Making the Drillhead
I received several requests for information on how to build a drillhead. There are many configurations of PVC parts that will suffice. One principle that should be followed is to avoid anything that will slow down the flow of water. In a previous drillhead I had two 3/4' pipes flowing into one 3/4" pipe. That no doubt cost me some "drilling" power. Water flow is absolutely critical. In the updated drillhead I have the two 3/4" pipes flowing directly into a 2" pipe to avoid any loss of pressure.
If anybody has any suggestions on any other ways to enhance water flow, please let me know and I will post them. The video below demonstrates the best combination I have come up with.
MAKING THE DRILLHEAD
Here is the old drillhead. As you can see, it has two 3/4 inch pipes leading into one 3/4 inch pipe restricing the water flow.
Pieces for the New Drillhead
2 inch PVC T - Lowes Part 23908 - $2.49
3/4 inch by 2 inch bushing - Lowes Part 23003 - $1.19
Four pieces of 3/4 inch PVC, each cut 1 1/2 to 2 inches long
Two 45 degree 3/4 inch elbows - Lowes Part 23891 - 75¢ each
Two 3/4 inch slip to 3/4 inch hose connectors - Lowes Part 194629 - $1.47 each
Everything dry fitted together
Mounted on a piece of 2 inch PVC ready to connect hoses and use
Here is a handy parts list for al the fittings from Ed in Navarre, Florida.
UPDATE: Nov, 2012: I have updated the drill head to permit easy insertion of bentonite into the drillpipe. It is the same drillhead as above but it is based on a two inch cross instead of a two inch tee and it has a two inch valve on top.
Please note that since there is a valve on top of this type drillhead, no weep hole is necessary. You can simply open the valve on top (if you can reach it) to let the air out when needed.