Re: [Emc-users] Limit switches for my lathe

[Gene Heskett]

On Monday 26 October 2020 11:27:20 Alan Condit wrote:

> Hi all,
>
> I am trying to wrap my head around limit switches for my Grizzly G4000
> lathe that I have converted to CNC.
>
> The X limit switches are not a major problem. They always goes to the
> same spot. I have the X+ switch mounted. Figuring out where to mount
> the X- switch so it doesn’t interfere with anything else is a little
> tricky.
>
>  I am having trouble figuring out the placement of the Z limit switch
> or switches. I can mount the Z+ limit switch on an adjustable mount on
> the ways down by the tailstock or even on the tailstock itself. But
> having a limit switch that is moveable seems problematic for
> configuration. The Z- limit switch could be attached to a moveable
> mount on the ways down by the head but it seems that it might be
> desirable to have the limit set to keep the cross-feed from running
> into whatever chuck is mounted. I have a 3” 4-jaw, a 4” 3-jaw, a 5”
> 3-jaw and a 5” 4-jaw. So I might need a different config for every
> chuck. What do you guys think.

I have the x switch on the front of the apron. with its roller reaching 
up so the crossfeed backs into it at the front, a long ways from center.

I found a bolt hole in the bed about a foot away from the chuck, and have 
another identical switch mounted there which gets dinged by the gib 
strip which is full length of the carriage H pattern so the switch also 
tells the homeing function which way to the switch. 

Just to make sure there is work clearance, I remove the tool from the 
QCTP before homing.  But if it hits, the steppers are now 3 phase 
stepper/servos, and Z will trip off before wrecking the tool.

The rest is just .ini file vars.

HTH, Alan
>
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Cheers, Gene Heskett
-- 
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 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
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 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] Limit switches for my lathe

[andy pugh]

On Mon, 26 Oct 2020 at 15:29, Alan Condit  wrote:

>  I am having trouble figuring out the placement of the Z limit switch or 
> switches

I was troubled by the same issue, and did some bodgery to make the
resolvers return an absolute position, so that now I can home without
moving.

This might be an argument in favour of fitting linear scales.

Otherwise, it's probably best to home towards the tailstock and accept
that it's your job to move it to the end of the bed before pressing
the button.

You can (I think) move the soft limits using the ini.* HAL pins to
allow for different chucks.

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912


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Re: [Emc-users] Limit switches for my lathe

[Sam Sokolik]

If it is a small enough lathe - I would just take the tail stock off to
home..  (that is what I do on the emco)

Have a cam style follower.   So it home somewhere halfway down the travel.
(so most of the time the tailstock is out of the way.  (if it is past the
trip point - it will home the other direction)  Then have a switch on the
tail stock that acts as an overtravel.

On Mon, Oct 26, 2020 at 10:29 AM Alan Condit  wrote:

> Hi all,
>
> I am trying to wrap my head around limit switches for my Grizzly G4000
> lathe that I have converted to CNC.
>
> The X limit switches are not a major problem. They always goes to the same
> spot. I have the X+ switch mounted. Figuring out where to mount the X-
> switch so it doesn’t interfere with anything else is a little tricky.
>
>  I am having trouble figuring out the placement of the Z limit switch or
> switches. I can mount the Z+ limit switch on an adjustable mount on the
> ways down by the tailstock or even on the tailstock itself. But having a
> limit switch that is moveable seems problematic for configuration. The Z-
> limit switch could be attached to a moveable mount on the ways down by the
> head but it seems that it might be desirable to have the limit set to keep
> the cross-feed from running into whatever chuck is mounted. I have a 3”
> 4-jaw, a 4” 3-jaw, a 5” 3-jaw and a 5” 4-jaw. So I might need a different
> config for every chuck. What do you guys think.
>
> Alan
>
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>

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[Emc-users] Limit switches for my lathe

[Alan Condit]

Hi all,

I am trying to wrap my head around limit switches for my Grizzly G4000 lathe 
that I have converted to CNC. 

The X limit switches are not a major problem. They always goes to the same 
spot. I have the X+ switch mounted. Figuring out where to mount the X- switch 
so it doesn’t interfere with anything else is a little tricky.

 I am having trouble figuring out the placement of the Z limit switch or 
switches. I can mount the Z+ limit switch on an adjustable mount on the ways 
down by the tailstock or even on the tailstock itself. But having a limit 
switch that is moveable seems problematic for configuration. The Z- limit 
switch could be attached to a moveable mount on the ways down by the head but 
it seems that it might be desirable to have the limit set to keep the 
cross-feed from running into whatever chuck is mounted. I have a 3” 4-jaw, a 4” 
3-jaw, a 5” 3-jaw and a 5” 4-jaw. So I might need a different config for every 
chuck. What do you guys think.

Alan

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