No air

How much in your opinion, damage can be done if any, if the air shut off while cmm is running?

[Snaggy]

I wouldn't have thought that any damage will occur. The CMM will lock up to prevent damage, kinda like the air brakes on a truck. The air keeps the brakes off.

[JM222]

or you can drive your PH10T/MQ into the quill...FUN!!

[Matthew D. Hoedeman]

It would depend on IF the pressure locks are properly set. If someone monkeyed with them to get the machine running when the pressure was low (or if they broke), then I could see some damage happening. If the pressure locks are set properly, when the pressure drops below minimum (or minimum +5), then it shuts off the motors, locks the column and just sits there.

[#2#]

It would depend on IF the pressure locks are properly set. If someone monkeyed with them to get the machine running when the pressure was low (or if they broke), then I could see some damage happening. If the pressure locks are set properly, when the pressure drops below minimum (or minimum +5), then it shuts off the motors, locks the column and just sits there.

Right, it should be able to run without damage (air bearings maintain adequate clearance, etc.) at a pressure lower than that at which the air locks (brakes) are set. So, it should not suffer any damage if air pressure were to drop while the machine is running. I'm assuming it isn't an instantaneous drop from running pressure to zero. If it was instantaneous, theoretically damage could occur because the point in time where the locks engage and when the pressure is zero (zero clearance for air bearings) is the same instant.

[Matthew D. Hoedeman]

Right, it should be able to run without damage (air bearings maintain adequate clearance, etc.) at a pressure lower than that at which the air locks (brakes) are set. So, it should not suffer any damage if air pressure were to drop while the machine is running. I'm assuming it isn't an instantaneous drop from running pressure to zero. If it was instantaneous, theoretically damage could occur because the point in time where the locks engage and when the pressure is zero (zero clearance for air bearings) is the same instant.

If tyhe safety lock is set too low, it WILL keep trying to move even when it shouldn't be is what I was getting at. Guy that was in charge here when I started had to pressure lock set too low, the pressure bled down, the machine keep running, the column started dropping while it was moving (not enough pressure in the counter-balance) and it almost ran the head and column THROUGH a bolted-down fixture. This was a gradual pressure drop due to maint. turning off the compresor to work on it without telling us they turned it off.

[EHines]

Depends on the machine. Had one that had the air shut off and the machine didn't stop. Killed the x-axis motor. It was an old machine and no spares on hand. $10k's and months later we finially had the machine fixed. Installed a backup compressor and pressure warning light right after...

[djayne]

We had it happen a couple of times with no damage on our LK & Mitutoyo machines. I was usually the first one to notify maintenance that an air compessor was down because the CMM would lock up or I would hear one of the air bearings start to rub the granite. Adding a hold up tank helped with the pressure going down gradually instead of all at once.

[justncredible]

I seen a validator that the Z would fall when the air died. Every nite we had to park it on a foam cushion. That thing must have been 20 years old, big huge keyboard thing.

[Matthew D. Hoedeman]

I seen a validator that the Z would fall when the air died. Every nite we had to park it on a foam cushion. That thing must have been 20 years old, big huge keyboard thing.

That is what we have, but it DOES have a pressure safety on the column, it would snap locked when the pressure was cut off (with the valve) but if it bled down slowly, it would start dropping before the lock clicked into place. Of course, this handy-dandy safety feature was removed when B&S did a retro-fit on the machine. You could also go up to the machine ANYTIME and flip a manual toggle switch that put the mechanical lock into place (also gone from the retro-fit). Never had to prop the head, the lock always worked. Now, since the retro-fit, all it has is a mechanical lcok that ONLY activates when the pressure drops below a certain point, and I can't adjust the pressure and I can't lock it without shutting off ALL the air.

[STANLEY]

I doult any dmage would be done.