Buddy 48 Alpha "home"

[Ajcoholic]

Is there an actual "home" zero for x,y? Or is it entirely up to the user to set the coordinates?

When I set up to surface my 48" by 48" work surface, I had to try several times to get close to the corner (which I would call x & y zero) I kept hitting the limits, and would have to reset and jog over a bit, and try again. Eventually I got to the point closest to the lower left corner without hitting the limits and then I was OK to surface the 4' by 4' top.

Is there an easier way I am missing?

Thanks,
Andrew

[Ajcoholic]

97 views and no one knows?? Will look in the manual again...

AJC

[bleeth]

Corner zero,zero is arbitrary and depends on the exact position of your spoilboard. Table zero,zero is determined by your prox switch placement.
The difference in the distance from the prox switch to the spoilboard can be manually input in a couple of ways. One way is to re-run "setup" under tools and select that you want to "do it the hard way" and use your own co-ordinates instead of the default settings. It sounds like your spoilboard corner is closer to the prox switch then the value entered into SB3.

Alternately you can trim your spoilboard, say with a 1/2" end mill running minus .25 from 0 and then your board will match your prox/spoilboard offset settings.

[Brady Watson]

On my BT48 I swapped the X & Y for each other so that the X was parallel with the gantry beam. So my 0,0 was at the bottom left corner when I looked at the tool from the front. If you decide to do this, don't forget to swap input 2 & 3 with each other or C3 will not work.

The default configuration is if you are standing on the right side of the tool with the table moving in & out as the X and parallel with the gantry beam as the Y. I didn't like this config, which is why I swapped out X for Y. With a long power stick it makes more sense...but for ease of use I like my way.

-B

[dana_swift]

Andrew- Im with Brady on swapping axes. The "front" of the machine is when I am standing looking at the gantry. In order to swap X and Y you need to change your driver definitions, and also swap the signal wires on your X and Y prox switches, then everything works the way you would expect.

Also I concur with Dave on the arbitrary corner of your spoilboard, it may move depending on how you mount/build it.

My generation of BT-32 has an aluminum plate with drilled and tapped 1/4x20 holes in a known grid. My home is always set relative to this grid, and I can check the accuracy of homing by how accurately I can position above these holes.

I don't know how well the latest BT-48's are at repeatability, but the repeatability of the home position on my BT-32 measures at +/- 0.002 in both X and Y.

The most accurate location method is "center in hole", which will establish a reliable zeroing to better than 0.001 in X and Y. The bots seem to have about 0.002 in position repeatability (their advertised spec) after driving X and Y around and then coming back to the hole used to define zero and measuring the center. I have just verified that.

Consider "home is where the bit is when you type Z2". Or somewhere around 0.002 of that!

D

[garyc]

AJ...
The term "HOME" is as relative on a CNC as it is in real life.

In life home could mean your home country, state, town or house.

In CNC it can be used as a noun or verb.

ShopBot [J] [H] command jogs the tool to the 0,0 location by default. It can be user modified to traverse to any location.

That 0,0 location is set usually by the prox switches and the XYzero (C2) routine. The distances from the trigger point to the axis zero set point are user set (default is .5") That .5" will allow most bits to outline cut a file designed at the 0,0 corner.

Certain files benefit from a 0,0 location in the center of that material, others dont.

As Brady and Dana note, the both the locations and axis directions can be user modified.

In many shops, to "home" the tool is to park it for loading, while in others it means "zero using prox switches". Some set the home (0,0) manually with a Z2 command using edge finders or lasers.

So in the end, the 0,0 location is fully user definable. The ShopBot machine and software will allow you to place it wherever it makes the most sense to you. And whether you call that 0,0 location home, is also up to you.

[Ajcoholic]

To clarify - what I mean is this:

I know I can set the 0,0 point anywhere I want... but what I was asking, is if there is a preset "zero" that would be used, say to level the spoilboard without first manually finding the extreme corner without allowing the machine to hit the stops and interrupt the program run.

I am fine with the "stock" layout - having the X and Y as set up from Shopbot. I stand off to the side of the machine anyhow when running, so I am already accustomed to the axis and how my parts are to be placed on the table.

That being said, I am still unclear if the machine will go to the lower left corner (when I am standing on the right hand side of the machine of course) with a preset program, or do I have to get it there - without setting off the limits - and then manually move it there each time I want to use that coordinate as the zero?

AJC

[garyc]

AJ..
Run the C3 routine.
Open the keyboard and move in the +X direction until it hits an Estop. back off 1/2" Write down x coordinate. Do the same for Y. Use these X & Y cordinates as max dimensions for the table surfacing routine that starts with the machine at the 0,0 location.

[Ajcoholic]

OK, will do. I know the true working surface on my buddy with the 6' powerstick is 48" by 48" - your way sounds far easier (and faster) than what I was doing...

Most of what I am making, and am going to make, can be set in the center of the working area. However, I do have some parts I am planning to cut from 1/2 sheets of ply, and that is why I wanted to find the true working area with the zero down in the corner, rather than in the middle.

Will give it a go this week after I get everything moved and set up in the new room, and report back.

Thanks for the help, fellas!

AJC

[Ajcoholic]

C3 routine works great... finds the corner all by itself!

Thanks again.

AJC