Machining Origin and tool offfset question

[scalecreations1]

As a new user, it seems odd to me that CAMBAM does not compensate for the tool radius.  When I zero my 1/8" mill against the x and y edges of my stock I would think that CAMBAM would use the tool settings to establish the correct point when starting a cut when creating the g code.  It looks to me like this is not the case and you would really need somehow to zero the tool at the tool's center rather than at the tool's edge.  My cutting seems to be cut 1/16" off in the x and y direction with my 1/8" mill  Am I correct? 

The actual cuts are very accurate, it's just that the relation of the part cutting to the stock is xy offset 1/16" in my case using the 1/8" mill.
 I would really prefer using the edge of whatever tool against the stock rather than trying to find the center of the tool when zeroing on the stock.
If that is the case with CAMBAM, would changing the  machine origin setting in CAMBAM to compensate for this work?  Or am I missing the boat?  Any help would be appreciated... 

I'm using CAMBAM0.9 REL8N with MACH3 on a Zenbot 2448

Thanks!

[Bob La Londe]

You set zero relative to your stock on the machine.   On two of my machines I use a wobbler for 99% of my work by touching off in X & Y and a tool height setter for Z.  Most of my tool height setters are zeroed at exactly 2 inches, and my wobbler is 0.20 inches in diameter.  I touch off two sides and set X or Y to .1 or -.1 as appropriate and then I place the tool height setter on the stock and bring z down until it zeros and set Z = 2.0"  

Occasionally I'll use a coaxial indicator to find the center of a hole or round boss, and then set X and Y to the desired coordinate for the center of the element.  I use this for repeatable cuts using jigs modestly often.  

If you are squaring up stock it can pay to setup your job with the wobbler and set .11 instead of .1, but how you choose to approach that will come with experience.    

I do have a 1" tool height setter that I use on my router where I have less clearance, but its quite awkward to use consistently.  

IN MACH 3 ALWAYS REGENERATE TOOLPATHS AFTER MAKING MANUAL CHANGES TO THE CURRENT OFFSET OF X OR Y.  Its not an issue for Z because Mach 3 expects Z to change when you change a tool.  I don't know about A B C axis, but I would err on the side of caution and regen after making manual changes there too. 

[dh42]

Hello,

It looks to me like this is not the case and you would really need somehow to zero the tool at the tool's center rather than at the tool's edge.

Yes, sure, on your machine you must set the XY zero related to THE CENTER OF THE TOOL, not related to the edge.







++
David

[Bubba]

Apparently you have more reading in front of you. CB does compensate for tool diameter/radius. If you want to profile 1X1" inside with .25" EM all you need to keep in mind the origin in CB should be the same as Mach3..  In Mach3 you need to tell it where X-Y-Z zero is. Good luck.

[dwc]

Hi Creations,
There are many ways and tools that can be used for determining the position of stock, but using a cutting tool is one I would not recommend.
A cutting tool is for cutting and I have more than once broken the cutting edge of a tool by lightly touching off a not rotating tool by accident.
CB does do tool offset compensation for cutting paths, as a CAM SW should.
But with the multitude of ways of setting stock positions, that is more a controller, lets say Mach3 for example, function, not something for CB itself.
Best,
Don

[lloydsp]

CamBam is CAM, not a machine controller.  It tells the machine "where to go" to do it's operations, based upon where the machine thinks is 'home'.  Zeroing of the axes is always done on the control, not within the CAM package.

Lloyd

[scalecreations1]

Thanks for the confirmation.

What I am trying is to still do is setup using the xy edges but hopefully the  CAMBAM "machine origin" setting will compensate for the offset?  Is this worth a try?  It just seems so much easier and accurate to use the tools edge against the stock than to play around jogging to the center of the tool or having to install a tool with a pointed tip and eyeballing it and reinstalling the actual 1/8" mill.

Would changing the  "machine origin" setting in CAMBAM to compensate for this work out? In my case using an 1/8" OD mill I would set it to x=.0625 and y=.0625 (or possibly negative values)

Thanks

[homebuiltncrouter]

Creations, I don't think you're quite getting it. CamBam makes the code that defines the part you're controller software (mach3 Mill in my case) defines the table. You're cutter is part of the table so it's Mach3 that's determining the edge of the cutter.

[Dragonfly]

I assume you are using Mach3.
So when you touch the tool edge to the stock and the tool has diameter D, its center is exactly at D/2 from the stock edge. You enter this D/2 value in the corresponding DRO indicator in Mach3. Usually with a "-" (minus) sign if the machine coordinate system mirrors the one used with CB.
For example you touch the stock in X axis setup on its left edge with a mill of 4mm diameter and enter -2 in the X DRO display in Mach3. Same with Y axis. Now when you issue 'go to zero' command the tool center will be positioned right over the stock corner.
Some times, in fact I think more often, the machining zero has to be some distance into the stock because of holding brackets and fixtures. CamBam is a CAM program and it couldn't know where the fixtures are or what offset it should apply respective to the stock edge. It is the operator's job to set the zero on the machine. This gives you some flexibility when selecting the zero coordinates.

[scalecreations1]

Great, well thought out answer Dragonfly.  It's so much appreciated when someone takes the time and cares enough to actually read your questions and answer them clearly and accurately.  This is exactly what I needed to know   Thanks!!

[scalecreations1]

Thanks guys!

[lloydsp]

Scale,
Just so you understand, you will NEVER find another on-line community so dedicated to helping each other through such questions.

Every experienced user here is willing to take the time to answer (sometimes complex) questions about CamBam.

Andy created the environment, and promoted that sort of cooperation, and it persisted even in his forced absence.

Now that he's back, you should see even more enthusiasm!

Lloyd

[scalecreations1]

Thanks Lloyd-much appreciated