G73 - Pattern Repeating

[newbie70]

Hi Members

 

I need help with G73 Pattern Repeating cycle.

 

I make a profile and like to machine with pattern repeating cycle rather than G71 rough machining canned cycle.

The graphic shows the tool is in collision with stock material and the tool goes directly to the profile

rather than machining the stock first. I tried this without giving stock to this profile, same result.

 

Where am I going wrong here in MCAM? There's one manual tutorial in Fanuc asking to use G73 rather than G71.

 

Thks in advance.

 

Newbie.

[Guest]

2 things come to mind immediately.....

 

Do you have stock defined?

Have you checked your lead in/lead out directions?

[newbie70]

I did define the stock. The lead is by default and the lead out is blank. I also set the stepover to Zero.

[The Cathedral]

Well, you're going to have to set your stepover to greater than zero, otherwise all it will do is try to do one pass. Stepover is how much it takes off between passes, zero stepover = one pass because there is zero to take off. Set it to .06 or whatever you want your roughing DOC to be.

[newbie70]

What I done is, I left a step over of 2 and  checked the Add line in lead-in and then I added  5mm to Length. It  works fine  for profiles other than ball shape at the front face. Now, when am trying to pattern repeat a  ball shape at the front face, it  won't select all of the profile up to  the top diameter. The machining starts straight away from the profile and keeps repeating even after checking the Add line in lead-in to 5mm length. Maybe, I have to give the length equal to the radius of  ball shape so that the tool starts 5 to 7 cuts away from the profile.

Any suggestions on this?

[The Cathedral]

I think I understand. Adjusting the lead - in adds an imaginary line that is tangent to the start of the profile. When you have a full radius as the start of your profile, that imaginary line is drawn straight down accross the face of the part--it goes straight down in your x axis of movement. Mastercam ignores movements like that so you could set it to 100mm and you would see no change. What I would do is add an extra line of geometry and use it just for that toolpath. So, if I understand correctly, what you are seeing is like picture one below. In picture two I added the line, and then all of a sudden you can see the lead in adding the extra length.

 

 

[newbie70]

Thks. Cath.  for your suggestion. Will give it a go. I tried with mine, it won't work.

[newbie70]

Hi Cath. I tried your way but to no avail. Did you define stock at all?

[The Cathedral]

No I did not. Do you have a part file you can share? I can take a look at it and see if you have something set wrong.

[newbie70]

Ok. I have attached 2 files one without ball shape at the front and one with ball shape at the front. I tried this without defining the stock with a straight line geometry up X0.

The tool gets embedded in the stock on simulation even after adding line in lead-in. Here the step over is 1.0

I tried with -ve stepover of 1.0 same result. The tool cuts the profile and starts repeating.

 

[Guest]

How about the actual Mastercam file?

 

Moved this to the main forum too as this is not an educational user issue

[newbie70]

It should not happen when there's ball shape at the front face. It's a technical issue.

Like I mentioned in my earlier query, it is one of the tutorials.

[newbie70]

I fixed the problem without going into technical issues.

 

I made a step of 0.2 diameter by 0.2 length. It did work.

I have attached the ball shape profile at the front face machined with a stepover of  1.0 - 27 passes, add line in lead-in to 5 mm. 

Done n Dusted.

[crazy^millman]

I fixed the problem without going into technical issues.

 

I made a step of 0.2 diameter by 0.2 length. It did work.

I have attached the ball shape profile at the front face machined with a stepover of  1.0 - 27 passes, add line in lead-in to 5 mm. 

Done n Dusted.

 

Can I throw this out here. If you used Material then you would not have all that wasted movement. That is a lot of air cuts that is wasting too much time. If you came into any shop I was running and programmed a part like that I would call it no good.

 

Either define the stock or offset the finish chain and then trim it to the stock to get rid of all air cuts.

[newbie70]

Yes. I reduced the air cuts to nearly 0 times  by changing the pattern offset angle to 90 deg, the step over to 2.0,  reduced no. of passes, reduced the add line length to 1mm.

But it was just a try out.

[Dharanmaddy]

What is Pattern Offset Angle in mastercam and then how to gives in  canned pattern cycle (G73)