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Author Topic: Permanent Offset Error  (Read 3209 times)

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Permanent Offset Error
« on: August 30, 2009, 06:24:01 AM »
Ok i am having difficulty with tool offset and now have got a new problem.

I appear to have a permanent offset.

I command a move to X0 Z0 the machine moves to X-0.7960 Z-0.3975 THIS IS DISPLAYED ON THE DRO'S.

I command a move to X120 Z80 the machine moves to X119.2040 Z79.6 THIS IS DISPLAYED ON THE DRO'S.

If i command the same move no move is made as as far as the controller is concerned the machine is at the correct location

I have attached my xml
« Last Edit: August 30, 2009, 06:40:05 AM by Phil_H »
The Good Thing About Mach3, Is It's very Configurable

The Bad Thing About Mach3, Is It's Too Configurable

Offline Hood

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Re: Permanent Offset Error
« Reply #1 on: August 30, 2009, 06:48:48 AM »
You have your motors tuned too fast for your kernel, try increasing the kernel to 45KHz or detune your velocity.

Hood
Re: Permanent Offset Error
« Reply #2 on: August 30, 2009, 08:34:40 AM »
Hood

I am using a smooth Stepper

Phil
The Good Thing About Mach3, Is It's very Configurable

The Bad Thing About Mach3, Is It's Too Configurable

Offline Hood

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Re: Permanent Offset Error
« Reply #3 on: August 30, 2009, 08:52:44 AM »
Ah Ok, have the new test  version of Mach on this computer so had to remove the plugins, thats why it never asked for the plugin at the start LOL.
Will look through the rest and see if I can find a problem.
Hood
Re: Permanent Offset Error
« Reply #4 on: August 30, 2009, 09:25:44 AM »
Just to clarify this problem relates to the lathe

Phil
The Good Thing About Mach3, Is It's very Configurable

The Bad Thing About Mach3, Is It's Too Configurable
Re: Permanent Offset Error
« Reply #5 on: August 30, 2009, 10:07:57 AM »
Hood

I am playing around blindly with the tool offsets

My accurate homing switch =0

I ref "Set Home Z"

I zero the Z dro

I jog away then command a move it now goes to where commanded

So i believe this is my failure to get to grips with the tool tabel that is causing the problem

The manual is very poorly written "Sorry" and full of contradictions

The manual in the tool setting section which i am complaining about states

7.3.1.2 Setting Home if there is a home switch on an axis
Unless you have a quick change tool holder which allows you to insert tools in a repeatable
position or a tool changer then it is not worth using home switches; you will have to set the
position of each tool as it is put into the machine by the touching process.

You will of course not be able to use soft limits by following this advise and it is new users that need the help that soft limits give.

I am using mechanical limit switches also BTW

There are also Touch Z Touch X Buttons which i understand how they work BUT there is also a Touch Button underneath with no mention of it in the manual  ???

Does anyone know ?

Phil
The Good Thing About Mach3, Is It's very Configurable

The Bad Thing About Mach3, Is It's Too Configurable

Offline Hood

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Re: Permanent Offset Error
« Reply #6 on: August 30, 2009, 10:18:04 AM »
Dont have a clue about the way the standard screen works, looked at it when I first got the lathe going and after 10 seconds just decided to make my own screen up. Its actually my mill screen with stuff I didnt need removed and some things added. I really need to get it sorted out and done properly but I never seem to get round to it LOL
 If you are homing to an accurate position then choose a tool, preferably Tool 1 and dont have any offsets in the tooltable for that. What you do is set a Home Off distance on the Homing and limits page for the X axis. The Home off value is the amount that it takes to get the tool to the lathes centre position. After that then you can set each tool as an offset to your master tool.
Thats the way I do it anyway, maybe others do it differently. You do need accurate homing though, mine home in the servo drives themselves and it is the index pulse gated with A and B channels of the encoder so is extremely accurate.

Hood
« Last Edit: August 30, 2009, 10:19:41 AM by Hood »