Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: menglor on January 01, 2014, 12:08:14 PM
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Problems understanding why my X and Y are coords dont = mill ?
So this morning I decided I wanted to play a bit on the mill, I am still thttp://www.machsupport.com/forum/index.php/board,1.0.htmlrying to learn Cam, Cad and CnC so please forgive if this is an obvious duh moment!
So, I am in BobCam, I make a box (120mm x 60mm) , I put a pocket in the box (100mm x 50mm) , I export to Gcode.
I open it up in Mach3 , I home the machine, then I Zero the work piece. and then I click start.
it seems to plunge into the work piece about 3mm (as it should), then it cuts the Y axis. iy goes from 0 to 48 (ish)
then it starts to travel to X 97 but I dont want it too, I want it too move about 10mm over, then travel to 0 on the Y.
Kind of like you see in the picture.
But as I am typing this, it looks like its trying to up to 90 and start from right and come back?
So its starting to look more and more like I still havent figured out my zero'ing problems. which historically is always been my problems with all my posts.
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so as you can see in BobCad, the work is in the upper right quadrant.
when I run the verify of the work. it starts on the left, works it way over to the right.
But I am getting the feeling, in Mach3, it wants to start on the right and work its way right, but I dont want it doing that.
does anyone know how to make it work from left to right
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attach you .bccd file and your xml and I will take a look.
Hood
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I really appreciate this!
p.s. I am not 100% this is the right bbcd, bur i am 99% sure
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its not letting me post my xML file, its telling me that its already posted. I will have to look through my posts and see if I can find it
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ok found it.
http://www.machsupport.com/forum/index.php/topic,25821.10.html
as I read that post though, really it seems like its the same problem, pretty much its a lack of understanding how it generates the Gcode, I seem to expect one thing from bobCad, but Mach does is differently.
I think Mach3 is doing what its told. so it has to be either Bobcad doing something weird, or its me. but that wouldnt be a first.
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You will need to either zip or rename your xml. The forum only accepts a file name once no matter whether it was you or another that attached it.
So easiest to just zip with a unique name such as menglor1
Hood
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Testing 1 2 3
Ok, I posted it as directed
thanks.
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I understand that Gcode is like a coordinate system, like GPS. So I am expecting your going to tell me there is nothing mach3 can do to change it, because its only doing what its told.
So I kind of expect I am going to have to change something I am doing in Bob (which is tottally fine) or I am going to have to go to bobcad website and ask the same quest. I hope you can help, but I totally understand if its beyond your expertise, since there are like a million flavors of CAM out there.
Just from looking at this code:
N09 X60.153
N10 Y31.743
N11 X53.803
N12 Y66.503
N13 X47.453
N14 Y31.743
N15 X41.103
N16 Y66.503
N17 X34.753
Its sending the X to the far right, then coming back, and I suppose this is the part I don't understand. since when I watch the "verify" its actually doing the opposite (see 2:22) http://www.youtube.com/watch?v=K-gSa9wvKOE
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Ok only have V26 Bobcad here at the workshop so will have to wait until I get home tonight to try it out.
Hood
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Ok just looked at the video, where you seem to be having the problem is you are not setting up a work offset. I will presume BobCAD is posting the default G54 offset so what you need to do is jog to a position on your table where you want to start cutting, you then zero the X and Y DROs in Mach then when you either load the code or press the Regen button the toolpath should be where you expect it to be.
Jogging and pressing the zeroes is basically you setting up a work offset.
The cube you are seeing is the work area of your machine as defined by your soft limits, whether you have them right or not I am unsure.
Hood
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ok so I am definitely loading the code before zeroing everything. but I am 99% sure I did a regen tool path, but I will have to do that tonight to make sure 100%.
I guess I am curious why the code looks like : (Y is set too ?? because I am saying they dont matter for the example)
N09 X60
N10 Y??
N11 X53
N10 Y??
N13 X47
and not like
N09 X0
N10 Y??
N11 X10
N10 Y??
N13 X20
anyway, thanks again.
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That could well be the way you have your axis set in Mach or it could be the way you have BobCAD set up.
In Mach if you jog so that the cutter is moving right does the X increase in the DRO or decrease? Remember I am talking about cutter moving right and not the table as that could be different depending on the type of machine you have. For example on a mill with a moving table if you move the table left the cutter is in effect moving right when you think in relation to the material.
Hood
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Ok I just loaded your file in BobCAD and then produced the code and ran in your Mach profile and it looked fine. It starts at the right hand end of the pocket in both BobCAD and Mach.
If you want it starting at the left hand side of the pocket you would need to choose the start point in BobCAD.
I used a different post processor than you as I didnt have the one you have.
Hood
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Could you post your guide. Just so I can see the differece?
Please and thanks
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Not sure what you mean by "guide" but here are screenshots of BobCAD and Mach doing the part.
I did have some issues with the Z axis, that could be because I am using a different version of BobCAD but as I dont have the machine definition and post processor that you are using it is hard to say, if you attach the G Code you get I can have a look.
Hood
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Hahaha auto correct on my phone!!!!!
I meant g code
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Ok here is the G Code, as said there is a problem, even now with the Z as it goes lower than intended for the first and last move of each cut before rising to where it should be. This could be the post processor I used or could be the difference in things because your file is done in V24 and I am testing with V25.
Hood
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ok, its possibly because I am total newb to Machining. but let me ask you this question this way.
Ok, so my Mill is an X2, which really means that my table moves.
so, If I draw a box in BobCad, then put a pocket in it.
So based on my code
Its my understanding, that the table will move in what ever direction it takes, to put the bit at B1, then Cut to A1, then move down a bit to A2, then cut till it reaches B2 , then move down, and so on and so on till it reaches D 8.
A B
1 *********************************************************************************X 1
2 *********************************************************************************X 2
3 ********* XX 3
4 ********* XX 4
5 ********* XX 5
6 ********* XX 6
7 *********************************************************************************X 7
8 *********************************************************************************X 8
C D
is this a fair representation of whats going to happen?
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In the BobCAD sim I got and also the code produced the cutting is in the Y axis so it would be D8 TO A8 then A7 to D7 etc. If you attach the code you get I can have a look.
I am wondering if you have your machine set up correctly? X axis is left to right as you stand in front of the machine, Y axis is away from you to towards you, is that the way yours is?
Hood
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I still need to play with the mill a bit, ran out of time last night.
but if I can ask this, is your explanation of "D8 TO A8 then A7 to D7 etc." what your saying is the normal?
Maybe I am just expecting things incorrectly, In my head, I see the drill bit moving like it was reading a book. A1 -> B1, then B2 -> A2, then A3 -> B3.
But if I read what your saying, I have some core expectation that are wrong, which is good, because it makes sense why things are happening outside my expectation.
Well at least I am learning ;D.
Probably going to be going into work this weekend, so not sure how much play time I am going to get.
I love this hobby!
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Well if the way BobCAD V25 is doing the operation is the same as your V24 then it starts furthest right and nearest to you on the pocket, it then moves in Y away from you then along in X to left by a small amount (11mm maybe) then back on Y towards you then continues like that to the end.
Remember I am talking tool in relation to work rather than table movement..
Basically what I showed in the screenshots is exactly what you would see if you were looking from above the material.
Hood
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BTW you can likely tell BobCAD where to start.
Hood