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Author Topic: 4th axis setup  (Read 27076 times)

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Offline Katoh

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Re: 4th axis setup
« Reply #20 on: June 15, 2011, 11:07:42 AM »
lgr
I have a 4th axis on my machine, and it seems to work quite well, its not super fast, but its a lot faster than 200deg/min.
Of memory it runs a revolution every 10secs.
I dont really have much advise to offer, but if you like I can send you my XML file and you can look through it to see if and what differences are between yours and mine, especially in the configs and motor tuning.
My 4th axis is my B axis as it runs parallel to the Y, and I'm using CNC4PC bo.boards, I cant see why or what could be at fault.
« Last Edit: June 15, 2011, 11:15:14 AM by Katoh »
Cheers
Katoh

Offline BR549

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Re: 4th axis setup
« Reply #21 on: June 15, 2011, 12:26:38 PM »
Now an interesting side bit.Long ago I did play with a macro to monitor the Z height and apply a FRO based on Z height above the A. That was before Brains and the macro was a bit slow. BUT it did help.

Might be time for someone to try a Brain or a plugin.

You could base it on IF A & XorY are moving then Zheight x PIE =area.  That might be able to help adjust the FRO to speed up the comp in 3d moves.

Hopefully Ver 4 will properly adress the issues. (;-)

Just a thought, (;-)TP
Re: 4th axis setup
« Reply #22 on: June 15, 2011, 02:35:20 PM »
I wrote this program for a test and measured my results with a contact tach (probably not real accurate). All the option boxes left unchecked.

G1 F150 A720 X5
G0 A0 X0
M30

radius comp on with radius of 4" chuck, measured feedrate was 32 ipm
radius set at 0.0001, measured feedrate was 45 ipm

To get my feedrate up to 150 ipm I had to set a feed rate of F540 ( this was with chuck radius entered)

Richard

Offline RICH

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Re: 4th axis setup
« Reply #23 on: June 15, 2011, 04:43:02 PM »
Is the 4th axis driven by a stepper?

RICH

Offline lgr

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Re: 4th axis setup
« Reply #24 on: June 15, 2011, 09:02:55 PM »
Thanks everyone. I'll try your ideas, Rich it's a stepper machine. Katoh I would like to try your XML file, thanks for the offer.

Offline Greolt

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Re: 4th axis setup
« Reply #25 on: June 15, 2011, 11:11:08 PM »
Now an interesting side bit.Long ago I did play with a macro to monitor the Z height and apply a FRO based on Z height above the A. That was before Brains and the macro was a bit slow. BUT it did help.

Might be time for someone to try a Brain or a plugin.

You could base it on IF A & XorY are moving then Zheight x PIE =area.  That might be able to help adjust the FRO to speed up the comp in 3d moves.

Hopefully Ver 4 will properly adress the issues. (;-)


Unless I am having a bad day and completely miss the intent of what you are saying, this feature already exists in Mach3.

It is often referred to as  "Use Radius for Feedrate".   The calculations were all wrong for a long time, but were fixed Christmas before last, and now works great for me.

Greg

Offline BR549

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Re: 4th axis setup
« Reply #26 on: June 15, 2011, 11:32:19 PM »
SO you are saying that MACH can adjust the feedrate blend based on the height of Z off the A axis centerline automatically ?
I must have missed that.

(;-) TP

Offline Greolt

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Re: 4th axis setup
« Reply #27 on: June 15, 2011, 11:44:44 PM »
Yes.

It gives the called for feedrate of the tool through the material at any given radius.  Within certain constraints.

Ascertains the radius by taking the value of the Z axis DRO, together with the  "Rotation Radius" DRO.  (IMO this DRO could be better named)

Greg

Offline BR549

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Re: 4th axis setup
« Reply #28 on: June 15, 2011, 11:48:35 PM »
OK COOL but if it runs from the Z height what is the DRO for ?? I'll have to do some testing next week.

(;-) TP

Offline Greolt

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Re: 4th axis setup
« Reply #29 on: June 15, 2011, 11:51:29 PM »
OK COOL but if it runs from the Z height what is the DRO for ?? I'll have to do some testing next week.


It is needed if Z axis origin is not at the centre of rotation.  So in effect it is an offset value.

Greg