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Author Topic: Mach4 Screw Error Mapping  (Read 8690 times)

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Offline Dan13

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Mach4 Screw Error Mapping
« on: March 07, 2015, 04:04:51 AM »
In the announcements it says that version 2251 has added screw error mapping ( see here ).

But I can't see this... where do I find it? Any info and instructions available?

Dan
« Last Edit: March 07, 2015, 04:06:51 AM by Dan13 »

Offline smurph

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Re: Mach4 Screw Error Mapping
« Reply #1 on: March 11, 2015, 12:08:36 AM »
It is new and being tested.  When it runs out good, we will document it in the setup guide.

Steve

Offline Dan13

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Re: Mach4 Screw Error Mapping
« Reply #2 on: March 11, 2015, 02:02:54 AM »
Thanks for the information Steve. Waiting forward to playing with it.

While at it, just would like to make sure we are talking about the same thing. I have a 4.5m long cylindrical grinder. It is real hard to get the 4m long linear guides absolutely straight by mechanical means. I have done so to about 0.05mm. So when grinding a 4m long shaft the fluctuations in diameter are up to 0.1mm. I would like to be able to map the Z axis so that for each Z value, the X moves to correct the straightness error. Is this the feature you're working on now? Asked this on the Yahoo group and had Brian answer this was it, but now I am afraid we didn't understood each other.

Dan

Offline smurph

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Re: Mach4 Screw Error Mapping
« Reply #3 on: March 11, 2015, 02:21:41 PM »
I don't think you two understood each other.  What you are talking about is kinematics.  Screw mapping is the mapping the error in a screw or rack in only one axis of travel.

Steve

Offline Dan13

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Re: Mach4 Screw Error Mapping
« Reply #4 on: March 11, 2015, 03:26:14 PM »
:( So no kinematics? Is it possible? I know I can do it with a PLC - the pulse train from Mach would go through a PLC which would have the mapping data and add or subtract a few steps to account for the error. But having this in Mach would greatly simplify things.

Dan

Offline smurph

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Re: Mach4 Screw Error Mapping
« Reply #5 on: March 11, 2015, 04:26:09 PM »
Eventually we will have a kinematics module.  But for now we only have screw mapping and that will not do what you want.  :(

Steve

Offline Dan13

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Re: Mach4 Screw Error Mapping
« Reply #6 on: March 12, 2015, 05:06:05 AM »
Thanks Steve.

Dan
Re: Mach4 Screw Error Mapping
« Reply #7 on: March 23, 2015, 05:03:54 PM »
Hi Steve,

Will screw mapping apply to rack and pinion systems as well? 

Also, I want to make sure I understand how it will work.  I am looking at routers now and a typical accuracy I see is: .02mm/300mm which over an 2500MM x axis equates to .0065" .  With screw or rack mapping, if I can get someone in here with a laser or some other super accurate measurement system and I can map the screw or rack accurately, then the error I see should be limited to the backlash in the system plus the mapping error.  Is that correct?

Thanks,

Bill

Offline smurph

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Re: Mach4 Screw Error Mapping
« Reply #8 on: March 24, 2015, 01:08:11 AM »
Screw error mapping will work for the rack.  But it as yet untested.  So I would not say it is ready for prime time.

Steve

Offline RICH

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Re: Mach4 Screw Error Mapping
« Reply #9 on: March 24, 2015, 07:04:06 AM »
Quote
if I can get someone in here with a laser or some other super accurate measurement system and I can map the screw or rack accurately
Look into folks that do optical allignment. ( 0.00078" per foot accuracy, well, make sure you understand the spec )
Screw mapping takes time and if opticaly done must be done using calibrated scales and equipment, else, maping is is only as accurate as the uncalibrated system.
Get ready to spend some money to have it done.  

RICH