Re: [CAD_CAM_EDM_DRO] Setting up end mills for CNC, and other things.

On Sun, 17 Jun 2001 06:02:23 +0000, Jon Elson <elson@...>
wrote:

>If these comments don't help, send me a message, as I also use Bobcad,
>and have done this. I can't fully understand what you are asking about
>manually taking the cutter centerline past the edge. But, it sounds like
>maybe
>you are asking about lead-in and lead-out.

What I may do, if I don't get it figured out in a day or so, is send
you a simple BobCAD drawing with the matching CAM file (tool offsets
already entered) and have you do the path setup as an example.

>> Second: Do you have any trick ways of setting up the vertical
>> offsets? My current plan is to go to the machine, install tool 1,
>> move it down to touch the top of the tooling fixture, read the "Z"
>> readout. Then do it again with tool 2, repeat for all tools needed.
>> Note the difference in "Z" readings form some "standard" and account
>> for that by manual programming. Is there an easier way?
>
>This is somewhat similar to what I do. You can make an height block
>that has, say, a 1" height, with an insulated flat place on the top, and a
>battery and lightbulb (or beeper) in it. When you bring the tool down until
>
>it touches the top, you get a light or beep. The tool is then 1" exactly
>above the workpiece. Make your shortest tool (handy if this will be your
>first tool, like a center drill) the reference, and call it's length 0.
>Now, measure all other tools against that, and enter the difference in
>the tool length table, generally as a positive value.

I've stumbled into something sort of similar. I use the longest tool
(which so far is the only tool), take it down to just touch one inch
above the work surface on the side of a 1-2-3 block, and call that
zero. I end up giving up an inch of "Z" travel, and "Z" travel is in
short supply on this machine, but since I've done that, and had the
first program movement command be to take "Z" to zero, I haven't run
into anything. <knocking on wood, mumbling incantations>.

>> Third: How do you go about measuring tools in holders so that it
>> isn't necessary to re-baseline the tool in the holder by installing it
>> and going to some place to touch it down? My number of tools is small
>> enough that touching it down to the top of a 1-2-3 block to find out
>> where it is relative to home isn't that big a deal, but it seems like
>> it would be better if I had a fixture I could put the end mill holder
>> in and measure the "Z" offset that was going to need to be in the
>> program.
>
>I did exactly that. I made a think that is similar to a cylindrical square,
>but it is bored and ground internally to fit an R-8 taper toolholder.
>I bought a bunch of toolholders. I rarely take the center drill out of the
>holder, so it becomes the reference. I record the length of this tool on
>a sheet of paper that stays next to the machine. Whenever I will be
>switching tools in a program, or for other reasons will be using length
>offsets, I can measure my other tools, subtract the length of the reference tool,
>and enter that in the tool length table. You can see my poor-man's
>tool presetter at http://pico-systems.com/preset.html

Looks like a good setup. I think I will do something similar only set
up for #40 taper. I have a surface plate so that part is ready
anyway. Its a good excuse to buy a height gage too. <G>

>If I lower the ref tool to touch the work, then do a G92 Z0 to set the
>coords to 0, when I mount the next tool and select it, the next Z
>move will take the length into account.
>
>Using the tool length offset only sometimes is dangerous, by the way!

I can see that.

Thanks for the good input.

Fitch
In So. Cal.

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