[AdvancedEng]

I have a 1996 Haas VF-4 that we have just recently started having issues with. During a tool change it will sometimes (becoming worse actually) fail to orientate the spindle to where it needs to be to lock in place, almost like its slipping. If I help it spin clockwise, like an 8th of a turn, it will start spinning by itself, hear the pin lock the spindle and all goes smooth from there.

I called Haas and told them what was going on and they concluded it was the encoder belt. Ive since disassembled all the panels giving me access to the belt and accompanying assembly. Ive inspected the belt and pulleys and everything appears good. There is tension on the belt and no teeth are missing. Im wondering if there is another part I should be looking at, like the pin assembly for example. Any ideas on where to look, or confirmation on the encoder belt being the issue, are greatly appreciated.
-Bob

[Machineit]

I could be wrong, but I don't think it is the encoder. On a 96, the encode that you are looking at is not what determines the spindle lock, the shot pin assembly does. On a 96, the external encoder assembly is for the rigid tap only anyway. Perhaps it is the switch that shows when the shot pin is engaged. If it already shows engaged, the spindle would not move.

Check for a worn shot pin and/or switch problem.

Mike

[haastec]

I could be wrong, but I don't think it is the encoder. On a 96, the encode that you are looking at is not what determines the spindle lock, the shot pin assembly does. On a 96, the external encoder assembly is for the rigid tap only anyway. Perhaps it is the switch that shows when the shot pin is engaged. If it already shows engaged, the spindle would not move.

Check for a worn shot pin and/or switch problem.

Mike

Agreed!

Look at the end of the actual shot pin. I have seen them so worn down that they have a large flat spot on the face. If the shot pin is bad, replace the ring as well.

[jellyberry420]

Agreed!

Look at the end of the actual shot pin. I have seen them so worn down that they have a large flat spot on the face. If the shot pin is bad, replace the ring as well.

Can i remove the pin by unscrewing the hex head on the end of the actuator or do i need to remove the entire mechanism?

I'm no pro and can't afford a real mechanic to do it, hoping there was a shortcut to the pin tip

I do have a small amount of damage to the orientation ring, just looks like it's been used a billion times

i really don't see having the $500 to buy the parts either