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Tool Offset
« on: May 09, 2008, 09:05:45 AM »
I tried to cut my first part last night and found that the center of the tool is actually following the line of a circle inside another chain. The outside chain seems to be correct but the inside chain (circle) is too big (the diameter of the tool too big - 1/4"). It doesn't matter if you leave the circle as an outside chain or re layer it to an inside chain in Lcam, it still runs the same path. Shouldn't the tool diameter in Lcam compensate for this when posting the code? Is the Pro version of Lcam the only way to correct this problem by using offsets?

If Lcam asks for tool diameter in the layers tab, is it still necessary to select the same tool in the Mach tool window? I tried it both ways and got the same results.

I'm also getting a tool change command in my G code and I can't remember how I got around this. I'm sure I'm doing something out of order in Lcam but can't figure out what it is.

Thanks for your help.
« Last Edit: May 09, 2008, 10:42:30 AM by lowslo »

Offline jimpinder

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Re: Tool Offset
« Reply #1 on: May 10, 2008, 03:59:01 PM »
I do not use Lazy Cam so I cannot say for sure.

Does Lazy Cam compensate for Tool Diameter, or is it just drawing the shape that it sees. The simple way to check is to draw a 2 ins radius circle (4 ins diameter) (100mm diameter) using LCam and then print the G Code.

See if the tool is being lined up exactly on the circumference line or not - it should be easy to see if the numbers are simple. eg assuming you are starting at 0,0 the command will be  G2 (or G3) X0 Y4 R2 or something similar using I and J  The other thing to check - does LCam ask you for the details of the tool you are using.

Tool offsets (diameters and lengths) are normally entered in the tool table on your Mach 3 mill, and are called in GCode - allowance is not made in the CAM program. The Tool change is therefore ask for at the beginning of the program so you can enter the tool number into it and then the machine knows what allowance to make.Check your code and see if there is a G41 or G42 call - which means that the allowance is being made by your machine and not by LCam

You should enter your tools in the tool table. When the machine stops for the Tool Change command, enter the tool number in the tool window and press cycle start - the machine should now cut your shape, making allowance for your tool diameter.
« Last Edit: May 10, 2008, 04:04:18 PM by jimpinder »
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Re: Tool Offset
« Reply #2 on: May 12, 2008, 11:40:07 AM »
Thanks jimpinder for the response! I did have the tool info in the tool table in Mach. I think thats why the outside measurement was correct. I upgraded to Lcam Pro so now I can do offsets to compensate for the inner distances. I need to put some scrap in the machine and just make a few cuts and play with it a bit. I have a LOT to learn. I have another issue with Lcam that I'll post in that forum. Thanks again!

Ryan
Re: Tool Offset
« Reply #3 on: May 12, 2008, 03:57:55 PM »
I used LCam b4 I got into BobCAD/CAM.  The thing is, when you set your tool, you have to make sure you save the peramiters set right b4 choosing the tool for a project. Then, when you choose that tool, make sure you check the peramiters  assuring the the  selected tool is the tool you're working with(ITS A LITTLE TRICKY SOMETIMES). Then,Once you are sure, hit, send to all layers. Now you are set. (note:if you are working with your first or only tool, that is considered tool 0.) Then set your Rapid Height, Cut Start and Cut Depth. Hit set all layers. Once you are sure of all the moves, then OutPost it to your cutting program(Mach3  etc...)

One other thing , if you dont want a path to be cut, delete it and outpost , only the path lines you want to cut.

If you do this and still have a problem. Your program must have a glitch!!!!!!!
In which case, contact Tech Support....

Good Luck! fellow machiner......
« Last Edit: May 12, 2008, 04:23:08 PM by SmoothOperator »
Re: Tool Offset
« Reply #4 on: May 12, 2008, 09:39:57 PM »
Thanks Smooth. Great info. One of my biggest frustrations was that I had renumbered my tools. Changed them all back to tool # 0 and got rid of the tool change command in the code.

If I did indeed want to use more than one tool on a part, how do you get mach to continue after the tool change? I tried every thing I could think of and no luck.

Thanks for your help guys! I'll be making parts before long. I need to get this figured out so I can cut a mount for my vac hose. I'm tired of holding it and following the tool around the table drilling holes.

Ryan

Offline jimpinder

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Re: Tool Offset
« Reply #5 on: May 13, 2008, 02:37:57 AM »
If you have tool changes on your program, then Mach can do several things with them.

