Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: arboleda4 on November 10, 2008, 04:56:44 AM

Title: manual feedrate override pot
Post by: arboleda4 on November 10, 2008, 04:56:44 AM
Hi all
I am new to this forum and would like some help with fitting feed override (pots) to my Wabeco mill and lathe.
I dont like the mouse one on the monitor and prefer a manual one.

Pick your brains please

Dave
Title: Re: manual feedrate override pot
Post by: Hood on November 10, 2008, 05:07:11 AM
You can do it a few ways but for a Pot you will need analogue inputs to the computer. Several ways you can get that, PLCs over ModBUS, Peter Homann does a ModIO board that has analogue and also there is the PoKeys that has analogue (not sure if they are working well enough yet)
 Another way to do it is have two or three momentary switches, one for Up,one for down and the other for reset, you can then make up a brain that steps up or down through the speeds when you keep the button pressed.
 Lastly you can get a rotary switch and make up a Brain to set the feedrate to a different amount depending on the position of the switch.
The analogue/pot option is probably the best but the rotary switch comes a close second and is obviously a lot cheaper.

Hood
Title: Re: manual feedrate override pot
Post by: arboleda4 on November 10, 2008, 05:58:38 AM
Well Hood your brain is certainly active
Thanks for the instant reply & remedy
Dave
Title: Re: manual feedrate override pot
Post by: Hood on November 10, 2008, 06:08:16 AM
Well Hood your brain is certainly active
Thanks for the instant reply & remedy
Dave

No chance, its not been active for a long time, if ever ;D

Hood
Title: Re: manual feedrate override pot
Post by: Overloaded on November 10, 2008, 07:41:10 AM
Hey hood, (I hope to get this in while there are still signs of activity) he he

With the 3 momentary switches, I assume I would need 3 input pins. ? ? ?

With the rotary switch, would I need 1 input pin for each position ? Not sure.

Thanks,
RC
Title: Re: manual feedrate override pot
Post by: Hood on November 10, 2008, 08:10:12 AM
Well there is never much activity with me whether brain or otherwise :)

Yes thats correct on both counts.
It might be good to get a pokeys for something like this as even if the analogue isnt good enough then you could use it with a rotary switch as you have 55 digital I/O on it so plenty there :) I have tried that and it works well but not tried the analogues on the pokeys yet.
 The most economical as far as I/O is concerned is PLC or ModIO using analogue input but obviously a bit more expensive.

Hood
Title: Re: manual feedrate override pot
Post by: arboleda4 on November 10, 2008, 10:28:06 AM
Been on to Peter Homann's site and looks like what I need
Excuse my ignorance but will it work in cnc mode or only manual
I have zero electronic knowlege so put up with me for a while
Im just north of you in Aberdeenshire (Newburgh)

Dave
Title: Re: manual feedrate override pot
Post by: HimyKabibble on November 10, 2008, 11:00:34 AM
Hey hood, (I hope to get this in while there are still signs of activity) he he

With the 3 momentary switches, I assume I would need 3 input pins. ? ? ?

With the rotary switch, would I need 1 input pin for each position ? Not sure.

Thanks,
RC

You can reduce the number of input pins required by using a rotary switch with binary or BCD coding.  That would allow, for instance, a 16-position switch to use only 4 input pins.   You'd then create a brain with 16 "lobes".  Each "lobe" of the "brain" would have to look at all four values to determine the switch position.

Regards,
Ray L.
Title: Re: manual feedrate override pot
Post by: Hood on November 10, 2008, 11:31:27 AM
Been on to Peter Homann's site and looks like what I need
Excuse my ignorance but will it work in cnc mode or only manual
I have zero electronic knowlege so put up with me for a while
Im just north of you in Aberdeenshire (Newburgh)

Dave

Good to have another Scot here :)

Yes this will work as you are machining just like the on screen one does.



You can reduce the number of input pins required by using a rotary switch with binary or BCD coding.  That would allow, for instance, a 16-position switch to use only 4 input pins.   You'd then create a brain with 16 "lobes".  Each "lobe" of the "brain" would have to look at all four values to determine the switch position.

Regards,
Ray L.

Yes Ray that would work great, never actually thought of that but dont know why as thats the way my servo drives can work if in indexing mode, 63 index positions from 6 inputs.

