Hurco VM1 tool sticking in spindle

[rpotgeter]

When I change a tool either maually or automatically the tool seems to sometimes stick in the spindle taper for a split second. I have already adjusted the gap between the air cylinder push rod and the draw bar to just over .100 the oil resevior is full and I don't know what to try next. O by the way this does not happen every time Anyone have any ideas? Rick

[lathe tech]

Do you have the correct length pull Rk knob?

[underthetire]

Does it stick after running, then sitting. Could be a spindle going out. Taper gets warm, sweats the tool in, then cools. Also had some or all of our hucos blow the seals in the unclamp cyl., causing intermittent sticking.

[bloke]

If it continues to get worse, it may be the solenoid valve. These can leak internally and prevent it from unclamping. If you get a total failure, connect the top of the booster directly to the 12mm incoming air pipe in the head and see if it releases the tool.
If it fails with the solenoid out of the equation, it'll probably need seals like UTT said above.

[rpotgeter]

I talked to hurco tech today and at this point I have increased the drip rate of the inline air lubricator slightly and cleaned and lubricated the spindle taper. I will monitor and post anything new. Thanyou all for your input.

[hurconotes]

You can put graphite lube on the holder. If it has the coated taper on the tool this will cause it to stuck also. It may be time to replace or rebuild the unclamp cylinder.

[Rockyr49]

Could be a couple of things. I would first check tool knockout. I know they want the gap set to about .100", but that is just an estimate. Hold a tool in the taper with the draw bar unclamped. Then clamp it. You should see the tool move up .020" or so. This is positive tool knockout. The drawbar should knock the tool from the taper. The other thing I would look at is contact from the tool holder to the taper. Use a small amount of non-drying bluing. Dykem is what we use. Not the spray or liquid, but non-drying bluing. A small amount of that on the tool holder taper. Clamp it in the taper and then remove. Most likely you will see all the contact at the small end. This will cause the tool to stick also. If this is the case a spindle regrind would b in order. Heat can also be a factor. Sometimes it is the tool before the sticking on that gets hot. This heats up the spindle. Then a cold tool goes in, the spindle cools, shrinks, and voila, stuck tool. Take a good look at that taper. Any fretting? That can be vibration from a poor fitting tool. Again regrind is in order.
Hope some of this helps.

Rocky
Spindle Grinding Service Inc.

[Hurco1]

All good advice except putting the lube on the holder. Lube on the holde, contrary to popular beliefe acts not as a lube but as a sealer. I'd advise against it.

When the tool holder seems to not want to come out of the spindle does it snap or is it a loud 'thunk'?

Remove and clean the exhaust mufflers from the unclamp air valve (located in the head next to the air cylinder) These get clogged with the excess air oil and water coming through the system and create a back pressure.

[jetpig1]

I have an 8K spindle, and I believe some of the drawbar components are toasted(belville washers), anybody know how to get the drawbar out of there?

I have removed the solenoid and the 4 screws on top of the unit and the retaining circlip, but I haven't figured out how to remove the drawbar nut.

I am guessing I might have to turn/mill/drill a tool to get down in there and turn that bugger out. Any suggestions ?


GP

[jetski]

I would never put a graphite lube on anything I wanted to keep. Graphite is like throwing sand in it. It is the reason high dollar graphite machines that are fast and accurate do not stay thay way long. Graphite is more of an abrasive than a lubricant.