Switching from tip of tool to center of tool

[Thad]

I have been instructed to switch all of my future programs over to center of tool. The obvious place to start was selecting Center in the tip comp options on the machining parameters page. Are there edits that I need to make to my post to go along with that?

 

I ran a quick test and I see that changing to Center will make my top of stock and depth values in relation to the center of the tool, but I need more than that. Say I have a pocket that's .500 deep and Z0 is the top of the part and I'm taking .05 per pass. The cutter has a .063 corner rad. If I put 0 as my top of stock and -.500 as my depth, the first pass is really .113 deep (.05 + .063) and the finished pocket measures .563 deep because the center of the tool went .500 deep. I would expect MC to start higher so the first pass isn't deeper by the corner rad of the tool and also to stop short of the depth so the finished pocket depth is correct. That's where I'm guessing the post edit comes in.

 

Anyone?

 

Thad

[Mic]

If you center compensation you also need to measure your tools to center and not tip.

[gcode]

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I have been instructed to switch all of my future programs over to center of tool.

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Why???

You get smoother 5X motion using a ball endmill

but that's the only good reason I can think of..

How will you handle bull nose endmills??

Sounds like a huge pile of trouble to me??

[Mic]

By the way, If you only have a Level 1 you don't have multiaxis. In that case I don't see any benefit from using center comp.

 

Normally center comp is usefull for 5 axis simultaneous to get a smoother path and better surface quality. But in 2/3D this doesn't have any effect.

[Josh T™]

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Sounds like a huge pile of trouble to me??

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Me too. What is the logic behind the switch. I've never used tool center postitioning and have never thought of a reason why I should.

 

Have you programmed a part and verified it using tool center? For some reason in X3 I had an issue with the tool defaulting to tool center. The only reason I caught it and didn't srcap a part was the tool was acting very strange during verify... like it was ramping instead of using depth cuts.

 

Push back against this one as hard as you can IMO

[Dave.L]

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I have been instructed to switch all of my future programs over to center of tool.

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Thad, maybe a bumb question, but do you mean center of tool as in cutter comp?

 

That makes more sense than the tip.

[Thad]

I'm against it myself, but the other programmers are using it with other software so they want to standardize it. We've been having issues with the operators setting tools for it when they shouldn't and vice versa. We also have a bunch of old programs that we use on replacement details that were done with center of tool and that would require those all to be reprogrammed if everyone switched to tip of tool.

 

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How will you handle bull nose endmills??

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Bullnose also get comped to center of rad.

 

Thad

[Thad]

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Thad, maybe a bumb question, but do you mean center of tool as in cutter comp?

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Center of tool as in tip comp.

 

Thad

[Cad-Camr]

Would that mean that the operator has to input the radius of the tool in the offset register, If so thats quite a step backwards IMO

[Thad]

Yes, the operator has to enter the tool corner rad in the offset page. They've been doing it since the beginning of time, so that's what they're used to.

 

Quite often, I'll do the 2D programming (typically just holes) and the 3D programmer will do the 3D programming with WorkNC. In the various setups, sometimes there are 2D programs that have to be run before and after the 3D for machinibility's sake. Currently, my programs are tip of tool and the 3D is center of tool. You can see how the flip flopping in changing offsets can cause errors. Apparently, it has one too many times. I was chosen to make the switch.

 

Thad

[YoDoug®]

So if you have a program that has a ball em, a bull em, a flat em, and drills, etc. They have to touch some off to the tip and some to the center. That sounds like trouble to me.

[Thad]

Doug,

 

It can't be much worse than setting tools differently for different programmers.

 

Thad

[Thad]

Does anyone know of a post edit that will do what I want?

 

The way it is now, I can't click the Depth button (or top of stock, or...) to allow me to interrogate the depth of a pocket unless I manually edit it afterwords to accommodate for the tool rad. That can't be right.

 

Thad

[RandleXX]

Sounds like a huge PITA.. Never heard of this being done in any shop, ever...

 

Might as well just go back to programming at the control..

 

Good Luck!

[PeterM]

Perhaps putting a switch into the post to generate a quote identifying which type of tip comp is being used would be a more sensible approach. I had to do this for tool comp when I started switching over from control comp to wear comp, because the setup guys and operators were confused.

[LaszloK]

There are times when programing to the center of a ball mill and playing with the cutter radius values is quicker and easier than offsetting surfaces and changing the model. Especially when machining EDM electrodes where a large negative over thickness is required.

[Jimmy Wakeford from Barefoot CNC]

YOu could have the post raise Z by the tool corner rad, but I wouldn't. Verify would then be inaccurate.

 

Instead, on 2d paths set your top of stock and depth + tool rad. I know its a pain, but the verify and code will then match up.

[Cad-Camr]

Center of Tool was a common method used back in the early 80's. The downside was the operator either forgot to enter the radius of the tool or left the value from the previous job in the register resulting in a scrapped first part. This happened a lot and eventually the format was done away with. I for one would have a hard time accepting this method of programming.

[Thad]

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Instead, on 2d paths set your top of stock and depth + tool rad. I know its a pain, but the verify and code will then match up.

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That would really suck. All of my toolpaths are 2D.

 

Thad

[jeff]

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We've been having issues with the operators setting tools for it when they shouldn't and vice versa.

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Wouldn't a simpler fix to this issue be to just have a static text entry in YOUR post saying that the tool not set to center? or whatever?

Then all the operator needs to do when he sees the tool list is look at the 1st line of the program.

 

Thad, I feel sorry for ya LOL! I see nothing but headaches involved with this.

[dolphin1]

you guys are missing the real reason for this. if you dont go to the center of the tool for surfacing it comes out wrong. this has been covered many times.

[jeff]

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you guys are missing the real reason for this. if you dont go to the center of the tool for surfacing it comes out wrong. this has been covered many times.

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He only programs 2D toolpaths.

[Clarence L Cook]

What about G10s to add the radius amount for the particular tool in the tool length. It can be easily done with some manual entries.

[Redfire427]

It gives me a great sense of job security knowing that there are shops out there making decisions like this. I'm sure your materials suppliers will be very happy. Good luck.

[Colin Gilchrist]

^^^ THIS.