Need Help!- Haas Mill drawbar / tool clamp probem

[metalmansteve]

I have a tool unclamp alarm because the 'springed piston' above the draw-bar does not reach the limit switch. See attached picture. After several minutes it will go up again. I have spayed WD40 and dry lube in the airline and it doesn't seem to make a difference. The tools also seem to have adequate clamping force (although I haven't measured)

Do I need to replace the drawbar?

Any help is much appreciated.

-Steve

[Geof]

This is a new one to me.

Spraying stuff in the airline doesn't work because that supplies the cylinder that pushes the drawbar down for a tool change.

Perhaps try spraying penetrating oil around the base of the springs and operate the manual toolchange but to try and work some lubrication into the stack of belleville springs inside.

[rlabonte18]

I can't see the valve in your picture but sometimes there is a cone shaped diverter for the precharge it is silver maybe two inches long there is a rubber diaphram inside if this is torn or warped it will cause your problem.

[Loose Nut]

Remove the smaller airline on the right, going into the T above the piston. This line is the precharge line. Does the piton retract fully with line removed?

If not, the large solenoid to the left of the T has an exhaust muffler on the backside. Remove the muffler and post results.


Loose Nut

[Delw]

Originally Posted by Loose Nut Remove the smaller airline on the right, going into the T above the piston. This line is the precharge line. Does the piton retract fully with line removed? If not, the large solenoid to the left of the T has an exhaust muffler on the backside. Remove the muffler and post results. Loose Nut

Thats good thinking and its something we always tend to over look, it happens on my air collet closers often on my omniturns.

took me a week to figure out why I was having issues here and there with it was the exhaust stone.

[metalmansteve]

Loose nut - you are exactly right. The service rep at Selway Machine Tool had me remove the pre-charge air line on the right just as you suggested. The piston indeed returned to it's "up" position. If you follow that precharge line to the back of the spindle motor it leads you past a regulator and to a manifold with an array of solenoids. I took it off and tried to clean / rebuild it to no avail so I purchased a new one for $500. Part was in stock local at Selway (my HFO) and we're up and running.

I bought this machine in 1993. It's the plastic space-ship looking model. I have a love-hate relationship with this machine but overall I am very pleased. Had I bought a commit / vipor or or some other off-brand machine, would I be able to get parts 16 years later? - let alone the same day in stock?

Thanks for the input gentlemen. This is a great forum!

[JoBwan]

Originally Posted by metalmansteve If you follow that precharge line to the back of the spindle motor it leads you past a regulator and to a manifold with an array of solenoids. I took it off and tried to clean / rebuild it to no avail so I purchased a new one for $500. Part was in stock local at Selway (my HFO) and we're up and running.

metalman,
Can you clear up what exactly you tried to clean? The regulator or the manifold? Solenoid? What did you need to buy? I am experiencing the same symptom on a VF-10. To get myself running on a super hot job, I shimmed the switch with a .010" shim last nite to try and get me through the weekend. I know this may be more harmful on the drawbar, but I'm risking it for a "new" satisfied customer. Yes, there was no switch adjustment left, so shimming it got me temporarily running.

[Loose Nut]

Originally Posted by JoBwan metalman, Can you clear up what exactly you tried to clean? The regulator or the manifold? Solenoid? What did you need to buy? I am experiencing the same symptom on a VF-10. To get myself running on a super hot job, I shimmed the switch with a .010" shim last nite to try and get me through the weekend. I know this may be more harmful on the drawbar, but I'm risking it for a "new" satisfied customer. Yes, there was no switch adjustment left, so shimming it got me temporarily running.

Is your machine a 40T or 50T?

If it is 40T then if you follow the smaller airline going to the right it will lead you to a regulator. Net to the regulator is a manifold with a couple of solenoids mounted to it. If your facing the back of the machine the solenoid on the left is the pre-charge.

First you'll need to remove the small air line and see if your piston retracts correctly.
If your switch is all out of adjustment, your switches and tool release piston are not set up correctly and you could end up ripping your tool changer off or crashing due to tools hanging up in the spindle. Be carefully.

Loose Nut

[JoBwan]

Thanks for the info.

[JoBwan]

Originally Posted by Loose Nut Is your machine a 40T or 50T? If it is 40T then if you follow the smaller airline going to the right it will lead you to a regulator. Net to the regulator is a manifold with a couple of solenoids mounted to it. If your facing the back of the machine the solenoid on the left is the pre-charge. First you'll need to remove the small air line and see if your piston retracts correctly. If your switch is all out of adjustment, your switches and tool release piston are not set up correctly and you could end up ripping your tool changer off or crashing due to tools hanging up in the spindle. Be carefully. Loose Nut

Loose Nut,
I found the snap ring from on top of the piston spring was cupped and finally busted off. This was the reason the unclamp (lower) switch was not getting a proper contact. I installed a new snap ring and removed the switch shim, and all was fine for 3 days. Now, I have am seeing a new symptom. When I push the tool unclamp button(s), I am not seeing a proper pre-chage, but rather a full blast of air coming through the spindle. This is making it hard to insert a tool holder into the spindle. I am going to try to inspect the solenoid today. Maybe it has a frozen contact or spool??? Any other ideas?

[koolaidkid]

I am having a similar issue to the original poster. The drawbar is clamping slowly the last .250", sometimes not far enough to engage the clamp switch. I took off the precharge line and it snaps all the way up. I removed the "muffler" from the valve and it snaps up. I am getting some air through the precharge side all the time. Is this normal, or is it supposed to only have air pressure just before the main line does? How does the precharge air do anything if the main valve is set to exhaust prior to engagement? It seems that any air the gets pushed through on the precharge side would just go out the exhaust port.

Thanks

[haastec]

The pre charge is set to about 5psi and is designed to lower the tool release piston onto the drawbar gently prior to the main tool release solenoid activating. If the precharge is not working you will hear more of a pop prior to the tool being released. If it is stuck on you will see symptoms as described prior.

The silver T manifold acts as a check valve when the main solenoid is engaged to prevent air flow back to the pre charge solenoid.

Water and/or oil contamination in the air line is the biggest cause for the solenoid to become sticky and not work properly. I have tried on several occasions to clean the soleoid with mixed success but that could just be me.

Also, if the exhaust port is appears to be blocked by sludge/dirt, try cleaning it as that will have an effect on performance as well.

On a different note; if you are experiencing a weak tool release, check the o-rings for the tool release piston assembly. The shaft that runs down the center has 3 o-rings that will develop a flat spots. Snap ring pliers and an extra hand to compress the spring is all you will need.

Good luck all.