Zero at LL corner vs center of sheet problem

[johnm]

Folks -

Okay, I am trying to set up some symetrical layouts so that I can v carve on one side, then cut the parts out after flipping the panel. I think I have it, and I laid everything out block copying and mirroring by quadrant with 0 being the center of the sheet. So far, so good. But when I load the file for preview, SB uses LL for zero instead of the center of the sheet. I may be covered in lame sauce, yet again, but how do I fix this?

I'd appreciate any assistance... Santa's Elves are waiting...

John Moorhead

[mrdovey]

John...

I mounted a 2x4 registration "rail" and machined it flat and straight for its full length at y=0. That allows me to position and align sheets repeatably.

Having done that, I can position the bit at x = -(bit radius) and z = (between table surface and top of sheet) and, with the sheet against the rail, slide it until it touches the bit. At that point I either clamp it or turn on the vacuum and cut side one.

With side one cutting complete, I loosen the clamps, flip the sheet end for end, move the bit to x=(sheet length + tool radius) and z as before, and again slide the sheet against the rail until it touches the bit. After I've secured the sheet in position I cut side two.

You can see my registration rail lash-up somewhere near the middle of this web page (http://www.iedu.com/DeSoto/pix.html).

When I need to cut the side of the sheet nearest the rail, I put spacers between the sheet and the rail during positioning and remove them after securing the sheet. I use a pair of 3/4" UHMWPE strips as spacers because they're slippery enough to be easily removed.

Using the bit to position the work has been a useful technique for me for the kind of operation you've described.

[johnm]

Morris -

Thanks for your comments - I checked out your site and how you have the rail mounted.

But can you, or any of the other botters out there, tell me how to set up the SB control software so that "0" is in the center of the sheet in preview? For my symetric layout I am working from there, not the lower left edge. When I run a file, everything runs off "the edge of the Earth" in preview, because of XY-0 being in the LL corner and I don't know how to correct it, tho' I am sure it is a simple thing.

Halp!

John Moorhead

[paco]

Hi John!

This "all" depends on the CAD/CAM part... assuming you use PW, take a closer look at when you start a new project... settings...

As for registering a such projects as the one your trying yourself at, I use dowels... it's easy; but do need to be done correctly and tested the first time...

[mrdovey]

John...

Look at the VA and Z2 commands. VA allows you to set the current position; or if you position the tool in the center of the sheet and issue the Z2 command, that position becomes the (0,0) location on the table. You can probably use either of these strategies to arrive at the same result.

...Morris

[johnm]

Morris -

Okay, I understand about centering on the physical sheet; my question is with the SB control software in preview mode, and I am sorry if I am not being clear... How do I set preview so that zero is in the center of the sheet. I have everything centered and aligned in PW, but when I import the file to preview, Zero has moved to the lower left corner. How, in the SB software, do I move zero from the lower left to the center of the sheet for preview so that I can test a file?

Thanks!

John

[hippo]

Zero is a relative term. It is wherever you want it to be. Just move the cutter to M2,48,24 and then Z2 and you should be all set. Just like you would on a real piece of wood.

-Dan

[johnm]

Dan -

Yes, I understand. My question, again, is in the preview mode in SB Control Software, how do I set 000 so that it previews in the center of the sheet? My PW cut file has 000 at the center of the sheet, but when I open it in preview it moves 000 to the lower left corner.

I rezeroed in preview, as you have suggested, and it moves and zeroes, and then when I open my file it's back in the LL corner.

It's not climbing the mountain that hurts, its the rocks in my shoe. Any ideas?

John

[paco]

Both the previewer (and the control box) will ONLY read the code from the output files... from CAD/CAM... or typed by and code...

As for displaying your file the way you want (John), I think you just need to use the offset option on the filling sheet when you load the file (using FP)...


4127

...say your blank (set dimensions of CAD file) is 96" X 48"; then offset by half of thoses (48" X 24") BEFORE running the file and use the 2D offsetting setting of the FP command...

Is this help?!

[bill.young]

Hey John,

I'm not sure what's happening with your file...once you've re-set the zero point in the previewer it shouldn't reset until you close the previewer. Does it do the same thing if you do the same re-zeroing steps and then type "C1" to run the ShopBot logo in preview? If not, how about emailing your file to me and I'll give see if I can figure out what's going on.

One thing to remember is that the grid always stays linked to the bit...the corner of the bit is always at the Lower left corner of the grid. The big blue rectangle with the yellow border represents the table. You can get a better visualization of where the bit (and 0,0) is in relation to the "virtual" tool if you check the "tool visible" checkbox on the previewer window.

Bill

[dmdraper]

While we're on the topic...

It the Z2 command supported the preview mode when passed from a file? My situation is this:

I have a master file that calls two .sbp files. After the first file finishes, I use Z2 in the master file to zero in a new location, then run the second .spb file. I've never been able to make this work in the preview mode even though the master file cuts just fine.

Dave

[rmyers2051@bellsouth.net]

I do use th e lower left corner to zero, same on the cnc mills in my shop.
I have run into a snag though, I recently found it necessary to move my table, and in doing so the orientation of the table to its new home is 180 degrees from where it was. The LL is now the Upper Right. So, I want to move my zeros and home to the opposite corner but cannot find info making the machine think positive moves are in the opposite direction. All programming for the four mills and the SB start as LL for reference/home/zero. Any one?

[ron brown]

Bob,

You can "mirror" the part or switch leads on steppers. IIRC (somebody step in here and verify or correct) the green and black wires switch.

Ron

[rmyers2051]

I would have thought there would be a softwre solution to this. All Of my cnc mills have a procedure to which you can reverse the +counting and make it- thereby reversing the axis tavel

[mrdovey]

Robert...

ShopBot provides a way to do what you describe. All thats necessary is to change the sign of the axis units (using the VU command) for the axis you want to reverse.

If you do that, you'll probably also want to adjust the origin for that axis using the VA command.

...Morris

[mrdovey]

John...

I think I misunderstood what you were originally after. Please take a look at the VP command - I think it may do what I think you said you want to do.


...Morris