Is there a special reason to have the vacuum selonoid mounted close to the pick up tube?
It could save 2 more wires to the head if I am allowed to mount it nearby the vacuum pump.
Vacuum selonoid
Re: Vacuum selonoid
Well, having solenoid far away means extra latency - you would have extra time to fill/remove air from tubing
Re: Vacuum selonoid
What jarekk said. But truth is, I tought it would be like that, I didn't actually try it. It might actually work fine by the pump, although I do think that you would need to adjust the vacuum times.
Re: Vacuum selonoid
From my experience, the farther away you mount the valve, the more tube length ("capacity") is in between and as a result, latency increases. The effect is actually similar to trace capacitance in electronic circuits but much slower 
If you have the valve mounted to the table, not the head, you need to increase the wait time after actuating the solenoid by quite a bit - otherwise your components will still stick to the needle. This delay will slow down overall operation.
There are ways to solve this: I have built a slightly more complex pneumatic system for my machine. I am using an external compressor and two small storage tanks for vacuum and compressed air. Both vacuum and pressure are controlled by independent valves. Basically, this enables me to run a small "puff" of compressed air into the tube connected to the needle to counter this effect once the component is placed and vacuum signal turns off. This works great but requires a lot more effort than a simple 3/2 way valve mounted close to the needle.
If you have the valve mounted to the table, not the head, you need to increase the wait time after actuating the solenoid by quite a bit - otherwise your components will still stick to the needle. This delay will slow down overall operation.
There are ways to solve this: I have built a slightly more complex pneumatic system for my machine. I am using an external compressor and two small storage tanks for vacuum and compressed air. Both vacuum and pressure are controlled by independent valves. Basically, this enables me to run a small "puff" of compressed air into the tube connected to the needle to counter this effect once the component is placed and vacuum signal turns off. This works great but requires a lot more effort than a simple 3/2 way valve mounted close to the needle.