1. Mach will ignore the tool change completely.
2. Mach will stop, turn off the spindle and wait for you to do what it is you want.  (You can manually change the tool, set it to the correct height, depth etc., and change the Tool number.  On one of my programs, I had to move the workpiece, jogg the tool to a new position etc.) When you are ready to continue, press "cycle start".
3. Auto Tool Change - Here Mach uses the M6 macro and executes a Visual Basic program. This can be anything, since most tool change system differ. You can have the spindle stop, the tool move to a safe position for you to change, or you can use an automatic tool changer and let the machine do it for you - but you have to write your own program (although there are some about in this forum that you can use).

See Config/General Config/Top left hand corner of the page to select what you want.
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Offline jimpinder

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Re: Tool Offset
« Reply #6 on: May 14, 2008, 05:48:03 AM »
Unfortunately Mach 3 is far more complex than being able to knock a few things together over the weekend, and be ready by Monday.

There are many things to learn, and before designing your own screens, then learning the workings of the ones on offer must come first.

I assume you have set up your system, from what you say, and you have the axis working. I can only suggest that you use the standard 1024 screen(s) set to start with. I, personally, would not even try to write a full screen (s), even though I know my way round the system fairly well. The 1024 set has been designed by the man who designed Mach 3 and must, by definition, be a good start.
It seems to provide all that is required to do some useful work. It has a choice of screen (not for everyday use) to set up the machine, to do diagnostics, to set up offsets - as well as the three main screens.
Screen 1 is the general "maid of all work" and you can control the entire machine from this. If you are doing a small job, and typing in instructions on the MDI line, then you use page 2. This also contains enough information to know what the machine is doing. Page 3 supplies a much simpler screen set with a large tool display. You can still control the machine from here, but it intended for you to switch to this screen for the tool display, and switch back.

You can switch between screens whilst the machine is working. You can make minor alterations to the screens quite easily, which is the best way to start - if you need to alter things. For example, jogging is not available on all screens - you could soon add it.

Most DRO's can be altered. There are some that read information from Mach3 only, but the positional DRO's, the Tool DRO, the Speed DRO can all be written to. Click on the DRO (it will light up) - type in the new information - PRESS RETURN. If you do not press return, the display will revert to the previous information.

The axis positional DRO's display 2 positions - one is the machine co-ordinates, the other work co-ordinates. Machine co-ordinates relate to the homing switches fitted (or not) on your machine. Professional machines have homing switches fitted, and the first job of the day is to home the machine. This puts the table (or cutter) at a position the machine knows, and resets the DRO's to zero. Mach 3 has the equivelant switch "Ref All Home". If you have home switches fitted, then the machine will home. If you do not have home switches set up in your Ports and Pins table, then the DRO's will merely zero without the table moving. You cannot change the machine co-ordinates other than by zeroing them using this switch. Once it has homed, the machine now knows where all other "things" are (e.g. automatic tool changer - chuck centres etc). If your homing switches are not operational then all you have done is tell the machine to regard this poisition as it's new home.

When the machine is moved to a position ready for work, the machine DRO's will change until it gets to a point where it is to start running your program. Dependent on how you (or your CAD) have written it, the position at which you start may vary BUT if you now press the Machine Co-ordinates button, the DRO's will now display the work co-ordinates (or program co-ordinates) - THE FIGURES WILL BE THE SAME HOWEVER. We will pretend you have jogged your table(or cutter) to a position that your program knows as 0,0 (usually the bottom left hand corner of the table). You can now ZERO the work co-ordinate dro's either by using the zero buttons, or typing zero in. If you have jogged to another position to start , say 10,15 then you can type that into the DRO's instead.

If you now press the Machine Co-ords button (i.e. the button surround is lit) the display will still show you the original machine co-ordinates. Toggle it again (the surround goes out) the display will show you the program co-ordinates that you have just set.

The program co-ordinates also record changes to the tool offsets (and any other offsets that you use). Tool offsets are entered in the Tool Table - see Config/Tool table. Enter in the information in the table - the name - e.g. 9mm drill and the diameter (which MUST be in the units you set your machine up in - e.g. 9 mm drill - 0.3543 inches diameter. Dont forget to press return and apply. The details will be saved and available next time you use the machine. There is no tool 0, which means that if you use tool zero all its measurements are 0 as far as offsets are concerned. Length and wear are not important (unless you have an automatic tool changer)

The ideal program would be -  set all home - select the machine offset to move to the workpiece - use imperial (or metric) - select the tool(s) in order with diameters and lengths - cut the work - move the cutter out of the way so you can admire the finished product.

It doesn't actually take all that much doing - setting the machine up takes about 5 or 6 GCodes in a program, once you have it all "set up" on the ground.

I suggest you look through the Tutorial videos which cover a lot of the basics. I downlaoded them onto my machine, and I can refer to them when I want to.

If I've covered a lot you already know, I apologise - once I get on my soap box!!


« Last Edit: May 14, 2008, 05:59:05 AM by jimpinder »
Not me driving the engine - I'm better looking.