Hood

Title: Re: manual feedrate override pot
Post by: HimyKabibble on November 10, 2008, 11:37:05 AM
Hood,

    Actually, you could do it with a normal selector switch as well, using diode logic, or a few logic gates.

Regards,
Ray L.
Title: Re: manual feedrate override pot
Post by: Hood on November 10, 2008, 11:56:23 AM
Ray yes that would work, think you could also use encoder inputs as well.
Hood
Title: Re: manual feedrate override pot
Post by: cjmerlin on November 10, 2008, 03:44:57 PM
What about getting a cheap USB Joystick ripping out the guts and using keygrabber, You'll have 2 analogue inputs with either slider or potentiometer (older ones) controls.

Haven't tried it, just an idea.

John
Title: Re: manual feedrate override pot with an encoder
Post by: CUTMORE on November 12, 2008, 12:49:41 PM
Hi Hood,
You mentioned that you could do the feedrate override with an encoder, Could you elaborate a bit? It seems like you might be able to just use the encoder pulse to move the feed override up/down but I am not sure how you would set that up.

Any help appreciated,
Thanks,
Cutmore
Title: Re: manual feedrate override pot
Post by: Hood on November 12, 2008, 02:46:25 PM
Cutmore,
 I actually said I think ;)
 The way you said is what I ws thinking, set up the A as an input or oem trigger and the B up as another. You could then make a Brain to look at these inputs and do a Up or Down button press. Whether it will work I dont know as I have never tried, possibly the pulse from the encoder will be too short to be seen properly.

Hood
Title: Re: manual feedrate override pot
Post by: HimyKabibble on November 12, 2008, 09:31:48 PM
Cutmore,
 I actually said I think ;)
 The way you said is what I ws thinking, set up the A as an input or oem trigger and the B up as another. You could then make a Brain to look at these inputs and do a Up or Down button press. Whether it will work I dont know as I have never tried, possibly the pulse from the encoder will be too short to be seen properly.

Hood

The service rate on brains is rather slow (4-10 times per second, IIRC), so I think this would be very unreliable, unless you turned it very slowly....  And with quadrature, if you miss a transition, the next one can be interpreted as a move in the opposite direction.

Regards,
Ray L.
Title: Re: manual feedrate override pot
Post by: Hood on November 13, 2008, 02:46:30 AM
I thought Brains were faster than that (mine excepted) but in any case I have tried it. It does work but is not that great. This is probably due to the reason you have said but could partly be due to the Pokeys plugin delay as that was how I had it connected. I am wondering if the MPG counting could be used in Brains for this or even writing a macropump, although macropumps are definitely slower as I think they are around the 4Hz.
 I see in the customisation manual it mentions encoders and keyboard emulators for FRO and SRO so thats another avenue to look down.
Hood
Title: Re: manual feedrate override pot
Post by: CUTMORE on November 13, 2008, 07:10:02 AM
Hi Guys,
Thanks for the replies,
I was thinking more of just hooking the encoder right up to the breakout board. I have an MPG already hooked up.

Have you guys seen  the I mach pendant from vistacnc? That can change the feed over ride, the spindle speed, and act as an mpg.
The video is here
http://www.vistacnc.com/iMach3_pendant_rate_v/iMach3_pendant_rate.html

I want to set up a fixed control panel for my lathe. On the panel I want a feed override, spindle speed override, axis selector for the mpg, and the mpg. after reading about the Mach3 oem codes, I think I can do that without brains or scripts, but I have been known to be wrong before! :)

Regards,
Cutmore

Title: Re: manual feedrate override pot
Post by: Hood on November 13, 2008, 04:16:26 PM
I have just tried using the PoKeys and the MPG, I used the Pokeys as a keystroke emulator and asigned the MPG to FRO up/down. It works well, maybe not as good as a pot would but it still only took 2 seconds to wind from 1% to 300%
Hood
Title: Re: manual feedrate override pot
Post by: arboleda4 on November 13, 2008, 05:24:28 PM
Hi guys
the vista cnc pendant looks great. has anyone used one.
I tried to get the Homann one but they are out of stock (more expensive)

Dave
Title: Re: manual feedrate override pot
Post by: fever16 on November 13, 2008, 10:16:09 PM
http://markusmechatronics.com/Handrad_HowTo.html