5 axis curve on a rotary table

[loraxian]

I'm in a little over my head here but I figure you don't learn if you don't push the envelope.

 

I have a 3 axis mill with a rotary table that I've used to machine a part with an odd contour. I'm now trying to engrave text on that surface. The approach that I used was to use a 5 axis curve operation with a 4 axis output.

 

Everything seems good except I get a "rapid move hits operation surface" error when I attempt to update the operation. That is exactly what it's doing I have the broken tool to prove it.

Any suggestions?

[Tyler Robertson]

Did your backplot/verify look okay? Often the case with this is that your toolpath starts in one location and ends in a location on the other side and your machine wants to go from one side to another through the part. If you get this warning, check your surface normals, feed and rapid heights initially

[loraxian]

Initially it did exactly what your talking about. It attempted to place tool path on opposite sides of the part. I fixed that and double checked the feed and rapid heights.

Dumb question - how do I check surface normals?

btw - I don't have true solids so backplotting is my only method of checking things out.

[Guest]

quote:

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I don't have true solids so backplotting is my only method of checking things out.

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If you have X3 and multi-axis you do

 

It is included now

[Jim at Gentex]

quote:

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how do I check surface normals?

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Analyze > Dynamic > Select the surface

 

I'm 99% sure that's not your problem.

Usually when the surface normal is reversed somewhere, the tool enters from the 'bottom' of the surface instead of the top (tool side) in the backplot.

 

I've had this happen before too. Try manipulating the retract height and the feed plane as well as the clearene plane until you get the clearence you need.

[loraxian]

I'm still stuck. It doesn't matter how much clearance, retract or feedplane clearance I use it still indicates a rapid move impact.

 

 

It seems like it has to be something pretty basic

[Jim at Gentex]

sorry...I can't view the images here at work.

 

I will look at them when I go home tonight.

 

Also there's the Absolute or Incremental selection.

That could be messing it up too.

Try manipulating that too.

[crazy^millman]

Ignore them. They are dummy hits. I see this all the time in Mill/Turn and it is nothing. I just tell the operator to pay close attention as they run the first part and you will see it does not hit. If it does just change it right there on the machine for it will probably be so close it will seem funny when you find it.

 

 

HTH

[Jim at Gentex]

Here's one for the gurus...

Why are the 'absolute' buttons greyed out on the curve 5 axis parameter menu? I always wondered about that.

 

Your 'incremental' clearance plane might not be high enough. Depending on where your Z zero is, you can try creating a point on your model at a higher Z position where you know the tool will not touch anything, then select the point as the clearance plane instead of entering a value.

[CM_BR]

Check Entry/Exit options

[Dan@home]

The reason the absolute button is greyed out is because when the surface is uneven you have no distinct absolute distance from surface so it is inc from surface. If this makes sence??

[Jim at Gentex]

quote:

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you have no distinct absolute distance from surface so it is inc from surface.

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Yes, it makes perfect sense to me!

 

Thanks.

[loraxian]

This is all helpful. Thanks.

I've been looking at this some more and just realized that the feed rate outputs are bizare. I have the feeling that I'm off in the weeds on this. Is my approach logical?

 

[Teh Bear without Brains kinda idiot]

outputs are bizare

~~~~~~~~~~~~~~~~~

looks like inverse feed

[HEED]

I have found that like ron said that a lot of those alarms are false. Check your lead in and lead off though and that is generally where I get rid of them. Inverse time feedrates are definately odd but they have been discussed extensively here just do a search and much will be revealed...

[loraxian]

Good tips. thanks. I'm starting to have some clew about what's going on.

 

The confusing part is it's outputting a G94 command rather than a G93 and it's placing a Feed rate command on almost every line but not all.

 

Based on info from other threads I changed the control definition to output unit/min on the rotary and 5th axis but it still is outputting the inverse feed rate.

 

Can I change the post to output something else?

 

[ 01-14-2009, 10:06 AM: Message edited by: loraxian ]

[loraxian]

I can't get it to output anything other than inverted feed - on most lines not all. I've looked at the post and it seems like it's set up to output units/minute. Am I missing something?

 

[HEED]

inverse time is a better feed scenario for 5 axis work... I don't know why really but that's what I have been told. Yes, it's confusing...VERY confusting to look at the code but also yes it's correct for a g94 to have and it has to have a "feedrate" on every line because it's not really a feedrate, it's a measure of time for the distance traveled. It has been explained/how I interperate it as in a feed move, xyzabc will all reach the point at the same time and it is smoother or better somehow. Someone that knows hopefully will chime in but it's how you want it from what I understand.

[HEED]

But if you really want to start to see some confusing stuff wait till you get into full 5x work... All tool positions are relative to COR on the machine. The tool is in outer space the whole time it's cutting and you have no idea where it is in relation to your part without some math. There's where a rock solid post and simulation come in I guess