Underpinner losing "pressure" before compressor replenishes

[boscawen46]

Hi,
I have a Minigraf underpinner and a Hydrovane compressor. They both work well together but I have noticed that the underpinner pressure drops for about the last ten wedges before the compressed replenishes. This means that the last wedges don't fully drive in. The pressure is otherwise plenty to drive edges into the
moulding I am using.
Any advice welcome. Thanks

[Not your average framer]

You are just describing a fairly classic situation, which you can get with a compressor which does not have adequate capacity in the receiver tank for the number of underpinning operations that the tank can supply in between the compressor refilling the receiver tank. As I have worked at a place were they had a hydrovane compressor, I therefore know that most Hydrovane compressors are seriously heavy duty compressors and should not normally exhibit problems like this.

So I am wondering, how often you are bleeding of the accumilated water that collects in the reciever tank, as I am wondering if the reciever tank has a very large amount od water sitting into bottom of the tank and it's preventing you from being able to have a full tank of compressed air, or if the pressure sensing switch, which starts and stops the compressor needs replacing. Also when did you last get the compessor serviced, it might be due for another service.