Things you need to know about Shop Vacuums and Hoses when using your Holey-Moley Digger.
To optimize the vacuum assisted hole digging process, especially when using Cat 6 Tools such as the Holey-Moley Diggers, one should pay special attention to vacuum flow rate and hose size.
Vacuum and Hose Requirements
by Titus Nelson, PE
Inventor of the Holey-Moley Digger
The Rigid WD19560 Shop Vacuum meets the Holey-Moley Digger Vacuum and Hose Requirements for optimum post hole digging. This vacuum rated at 6.5 HP pulls 203 CFM with a 2-1/2″ hose. In addition, the vacuum should have two sturdy wheels on an axle.
A 6 inch diameter post hole will generate approximately 15 pounds of soil per foot of depth. The volume of the removed soil will be approximately 2 gallons. A 6-inch diameter hole, 3 feet deep, will generate 6 gallons of soil weighing approximately 45 pounds. Likewise two holes will generate 12 gallons of soil weighing 90 pounds.
This weight can rapidly become unmanageable. So a shop vacuum with larger wheels on an axle and a steel tube of around 16 gallons will still have head room around the filter after digging two holes. The sturdy handle and wheels allow for easy movement of the dirt.
In addition, the two wheels and larger canister make for easier dumping of the dirt from the vacuum.
The Rigid WD19560 Shop Vacuum Specifications meets Holey-Moley Digger Vacuum and Hose Requirements.
It has been our experience that the Rigid Shop Vacuum WD19560 fits the bill for the Holey-Moley Digger Vacuum and Hose Requirements. It comes with 7 feet of 2-1/2″ hose, pulls 204 CFM, pulls an impressive 45″ H2O suction, and carries the 6.5 HP rating. This vacuum has two large wheels and a sturdy detachable handle. This vacuum is easy to break down and transport in a car. See the Rigid WD19560 Specifications for more information.
The 2-1/2″ Hose Cuff fits over the 2 inch suction tube of the Holey-Moley Digger with a slip fit and works very well.
We have dug 20 feet deep holes using this vacuum (out of the box) with the Holey-Moley Digger.
The only improvement to turbo charge the system is to add Low Loss Vacuum Hose to get 20% more flow rate over the standard hose. With 8 feet of low loss vacuum hose, we have measured over 240CFM and easily pulled in over a pound a second of sand and gravel.