fadal with wobbling tool holders

I am not the usual operator of this machine. I am more of a button pusher on the cnc's so not sure what to look for. I believe it is a Fadal VMC 3016 built around 1992. The tool holders have a visual wobble when the machine is running about 3,000 to 6,000 rpms. Tolerances on work pieces are are all over the chart, some parts on dead on some are .008 off either over or under.

I think the spindle and the tool holders are past due for replacement. I am guessing that it has between 15k and 23k hours on the spindle and bearings based on 4 hours aday run time for since 1993?

How can I check this out so I can have something intelligent to say to the supervisor when he comes back on tuesday?

Thanks,

karl

Can you Blue up a tool holder and check the spindle contact pattern?
What about using a bar to get an idea about the retaining spring pressure?

The drawbar belleville spring washers are probably shot. You have lost all your tool retention from the drawbar. Don't operate the machine in this condition until it is fixed or you will damage the spindle taper. Check your PM for a message.
Bill

I can tell with almost 100% certainty that this is a belleville washer issue. The bellville washers keep tension on the drawbar to hold the tool in the taper. On Fadals, they wear out all the time. We also had a Fadal 3016, as well as a 4020 and an 8030. The 3016 seemed to have had this issue a lot more often than the other two. The tools wobble and don't cut to size because they're not even all the way up in the taper.

I seem to remember that it wasn't a very expensive repair, especially for parts, since they are after all, just washers.

~eric

Probably the #1 reason people think Fadal's suck and why they sell them cheap.

Bellevilles. They are $50 or $60 from FadalCNC.com. Don't forget to also get the "drawbar floater", that has almost as much to do with tool retention as the bellevilles, that's a whole other $20, and 2 more minutes to replace since you are in there anyways.

Figure half a day if its the first time you've done it. It will almost be like having a new machine.

fadal with wobbling tool holders.

Karl,
The problem you describe could very well be the bellevile washers.
However, it would be best to isolate the problem and make a sound recommendation to the powers that be.
1. Clamp a tool and see if it being held tight in the spindle.
Possibilly remove the drive keys and see if you can turn the tool holder in the spindle when it is clamped. That would indicate bellevile springs. Check the tool retention knob, make sure you are using the proper ones.
2. 3t3d mentioned bluing up a holder and see what kind of contact you have in the taper. While you have the drive keys out, try a tool holder with out a retention knob. Hold it up in the spindle and twist it a little one way and then the other way. Less than a quarter turn total. See what kind of contact you have and look for high spots. The high spots will show as clear areas on the holder. What you are looking for is even pressure over the entire length of the holder. I find it is best to use a shinny holder not a black oxide holder. The ground shinny holders are easier to "read".
O yes, use "non drying" Hy-Spot bluing. NOT lay out die.....
3. If the spindle taper is messed up, call us we can fix it in place.
Regards Walt Ammerman Jr.
Spindle Grinding Service Inc
Albion, Michigan
"Have Grinder Will Travel"

And if you elect to have the taper reground in place, LET ME KNOW.
We can split the travel charge.

Joe

drive keys

You can not remove the drive keys on a Fadal, ther are part of the spindle nose.

Do a little checking with a dial indicator to see if the spindle runs true without a holder. My guess is also tool drawbar belleville spring washers.

Simple after checking RO...

...on spindle. Bellevue spring washers.

Steve

Fadal w/wobbling tools

in2glam,
By golly, I believe your right.
I was thinking of a test bar w/o a tool flange.
Never the less, how about just checking tool retention.
That would give us all many answers.
Then ofcourse getting a readout on the contact "tool" to "spindle"..
Then check the retention knob to see you have the proper one.
Proper length as well as the proper angle on the clamping face.
Then check the drive keys for burrs....
Regards Walt....

thanks everyone it was the washers

Thanks everyone for the fast help. Pulled it apart yesterday and 28 of 40 washers were busted.

Had the washers on the shelf, as well as a new draw bar, floater, and ball bearings.

I just didnt know what they were. A little training goes along way.


Thanks again for your help.

Karl

wobbling tool holder

Karl,
When you get the drawbar reassembled and reinstalled the retention should be 2000 pounds on a 40 taper and 4000 pounds on a 50 taper.
Then make your runout checks and the bluing checks to determine the condition of the spindle taper.
Regards Walt...

Walt,

Shy of an expensive special gage to check the draw bar tension, is there any other way to check it? Also, what is a common amount of pull back on the draw stud? I ask because I have some tool holders that when installed into my spindle (old Milltronics Partner 4) they are just maybe a few thousandths shy of seating, i.e. they will shake against the drive keys. Then I have other tool holders that suck up and checking the height of the draw bar with nothing, then with one of those tool holders, I have about .020" difference... which according to Milltronics, is correct.

I have checked my Bellevilles, they are in good shape, the proper number and installed correctly. The inner spindle surface is a bit worse for wear to say the least, but it doesn't seem to have ever had a tool spun or really hammered it there... more like 20 years of someone banging the draw stud into the side of the taper as they were changing tools (not an automatic tool changer).

Before I take it all apart... again... and try to reset the height of the grabber, I was hoping to get an idea on how much pull back distance and such is "normal". I also suspect I might be able to calculate gripper tension as I have a big pancake air cylinder that pushes the draw bar down to release... if I forget to turn on the compressor and pressure drops under 75 or 80 pounds, I can't depress the draw bar enough to release the tools... so I was thinking of measuring the bore, checking the pressure and seeing what the down force is, would that be the right calculation? Or is the balls working on the angled surface of the draw stud adding any mechanical leverage to the equation?

