4th Axis Positioning

[Rob B]

I can't get MC to post A axis rotation correctly. I'm using Transform toolpath to rotate to the cut postion. I need the machine to rotate 1.5 Deg pos and 1.5 Deg negative. My 1.5 pos is posted correctly, but when I enter my 1.5 Deg neg in my Transform para page, the post generates code that is 358.5 deg. I want the post to generate code that is -1.5 deg so my 4th axis doesn't have to do a complete revolution each time. My boss hates to see this thing take so long to move a total of 3 deg. It wouln't be a big deal except tise is production job and needs everything trimmed as much as possible.

 

Thanks

Rob

[Eric S.]

Hi

 

A quick fix if you are going to run lots would be just to edit the program. Find A358.5 and replace with A-1.5. At least it would be running ok until the post get worked out

[Eric S.]

So when you backplot the operations does it look right?

[Rob B]

I would like to get MC to post what I need. So if this program is needed and I'm not here. It will run correctly when post.

 

I'm using mpmaster post v9.

 

Thanks for the suggestion Eric

[crazy^millman]

Hum would think thiscould be a machine parameter. Look in the book and see if it will do shortest position. If not you could always put an maunal index in the mi & mr to get the angle you want exactaly a pain but does the job. I think the post can be configured for shortes distance but think you need to look at the +/- axis direction callout and something to do with must be 0 to 360 as well could off base there kind of need a smaple file to see if on the right track.

 

If the Maunal index intrest you Zip up your post email it ot me and I will add it to it for you and send it back.

 

HTH

[TomHemphill]

don't know if this is the same thing but I had a similar problem on a 5x cylinder head program and I was told to set misc.integer #4 to an angle close to where I wanted to go and force a tool change in the "change nci' button and it fixed my problem ,this was using MP_GEN_5X post I was moving more than a few degrees though more like 90 to 180 The other thing was the prog would stop at the forced tool change and need to be restarted manually I was told this could be fixed in the post but I haven't figured out how...

don't know much about post editing yet

 

Tom

[Travis_Buchanan]

I don't know 4-axis, but on all my 5-axis post I use a misc int to flip the b axis if I don't like the way it positions, or if I can save a retract/unwind. Looks like a post for a 4 axis should have a misc value for +/- 360 to help you get the angle you want. I don't know why sometimes the head will start at C0 B90 and on the next tool path C180 B-90, but using a misc int is the way I fix it.

 

Also your machine parameters are set in the post, min & max angles. If they are set from 0 to 360 you aint going to get a -1.5. This is what I would look at 1st.

 

Crazy Millman, straighten me out if I am wrong here.

[Rob B]

Travis,

 

MAN!!!!!!!!!!

 

Travis that was to easy!!!!!!!!!!!

I have looked at that so many times and told myself it needed to be limited to 0-360Deg. That sucks. I spent so much time looking all around this. Thinking all the time that I had this set correctly.

 

Thanks for turning on the light. I can see clearly now. Out of the Dark and into the Light.

 

Isn't it funny how we all are able to pickup on different things. Thats what makes this forum rock. It's like we all work in the same shop and are able to help the guy thats working next to ya.

 

Thanks again to all who posted.

Rob

[Rob B]

This isn't right.

I now get -718.5 deg posted instead of 1.5 deg. The above mentioned fix by Travis worked to get post to output -1.5 deg. But now it outputs -718.5 instead of 1.5 deg.

 

Now where's the problem.

 

I feel so stupid sometimes!!!!!!!

[Travis_Buchanan]

try settting your min at -180 and max at 180.

[Rob B]

Travis,

Were do I find this setting. I'm looking in the post but can't find it.

 

Using mpmaster post

[Travis_Buchanan]

Sorry that is not in the mpmaster post. What did you change to get it to output a -1.5? I just downloaded the mpmaster post.

[Travis_Buchanan]

After looking at the post I don't really know anything else to add except maybe you need to add logic somehow to toolchanges like (if A - previous A > 180 then a=a-360.) I think I am in over my head now so I am done. Millman?

 

[ 05-03-2005, 10:22 AM: Message edited by: Travis Buchanan ]

[crazy^millman]

Been in email with him took yesterday off to help my wife become a citzen of the United States of America. She does the sewar in and we are done with whole system thank god. Sorry had to get that off me chest.

 

Ok honestly it can be done but it will require soe mtweakign with the post. Now we can use C-planes to do this but need ot add the type of logic used by MPGEN5Ax so wit hthat you were on the right Track Travis. Now the hard part adding that ang etting that to work right will take me a little time but I will get it or ask the right people for help. Yeah I got some connections and some favors owed besides I see a need for this and will only help make everyone's life easy. I will posr back me results. Oh yeah for all the speel checkers I know it is suppose to be my but I like me better.

[crazy^millman]

Well this is very instresting becuase there may be a easy fix for this. Have your dealer contact Dave and get the MPMASTER_FADAL post all of the logic is there for this. It will post the A- and A+ in my mind perfect for a job like this. The Fadal uses the A index logic different than most other machines and in this case might do exacly what you want. It will post out A-358.5 then post out A1.5 try to see if they are like this will it work.

 

Check your mail.

[Richard@WCCH]

Ron, you're correct as usual. My Fadal post outputs A360 and A-360 moves. I remember being told that there is a difference between Fadals and most other controls. The + and - indicate the direction of the axis movement while angular values indicate position relative to zero. As you stated A-358.5 will move A-1.5 from zero.

 

Richard

[TomHemphill]

Richard,

Had a problem posting some 4x manifold runners...said I had post errors I think the problem is I'm not set for the angle wind up machining around a rectangle with radius corners traveling parallel to x using rotary 4x Do you think the Fadal post will fix that? (Don't mean to hijack the thread)

 

Tom

[crazy^millman]

Nope Tom might need to look to the C-plane and make sure the X is facing to the right when you are looking down on the cut. ( We call this the X axis right hand rule for 4th axis work ) If the X is not you will get a post error if you close the window with code should see X axis rotation error and that would confim what I am saying. If not sure what I mean send me a file and will be glad to write you some text and give you some examples of what I mean in your File so you have a more visual verse worded example.

 

HTH

[TomHemphill]

Thanks Ron ....that's probably it I know I have x facing left ...didn't know it mattered.. but as I'm typing I'm not even sure about that When you say looking down the cut do you mean looking through the center of the part that is on the rotating axis? Thanks for the help offer If I can't get it through my thick head this way I'll send it

Thanks again

Tom

[TomHemphill]

oops.. I see you said down ON the cut not down the cut I'll work at it a little more before I give up

 

Tom

[crazy^millman]

Well what I mean by this is the apporach of the endmill in Z. If the part is coming from the bottom then the apporach of the endmill is 180 from the top. So you need the X to be facing the opsite if you were looking at it from the top but if you were looking down on the cut in Mastercam then it would look just like if you were looking at it from the top view. The X is always the postive direction of the axis so if you have it facing to the left you have the X facing toward a negative direction when looking at the Rotate C-plane tool. This in my mind is the best way to keep it straight. Go to isometric view then hit the rotate button if the X is not facing you then the X is not facing the right way. Most time about y solves the problem but other time you may have to rotate thing alot of time before you get it to be exactly right.

 

HTH

[TomHemphill]

Thanks Ron I think I understand now and that seems to have solved the problem The code looks right I load it later and give it a try I owe you a cold one

 

Tom