Determining length of tool sticking out of spindle

[PhoenixMetal]

I need to determine how far my tools are sticking out from the base of the spindle - for input into my CAM software.

I have read before about tricks such as using a piece of paper of known thickness and lowering the tool until it grabs the paper... Should I use this same technique to touch the spindle base to the paper to determine a baseline measurement? It just seems odd... Is there a more sophisticated method that I should know about?

Sorry if this question has been asked a million times before... I tried searching searching previous posts but at this moment the search feature seems to be broken.

Thanks,
-PhoenixMetal

[mc-motorsports]

If you really want to spend the money:
http://www.directindustry.com/prod/c...026-55903.html
click on "watch the video" for a demonstration.
The optical tool setters can actaully also be used to optimise multi insert milling cutters and such. You can shim and fine tune the inserts on anything from a facemill to a multi insert endmill cutter to get optimal performance.

[BobWarfield]

Phoenix, the method depends greatly on what level of accuracy you must achieve. Note that your machine (you haven't said what it is) has a bearing on this too in many ways.

For example, R8 is not a taper that repeats very well. Every time you change the tool you need to reset that value. That doesn't bode so well for entering it into a CAM program, so you'll want to do it in Mach instead.

If you have a tooling system like Tormach sells or Hoss made, you have a way to get R8 to repeat. If your taper is one that naturally repeats like a CAT or NMTB, you're also set.

Next you need to measure. With a repeatable system, you probably want to measure once, record it and go on. You may invest in something pretty fancy because you do it once and want to do it accurately. The optical presetter mentioned is one approach.

Otherwise, you may want to go cheaper. You mention touching off with a paper. That's one approach. It may not be that accurate for you, however! Run some trials and see. I tried a bunch of different ways one time, measured the actual results of the cuts, and came away unimpressed with the paper approach. You can read about that near the bottom of this page:

http://www.cnccookbook.com/CCMillTipsTechniques.htm

You'll see mention on that same page of a Z-presetter. They're available pretty cheaply from eBay and seem accurate to a thou in my experience.

You can also build or buy a touchsetter. It's a little plate of known thickness that makes electrical contact with the tool. You can customize Mach3 to deal with all that in a nice way. Hoss and others on this board have done so.

That should give you an idea of your range of options.

Best,

BW

[mc-motorsports]

Very true...
What machine? What CAD/CAM?
What tool taper?

There are only 2 REAL needs for an optical comparator that I know of, a 5 axis head, or high production where you just need to grab the old tool/tool holder and swap in a new one to get back up and running without having to "touch off" using a tool setter or even a jo-block or shim (paper).

More then likely, your CAM software just wants to check and make sure your not going to plow a tool into the part, like a tool that is hanging out 1" and your trying to mill 1.5" deep, or around another entity.

[PhoenixMetal]

Hey guys thanks for your input. That CNCCookbook site looks great - I'll definitely spend some time reading through it all!

The Z-axis presetter device sounds right up my alley - simple, inexpensive and accurate. I'll order one tomorrow.

High accuracy is very important to me as I will be using this machine almost exclusively for making stamping dies and other tooling, generally with many parts that all need to fit together just right.

To answer your questions, the machine is a Kitamura Mycenter 1 Vertical Machining Center with BT35 Tooling and Yasnac i80M controls. I am using ER collets for nearly all the toolholders, and most of my tools are relatively short, so they don't bottom in the toolholder (so every time I change a tool it will be sticking out a different distance from the toolholder).

The CAM Software I am using is GibbsCam. Now normally in that software you would tell it what type toolholder you are using (selecting from a list), and you tell it how far the tool sticks out from the toolholder... However my toolholders (from Lyndex/Nikken) aren't on that list, and it looks like a pain to manually define the dimensions of the toolholder, so I opted to take the option in the software to simply tell it how far the tip of the tool is from the actual spindle bottom, ignoring the existance of toolholders.

Anyhow, I used the paper trick tonight to figure out the tool lengths as I'm anxious to get cutting. I'll let you all know how it works out. Tomorrow should be the day I cut my first thing on a milling machine, ever!

Thanks again for all of your help!

[mc-motorsports]

Tomorrow should be the day I cut my first thing on a milling machine, ever!

Holy hell your bringing back memories! LOL! I honesty don't remember the first time I ever used a milling machine, or even a CNC, but I do remember my first day at my first REAL job in a CNC shop...
I'm too embarrassed to tell the story! Let's just say I would have fired me... LOL... I was just a 18 year old kid, didn't know crap about crap and I remember when the shop owner asked me "hows it going"? And I made jokes about the tool falling out of the spindle and dancing on the table like a "spinning top" before scrapping a bunch of parts and chewing up the table... LOL... Oh boy. The look on his face was priceless, looking back that is. Thank god he had patients and realized I was just a clueless kid who didn't take things seriously, but like I said, I would have fired me...!

MC