Hey guys, I'm trying too cut a part with multiple parts. I finally got the tool change too work. But what good is that when I can't offset my height after I change. I just shut the spindle off and then after I change tools, click continue on the screen, however....I can't reset the height after I change tool. So it either cuts my piece way too deep or won't cut it all because I'm "eye" balling it. How do I get it so I can offset the height after?


-Jason

If you want to use offsets from the tool table you need tooling that allows you to remove a tool from the spindle and put it back in the spindle without the Z length changing.
This is one of the simpler systems for an R8 spindle.
http://www.tormach.com/document_library/DS_TormachToolingSystem.pdf

If you do not have tooling like that I would just split the program up into separate programs for each tool, and not do tool changes in the program.

Really? That sucks! I guess I will need too run separate programs....

-Jason

Jason,

I haven't totally solved this problem myself, but how about making some kind of little jig that helps you set the tools to the same length?

Alan

I'm guessing that you don't have a quick change tooling system that maintains the same length for tools from one load to the next. If you are simply stuffing a drill or mill into a collet or chuck like I often do then the length can be a real guess. While I"m setting up the procedure shown below I include tool length offsets to allow for the difference in length of a drill v a mill. You could also simply change the working depth in the program itself.

I often set up a block on the bed if I don't have a flat on the part that I can work from. On this block I'll use a bit of shim stock or paper of known thickness and set my new tool's length from that fixed height. Then I program the tool changes something like this.

Raise the head away from the work at the start of the tool change.
insert a pause to remove the old tool and insert the new one.
leave new tool a bit loose so it can slide.
move xy so the tool is over the block or flat.
feed slowly down to the proper tool length.
tighten tool
raise z, pick up tool offset. and go to work

I like to use brass shim stock because it gives just a bit. Many cutting tools are very hard and will chip a sharp corner easily.

HTH

Rayh

The problem is, I only have about 6 collets with many different bits. Some end-mill have tapered ends but the same diameter shank. So I'm constantly using one collet for many bits. I guess I will have too make a jig so there all the same length. A Pain in the butt considering that the collet won't fit into the housing unless the tool bit is out. I'll think of something. Maybe I'll mark all the tools ata certain height and then always insert the tool and line up the marking too the edge of the collet. Pretty simple.....


-Jason

Another cheap fix if you don't need to be too precise get a couple of Drill bit depth stops to fit the shank of your tools.
Those are just rings with a setscrew to position around your tools then when inserting your tool run it up until the stop hits the collar then tighten this way you will always position the tool the same length.
Now you can just record the tool length into you'r offset table.
An example of a Drill depth collar can be seen here.
http://www.brandsonsale.com/ht-002097.html

Note this is just a example you can get them from anywhere.

Great idea!

-Jason

Just bought some drill stops from ebay. Great idea.


-Jason

If you really get fancy - you can mount a switch on the machine to set tool length. Then after you set the first tool to your work - the rest will be correct by touching off the switch.

You can look at an example here
http://cvs.linuxcnc.org/cgi-bin/cvsweb.cgi/emc2/nc_files/tool-length-probe.ngc

sam

Samco,

Thanks, I figured someone actually knew how to do this.

Could you do this with just a piece of PCB, with the top surface connected to the probe input and the tool bit (via alligator clip) connected to GND?

Alan

Maybe I'll hold off fancy stuff and first set everything up and trying too work right for now. It's good, and this idea should work nicely. I still have so much too do!


-Jason