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CUTTER COMP PROBLEM


bensls
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I'm with John. If you are using Cutter Comp, you really should use a Perpendicular move for your entry. If you need to extend the start or end of the contour, you can do that as well, but you must have some type of actual "entry" move for the comp to be applied. This gives your machine room to "shift" the tool, based on the value in your tool diameter register.

 

The only time I've ever used "Tangent" lead in, was when using a line and an arc. The Arc move gives the control something to "comp to", when applying your "tangent" lead in move.

 

Honestly, even if the move is just now showing up in X9, I'd say the way you are trying to apply comp is not correct. Either switch to Perpendicular, or add some bit of "Arc" motion.

 

Something I'll do quite often is add a .500 radius arc move, but change the "sweep" to something small like 15%. That gives you a small "lead off" motion before the cutter comp is cancelled.

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I see what the OP is saying... Ignore the finer points of cutter comp, and look at the output.

 

Mastercam should be outputting 3 elements; A lead in, a move along the chained geometry, and finally a lead out.

Even if all 3 are parallel, it should output them all separately. I personally use tangent lead's with no sweep all the time and it works for me(X9).

 

That being said, if you actually need cutter comp, you need to go "perp" OR add a sweep to the lead. The straight move combined with a comp move may result in a tapered feature as the control will gradually apply the comp over the course of the move. Results may vary based on how much comp you have.

 

If you really need the straight move, you could add .0001" to the ramp value on lead in and out. That should fix it and be basically imperceivable in real life.

 

J

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Another thing to check (that I really hope you are not doing) is if filter turned on.

 

Ugh.  It was actually the "Smoothing Settings" checkbox that did the trick.  It still works with filtering (not that it's necessary for a straight line) as long as that box isn't checked.  Thanks.

 

Looks to me like garbage in, garbage out.

 

Very helpful.  God forbid I need to use something as basic as a tangent lead in/out.

 

I see what the OP is saying... Ignore the finer points of cutter comp, and look at the output.

 

Mastercam should be outputting 3 elements; A lead in, a move along the chained geometry, and finally a lead out.

Even if all 3 are parallel, it should output them all separately. I personally use tangent lead's with no sweep all the time and it works for me(X9).

 

This is exactly what I was getting at, but I can see why having the smoothing settings turned on would affect the tangent lead out like that.

 

To all others, thanks for your input.  I generally do use a perpendicular entry/exit where the filtering settings wouldn't affect cutter comp output.  But for those instances where I need to use a tangent entry/exit, it's good to know where this problem was stemming from.

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I use tangent entry and exit on straight lines all the time. Anybody who is claiming there is something wong with programming that way needs to give their head a shake...

 

Good to know you figured out what was causing the problem

with CDC??

that violates everything I ever learned about CDC

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with CDC??

that violates everything I ever learned about CDC

 

If you're using Control compensation (entering the radius of the tool into the machine control), you might not want to use tangent lines to avoid large comp moves while entering a cut.

 

But I use Wear compensation almost exclusively, so tangent lines wouldn't make the cutter move a significant amount before the cut.

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If you're using Control compensation (entering the radius of the tool into the machine control), you might not want to use tangent lines to avoid large comp moves while entering a cut.

 

But I use Wear compensation almost exclusively, so tangent lines wouldn't make the cutter move a significant amount before the cut.

I learned CDC many years ago on old stupid machines.

Turning on CDC on a straight move was begging for heart ache.

Some machines wouldn't do it, some would alarm out some would do crazy things  

trying to get to the comp point or even comp to the wrong side of the cut.

Hard learned lessons last a life time :laughing:

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I learned CDC many years ago on old stupid machines.

Turning on CDC on a straight move was begging for heart ache.

Some machines wouldn't do it, some would alarm out some would do crazy things  

trying to get to the comp point or even comp t the wrong side of the cut.

Hard learned lessons last a life time :laughing:

Maybe I have just been lucky enough to not have to deal with any machines that old yet, lol

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The first NC machine I ran, a TREE knee mill had a 2X control with no CDC at all.

The quill was run by hand like a Bridgeport.

It used to run for home destroying everything in it's path for no good reason.

I nearly got fired before I found the cause.

It was wired to the same switch box as the air compressor

If it was cutting an arc and the compressor started up the power spike caused it to G0 G91 G29 X0 Y0.

Good times :laughing:  :laughing:

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Regardless of what we learned on, wear or control it is my opinion that some sort of lead in is an absolute must. I won't lie, sometimes that is 0.005in for tight spots but I do believe it gives a better chance of predictability on the real world.

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Anybody who is claiming there is something wong with programming that way needs to give their head a shake...

 

 

Just because you *can* do something doesn't mean you should.

 

Using tangent entry/exit with wear comp is unpredictable. Period. Using a perp line is not. That's why it is taught in schools that way, that's why it is taught in shops that way, that's why books are written that way and that's why people do it that way. You may have used tangent lines for years without problems, but one day, it will bite you.

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Just because you *can* do something doesn't mean you should.

 

Using tangent entry/exit with wear comp is unpredictable. Period. Using a perp line is not. That's why it is taught in schools that way, that's why it is taught in shops that way, that's why books are written that way and that's why people do it that way. You may have used tangent lines for years without problems, but one day, it will bite you.

 

 

What sort of problems can I expect? Educate me.

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