[HackMax]

I recently have found out (at least I think) a problem i have been fighting with over the past several months. I have a jig set up to machine parts in small quantities and every time I start a new part I never know if the tool is still zeroed in the y direction. I cut one part and then set it up for the next part which should be the same coordinates but sometimes the y axis is off by as much as .040 or so.

In the gcode I send the machine back to the machine home position after each process. I think I have found the problem to be a collection of chips getting pinched between the column and the table and then stalling the motor the last little bit of returning to machine home. I need to make a bellows or something to deflect the chips. Right now I just use a heavy piece of plastic which bunches up in the way when the tool is cutting. Normally this kind of thing doesn't happen on an X3 machine because the table doesn't get back that far but I have made it possible to move the table until it actually hits the column. So in the mean time I have set the machine y zero about .5" away from the column.

I don't really like doing this because I want as much travel as I can get so I added homing switches. Problem is I don't really know how to use them in gcode. I know I need to use G28 but from there I'm kinda stumped. I want the machine to go back to machine home at the end of each process. Can anyone clue me in on how they use their homing switches? I have the switches mounted and working I'm just a little hesitant about using them in the gcode.

Thanks,

Rick

[Starleper1]

Not sure about using them in gcode but if you need a cheap solution for bellow covers. Go to lowes/home depot. Buy bath tub liner. Its about $5 for a 12"x48" peice. I'll get some pictures for you.

[HackMax]

Not sure about using them in gcode but if you need a cheap solution for bellow covers. Go to lowes/home depot. Buy bath tub liner. Its about $5 for a 12"x48" peice. I'll get some pictures for you.

Please post some pictures. I would really like a quick solution to my cover problem. I'm sick of fighting with this piece of plastic.

Thanks,

Rick

[Bubba]

Rick,
In my situation, I make it part of my routine when setting up for the day to "home the machine" This way I know where machine home is. Also, on my Y axis, I home AWAY from the column because if I have my 6" vice on the table, it will hit the column if I try to home to Y0 (this would also help you with your swarf problem). Once you have it homed, you know where the machine coordinates are and don't need to home again in G-code.
Then I mount my stock and use fixture offsets to find stock X0 and Y0, this can be done by any of a myriad of touch off methods.

Hope this helps answer your original question.

[Torsten]

Rick,
In my situation, I make it part of my routine when setting up for the day to "home the machine" This way I know where machine home is. Also, on my Y axis, I home AWAY from the column because if I have my 6" vice on the table, it will hit the column if I try to home to Y0 (this would also help you with your swarf problem). Once you have it homed, you know where the machine coordinates are and don't need to home again in G-code.
Then I mount my stock and use fixture offsets to find stock X0 and Y0, this can be done by any of a myriad of touch off methods.

Hope this helps answer your original question.

I agree, this would be the way to run a machine that dose not loose any steps durring operation.
With somewhat less confidence in the machine it may make sense to rehome after each run.
Now we normaly use the code "G00G91G28X0.Y0.Z0." to return to machine zero. You may leave out the Axes that do not need to go there.
Question? I know this will go to zero but will this also reset zero?
Anybody know?

[Bubba]

In my controller, when you issure a G28, it will move it to the "home" position AND set the DRO to the appropriate setting. Like I said in my first post, I home the Y axis away from the column on my mill/drill due to potential crash problems. In this case, I issure G28 Y0 and it actually homes to Y=7.0 and sets the Dro to that position.
These settings are in the initial configuration set up of my control software.

[HackMax]

I agree, this would be the way to run a machine that dose not loose any steps durring operation.
With somewhat less confidence in the machine it may make sense to rehome after each run.
Now we normaly use the code "G00G91G28X0.Y0.Z0." to return to machine zero. You may leave out the Axes that do not need to go there.
Question? I know this will go to zero but will this also reset zero?
Anybody know?

I know that on mine with Mach3 I have it set to auto-zero once the switch has been hit and backs off of it. It resets machine zero. If I don't have auto-zero set on it the display reads about .005 when it backs off the switch.

Rick

[pminmo]

I have the switches mounted and working I'm just a little hesitant about using them in the gcode.

Thanks,

Rick

What control software are you using?

[HackMax]

Rick,
In my situation, I make it part of my routine when setting up for the day to "home the machine" This way I know where machine home is. Also, on my Y axis, I home AWAY from the column because if I have my 6" vice on the table, it will hit the column if I try to home to Y0 (this would also help you with your swarf problem). Once you have it homed, you know where the machine coordinates are and don't need to home again in G-code.
Then I mount my stock and use fixture offsets to find stock X0 and Y0, this can be done by any of a myriad of touch off methods.

Hope this helps answer your original question.

Yes I was thinking it would be nice to have the table home towards me since this would also make it easier to set up for the next piece but I can also just leave the final resting place in the gcode. I do it this way when I know I need to switch the material out or reorient it for the next process. I set it to go to machine home when I just need to change a tool for the next process. This is where .040" REALLY screws me up. I'm taking it for granted the table is still set to the proper zero quadrants for the material but when it returns to the machine home the buildup of chips stops it from going all the way and there is really no way of knowing that happened without maybe a DRO. So if it doesn't hit the switch now it will keep trying and I will know that the table is blocked. At least I'm hoping this will help.

I just thought of another problem though. When the process is finished it will return to the machine home and just sit there and buzz the stepper until I get back to it if the table is blocked from hitting the switch. Hmmm I leave the mill unattended for quite some time sometimes. I wonder how I might prevent this if the table hasn't reached the switch when it should have. Need to go test this out.

Thanks Bubba for your help,

Rick

[HackMax]

What control software are you using?

Sorry, Mach3

[Fixittt]

I agree, this would be the way to run a machine that dose not loose any steps durring operation.
With somewhat less confidence in the machine it may make sense to rehome after each run.
Now we normaly use the code "G00G91G28X0.Y0.Z0." to return to machine zero. You may leave out the Axes that do not need to go there.
Question? I know this will go to zero but will this also reset zero?
Anybody know?

Just a bit of FYI, if you are using the probe routine after tool changes, it is typical inusdtry standard to send the Z up to machine zero. Using something like the code posted above "G00G91G28X0.Y0.Z0." The probing routine will not work in incremental mode. "G91" You will get an error in mach 3 on the status line "Cannot use g53 incremental" You need to have a g90 after the "G00G91G28X0.Y0.Z0." before probing tool. again just FYI

[Starleper1]

Please post some pictures. I would really like a quick solution to my cover problem. I'm sick of fighting with this piece of plastic.

Thanks,

Rick

http://www.cnczone.com/forums/showth...t=79060&page=3

Scroll to the bottom and view the video.