584,830 active members*
5,513 visitors online*
Register for free
Login
IndustryArena Forum > CAM Software > MadCAM > Box and model position with respect to Cplane zero?
Results 1 to 9 of 9
  1. #1
    Join Date
    Sep 2012
    Posts
    62

    Box and model position with respect to Cplane zero?

    Hi, sorry for the naive questions. I have a new CNC mill, some basic Rhino skills and have just in the last week begun practising making toolpaths and cutting small shapes with Madcam. My main aim at the moment is to be able to cut model aircraft wing mould shapes - female (negatives) directly into board.

    I want to face the mould parting line (flanges) flat, so I want to start with 0.2mm of stock material excess above the model. I mark a spot on the stock outside the cutting area as the zero, where I touch down to reset zero at each tool change.

    Should I position the model with the parting line at 0.2mm below the stock box, with the top of the stock box at zero??

    Or leave the model at zero, let the stock box selector set the top of the box to the parting line, and tell Mach3 that the zero position is 0.2 not zero?

    Advice appreciated - confused!
    Andrew

  2. #2
    Join Date
    Mar 2004
    Posts
    1661
    I wouldn't do it this way. Always use a fixed position as your origo. If you set Z zero to the mould surface plane or the table doesn't matter but do it the same way every time. And do it the same way on all your moulds, by doing specials every now and then you will end up in a zeroing mess you don't want. Let's say you prepare a mould and don't mill it directly you will end up sooner or later with a mould you setup wrong, simply by forgetting how you prepared it in Rhino.

    Next time you bring up a mould in the machine to adjust a cavity for example, if you know where origo it's all done in minutes. Back in the days when I was doing large alu moulds we always made a 10 mm honed hole right in X0Y0 and always carved a text saying were Z0 was supposed to be. If someone else picked up my work or made a change in a model that guy could setup my work pieces without asking me.

    If this is one shot surfacing why don't set the tool zero just below the surface and run a planar as usual? Lets say you have the parting line at Z50 (assuming it's a flat mould) simply set the first tool to 50.2. All tool changes after that will set Z50 at the same spot.
    Best thing is to zero the tools absolute. I do it with a digital height gauge which is exactly 50 mm high. It sits on the table, which means all my tools will have Z-zero at the table surface. Doesn't matter if the parting line is at 52.2 or 101.245.

  3. #3
    Join Date
    Sep 2012
    Posts
    62
    Thank you very much Svenakela. Yesterday I had another attempt and this time I moved the model down 0.5mm in the drawing. I then used a marked point on the stock, just outside the milled area, as Z zero for all the tool changes. It worked well.

    Can I ask what is the purpose of raising the top height of the stock box? Is it to let Madcam know that there's that amount of material to remove before the zero plane is reached? If so I can understand that.

  4. #4
    Join Date
    Mar 2004
    Posts
    1661
    Quote Originally Posted by AvB View Post
    Thank you very much Svenakela. Yesterday I had another attempt and this time I moved the model down 0.5mm in the drawing. I then used a marked point on the stock, just outside the milled area, as Z zero for all the tool changes. It worked well.

    Can I ask what is the purpose of raising the top height of the stock box? Is it to let Madcam know that there's that amount of material to remove before the zero plane is reached? If so I can understand that.
    Yes. You more or less always use a stock material with different size than the model in the machine, and if you don't warn MadCAM that the material actually is higher that the mould you're going to cut, you can end up with bad consequences. It's not a problem if you use high density foam or wood, but lets imagine what happens if you throw in a chunk of metal that happens to be 10 mm higher than expected...

  5. #5
    Join Date
    Sep 2012
    Posts
    62
    OK, I get it, thanks. I naively thought that when I raised the box, that height would become the new zero but I worked out that the zero doesn't change when the machine just cut flush with the top of the stock!

    Can I ask, if you are creating toolpaths and you decide to delete one of them (delete the layer and then recreate it) is that a problem for Madcam? I am guessing you need to put the new toolpath into the correct order in the layers. But can you tell me what is a no-no when changing toolpath layers?

  6. #6
    Join Date
    Mar 2004
    Posts
    1661
    Just delete it if you don't want it. Change them to the order you want, hide them etc. When you post process only the visible layers will be included.
    You have a few videos here if you want to get more knowledge.

  7. #7
    Join Date
    Sep 2012
    Posts
    62
    OK but if you created paths in the order of roughing - finish leaving 0.5mm - finish to surface - pencil and (to make an extreme example) you deleted the roughing path, what do you need to do to ensure Madcam now realizes that the material from the first cut is still there??

    Thanks very much for providing such a great service by giving advice like this, it's generous and of huge assistance.

  8. #8
    Join Date
    Mar 2004
    Posts
    1661
    Make a new roughing?..
    You can recreate a step any time you want. If the roughing must be updated or replaced you can do it whenever you want. But if you change the roughing properties too much you night need to update the next coming step as well. I am not sure if it depends on license level but you can update a path without deleting it. There is a button in the toolbar for updating tool paths. Click the Burton, select the beginning of the path and the cutting dialog comes up again.

    Glad it helps you.

  9. #9
    Join Date
    Sep 2012
    Posts
    62
    Yes, I've been using the recalculate button regularly. That's a good answer - I'll remember to recalculate subsequent toolpaths if I change a higher one.

Similar Threads

  1. LulzBot AO-100 3D printer now FSF-certified to respect your freedom
    By Jonlulz in forum 3D Printer / 3D Scanner Discussion
    Replies: 0
    Last Post: 12-03-2012, 06:27 PM
  2. Easily identify a previous T/Cplane
    By PRINT_FX in forum Mastercam
    Replies: 13
    Last Post: 06-05-2012, 05:30 AM
  3. home position for fanuc 0i mate model C
    By beth_piyik in forum CNC (Mill / Lathe) Control Software (NC)
    Replies: 0
    Last Post: 03-23-2011, 10:03 AM
  4. losing position, lots of position
    By cyclestart in forum LinuxCNC (formerly EMC2)
    Replies: 8
    Last Post: 01-24-2010, 08:50 AM
  5. Replies: 4
    Last Post: 10-28-2009, 06:39 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •