1994 vf3

[dustincram]

Hi all,

I ran a few dozen 6061 parts on a new to me 1994 vf3 last week and I was having trouble with the x or y axes over traveling on higher feed rates. I had a trapezoid shaped pocket with acute angles in the corners and roughed it out with a 3/4 end mill, then cleaned up the corners with a 1/2, first by taking .2 doc climb cuts at 125 ipm, then finishing it with the 1/2, .005 cleanup. By feed holding after each op i narrowed the problem to the corners during the .2 doc cuts, it would leave .015 or so deep gouges at the end of travel. When I single blocked through it was fine, and changing the feed to 40ipm fixed it.

I thought it might be cutter deflection, but it was at the end of travel where the tool was cutting air and it did the same thing cutting polyurethane foam.

I searched the forums a bunch and there was talk of a parameter for maximum corner rounding but I think my machine does not have that, all I can find are servo parameters that I am hesitant to mess with.

All other tool path seemed ok, I ran the 3/4 at 80-100 ipm. Also, I re made the tool path in sprut cam with circular lead in and lead out and it still left a big mark at the end with high feed rates ( well higher, anything over 40).

One thing I noticed was a little groaning/ buzzing of I think the x while stationary. Loading the axis a bit by pushing on the table quiets things. Seems to just be dithering a bit between encoder counts, probably not a big deal.

Ideas? Thanks!

[txcncman]

Have you measured for/adjusted for backlash?

[dustincram]

Have you measured for/adjusted for backlash?

Hi, I have measured it with an indicator in the spindle in all three axes, seems less than .0005 but it is hard to say how it is under load. Is there a good way to test that? Also, it holds tolerance well on the other operations. Thanks for the reply.

[txcncman]

I do not know about your machine, but some have a code or setting for "exact end point". The only other solution I can think of is to compensate in your programming as it seems you are doing.

[underthetire]

Let's get to the history of machine tools. It wasn't till mid 90s that you started to see some of the high end machines really get capable of high speed machining. Haas was still pretty early, and hadn't got anywhere near where they are now. Small dc motors, cheap encoders, not a lot of processing power. They were good for what they were back in the day. straight lines, go like snot, but angles and radius were a problem. The first high speed horizontals were comming out about that time, and I can even remember the first mori sv50 to hit the market, around 1995. This is not to say you can't make it better, idk. Drive tuning, checking the motors for wear, etc., but just don't expect it to run like a 10 year old haas.

[txcncman]

I was about to add that I have not run or even seen a 1994 Haas since about 1999.

[dustincram]

Let's get to the history of machine tools. It wasn't till mid 90s that you started to see some of the high end machines really get capable of high speed machining. Haas was still pretty early, and hadn't got anywhere near where they are now. Small dc motors, cheap encoders, not a lot of processing power. They were good for what they were back in the day. straight lines, go like snot, but angles and radius were a problem. The first high speed horizontals were comming out about that time, and I can even remember the first mori sv50 to hit the market, around 1995. This is not to say you can't make it better, idk. Drive tuning, checking the motors for wear, etc., but just don't expect it to run like a 10 year old haas.

Hi underthetire, thanks for the post. I was hoping to run accurate tool path at at least 200ipm with this machine, is that in your experience not possible? Would that really be considered high speed machining? My open loop stepper system does 60ipm on a knee mill with no problem, it would be disappointing to not even be able to do that on the haas. I am guessing there is something else going on here, maybe with the code or tuning but there are so many of these things out there running in shops it's hard to believe they are all running at 40ipm or below.

[dustincram]

I do not know about your machine, but some have a code or setting for "exact end point". The only other solution I can think of is to compensate in your programming as it seems you are doing.

Thanks txcncman, I looked into the exact stop setting some and it seems to just apply to canned cycles, but I might give it a try anyway. Good tip, thanks.

[metalmansteve]

I would say 200 inches per minute is pushing it on a 18 year old HAAS....that's pretty fast

[underthetire]

Ya, no way your getting any accuracy at 200ipm. I'd say anything over 75 for tight contouring would be pushing it. Early haas we're known for blowing corners out at fast federate. 100 ipm was considered pretty fast back then, you couldn't believe my surprise when I saw that first sv50 mori contour at 200ipm. Early days of high speed contour control, brings back memories.

[dustincram]

Ya, no way your getting any accuracy at 200ipm. I'd say anything over 75 for tight contouring would be pushing it. Early haas we're known for blowing corners out at fast federate. 100 ipm was considered pretty fast back then, you couldn't believe my surprise when I saw that first sv50 mori contour at 200ipm. Early days of high speed contour control, brings back memories.

Well, I suppose that will have to do! I am sure I will figure out where things can be pushed. Still think I have some troubleshooting to do on this, it is not consistent with how it is cutting on the rest of the parts.

[underthetire]

See if Haas has a tuning procedure of some sort. Motors might just be way out from each other. I'm not sure on the older haas setup, seems like you had to adjust lag on those so the motors followed commands the same. I'm sure ken or someone will chime in.