Hi,
nambass wrote:HI Dave
Thanks for this solid response. I hope I am not going to frustrate you too much and maybe I am still missing some points - please forgive me then...
No problem, if you can;t ask question sit gets hard to learn... I'm happy to help out. The caveat is that sometimes I may have to be a bit slow to respond to "educational threads" as I often have to give priority to other things.
nambass wrote:HI Dave
Ok I think I understand that I need to get rid of the screenset 2010 ideas. and I kind of understand some of the concepts like TLO.
I'd say to toss the 2010 screen set along with it's concepts...

(OK, I admit I'm a tad biased on this topic of 2010 vs MSM).
In all seriousness, have a good read through the MSM manual sections I referenced. They cover the topics in detail. I've been told that I have too much info in the manual as I cover several alternatives for TLO techniques. But I'm biased toward "you can ignore what you don't want, but can't read what is not there".
nambass wrote:
The spindle uses a normal collet so everytime I insert a bit (even the same bit) it will vary in length. What is great is that MSM will calculate the TLO.
That is a core reason I wrote MSM. See in the industrial world the only thing that is used are fixed tool holders that always mount a tool at the same length (often a CAt-40 holder). That of course doesn't work very well for machines that have things like R-8 spindles or use collets or for drill bits in chucks.
For those machines, the only reasonable solution is to measure the tool after it is physically mounted - and MSM is real good at that.
nambass wrote:Bit now my questions....
How do I define my default offsets for my spindle and also the table top?
Well, you don't - but you don't need to either... I'll try to explain.
I'm assuming that your machine has home switches. If not, you'll probably really want to end up adding home switches.
When you home an axis, Mach sets 0 in work coordinates for that axis "to the location the spindle is at when that home switch is triggered". (this is a slight simplification but will do for this discussion).
Most people put one home switch on each axis. Because the home switches are physically mounted to the machine frame and don't move, this creates a fixed frame of reference for the physical motion of the machine. We call this frame of reference the "machine coordinates".
Where you put the switches determines where the machine coordinates x,y,z = 0,0,0 point is located. The conventional arrangement for industrial machines is that this ends up putting x,y = 0,0 in the back left corner of the machine (as you stand facing the machine) and Z0 at the top of vertical travel. Think of a box that encloses the available travel area of the machine: zero is at the back, left, upper corner. I will assume this configuration as I write things.
Note that you don't have to do it this way, the math will not care, but it's easiest to do things like the rest of the world and there is no real advantage to being different here.
So, homing is the action that establishes the machine coordinate box in space. This is now anchored to the machine frame (thus the name machine coordinates).
The table top is at whatever location it is at in machine coordinates. Now we are going to go moving the spindle around in space.... conceptually we are moving around what is called the "controlled point". Where is that point physically? When a tool is mounted, the point is at the tip of the the tool (think drill tip). Now let's mount in our imagination a drill of zero length, in a holder that has zero length. This "controlled point" is now at the face of the spindle, in the center on the center of rotation of the spindle.
Now then, machine coordinate z0 is at the top of the Z physical travel. So if we lower the spindle until this controlled point is just touching the table, the point will be at the level of the table top. Since we moved DOWN from z0, the coordinate will be a negative value.
For example on my mill, I have about 12" max of Z travel. If I touch the spindle to the table, the controlled point is at -12" in machine coordinates. That is the level of the table top.
When I put a piece of metal in the vise, the top of the piece is at some other Z level in machine coordinates. Lets say it's at Z=-8" when in the vise.
But what's all this talk of machine coordinates....? This is why the world invented work coordinates. The machine coords are fixed to the frame of the machine. But work coords can be put any where we want them. So to make things easy, we typically set WC 0 to the corner of a piece of stock that we are about to machine.
So using my example, I have the top of stock at MCz=-8 and that same level is also WCz=0.
We generally write programs so that cuts are negative numbers in Z and positive numbers are above the stock in Z. This is what you are used to thinking of probably (because gcode programs are written in work coordinates).
Now you can see how it's possible to run a program to cut stock w/o knowing the MC info for the machine. The CNC control translates the commanded WC position into a MC position and it all comes fine. You just have to set the WC 0 to the desired place on the stock. You don't have to know where the stock is in machine coords.
The shift in x,y.z (a translation in math terms) is what relates MC to WC. In fact this shift is exactly what the "coordinate offsets" are that you see in DROs.
nambass wrote: I have a touch plate. I will be able to define my Tool Change Position and also know the thickness of my touch off plate.
Yep. MSM lets you define a tool change position. The position is defined in machine coordinates because you want it to be fixed in space relative to the machine frame (You would not want the tool change position (TCP) to be moving around as you moved the WC 0 around). MSM then has a button (tooling page, "Auto TCP") that says: "whenever you do a tool change, go to the tool change position at the start of the tool change".
Now then, MSM can do more.... You can install a touch plate and put it below the TCP. Then we can turn on another tooling page button: "TC Auto TLO". This button says: "during the tool change. probe the tool down to the touch plate to measure the tool, calculate the TLO value and put it in the tool table for that tool".
When you install the TCP TP (Tool Change Position Touch Plate), you set the plate location, thickness etc.)
MS then supports several different ways to calculate the TLO value. I suggest using Master tool mode - it's easiest and most convenient for daily use. The choices and what they each do are in the manual.
nambass wrote:can you explain this process to me. and then after this is all done, I will then be able to load a g-code file. I insert my 1rst bit. I jog to the Tool Change Position and do the TLO run?
Yep, except no need to hand jog - MSM will position the spindle for you.
The sequence ends up being:
1) Running codes sees an M6
2) MSM M6 handling stuff gets called and (depending on option buttons) MSM moves the spindle to TCP.
3) MSM says "hey human, inset tool #X"
4) human clicks cycle start to say "tool is mounted".
5) MSM measures the tool and updates the tool table
6) program continues after M6 line
That is the end of the tool change sequence. Note that there is an important point that I want to call out...
7) Next the program does G43 Hx to turn on TLO compensation (this is NOT automatic as part of the tool change as gcode defines this as a separate step. You only get TLO compensation when the program turns it on).
If you are hand writing gcode, and not using G43 now, you will need to. IT is G43 that tells mach to add the TLO value into the calcs that get done to convert WC to MC.
If you are generating code from a CAm program, you want the tool change output to be
Tx M6
G43 Hx
(on separate lines, mach has a big that screws up if all 4 are on the same line)
nambass wrote:
Second area - I downloaded the personal edition for now, will all this work with the personal edition?
Andre
Alas, no, The personal edition does not have probing support (which is what we are really doing to measure the tool).
However, you can Download the Professional edition and install it. It runs for 30 days fully functional with all features enabled. I encourage people to do this, as nothing beats trying it out first hand.
At the end of 30 days, it gets cranky, but if you decide to purchase a license, you just enter the info, it goes off and talks to the license sever for verification and converts to a permanent Professional installation.
BTW- a pro license is good for two controls at any given time, and you can move the license from PC to PC if you upgrade hdw etc. See the CVI web site for more info.
Dave