CAD Digger Help

   / CAD Digger Help #1  

mitchash

Gold Member
Joined
Mar 24, 2006
Messages
380
Location
Greene, NY
Tractor
Mahindra MAX 28XL, Jinma 254 (Sold)
Looking to build a CAD Digger 728 that someone started to build but never finished. I see there was a video with the plans on the order form but I didn't get that with mine (may have gotten lost). I tried to contact the company about it but never got a reply. Can anyone help me with this? Looking for as much info on this as I can to finish assembling it. Thanks
 
   / CAD Digger Help #2  
I bought the plans and built the 728 in the mid 90s. As far as I know,
they still sell the plans. If you want to buy a set, either call or order online.

How complete is your unfinished 728? There are some things in the plans
that are wrong, or just bad engineering.
 
   / CAD Digger Help
  • Thread Starter
#4  
The digger is almost done. Need to build the bucket teeth and main frame pivot point needs to be fitted. Whats wrong in the plans?
 
   / CAD Digger Help
  • Thread Starter
#5  
I did order the video from CAD Plans but haven't seen it yet.
 
   / CAD Digger Help #6  

Another good series of youtube videos of a towable backhoe build...

YouTube - Backhoe Project

This guy goes into great detail. The singing and guitar are a bit of a distraction, but aren't bad. If your backhoe is mostly built, you could probably go to the last few videos.
 
   / CAD Digger Help #7  
Whats wrong in the plans?

The most memorable problem was the woefully inadequate support for
the boom pivot cylinder. I had to significantly beef up the weldment on
the boom pivot after breaking it off. I stayed at 1500psi, too.

Also, I switched from a heavier engine to a Tecumseh 10hp and I needed
to add lots of ballast to be able to lift a load of dirt at full extension. I
put 2 55# lead ingots on the rear.

I followed the plans very closely. I should have used 1/4" hyd hose for
all of the work circuits, instead of the 3/8 I used. Hose routing and
pinching would have been better.

I had some trouble with breaking the ends on the two largest pivot pins...
the one on the boom pivot and the one on the boom/dipper pivot.

Other errors I corrected on the plans as I found them, but if your unit
is almost all welded up, it is moot.
 

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