Using laser pointer to locate zero

Discussion about Tooling and Fixtures. End Mills, Router Bits, Hold Downs, Fixtures, Etc.
Goose
Posts: 3
Joined: Wed Jun 18, 2014 4:02 pm

Using laser pointer to locate zero

Post by Goose » Wed Jun 18, 2014 7:18 pm

Hello,

I was wondering how, after a tool change for example, you bring back your tool to the exact starting point of the previous operation on the shapeoko. I was thinking about mounting a laser pointer to the spindle mount and homing this on to a reference point between tool changes.

Any other (better) ideas? The "return to zero" function in the g-code sender does act a bit strange on my machine.

Thanks!

WillAdams
Posts: 8628
Joined: Mon Apr 09, 2012 6:11 pm
Location: Pennsylvania --- south of the Turnpike, East of US-15
Contact:

Re: Using laser pointer to locate zero

Post by WillAdams » Wed Jun 18, 2014 7:34 pm

Shapeoko 3XL #0006 w/ Carbide Compact Router w/0.125″ and ¼″ Carbide 3D precision collets

twforeman
Posts: 1351
Joined: Tue Jan 29, 2013 4:51 pm
Location: Minneapolis, MN
Contact:

Re: Using laser pointer to locate zero

Post by twforeman » Wed Jun 18, 2014 8:03 pm

Home/Limit switches and Work Coordinate Systems: http://www.shapeoko.com/wiki/index.php/ ... te_Systems
Ender 3 3D Printer
ShapeOko v3 serial #0004 - upgrade thread
All of my ShapeOko related blog posts

Schruminator
Posts: 259
Joined: Wed Oct 30, 2013 1:04 pm
Location: Littleton, CO
Contact:

Re: Using laser pointer to locate zero

Post by Schruminator » Thu Jun 19, 2014 2:16 am

I too had considered lasers (two laser modules that each project a line, cross them at 90 degrees) to help out, but honestly once I installed homing switches, I didn't see the point. The homing routine is more consistent and precise that I will ever be manually.

After I home, I command the spindle to where it needs to be on the work piece. I pencil down the numbers and re-zero the coordinates and I'm good to go. This way even if I turn things off and start them back up the next day I can just re-home, move the machine as per the numbers I jotted down and I am good to go.
1.8m x 1.0m SO2 #3638 / Vectric Aspire / ACME Z-axis / View my photography at http://www.mschrum.com

twforeman
Posts: 1351
Joined: Tue Jan 29, 2013 4:51 pm
Location: Minneapolis, MN
Contact:

Re: Using laser pointer to locate zero

Post by twforeman » Thu Jun 19, 2014 7:17 pm

You can eliminate the "writing down the numbers" part if you set a work coordinate system.

The WCS are stored and remain usable after power off.

Just home the machine, send G5x to use the stored coordinate system and away you go.
Ender 3 3D Printer
ShapeOko v3 serial #0004 - upgrade thread
All of my ShapeOko related blog posts

Auarhau
Posts: 243
Joined: Tue Feb 25, 2014 8:46 pm

Re: Using laser pointer to locate zero

Post by Auarhau » Thu Jun 19, 2014 7:30 pm

Would it be possible for the work coordinate experienced to make some practical examples on the wiki? Simple stuff like resetting zero if you have to stop mid job, or change tools. I find the current wiki article a bit daunting. And after reading it on several occasions I'm really not sure how to use it in my work. and you never know, there might be others out there with a brain as thick as mine who also could benefit from simple examples to see the value of using work coordinate.B-)

Sent fra min D6503 via Tapatalk
ShapeOko 2. Nema 17 74 oz·in. GAUPS shield on Arduino Uno. DRV8825 Drivers x4 . Kress 1050 FME-1. Z Acme Screw. Threaded inserts table.

fl0yd
Posts: 87
Joined: Wed Mar 12, 2014 5:37 pm
Location: St. Louis, MO

Re: Using laser pointer to locate zero

Post by fl0yd » Thu Jun 19, 2014 7:53 pm

Let's discuss it before committing it to the wiki:

In short, there are multiple persistent (between reboots and resets) zero points that you can set via gcode. G54 = zero point 1, G55 = zero point 2, etc.

For me I use them as follows:
1) Home the machine - $H
2) Jog the machine to the point that I want to become the zero point (I'll be using G54, slot 1, for this example) - Manual jogs via UGS
3) Lower the cutter to the zero height for the work - Manual jogs via UGS to where a sheet of paper just drags between the bit and the material. Approx +.004" from true zero.
4) Issue a G10 command to define the G54 slot's zero points - G10 P1 L20 X0 Y0 Z-0.004
- I'll break down the G10 command above:
  • G10 - The command issued to define the new coordinate system
  • P1 - Slot 1, a.k.a. G54, for the other slots 1 - 6, you just change the P1 to P3 for slot 3 for example
  • L20 - Initiates the offset command for the chosen slot
  • X0 Y0 Z0.004 - Defined offset, indicates in the units to offset the zero point from the current position of the machine. Because I jogged the machine to the exact X0,Y0point for my work, I didn't indicate an offset. I know my Z0 is "high" by .004", so the "-0.004" part of the command will tell the machine that true zero is -0.004 units away. The wiki has additional details on how to use offsets.
Now my slot 1 X0,Y0,Z0 point is set, and can be recalled at any time by issuing a "G54" command.

After a power cycle, reset, or an error, to return that that exact point I would do the following:
1) Home the machine - $H
2) issue a G54 command - G54
3) Issue a move to the X0,Y0 position - G0 X0Y0
4) Lower the Z axis to the Z0 position - G0 Z0
5) Start sending my job from UGS

You could combine 3 and 4, but all 3 axis will move while doing so and you could crash the Z tool into a clamp or drag it across a high spot in the material, so I lower the Z as a separate action.

Fl0yd

Auarhau
Posts: 243
Joined: Tue Feb 25, 2014 8:46 pm

Re: Using laser pointer to locate zero

Post by Auarhau » Thu Jun 19, 2014 8:07 pm

Thank you very much for explaining and breaking down the g code string like that! It helps a lot!! Why do we have both G54 and p1, If p1 is G54?

Sent fra min D6503 via Tapatalk
ShapeOko 2. Nema 17 74 oz·in. GAUPS shield on Arduino Uno. DRV8825 Drivers x4 . Kress 1050 FME-1. Z Acme Screw. Threaded inserts table.

fl0yd
Posts: 87
Joined: Wed Mar 12, 2014 5:37 pm
Location: St. Louis, MO

Re: Using laser pointer to locate zero

Post by fl0yd » Thu Jun 19, 2014 8:10 pm

Auarhau wrote:Thank you very much for explaining and breaking down the g code string like that! It helps a lot!! Why do we have both G54 and p1, If p1 is G54?

Sent fra min D6503 via Tapatalk
I'm not sure how the G-code standard came to reference P1's coordinates through the G54 command, I find it odd too.

Aside from needing to remember the association of P1 = G54, P2 = G55, once you start using WCS, you'll quickly forget about the peculiarity and wonder how you ever survived without using it.

Fl0yd

madmike88
Posts: 52
Joined: Mon Nov 05, 2012 4:10 pm

Re: Using laser pointer to locate zero

Post by madmike88 » Thu Jun 19, 2014 10:57 pm

I'm definitely gonna cut and paste this into my notes.

Thanks

Post Reply