Walt @ SGS Inc. said:

Karl,
When you get the drawbar reassembled and reinstalled the retention should be 2000 pounds on a 40 taper and 4000 pounds on a 50 taper.
Then make your runout checks and the bluing checks to determine the condition of the spindle taper.
Regards Walt...

Click to expand...

Walt,

When you say 2000 pounds at what dimension is the 2000 pounds determined. Every spring has a force @ length.

Thanks!

I think Walt is referring to the "in position" length when retaining a tool. Obviously that force changes so that stack setup is pretty critical to get both length and force correct.

Fadal w/wobbling tools.

Karl, Glad you could isolate and repair your problem.

As far as the clampling force of 2000 lbs. for a 40 and 4000 lbs. for
a 50, that would be like Viper said, at the clamp position.

Another check I make is to clamp a tool in the spindle and make sure it is tight. Then loosen the retention knob and recheck.
Keep doing this until the tool is no longer clamped tightly in the spindle taper. Then remove the tool holder and measure the "gap" between the end of the tool holder taper and the flange on the retention knob. It is not rocket science but you can get an idea how much over travel the drawbar is capabile of.
Brian, another check for you to make is to place your tool holders one at a time in a taper (like the one you use to assemble tools) then measure to the clamping surface on the retention. See if they are all the same dimension.

Another thought, make sure they are all inch or all metric. The inch holders are about .110 longer than the metric holders. I am talking the threads in the holder where the retention screws in.
Make sure all your tool holders are the same. Not some Cat 40 and some BT 40....

Abnother thing to check is to make sure the holders are not jamming on the drive keys.

Thats all I can think of for right now.
We use Command Retention Gauges.
Regards Walt.....

Karl_Kunkle said:

Thanks everyone for the fast help. Pulled it apart yesterday and 28 of 40 washers were busted. Karl

Click to expand...

Karl, so I know what to look for, when you say the springs were "busted", do you mean literally cracked in two or were they just flattened out and thus not working anymore?

Thanks,

Paul T.

Draw bar check

Brian said:

Walt,

Shy of an expensive special gage to check the draw bar tension, is there any other way to check it? Also, what is a common amount of pull back on the draw stud? I ask because I have some tool holders that when installed into my spindle (old Milltronics Partner 4) they are just maybe a few thousandths shy of seating, i.e. they will shake against the drive keys. Then I have other tool holders that suck up and checking the height of the draw bar with nothing, then with one of those tool holders, I have about .020" difference... which according to Milltronics, is correct.

I have checked my Bellevilles, they are in good shape, the proper number and installed correctly. The inner spindle surface is a bit worse for wear to say the least, but it doesn't seem to have ever had a tool spun or really hammered it there... more like 20 years of someone banging the draw stud into the side of the taper as they were changing tools (not an automatic tool changer).

Before I take it all apart... again... and try to reset the height of the grabber, I was hoping to get an idea on how much pull back distance and such is "normal". I also suspect I might be able to calculate gripper tension as I have a big pancake air cylinder that pushes the draw bar down to release... if I forget to turn on the compressor and pressure drops under 75 or 80 pounds, I can't depress the draw bar enough to release the tools... so I was thinking of measuring the bore, checking the pressure and seeing what the down force is, would that be the right calculation? Or is the balls working on the angled surface of the draw stud adding any mechanical leverage to the equation?

Click to expand...

This is what works for me.

Take an old or unused toolholder and make a .050 washer to space the pull stud up. When you install it in the spindle it should not rattle back and forth on the drive keys. If it does your in need of bellevill washer replacement. I only have Fadals so not sure if this will help
with other type drawbar systems.

Walt,

I did the "back the stud off and measure the gap with feeler gages" trick too, first thing I did... and yes, I have .020" on some of my holders, and nothing on the others (the ones that are loose). I have a mix of BT and CAT, but my machine isn't a tool changer, and I have the proper pull studs, in several different brands, for each type, BT or CAT, and have tried changing studs with no effect. The ones that are loose, are loose with any brand of stud. I might also note, it's not just the BT's or just the CAT's that are loose, I have several of each type, from numerous different manufacturers, some are used holders, but quite a few of the loose ones are also brand spankin' new.

In2Glamis, according to Milltronics, their specs are to only have .020" of pull back. My draw bar has a shouldered washer, that washer rests on a step in the spindle itself. Between that washer and the top nut of the draw bar is the stack of compressed Bellevilles, under tension by screwing the top nut down so many turns and locking it in position. The opposite end of the draw bar (the bottom) has a carrier with 4 ball bearings to grip the draw stud, this is threaded onto the end of the draw bar to a shoulder and a setscrew up the center locks it in place.

I can take that gripper off and face some off the back to increase the "pull back", but before I do, would like to have an idea of what is standard, what would be too much, and really, the big question, is why do I have tool holder/draw stud combinations that vary about .020-.030" in effective length? Maybe this is common and most brands of machines have more pull back and it's never noticed... that I dunno.... and why I'm asking.

PaulT said:

Karl, so I know what to look for, when you say the springs were "busted", do you mean literally cracked in two or were they just flattened out and thus not working anymore?

Thanks,

Paul T.

Click to expand...

I'm not Karl, but I know the answer. They break into pieces.