[TechCenterTeach]

I recieved about 8 hours of official training on a Haas TM1 & TL1 last spring. I am now charged with the task of teaching high school students how to run these machines. I spent numerous hours practicing and getting familiar with the machines, reading books, forums, etc. I pick up things relative quickly and I feel I am good enough with the machines to teach the students the basics (of course, with high school students safety is of first importance). By the way - I love this stuff and may have to change careers in the future .

Anyways, my question is, what is the best way to set tool and work offsets? For the work offset G54 I set the X&Y offsets by aligning the corner with the tip of a center drill or other pointed tool when accuracy is not extremely important, or use an edge finder for greater accuracy. The problem is with the Z work offsets - what is the best way to do this? One way is to leave it at zero and then touch of each tool for the tool z offsets, but then sometimes the tool hovers a foot above the part - so when this happens I then set the z workoffset and the z tool offset to the same value - but I can't imagine this working when using multiple tools because the tool lengths are all differnent. Any suggestions?

Sorry for the long-winded question.

[HuFlungDung]

The short of it is, on the mill, that your workoffsets become active in all 3 axis as soon as the program reads the G54 (or whichever one you are using). So, the Z work offset has nothing to do with tool length, but everything to do with reference planes.

I feel that it is good practise to set the tools to a special gauge block (something that you and your students will reserve for this sole purpose). A vertical dial gauge called a presetter can be bought to serve as this gauge. I'd be remiss to have it in the lab for fear the students would crush it.....make that "for certainly they would crush it" But, any thing can serve the purpose so long as everyone agrees that the object would be the setting gauge. Such a device should at minimum have carefully faced and parallel ends. A 2-4-6 block would work.

So touch all the tools off this gauge block. This way, if you need to add more tools, or change out a broken tool, you'll have something you can quickly set on the table to touch the new tool off of.

Now, there will be some random difference in height between this gauge and the actual top of the workpiece. This difference is, of course, the same for all the tools in the set that you have installed and measured, and so the Z component of the current workoffset serves exactly as a method of compensating for this distance.

In jog mode, switch your Position display to the operator screen. Usually your last tool will be sitting on the gauge block because you just finished measuring the last tool length offset. So, if the tool is touching the gauge, and the Z axis component of the screen display is flashing (because that is the active jogging axis), press Origin to zero the Z axis display. Now jog away from the gauge, and over to the workpiece. Touch the workpiece. The jogged value in the Z axis display will be the measured distance between the gauge and the work. You'll have to key this value into the Z work offset register of your choice, you cannot teach this position in with a single button push.

I'd advise that your setting gauge be 'tall', that is higher than your typical workpiece when clamped in the vise. The gauge should sit on the table and not on the vise. If you follow this convention, then your Z work offset component will be negative in value. If your student forgets to type in the correct sign, the ensuing accident takes place up in the air In contrast, if you pick a setting gauge that is 'sometimes higher, sometimes lower' than the work, then you run the danger, almost with 100% certainty, of having a serious crash.

Many guys will set all the tools directly off the workpiece. This is okay, but then your Z work offset component is left as zero all the time. You'll also need to redo the whole set of tool offset measurements whenever you change workpiece height. There is a potential pitfall to setting the tools off of a workpiece, especially if it has no good reference surfaces on it, or if a series of rough cut bars will be machined and they vary somewhat in height. If you set the tools on a rough reference, then face it, the reference is gone and is not recoverable. Setting up a new tool to a new reference plane while leaving the rest of the set of tools unchanged can easily result in a spoiled part.

[mallenby]

First you get good, then you get fast. Then grouchiness sets in.

OK, i'm a student and just getting started in machining. Thanks for all the good info posted here. As time goes by I am understanding more and more of what is written on these pages. I'm in the first process of getting good. Can't wait till i'm "grouchy" LOL.
Thanks to all...
Happy Holidays

[helix77]

