How do I interpret tool hours?

[rawen2]

Here is a question that I'm sure doesn't have a black and white answer. On a Haas VF series what would 8,000 hours of spindle time be comparable to if I was looking at the mileage on a used car? I'm assuming most newer cars will easily go 200,000 miles if properly maintained.

I know there isn't a definite answer since the tool could have been operated by a little old lady who only machined wax on Sundays, never took the spindle over 3,000 RPM, and kept the rapids set to 50%. Or it could have been used by an underpaid malcontent operator who machined super-unobtanium (HRC 70) at 7500 RPM with the end mill buried until the load meter was at 120% or until the end mill snapped off - whichever came first.

I'm still looking for a used VF for my garage and would appreciate any insights.
Thanks,
Ralph

[HuFlungDung]

It is impossible to give anything except a general recommendation, because a crash could damage a spindle in the first few minutes of operation. Then they might have ran it that way for the next 7999 hours

You are getting it at a discount when used, so the normal wear and tear is to be expected. Some guys don't get good life out of an exchange spindle, so even though they like to pretend the spindles are mass produced, they are in fact, custom, each one of them. This is because the exact fit of the bearings, the way it was assembled, the care and attention of the technician who did the assembly, these all bear on the life and performance of the spindle.

So first you ask if the guy has crashed the spindle, and find out the details, and how often this happened, and what condition is the taper inside. Ask about changes in noisiness or compare it when running to other similar Haas machines.

Run the spindle on the warm up program and work up to the max speed and let it run there without coolant flow for an hour. Coolant flow through the head will normally cool the spindle, but by running without coolant, you can get some sort of idea of the rate of temperature rise. I've done this on ocassion with my machine when I happened to not want coolant on, and the bearings were redone just a couple of years ago. After an hour of running, I get a perceptible warmup of the spindle nose, but only a few degrees. Before I rebuilt it, the spindle would never warm up at all, and this was consistent with the internal condition because the preload spacer was loose and not locking the main bearing races together as it should have been. The tool finish I was getting before the overhaul was not as good as it was afterwards.

The rate of temperature rise as well as the noise level are your main superficial indicators of the spindle condition. However, the transmission also contributes to the noise, so it is difficult to isolate one from the other without a fair bit of trouble, ie., you can run the transmission and spindle together or the transmission alone with the drive belt off, but not the spindle alone unless you were to power it somehow with a drive motor on the table running a pulley on a toolholder.

So I changed the bearings after about 6000 hours, but it really should have been looked at many hours earlier, before I took possession of the machine. I suppose a machine that has 8000 hours that seems alright at the moment might run another 2000 or 4000 hours or more, plenty of time to make enough moola to replace it in the future, after you've subjected it to a couple of your own booboos Hopefully not, though

Now there are oilers on the ball slides, so you might have to remove some way covers and actuate the oiler and run things back and forth to see if you've got oil through to all the ports. Sometimes these will gum up and plug. The linear ways and the ballscrews should look clean and have a light oil film.

[rawen2]

Thanks Hu,
The reason I bring it up is that I've looked at a lot of Haas VMC's over the past year+. When I say "looked" I mean on the internet. There's only been one machine close enough to go look at in person. It seems that less than half of the ads state the hours on the tool. To me that's like advertising a car without stating the mileage.

Last week I was talking on the phone to a sales person about a VF-0 he had and I mentioned that I was also looking at a VF-0E. He asked the name of the seller. To my surprise he quickly found it on the internet and noted that it had about 8,000 hours on it. He said "8,000 hours is a LOT of hours on a Haas." Then he repeated it. OK, maybe it is or maybe he just wanted his tool to look more attractive. The one he was selling had a newer spindle and new software at some point. The tool was a 1999 VF-0 and a picture of the screen showed servo 3,350; motion 511; spindle 481. Seems pretty low servo time for a decade old machine that "made parts for Haas." But I seem to remember reading here that a software upgrade will reset the hour meters. He didn't think that was correct and was representing it as actual time. From the pictures it looked pretty clean and well cared for. But so did the VF-0E with 8,000 hours.

I can't afford to have every machine I'm interested in inspected so I guess what I need to do is negotiate the best price on a tool that looks promising and make the offer subject to a favorable condition report from a Haas tech. Is it normal in the CNC machine world to have a written contract stating "subject to satisfactory inspection" or something similar? I'm somewhat nervous that an unscrupulous seller could verbally agree to a good price but not honor it after I have the machine inspected. At that point the seller would have the leverage of knowing I'm invested in the deal to the tune of several hundred dollars. Of course if the inspection found any serious problems I'd walk away for sure.

In my machine search I've already run across a few individuals that I wouldn't turn my back on if I met them in person. Anyone want to recommend any used Haas dealers on the West coast? Or any to watch out for? I'm listening. Us newbies need all the info we can get. I've already contacted the HFO's in Portland and Boise.

Sorry for the long post. This forum has been a tremendous help and I've learned a lot from reading it daily. Thanks to all of you who share your knowledge.

Ralph

[Geof]

I looked at your picture and in the upper left corner of the screen where the flash reflection obsurs things you can see ....DAT (MDI)

The complete line could be; POS RAW DAT and if this is the case I think the numbers shown are the real numbers which are not set to zero by a software reload. These are visible in DEBUG mode.

Ask the Haas dealers you have talked to if DEBUG mode shows the true spindle hours or phone Haas and ask them.

But having said this the hours shown are very low for a ten year old machine, but not impossible I guess.

[rawen2]

Geof, I took your advice and found the time to call Haas on my lunch break today. I asked the phone tech if there are any hour counters that are not reset to zero when a software upgrade is done. He said that either a software upgrade or a processor change zeroes all of the hour counters. I forgot to ask specifically about DEBUG mode.

Hope that info also helps others.
Ralph