Vertical lines at attachment points

[KMI]

Hi,

I am currently having a problem with lines being left on our parts where two arcs meet or where a linear moves connects with an arc. I have tried retrimming them, moving the lines farther into the arc and then trimming with no change. If I move the attachment point it just moves the line. I went back to the geometry to see if there was a mistake but it seems perfectly smooth when I verify the file. Any suggestions? I have a feeling that it has something to do with the control.

[maestro]

What kind of control?

[GREG]

It could be backlash on the M/C or if you have exact positioning on it may be tool flex.

Try a tool path rotated 45degs, If the line is still there its probably not back lash.

Cheers

[KMI]

Thanks for the reply. We have a Haas VF3D with version 11.11 in the control. We have had problems from the beginning with the machine hestitating at each attachment point, even the techs that came to look at it dont know what is going on. Haas allowed them to turn on the high speed machine feature and the problem went away for the most part. It will not do it if we run slower than about 30 IPM. We do mainly aluminum work and run up in the 90 - 120 ipm range so the problem is there basically all the time. the local reps told me that the control is trying to be to accurate. Sounds like sales BS to me. Anyway I'm left with lines on the parts and its getting very frustrating. We also have a power problem with this machine. What we were told it could do is not even close to what it accually does. As for the tool flexing we have tried to minimize this by using only solid carbide high helix endmills. it will leave the line even if we are only taking a .020 cut. Any ideas to take back to the factory would be great. Thanks.

[cadcam]

KMI,

Does it look like fasceting on the surface like a tollrence setting?

[maestro]

I don't know about the Haas, but our Fadals default to a G9 which causes the machine to check to make sure it is in the programmed place when milling. This sometimes causes these marks you describe. Try inserting a G8 before milling to prevent this. This is what we do on our Fadals. Hope this helps.

[KMI]

Thanks for the quick response. The machine will seems to stop for an instant then continue around the arc. I think that when the tool slows for that instant the tool pressure goes to nothing and it leaves a mark. You can actually hear all the spots that it does it at. The cutting tone will be nice and constant then it hits one of these points and the pitch goes up and then back down to the nice cutting tone. When we are going at about 100 IPM and pocketing the noise is very easy to pick out. It will also leave a chatter line if we are doing a tight turn like say a .625 radius corner with a .500 end mill. We used to have this work done on a 4020 Fadal and the finish was perfect. It seems to be something in the way that the control is utilizing the code. I will try what maestro suggested and see if that works. The machine will also lurch at the four quadrants. If we go under 30 IPM it is a perfectly smooth circle. If we speed up to about 60-90 it will happen at two quadrants, if we go above about 150 IPM it will happen at all four quadrants. I guess that the circle is generated in mastercam using four arcs, and as we speed up the problem rears its ugly head.

[cadcam]

KMI,

You are having block look ahead problems running the machine at the 90to150f range.

When you purchased the Haas did you get the high-speed add-on for the software?

I was talking with Jean (Jean Haas) at open house last month about this.

If you have a newer machine the option is all ready there.

You can Call haas the will tell you how to turn it on for a certain amount of hours to try it.

This and the other add on are now shipping with the new machines.

Now if this takes care of it you will have to pay for the add-on.

[ 11-24-2001: Message edited by: cadcam ]

[KMI]

I am supposed to have the option. Haas originally gave it to me and it fixed the problem. They told me that they were working on the new software and that once they had it fixed I wouldn't need the feature, after all I'm just contouring at 100 IPM and from what most people have told me, including the Haas reps, you dont need highspeed machine until you get into the really fast range. Haas then wanted the option turned off or have me pay for it. It was quite a battle because I bought the machine under the premise that it could do the work. After many calls etc. the option was supposed to be turned back on. It says it is on in the control but it acts like it isn't on. At this stage I am not really sure who to believe. I just want to make good parts so that I can earn a living. I'm tired of all the BS that I have gone through with the local rep and the lack of contact from Haas when we have had so many problems. We have had a belt break and a second one replaced because it sounded weird, they have replaced the encoder for the taping, they have changed out the vector drive and the mocon board, the tool changer switches have failed twice and required the tech to come and fix and the spindle orientation went out of tolerance by 20 degrees. It certainly has been a trying experience, after all this machine is only 8 months old. If there are other shops with this same machine that are having similar problems I would like to hear from you. I'm wondering if some of these problems are unique to the vf3-D machine.( Non-gearbox) I look forward to hearing from you.