I HAVE NEVER BEEN A BIG FAN OF ANY OF MY OPERATERS USEING A GAGE BLOCK OR ANY OTHER HARD SOLID BLOCK FOR SETTING TOOLS..... A NEWBY APPRENTICE WILL ALWAYS OVER SHOOT THE TOOL INTO THE BLOCK.... WHICH FIRST OFF WILL WRECK THE TOOL POSSIBLY SENDING THE CORNERS OF THE TOOL SHOOTING LIKE SHRAPNEL AND IF IT DOSENT BREAK THE TOOL IT SLIPS INSIDE THE TOOL HOLDER WHICH OBVIOUSLY IS NOT AN ACCURATE WAY TO SET AN OFFSET... BUT SECONDLY IT WILL WRECK THE BLOCK... GAGE BLOCKS SHOULD NEVER.. EVER BE USED THIS WAY .IT IS NOT HOW A GOOD TOOLMAKER SHOULD TREAT PRECISION TOOLS (ESPECIALLY MINE!)
ONE OF THE FIRST CNC PROJECTS I DID IN SCHOOL WAS TO MAKE MY OWN TOOL PRESETTER USEING A 1.0 TRAVEL INDICATER...SO IF I WERE TO OVERSHOOT THE PRESETTING THEN IT JUST COMPRESSED THE TOOL FURTHER ALONG THE INDICATER TRAVEL.... AND YOU SHOULD BE TEACHING THE USE OF MEASURING TOOLS IN TANDEM WITH BASIC SAFTY AND SETUP ANYWAY.
FOR LOCATING X AND Y (G54) A STANDARD EDGE FINDER IS A VERY SIMPLE AND EFFECTIVE TOOL.... SWEEPING IN GAGE BLOCKS IS PROBABLY A LITTLE MORE ADVANCED OF A TECHNIQUE TO TEACH YOUNGSTERS.
I WILL BE GLAD TO GIVE ANY MORE ADVISE PM ME AND I WILL GIVE YOU A PHONE NUMBER

[HuFlungDung]

You're right Helix. A presetter is a great project, and what I always use is a short travel presetter on top of a 2-4-6 block to set my tools. But, with Haas jog set at .1" travel per pulse, a newbie would be out of travel in two clicks, so a 1" travel presetter would be a decent amount of overtravel. I know, they need to learn to be careful, but there's always a couple of carefree students in the batch

[SeymourDumore]

Helix

While I completely agree with you on the presetter, you have to be rather retarded to try to move the tool down in Z and hope you stup just before the tool shatters to million pieces.
What you do is move down below the gageblock's top, and then move up thou by thou until the block slides under the tool. In some instances a gagepin is almost a better solution to roll under the tool instead.
As for precision blocks to be used this way.... Well, I think they are cheap enough to purchase one, two or even ten for this purpose only. Not to mention that your final inspection tools should not be on the shopfloor anyway.
Garden variety gage pins and blocks in this shop often end up getting built into fixtures, alignment tools, inspection aids etc. Heck a decent amount of V-blocks and precision vises make their way straight from the box into the Wire EDM to be turned into something much more useful.
I guess I have no respect for precision instruments when it comes to saving time and effort in getting something done.

[helix77]

... WELL I KNOW THAT THATS THE WAY YOU USE BLOCKS TO SET TOOLS ... BUT I HAVE ACTUALLY SEEN GROWN MACHINISTS DOING IT THE WAY I DESCRIBED ABOVE (RETARDED INDEED)... ITS NOT A GOD AWEFUL WAY TO SET TOOLS (USEING BLOCKS THE RIGHT WAY) BUT I THINK JUST FOR GENERAL PRACTICE IT IS SAFER USEING SOME SORT OF PRESETTER.... EVEN AN IMPROVISED ONE.
AND STILL DO NOT USE GAGE BLOCKS FOR SETTING TOOLS...EVER. UNLESS YOU ARE SWEEPING EDGES WITH AN INDICATER THEY SHOULDNT BE USED FOR ANY TOOL SETTING. CHINESE 1-2-3 BLOX ARE MUCH CHEAPER AND READILY AVAILABLE.

[SeymourDumore]

Agreed

I use a 2" high presetter with .250" overtravel and a fixed calibrated side of 2" to be used with a 3D taster to pick up my work Z-location.
IOW when I hit 0 on the setter, I'm exactly at 2" from the base AND exactly at the same point as the solid side.
Takes seconds to pick up each tool and maybe 30 seconds to pick the Work Z0.

[gromit68]

I bought a light-up gage at a local place that wholesales machine tools and industrial supplies.

It is electrically conductive, has a precision ground spring loaded plunger on top.
When you overtravel, it just moves down. Move back up until the light goes off.

This solution cost me probably $40.

A hard gage block works just as well, as described above.

