Question for you CNC operators

[Kevin54]

I finally decided to get down to it and see if I can get my Bridgeport CNC Series 1 R2E4 programmed to do something. Some may remember that I had a problem with the "Y: axis having a hard time finding position and the guy I hired to look at it decided it was the encoder for the motor. So at the tune of $500, I put a new encoder on it, and I still have the same problem. It may be the ball screw that is bad, but before that, I decided to try and program something like a Turners Cube.

Now here is my question.......for the ones that programs CNC's, have you ever ran across one that the - (minus ) "Z" depth is programmed in a positive number instead of a negative number?

For example, while messing with it while running, I put some smaller coordinates in it, meaning that instead of taking a .100 depth cut, I would take (5) .020 depth cuts. I programmed it to go to a -.250 depth and it ask about the "Z" plunge depth which I put -.020 for each plunge. The quill would come up instead of down.

So in the canned program, which was for a pocket, I had to put a depth of .250 (positive) with each plunge at .020 (positive). The program then runs correctly with spiraling out and dropping -.020 at each start point, and by putting in a depth of .250 (positive), it then drops to the final depth of -.250 from Zero ("0").

This is the first time I have ever ran across something like this on any CNC I have ran. The "X" & "Y" coordinates are correct with the -"X" to the left at the 9:00 position and the -"Y" at the 6:00 position, but for the "Z" to go into the minus, the machine already knows that you are making a pocket, so you program it as a positive number.

Has anyone ever ran across something like this on other machines/mills?

 

[davewo]

It's not uncommon for CAM software to accept a positve Z. I think program engineers dropped the "-" because the only function of a Z move is negative. If you can jog in Z and the scale reads Z in the correct direction (+up, -down, of course), you are good to go. My experience from running a conversational type mill is that it still outputs to standard G-code, so all the G-code rules apply. It will still read ,,,Z-.25,,, in the code.

 

[steel 35]

Mach 3? each axis direction can be changed in the Engine Configuration...Ports and pins/motor outputs Dir LowActive.

Never mind

 

[rockwithjason]

i wish i knew enough about this to comment.

 

[longlivepunk]

Yeah, since it's a plunge it's already negative, so a negative in a negative makes for a positive move. [emoji14] Seems kind of silly to me too (and most people with a machining background from what I see) but it works the same on HAAS mills.

 

[Kevin54]

Mach 3? each axis direction can be changed in the Engine Configuration...Ports and pins/motor outputs Dir LowActive.

Never mind

Not Mach 3. This is an older Bridgeport running Boss 9 software. After running ProtoTraks for about 15 years, programming by pushing the buttons on the screen is sort of hard to remember. Especially when the dern thing doesn't want to agree with what I want it to do. To me -"Z" is down towards the ground, and just "Z" is positive. I'll slowly get it figured out. But I still have the "Y" axis problem that I had when I bought it. It acts like it can't find position and will shake in the "Y". I found out after I bought it that I got screwed because the person that owned the shop let it slip that he never could get it programmed.

I'm trying to decide where to draw the line as far as throwing money at it.When I bought it, no toolholders came with it, but he tells me tht you can find them on the internet almost everywhere for around $25 used. ********!!!! They take Erickson Quick Change with a #30 Taper. You can't find them. I imagine over the years almost everyone has trashed them. Now it it was Cat40, then I could find some. I did buy a collet holder and collets for a couple hundred, and did find 2 QC's for $30 each at a swap meet. Then of course I have $500 in a new encoder that didn't solve the problem. So altogether I have about $5500 in the mill. I'm just wondering where to cut my losses at. IIRC what I read before, it would cost me about $2500+ to convert things over to where I could run Mach 3. I don't know if I want to go that far into it. I don't mind programming by hand, if I just could get the "Y" axis straightened out to where it is stable.

And this is the first mill that I have ever ran where -"Z" is programmed in the positive.

 

[blind]

Hurco also uses positive Z for peck depths. It has an alarm if you try -Z pecks.

 

[longlivepunk]

Be careful, because with conversational Z movements will still typically be negative UNLESS you're filling in a value where negative is assumed. It's annoying.

As for the y-axis, does the servo motor have the ball-screw just kind of twitching in one spot? If so it might be from inadequate preload. Basically the ball-screw has to be refinished and the but may need different sized balls to compensate. Had that on a lathe at work.

 

[Kevin54]

Be careful, because with conversational Z movements will still typically be negative UNLESS you're filling in a value where negative is assumed. It's annoying.

As for the y-axis, does the servo motor have the ball-screw just kind of twitching in one spot? If so it might be from inadequate preload. Basically the ball-screw has to be refinished and the but may need different sized balls to compensate. Had that on a lathe at work.

I posted down below in another thread. All of the magnets in the motor case are broke and came loose. How it ran even is beyond me. So I either have to find a place to repair things, or find another servo for an arm and leg.