Troubleshooting Drill Head Pneumatic Controls

Is an air leak causing the drill head to not drill to full depth? February 17, 2012

I have a Komo VR510 with a drill head. When itís time for a drill bit to drill a hole, the pneumatic cylinder for that particular bit fills with air to push that bit lower than the rest of the bits, and then the head itself lowers into the part to drill a hole. If it's a set of holes, such as in a line bore, all seven heads will drop and seven holes are drilled.

One of the seven heads is not holding its position when engaged. I can visibly see the bit push back up into the cylinder slightly while a hole is being drilled. This results in a hole that is not being drilled full depth. What are some possible causes and remedies to this problem?

Forum Responses
(CNC Forum)
From contributor A:
Below are a few possible causes of your issue:

-Air leaking in the shaft cylinder for the drill bit in question, also could be a broken or weak pressure spring inside of the air cylinder.

-Wrong drill bit type.

-Dull drill bit.

-When gang drilling the motor to the drill bank might be slowing down due to excessive feed and load.

-Gear might be worn out for the spindle in question.

From contributor S:
Expounding on Contributor A's comment, make sure you don't have the LH bit in a RH spindle and vice-versa. It's unlikely, but check the simple things first.

From the original questioner:
Thanks for the quick responses. Yes, I did check the rotations. The bit is sharp and there's no burning. It's the correct bit in the correct spot. I tend to think itís a leaky seal somewhere.

From contributor J:
I would also check the air valve that actuates the spindle to come down. As mentioned above, if you have a seal in the cylinder that is leaking, it cannot maintain its position. The same will happen with a valve that is not completely shuttling position.

From contributor R:
Swap the airline to the cylinder with a known good one, that way you can narrow it down to cylinder or valve.