts are somewhere above the table! In my case, the part needs to be raised up even higher so I can "clamp" it in my jaws. The bed height of a Kurt D675 and D688 is 2.875" and the jaw height is 1.735". I want to leave at least 0.300" of the part above the vise jaws so adding that all up gives me a Z offset value of 4.910". We will enter that into the Work Offset Z value.

    Attachment 417214

    Now the tricky part. Adding a geometry element to the Machine Definition is easy, getting it to work "dynamically" takes a few extra steps and care. The first thing we should add is a User Defined Coordinate Transform element to the X axis. This is going to allow us to move our workholding around on the table, no matter how you saved the STL model for your vise or fixture. If this was a fixture, we might want to use the slots that are closest to the operator to reduce reach but the fixture origin was drawn at "zero". Without a way to transform the fixture it will always load in the simulation at your machine's defined origin point (center of table, flush with the top surface in our example). If you add a Coord. Transform to the Machine tree you can move the workholding device around to any point in the 3D space of your machine envelope.

    ***NOTE: In some versions of BobCAD, the "Shift" values you enter in the Coord Transform are occasionally multiplied by 25.4! I think this is a bug.

    Before we add the Kurt vise geometry, there is yet one more step we can take to make the simulation a bit more robust. Moving around the vise with the Coord Transform is helpful but it's not exactly user friendly to edit the Machine Definition for every part, and we really shouldn't do that anyway because as mentioned you should always take care when editing your Machine Definition. A better solution is to add a common Translation axis to the Coord Transform element. I want to restrict the vise in the center slot but I'd like to be able to move it around left to right if I need to. Hint, this is how I'm going to go about "clamping" the part as well. Jumping ahead a little bit, here is the final tree with all of the elements added for this setup:

    Attachment 417218Attachment 417216

    I'm giving the vise +-15" so I can slide it all the way to the extents of the table. The initial value is 0, centering the vise in relation to the Coord Transform. If you move the vise by adjusting the Coord Transform shift values, the Translation element will move with it because we have attached it in the tree to the Coord Transform element. You will also notice I added another Translation axis (Y) for the moveable jaw. It has an initial value of -4.00, a Minimum value of -6.75" (max opening) and a Maximum value of 0 (fully closed). This is tied to the Translation axis we added in the previous step - when the vise moves, so does the moveable jaw. Playing with the Work Offset values, we can simulate this very closely to how I'm running this part in a set of soft jaws.

    Attachment 417220

    The simulation engine in BobCAD is pretty amazing and will allow you to do a lot things like this that aren't advertised. Probably because most people won't need it but in the 5 axis world it's absolutely necessary. I hope this short tutorial will help someone attempting something similar. All files to build this Machine Definition are attached. Create a generic 3 axis machine in the Default Current Settings dialog and build the tree as shown in the 4th picture, it's not easy but straight forward with a little experience.
    Attached Files Attached Files
    -------------------------------------------------------------------------------------
    Mastercam X9/2017 Multiaxis for SolidWorks - Bobcad V29 3ax Pro 4ax Std.

  3. #23
    Join Date
    Apr 2008
    Posts
    1577

    Re: Simulation Pro - Setting up the Machine Definition

    To setup a collision pair is also fairly straight forward. To add collision checking for this setup, simply add a CC pair between your tool and the components you absolutely don't want to cut!
    -------------------------------------------------------------------------------------
    Mastercam X9/2017 Multiaxis for SolidWorks - Bobcad V29 3ax Pro 4ax Std.

  4. #24
    Join Date
    Dec 2015
    Posts
    20

    Re: Simulation Pro - Setting up the Machine Definition

    Thankyou for the great reply, always great info for somebody searching for information like I was then.

    I got the collision detection working and lived with the non positioning vice. I made quite a few 5 axis parts in the machine.

    We have just swapped out Bobcad for Edgecam so I'm now wrestling with cycle 19 in heidenhain !

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