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Fixture Offsets
« on: September 30, 2010, 07:24:03 PM »
Tool path displays reversed when fixture offsit is changed from G54 to another offset like G56 after tool change and half the time one axis or another will lose it's position
Any one else ever had this problem?
Re: Fixture Offsets
« Reply #1 on: October 02, 2010, 06:45:05 PM »
Tool path displays reversed when fixture offsit is changed from G54 to another offset like G56 after tool change and half the time one axis or another will lose it's position
Any one else ever had this problem?

I don't use offsets but if you want to pm me a small gcode file to test I will.

What do you have in your offsets page??

Mike
We never have the time or money to do it right the first time, but we somehow manage to do it twice and then spend the money to get it right.

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Re: Fixture Offsets
« Reply #2 on: October 03, 2010, 08:20:08 AM »
Mike
This was posted by egerber in another thread, its the xml, some code and the fixtures.dat.  http://www.machsupport.com/forum/index.php?action=dlattach;topic=16085.0;attach=22725
Hood
Re: Fixture Offsets
« Reply #3 on: October 03, 2010, 10:55:57 AM »
I am not feeling well with this freakin' cold but I did take a look.

1. All of his offsets in the fixture table are negative which may or may not be an issue.

2. It appears that he is using the Machmotion version of the DSPMC which looks to be different than the generic DSPMC stuff.

3. I am not that familiar with offsets and such but when calling a g55 or other offset I would put it on its own line.

4. If I feel up to it I will go out in the shop and run his code.

5. My machine is setup in inches and I think he is using mm. I think I cna just change the G21 to a G20 to test???

6. I am not sure if softlimits work with the DSPMC as of yet but I may be wrong.

When trying to simulate i kept getting soft limit errors so I turned off the softlimits.

Mike

We never have the time or money to do it right the first time, but we somehow manage to do it twice and then spend the money to get it right.

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Re: Fixture Offsets
« Reply #4 on: October 03, 2010, 12:15:43 PM »
iI dont know how/if softlimits work in DSPMC but the way I see them in egerbers xml they seem wrong to me as I would expect X and Y Min to be zero with Max the travel of each axis. Z Max would be Zero and Z Min the travel of the axis as a negative value.
 Maybe the DSPMC does things differently though so I will not say they are definitely wrong.
Hood
Re: Fixture Offsets
« Reply #5 on: October 03, 2010, 12:52:22 PM »
iI dont know how/if softlimits work in DSPMC but the way I see them in egerbers xml they seem wrong to me as I would expect X and Y Min to be zero with Max the travel of each axis. Z Max would be Zero and Z Min the travel of the axis as a negative value.
 Maybe the DSPMC does things differently though so I will not say they are definitely wrong.
Hood

Agreed.
They look incorrect to me also.

Mike
We never have the time or money to do it right the first time, but we somehow manage to do it twice and then spend the money to get it right.
Re: Fixture Offsets
« Reply #6 on: October 03, 2010, 12:55:26 PM »
Hey HOOD!!!

I hope everyone who has ever received help from you appreciates how much time and effort a simple answer can take.

I already have an hour into this and it could take several more just to find out where the problems lies, Mach, DSPMC, G-code or computer.

Thanks for taking the time to answer mine and so many other questions.

Mike
We never have the time or money to do it right the first time, but we somehow manage to do it twice and then spend the money to get it right.

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Re: Fixture Offsets
« Reply #7 on: October 03, 2010, 01:20:35 PM »
Mike
 I was given a lot of help from Art and especially John Prentice when I first started up so I am glad to be able to help others if I can.
Hood
Re: Fixture Offsets
« Reply #8 on: October 04, 2010, 06:29:20 PM »
Hood
In regards to the soft limits I am using limit switches for mim, max travel and the max travel limit is also the home switch. with DSPMC if you contact a limit the system disarms the servos and you have to manually back off the switch before you can re arm the servos. The soft limets are set so that you never come into contact with the switches, this allows you to backoff if you over travil without disarming the servos.
So everyone understands this system is set up on a grantry mill, so table is X, Y travels on the grantry and Z is attached to Y the home position is the back right hand corrner witch leaves the entire table exposed for setup.
I hope this helps
I have been doing constent debuging sence my last post and have fount that if I leave the T part out of the tool change call every thing works fine, I also have noted that only one axis changes sign and it is the last move befor the change in fixture offset, So if you make a move in X and change the position of X in the next fixture offset along with a tool change the sign reverces, same goes for Y

We can run all day as long as we stay in a given fixture offset and avoid using the T word in the tool change in conjuction with a fixture call

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Re: Fixture Offsets
« Reply #9 on: October 04, 2010, 07:02:40 PM »
Yes but your machine coords should be zero when the tool is fully negative in X and Y and fully up in Z.  From your description it would seem you have your home switches at the fully positive directions in X and Y, that is not a problem, you still set Soft Limits to X and Y min as Zero and X and Y Max as the travel BUT you then set a Home off value of your axis travel. What that does is set the machine zero to the correct end of the travel but when you home it will show the position you are at when homed as fully positive in machine coords.

Hood