I have built a Lehmann seismorraph using the 1/2 pipe and using the pipe union for a pivot point.
My question is when setting the period for the 30 inch boom.Is that from left to right then back to left if this is the case I am only getting to about 10 sec also should the boom be level. Should the gate effect take care of the swing back to center.
It has been about 4 years since I built the last one and I dont remember having so much truble setting it

I have built a Lehmann seismorraph using the 1/2 pipe and using the pipe union for a pivot point.
My question is when setting the period for the 30 inch boom.Is that from left to right then back to left if this is the case I am only getting to about 10 sec also should the boom be level. Should the gate effect take care of the swing back to center.
It has been about 4 years since I built the last one and I dont remember having so much truble setting it
thanks Bryan S Goss