Messages

471

General Mach Discussion / Re: Needing Help!

« on: June 23, 2014, 08:26:04 PM »

Something I learned from breaking stuff.  I like to use a large round pin for picking up the top of a part or even edges.  By using a large pin the tool is always far enough away that an oops like a jog in the wrong direction won't crash the tool into the part ruining your whole day.  On top I roll it back and forth quickly under the tool until it touches. On the side is a little trickier but no big deal.  It's like sailing a boat.  It not the water that gets you in trouble, it is the hard parts around the edges!

472

Mach3 and G-Rex / Re: Why does Mach 3 need a tool length?

« on: June 23, 2014, 03:34:59 PM »

Drill press time! Get a subland drill from McMaster Carr or other supplier and knock it out.

473

Mach3 and G-Rex / Re: Why does Mach 3 need a tool length?

« on: June 23, 2014, 07:08:27 AM »

Just a grounding buss for a computer room. It needed lot of holes.

474

Mach3 and G-Rex / Re: Why does Mach 3 need a tool length?

« on: June 22, 2014, 11:32:41 AM »

Learn,
I've done long part in the past, some long copper bus bars that needed a lot of tapped holes. How do you relocate for each position?  We actually did it by using a tool or pin in one of the holes. We put the pin in the hole, paused, unclamped the vise, let the tool move to a new programmed location, and reclamped.  I am getting ready to drill holes and finish both ends of a long part using this method, by using an end mill to make the holes, round the ends off and relocate the part.

475

Mach3 and G-Rex / Re: Why does Mach 3 need a tool length?

« on: June 20, 2014, 09:16:22 PM »

Learn,
Good to see you making progress on this.  It really does work and I expected you would see the value once you started to understand it.  Are you machining more than one of those at a time and using work offsets g54, g55 etc. for the different parts?

476

Mach3 and G-Rex / Re: Why does Mach 3 need a tool length?

« on: June 14, 2014, 08:27:20 PM »

Learn,
Bummer! I started writing the post above and stopped for dinner.  The answer to your crash is in that post.  Sorry about that.

477

Mach3 and G-Rex / Re: Why does Mach 3 need a tool length?

« on: June 14, 2014, 08:25:20 PM »

Learn,
I will admit that tool length setting in Mach 3 REALLY had me going for a while!  It took me a couple of hours one day determined to get it to work before I finally got it.  So I'll try to save you some of the tools I broke by giving you one huge hint.  When you press reset or rewind a program in Mach 3 it executes a G40 tool length cancellation automatically.  This is deadly!!  Because if you make a move with the previous tool still in the spindle it will move the Z to a zero length tool and almost certainly crash it.  The correct length for the tool doesn't get set until the program reaches a tool change for that specific tool.

In mach3 and other CNC programs the tool length is kept in a table of offsets.  The tool length gets applied at the tool change if you call the H word along with the tool number and then do a G43, which actually moves the Z to make the end of the new tool exactly where the end of the reference tool would be.

On the Offsets screen in Mach 3 in the lower right portion of the screen is where you enter the tool number and then touch off the tool to get the length.  The reference tool, my edge finder is tool zero and it's length offset is zero in the table.  All other tools get an offset plus or minus the length of my reference tool. You'll see this if you click the Save Tool Offsets button.  These offsets are retentive even if you turn the machine off.  So if you power the machine back up and pick up Z zero using the reference tool all other tools will still be the correct length when they are called, and you don't have to set them again.

If you are smart about this you may keep certain tools always in a holder and mark the holder with the tool number, then always use that tool number in your programs for that tool.  You then don't have to touch off that tool again until you change it out because it is dull.

You need to play with this some. I'll bet you view what you do at work in a new light once you have this working on your own machine.

478

General Mach Discussion / Re: Engraving Spindle.

« on: June 14, 2014, 06:12:52 PM »

Tweakie,
Those motors have a RPM/V rating.  The lower the number typically the more poles the motors have and the slower they run.  I've seen some with 28 poles, which allows swinging a large prop by direct drive.  So a motor like that might only need a small belt reduction ratio to be useful for milling. Also for small diameter carbide tooling you typically want high RPMS anyway, However I think the spindle loads should get carried by a separate set of bearings, not the motor bearings.

479

Mach3 and G-Rex / Re: Why does Mach 3 need a tool length?

« on: June 14, 2014, 01:53:29 PM »

Learn,
The reference tool could be any tool you use often. I use an edge finder because I use it all the time. I don't use a height gauge I use a 0.5" pin I roll under the tool. I like using a large pin so I never accidently jog the tool into the part or the table. You just tell Mach 3 the size of the pin or height gauge.

480

Mach3 and G-Rex / Re: Why does Mach 3 need a tool length?

« on: June 14, 2014, 08:53:21 AM »

Learn,
You are setting tool lengths when you touch off cutters to the top of a part, because in those machines it is done automatically.  Those machines all have a tool table in the control that you can access and see the length offset for each tool.

I worked at a place that did it that way for years.  Once I taught the operators that tools could be touched off anywhere, and any ONE tool could then pick up the top of the part we stopped setting tools to the top of the part. Using a common place, that is not the part, to set tools means that tools can be set at any time, even after the usual reference point on a part has been machined away. This means if a tool wears out you can replace it in the middle of machining a part if needed.

Using a reference tool, typically an edge finder or touch probe kept in a tool holder saves even more time.  I had to laugh that the machinists were installing and removing their personal edge finder at the beginning and end of every shift!  The company purchased an inexpensive edge finder and one more tool holder and it paid for itself by the end of the week!

My home machine uses Tormach holders that are repeatable.  I bought one extra holder for the edge find and never take it out of the holder, its my reference tool. I don't have accurate home switches, so I have to reset my tools only after a reset of Mach3, which typically means once I have set them I work all day without ever setting them again.