Place the tool below the top surface, and jog up until the block slides under the tool.

You can't teach common sense, but you can teach good shop practice

[Baketech]

A precision ground dowel pin works very well for this. Very easy to roll back and forth under the tool between jogs...so no danger of crunching things... :twocents:

[helix77]

IT LOOKS LIKE EVERYBODY JUST HAS TO USE GAGE BLOCKS HERE......LOL
I GUESS SOME OF THE OLD FASHONED DISIPLINE DIES OFF THROUGH THE GENERATIONS.
(IM NOT OFFENDED JUST AMUSED !! PLEASE DONT TURN MY COMMENTS INTO A DEBATE)

[HuFlungDung]

Well, it goes without saying, of course, you'd use Chinese gauge blocks

I call a 2-4-6 block a gauge block when I use it as a gauge, but I call it a spacer when I use it as a spacer. The blessing the Chinese have given us, is that we can actually use some of what used to be expensive sh!t, instead of worshipping it

[helix77]

YA.... GET THE CHINESE STUFF FOR THE PRICE..... AH CHINESE.. QUALITY ONLY A WELDER CAN LOVE!

[Shotout]

I HAVE NEVER BEEN A BIG FAN OF ANY OF MY OPERATERS USEING A GAGE BLOCK OR ANY OTHER HARD SOLID BLOCK FOR SETTING TOOLS..... A NEWBY APPRENTICE WILL ALWAYS OVER SHOOT THE TOOL INTO THE BLOCK....

This is the main reason we were not suppose to take the machine out of .001 when hand jogging in school :nono:. I always had to look over my shoulder before moving it to .01 or .1 first Even then I'd hear "Scott!" from time to time. Because of this restriction, which for some reason chaffed me, I started adding a move to bring my vise to me. Also we never used the jog lock function.

Realisticly the tolerances we held in school for the basic class were +/- .001. Very easy to use an edge finder and the paper shim method to hold that tolerance. We simply set the tool length, entered a negitive wear value to correspond to the mic'ed value of the paper, leaving the g5n value at 0.0

Not having been out of school that long I'd like to point out something. Keeping in mind we were learning to take the machine from a powered down state, home it, use MDI, load programs from disk, navigate the offset displays (as well as others), and make the machine ready to make chips all at the same time, keeping everything basic and straight forward helped protect the students and machine. By making tool setup basicly the same as we had learned in manual mill I it took one thing out of the equation. We, after being able to go from startup to m30 without mistakes, learned some very basics about other ways of setting up. Also it is assumed a student will recieve some on the job training and if they are setting up machines the shop will teach them their prefered way of setup knowing they are a student and knowing there is going to be a learning curve hiring a student. My .02 worth.
Scott

[smittys800]

Very imformative here, as I touch off to the part on all my tools, yep I'm a rookie.
So after setting the last tool, does the control compensate for the other tools?
Smitty

[HuFlungDung]

Smitty,
All the tools that have had their length offsets set to the presetter (gauge) are affected identically by installing a value in the Z register of the current work offset. The Z work offset in this method, is the difference between the plane of the gauge and the plane of the work.

[smittys800]

Hmmm,
I'm going to have to give this a whirl, looks like it will save time, and more consistant parts!!

[HuFlungDung]

Yup. I nearly spoiled a fairly expensive mold one time, when I was used to setting tools off the part. One tool broke when it plugged up, and when I reset the new tool, I forgot that I had already tweaked my Z work offset a few thousandths downward (to clean up a low spot) but the original tool lengths were set off a different plane (the unmachined top of the stock). So, the new tool started 'detailing' the bottom of the pockets in a most unwelcome manner Fortunately, I had some extra stock, but I had to refinish the whole thing again to get it all deep enough to get the marks out.

[duenow]

I set all tools off the table, then set my Z off the top of stock. After facing the stock
if a tool, drill snaps there is no Z0 to set to as you have faced it off.
My way just change the tool set to my setter off the table & it's right!
shown here.

http://albums.photo.epson.com/j/Albu...&a=32201742&f=

[bob1112]

Could someone post pics of either the dial indicator or LED presetter? We are still using the 1-2-3- block method sliding under the tool but want a more accurate way and will need to zero off parts and fixtures so small would be nice.

We always though we needed a stand alone presetter but not sure if that is really worth the money. Thought about just making something but we do need to make this deal faster.