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Author Topic: Opinion and advice - explain relationship of encoder to kernel speed  (Read 17020 times)

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Offline Dan13

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Re: Opinion and advice - explain relationship of encoder to kernel speed
« Reply #20 on: April 14, 2009, 01:41:23 PM »
SwapAxis, as for itself does work with SS - I can swap Z and X axes for instance, and it behaves as if I swapped their pins under ports&pins.

The problem is, I can't connect both A axis pins (14,16) and Spindle pins (7,8) to same input on the AC driver. It is like if I interconnected those pins between themselves. So what is the idea of SwapAxis?

The easiest way would be to just assign same pins to both A and Spindle, since I'm not going to use them both at the same time, but it doesn't work this way - only the A axis works, but the spindle doesn't rotate...

Daniel

Offline Hood

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Re: Opinion and advice - explain relationship of encoder to kernel speed
« Reply #21 on: April 14, 2009, 04:03:23 PM »
SwapAxis, as for itself does work with SS - I can swap Z and X axes for instance, and it behaves as if I swapped their pins under ports&pins.
Quote

I was meaning for spindle specifically, but again I am not sure I just seem to remember Greg, Art or Brian mentioning it.


The problem is, I can't connect both A axis pins (14,16) and Spindle pins (7,8) to same input on the AC driver. It is like if I interconnected those pins between themselves.

Ccan you explain further?
Hood

Offline Dan13

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Re: Opinion and advice - explain relationship of encoder to kernel speed
« Reply #22 on: April 15, 2009, 02:20:50 AM »
Hood,

You were right, the SwapAxis doesn't work at all with the SS. I must have tested it with PP before, when I thought it was working. I've just tried to SwapAxis X and Z, and it didn't work. Changed to PP and all was working.

And I was stupid... you don't have to connect both A axis pins and Spindle pins to the drive input. You only have to connect the spindle pins and once you use the SwapAxis, the spindle pins become the A pins. It does work with the PP. I need to find a way to do this with SS though...

Daniel

Offline Hood

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Re: Opinion and advice - explain relationship of encoder to kernel speed
« Reply #23 on: April 15, 2009, 03:17:03 AM »
You will have to wait until Greg implements it I think, however I am guessing that what we really need is the getting  the axis movement sync'd to spindle encoder, Greg has said he will be trying to do this at some point in time, just time is not a commodity that Greg has a lot of ;D
 I suspect you might be better looking at getting/making a floating holder if you are requiring tapping any time soon.

Hood

Offline Dan13

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Re: Opinion and advice - explain relationship of encoder to kernel speed
« Reply #24 on: April 15, 2009, 03:46:30 AM »
Yes, I need the tapping soon... I have a job in delrin and I wanted to test this approach. A floating holder is an option, but don't think it's good for my tiny Emco.... remember my tool turret? It has 10mm bores for ID tools. I think a floating holder will be too big for my turret.

As it looks now, Greg is not going to implement rigid tapping any soon :(

I think there might be simple work around - if I define the same pins to both A and Spindle, then I can use one at a time. Problem is, SS seems to be blocking this kind of setting. If setting so, I can move the A axis, but the Spindle won't rotate. I think it might be an easy fix for Greg...

For now, I'll have to use this same approach of defining same pins for A and Spindle, and disable the A under Ports&Pins each time I need the spindle, enabling it just when needed. It is a pain to do - will have to split the gcode.

But first let's see if I can use this approach of commanding Z and A move to accomplish rigid tapping. I need to tap M6 in delrin.... hope my spindle has enough power for M6 without being synched to the Z. The spindle does lag a bit under load, before it catches up... hope the load will be just small enough and won't affect the tapping. I only have a 4-flute hand tap, I wonder whether to do the tapping in pecks or whole the way down as you would do with a spiral tap.

Daniel

Offline Dan13

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Re: Opinion and advice - explain relationship of encoder to kernel speed
« Reply #25 on: April 15, 2009, 05:50:33 AM »
OK... Just tried it and it worked perfect. I set the A axis so that one unit is one revolution, and programmed as follows:

G1 Z-20 A20 F150
G1 Z0 A0

Got what seems to be perfect threads. The spindle motor hardly felt any load at all with the M6 tap in delrin. I probably could even go faster than 150mm/min, but didn't have the courage to try ;)

Now I have to find a more intelligent way of doing this, instead of disabling and enabling the A axis under Port&Pins each time.

Daniel

Offline Hood

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Re: Opinion and advice - explain relationship of encoder to kernel speed
« Reply #26 on: April 15, 2009, 05:53:17 AM »
Not sure if it works for all motion but there are oembuttons to inhibit axis, never tried but might be what you are looking for, ie write a macro to do the button and have the number of the macro in your code.

Hood

Offline Dan13

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Re: Opinion and advice - explain relationship of encoder to kernel speed
« Reply #27 on: April 15, 2009, 06:00:16 AM »
Yes, I know, it's OEMbutton 253 to disable A axis. It does disable the axis but the spindle still won't work - you must go to Ports&Pins and disable it from there.

Any other ideas? Another OEMbutton?

Daniel

Offline simpson36

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Re: Opinion and advice - explain relationship of encoder to kernel speed
« Reply #28 on: April 15, 2009, 09:31:40 AM »

Now, here is a new idea that occurred to me for a possible 'swap' method:

My spindle irection is changed by a Mach controlled relay on the DC power to the motor and it workes fine. I don't see why a similar setup could not switch the source of the power as well. Position 1 to the VFD (controlled by Mach) and then Position 2 to the  A axis output from the servo drive?

With this scheme, You would need only one Mach setup and could even switch the motor's power source with a Mach controlled relay. You would have speed control for turing and and indexing for single point threading when you run as a spindle and then switch the motor to A axis power for the other functions.

In my case, the servo drive yould be a Geckodrive 320 that is limited to 80v 20A which is probably not nearly enough for Hood's big motor, but for appropriate servo motors, unless there is something I'm missing, this seems like a workable solution.

Note that the above is for a lathe. For my purpose, I need both the mill spindle and 4th axis active at the same time.



« Last Edit: April 15, 2009, 09:46:42 AM by simpson36 »

Offline Dan13

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Re: Opinion and advice - explain relationship of encoder to kernel speed
« Reply #29 on: April 15, 2009, 12:14:12 PM »
You're right, I could use a hardware relay to switch from A axis to Spindle, but I don't want to do this at this point. I want to find a software solution to this. The problem is that the software guys keep saying they are just about to fix the problem, causing us not to want to do any fancy hardware changes. If someone of them were to tell us it isn't going to happen, I'm sure everyone were looking for other solutions.

Daniel