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My Experience Building and Using The CADDigger Model 821

How to Build Caddigger 821

I decided to build the CADDigger Model 821 after visiting the website in March 1998. I had seen their ad in the back of Popular Science for a few years and had always thought it might be a fun project to build and use. As it turned out, it was well worth the time and effort.

In the plans package you get step by step instructions, pre-construction tips, specifications for the purchased equipment, raw material list, photos of selected parts, and 29 pages of detailed drawings. All the parts to get it built as designed are listed.


If you decide to re-design something, that’s up to you. I re-designed the bucket so it would have a more rounded bottom. I added joysticks to the operating controls (stock spool valves come with single levers only), so this meant building a custom control valve mount.


The plans called for a horizontal shaft engine. When I priced engines, I found that horizontal shafts were much more expensive than vertical shafts. So, I built a custom vertical shaft engine mount. I also added a “control panel” which consisted of a throttle control, choke control, engine kill switch, lighting switch, and hour meter. The control panel is made from left over frame tubing.

I chose to buy the steel locally and cut the parts out myself. I used my O/A torch for the odd shaped pieces and a bandsaw for the rest. I have a circle cutting attachment for my torch that I modified to work as a “rip fence” so I could get straight cuts.

If so inclined, one can buy a steel kit from Metco Supply of Pennsylvania. (More on prices later.)


When putting all this together the old adage “measure twice, cut once” is something to remember. Be careful of thermal distortion – tack together, see if it fits, then finish the weld. Mechanical tubing (precision i.d. & o.d. tubing) is used in the pivot points.

Pivot pins have to go through the tubing. I managed to use a hand reamer to fit the two together, but let’s say I plan doing it on a lathe next time.

Engine Mount Assembly View 2

Engine Mount Assembly View 3

The plans recommend putting lead in the frame for stability, so I went to my local tire shop and bought three five gallon buckets of used wheel weights. I melted the weights down with my weed burner propane torch and made “ingots” that were approximately 1.5″x3.5″x6.0″. This made about 380 pounds of ingots. I put the majority of the ingots in the longest section of the frame for maximum lifting force. Weights can also be purchased from Metco. My machine scale weight was around 1800 pounds, so I used 3500-pound rating stub axles.

In addition to 18″ and 8″ wide buckets, I have built a “rock sorting bucket” (looks like an upside down fireplace grate), a 3′ long by 8″ tall blade, and a 5′ boom extension for lifting.


The machine excels at trenching because it has a great amount of side to side power which allows you backfill very quickly. I have also used it extensively for removing brush and fairly large trees.

I started my CADDigger project in March 1998 and finished in June 1998. I didn’t work on it much during the weekdays, but I did spend a fair bit of time working on the weekends. I have thoroughly enjoyed building and using CADDigger.

CadDigger Boom View 1


The information below reflects approximately what I paid for the items and where I purchased them. Each item is not limited to the business listed.
(e.g. Metco sells hydraulics and engines, too.)

  • $140 Plans:
    Cadplans Corp. Daleville,VA 1-800-211-4255
  • $1000 Steel ( I bought locally ); or call
    Metco Supply 1-800-521-8811 for kit prices
  • $900 Hydraulic parts from:
    Surplus Center, Lincoln NE 1-800-488-3407
  • $500 Hoses:
    Custom made @ NAPA Auto Parts ( $ could be less if smaller hoses are used )
  • $80 Hydraulic Pump:
    Northern Supply, Burnsville MN 1-800-533-5545
  • $400 Engine:
    Engine Mart, Merritt Island FL (407)452-0203
  • $800 Misc. Items:
    Paint, nuts, bolts, seat, hydraulic. oil, filters, lead, wheels & tires, hubs, etc.

$3800 Approximate cost for the machine.


Author: Jim Steeby

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