tools sticking in spindle, excessive runout

[stustev]

Does anyone have the problem of tools sticking in the spindle taper, excessive runout, excessive chatter, low tool life? I have 5 Haas mills. Each of them had all of these problems. I have a fix. We don't fight this anymore. I have 2 machines with more than 5 years on the fix.

[dertsap]

chatter and tools sticking in the machine at times can be caused by the pull studs being excessively over tightened which in turn causes the taper to swell (beleave it or not) , one machine we ve got sticks at times ,and when i remove the stud and retighten it the problem goes away ,some guys i work with far over tighten them , i beleave there is a suggested torque setting with the use of loctite

[pit202]

I had have those problems on my TM-1 ( europe - without ATC ) couse our polish service have gove me to short pull studs, and tapers have beed push out only by the air , few days after I try with longer pull studs and that was the solution - till now I haven`t those problems.

This is only my case, I don`t know whats your problem, try to establish how your taper are pushed out, by the air or by piston.

[dcoupar]

Stustev,

So, what's the fix?

[HuFlungDung]

Double check the taper for flaws, rust, scoring, etc. Examine the shanks for bright/burnished spots that are indicative of a bump in the taper. If you have actual tool runout, then there must be some kind of fault like this in the taper.

Do the limbo and get a bright light in there to examine the taper with. With a nice straight stone, hone away the bumps around any dents. Lay the stone in the taper, and swipe around over the dent while moving the stone up and down a 1/2 inch. Let the stone 'find' the burr around the dent.

If the taper has general rust, then use a fine grit emery cloth wrapped around a nice straight wooden dowel. Split the dowel down 1" from the end with a hacksaw cut, and slide the end of the emery cloth into the saw slot. Then wrap the cloth evenly around the dowel in barber pole fashion. The other end of the cloth you hold down to the dowel with a finger tip, the same one that applies pressure to the dowel. Keep it flat. Use a dowel large enough in diameter that it will not get stuck in the retention knob retainer. Run the spindle at 400 to 500 rpm and gingerly polish the taper. Keep in mind that you want nice even polishing from top to bottom, so don't carelessly overwork one area. Work it all as evenly as you can.

Then call Walt

[Geof]

Excessive runout and chatter suddenly arising without any crashes is very often due to a chip jamming in the taper. Sticking of the tools in the taper can often be caused by an oil glaze build up inside the taper. The solution in both cases is thorough cleaning. You can get a cleaning device with three helical shaped squeegee blades in either a rigid plastic or a slightly abrasive tipped plastic for doing this.

After a good cleaning and lubrication with light oil if the tools still stick look for problems with air pressure, line drop, sticky solenoid valves.

Leaving a tool in the spindle overnight oftens results in it sticking the following morning due to thermal contraction of the spindle.

Working a tool very hard without adequate cooling can cause sticking due to expansion.

By the way go through the threads in the Haas forum and you will find this has been discussed before.

[DEAN]

Why make such a post? You hint you have a solution to a problem but don't explain the solution, Sheesh

[stustev]

Gentlemen,
I was not asking for advice to fix my machines. I have fixed them. I put hardened steel inserts in the spindle taper. Each of my machines had excessive bell mouthed tapers. This caused the drawbar pull to be reduced. This caused the tool to touch the taper on only about the upper 1/2 to 3/4 inch of the tool holder. This caused the tools to runout a lot. This caused the tools to be not very rigid. This caused the tools to stick in the spindles a lot, not just after a long run. This caused the tool life to be short.
This was not from abuse. We use these machines almost exclusively on aluminum. We program them with a 40 taper in mind. I had Spindle Grinding Service from Detroit come in and grind them once. He check them the NEXT day and told me they needed ground again. I replaced the spindles in three machines. This I did each year for three years. That means a total of twelve spindles (the original and three replacements each for each of three machnies). Each time, within two months of replacement this problem started in each machine. I got tired of replacing spindles. I even installed the high drawbar pull options. We sent all of our 40 taper holders (a couple hundred) to a grind shop and had the tapers ground to make sure they were clean and straight. All this did not help.
I developed the fix and have had NO problems for five years. The machines cut more solid and accurate than when they were new. I purchased three of the machines new. They are just as accurate and solid after 5 years as they were when I put the inserts in. We have been able to increase the feeds and speeds of our cuts as a result of the increased rigidity of these machines.
I looked for past posts about this and found none. Would you direct me to where they are?
I posted this to start a conversation about this and to gauge the amount of problems people have with the spindle tapers. I have inserts to install and can do it or I would be able to help someone do it.
I waited for 5 years to make sure this is the fix and any problems would be found. I have had no problems whatsoever. This has worked on a VR-11, a VF-10, VF-6, and two VF-4's.
Thanks - sheesh - whew!
Stuart

[Geof]

Interesting but it would have saved bandwidth had your latest post been your first.

How old are these machines? What are your typical speeds, depth of cut and feeds? Do you habitually use very long tool holders? How do you machine out the existing spindle taper to install your inserts?

[stustev]

The three machines (VR-11, VF-10, VF-6) I referred to in my previous post were purchased new in 1998. Haas replaced the VR-11 in 1999. If you consider the first year for the original spindle and then one year per spindle for each of the next three years and then five years on the fix you will see the machines had spindle taper problems from the start.
They each have the 10,000 rpm 30 hp spindles. Our programs will usually go to 8,000 rpm max. Our typical cut would be .250 depth of cut and 100 ipm. We use the shortest length possible for all cuts.
We do mostly aerospace parts. Many of these will have deep pockets. For a pocket that gets deep we will use a short tool for as long as possible and change to a longer tool when necessary, somtimes more than one tool change with progressively longer tools. We try not to use just one tool and let it hang out a long ways.
The VF-6 has a Tsudakoma tilting rotary table that allows us to use short tools as much as possible.
These machines get used two to three shifts a day 5 and 6 days a week. They run continuously and remove a lot of metal.

[stustev]

forgot to answer the last question. boring bar in a vise.

[Geof]

Originally Posted by stustev ....These machines get used two to three shifts a day 5 and 6 days a week. They run continuously and remove a lot of metal.

This must equate to a lot of spindle hours per year. One year for you would be possibly 3 or 4 for my machines.

So far I have never had any of the problems you describe but my machines are smaller.