Hello Guest it is March 28, 2024, 04:13:22 PM

Author Topic: Drill chuck reference on lathe table!!!  (Read 1479 times)

0 Members and 1 Guest are viewing this topic.

Drill chuck reference on lathe table!!!
« on: March 10, 2020, 12:24:49 PM »
It seems with out switches on mach 3 turn you can not restart your machine and have a reference home.  I do not have a tail stock on my lathe.  So when I want to drill something I need to have something to bring back the tool post to proper x axis to be centered.

In researching switches it seems that they can be less than accurate unless you spend alot. 
This a hobby for me.  The closet thing I have been able to come up with is getting the drill post centered and making that machine cordinate x0 z0.   When I restart the machine the machine cordinates are the same as when you turned the machine off.  If I get the machine coordinates back to zero it seems to be at center.  This method requires you never change the machine coordinates.

Any ideas on best way to be able to call back the drill center?  Would home mechanical switches be OK ? 

Thanks in advance
Tom
« Last Edit: March 10, 2020, 12:36:24 PM by TomWh »
Re: Drill chuck reference on lathe table!!!
« Reply #1 on: March 10, 2020, 02:05:21 PM »
Hi,
I use good quality roller plunger snap action microswitches for home switches on my mill and achieve 0.02mm or
better repeatability. Home switches and index homing are required if ou wish to do better than that.

https://nz.element14.com/honeywell/bzc-2rq18-a2/switch-basic-top-roller-plunger/dp/1525198

Craig
'I enjoy sex at 73.....I live at 71 so its not too far to walk.'

Offline RICH

*
  • *
  •  7,427 7,427
    • View Profile
Re: Drill chuck reference on lathe table!!!
« Reply #2 on: March 10, 2020, 03:10:15 PM »
Have you considered probing?
I don't use switches on any of my machines. For the lathe I use probing for numerous tasks;
populate the tool table, measurements  / reverse engineering of turned forms, BUT, most importantly to
locate X axis center of the lathe.

A touch off fixture that is removable / can be re-positioned, easily attached to the lathe bed can be made to do what you want at any time. Thought ...it's just a tool setter and you use the probing feature.

I have found probing to be very accurate; typically 0.0001" or .0002" repeatable.


RICH



   

Re: Drill chuck reference on lathe table!!!
« Reply #3 on: March 11, 2020, 10:02:01 AM »
Hey Rich

Did a far amount of searching on probing but mostly found getting touch off points and reverse engineering part tracing.  Not sure how you would reference a drill chuck to x center point after you start the machine.  If there is somewhere to look to find more information or you could give me the procedure you would use to center this chuck after a start up, I would appreciate it.  Also are you using a touch plate device or a probe with internal switching? 

I am not rapping my head around with out a reference point how you can hit a button and have the machine take the tool post to a certain position. 

Thanks
Tom





















Offline TPS

*
  •  2,501 2,501
    • View Profile
Re: Drill chuck reference on lathe table!!!
« Reply #4 on: March 11, 2020, 02:38:49 PM »
IMHO there are two posibilities depending on the Motion controler and Motors (servos/Steppers) you are using.

1st: precise/indexed homing 
      -if you have a Motion controler witch supports index homing and servo Motors you have normally a real good Chance to do a precise
       homing (zero pulse from servo resolver)
      if you use Steppers the possibilities of an precise homing are very "limited"

2nd. as Rich sayed a probing Input would be a Option (does not matter witch Motors you have) to get a "accurate" x-axis Position.


sorry for my bad bavarian english
anything is possible, just try to do it.
if you find some mistakes, in my bad bavarian english,they are yours.
Re: Drill chuck reference on lathe table!!!
« Reply #5 on: February 10, 2022, 06:27:06 PM »
Hi

how can I do probing with G31 or other on a lathe like in milling MACH

BR

Gerhard

Offline Graham Waterworth

*
  • *
  •  2,668 2,668
  • Yorkshire Dales, England
    • View Profile
Re: Drill chuck reference on lathe table!!!
« Reply #6 on: February 10, 2022, 06:35:53 PM »
You need to build/buy something along the lines of this picture.  Then you can write macros to measure the tools.

Without engineers the world stops
Re: Drill chuck reference on lathe table!!!
« Reply #7 on: February 10, 2022, 06:50:47 PM »
Hi

are there macros available?
The sensor is not the problem.
Buy why in MACH4 milling are probing no Problem and in lathe not implemented?
BR
Gerhard
Re: Drill chuck reference on lathe table!!!
« Reply #8 on: February 11, 2022, 03:44:33 AM »
It's a myth that probing doesn't work in Mach 3 Turn!  It just isn't documented.  I use it constantly with a touch sensor that detects when the tool tip touches the stock. Happy to post details if there is interest.

I don't have limit switches on my lathe but I do have a hard contact on the saddle with a sprung earthed pin on the cross slide.  The contact is connected to an input and used in the inbuilt homing routine.  At the start of every session I home the x axis to this, and I could then have a stored tool offset for a drill chuck mounted on the cross slide.
« Last Edit: February 11, 2022, 03:46:55 AM by JohnHaine »
Re: Drill chuck reference on lathe table!!!
« Reply #9 on: February 11, 2022, 05:17:23 AM »
These photos show the homing contact and pin.  The pin is a long socket-head screw with the end rounded, held in a little bracket from the cross-slide end-plate.  The first picture shows this with a previous version of the contact pad.  The second phto is the most recent iteration of the pad, a small block of Corian with a plate of beryllium copper shim glued on to it.  A short screw into a threaded hole in the plate and block connects the wire from the switch input to the pad via a crimped tag.  There's enough movement in the pin so that the slide gets stopped before the spring compresses solid.  The block is super-glued to the front of the lathe apron.

When I switch on the lathe I select machine coordinates and jog the X axis until the pin is a mm or so off the pad.  Then click the Set Home X button on the Manual screen, which causes a slow -ve move of Z until the pad grounds.  Then I click Zero World X which zeroes the X DRO.  Actually having done this if the system is restarted and you go through the process again the DRO reading is very close to zero, I think it would be zero except that the steppers don't come back in the same position if powered off and on again. I home Z manually around the centre of the bed as the actual Z position of the stock in the chuck is variable.
« Last Edit: February 11, 2022, 05:19:59 AM by JohnHaine »