wrote in message
...
I am trying to collect material and ideas in order to make a mini
backhoe. I may never make one, but I am proceeding on the grounds
that I will.
Before starting in on how I should just buy a real backhoe, let me say
I do not need a real backhoe. I can really get by with just using a
shovel. But a mini backhoe that would be say 3 times as fast as just
using a shovel appeals to me.
I have thought about building a tiny mini backhoe, but the cost would
be nearly the same as a some what bigger machine. The hydraulic
cylinders and hydraulic valves are the major expense and they would
not be significantly less for a tiny backhoe.
I purchased the plan that are on Ebay for $13.99 and are not real
happy with them. Most of the drawings are three dimensional showing
all the hidden lines. And most dimensions are in the text. And the
pages all have the same title block. But I did not pay a lot so can
not expect a lot.
I am hoping to collect most of the material ( not including
hydraulics ) from the local scrap yard. I am intending to put the
engine, hydraulic pump, filter and tank as a unit with quick
disconnects. So I can remove that part and connect it to a log
splitter or what ever. And hope to find a boat trailer at the scrap
yard to supply the wheels. I have already bought some 3/16
rectangular 4 by 3 inch tubing for the booms and chassis. All in
pieces only 4 feet long, but I have a welder. I also have some cut
offs of 1 inch rod and some 1" bronze bushings.
So what I would like is comments. Especially from anyone that has
built a mini backhoe. Good sources for hydraulic cylinders and valves
would be nice. The Surplus Center is already bookmarked. Things to
avoid would be nice.
Oh yes, I am thinking about using my feet to swivel the boom instead
of of using a hydraulic cylinder. It seems like that might be okay to
do. Maybe have a plan on how to add power to swivel the boom if using
my feet is too much work. Or maybe figure out a way to use car clutch
and brake parts to swivel the boom. I am sure there will be comments
on that idea.
Dan
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After building a hydaulic bucket loader for my Sears GT18 garden
tractor I considered (and rejected) a backhoe, using the smallest
cylinders he
http://www.baileyhydraulics.com/#/hydraulic-cylinders
A 4"x6" bandsaw and a DC stick welder were enough to cut and assemble
the frame. I might have managed with a drill press instead of a
milling machine, but the mill and lathe were very useful to make
mechanical and hydraulic parts needed to salvage cheap used components
instead of buying new. For example the control valve assembly I found
for $40 had a fixed pressure relief set way too high so I made an
adjustable one.
Before designing anything in detail I took measurements of commercial
loaders and reconstructed the stresses on the parts, based on the
cylinder dimensions and oil pressure. The loads on the pivot pins are
high enough that I made the bushings from solid brass instead of
Oilite. Drilling and reaming the two holes in the outer forks of the
joints very straight was difficult and the long 0.501" reamer I found
set the sizes of the pivot pins and fork width.
The four bar linkage that rotates the bucket was the trickiest part to
figure out. You could build the boom and bucket first and play with
slotted angle etc to find where to weld on the linkage pivot and
cylinder attachment. I made a wooden model to experiment with
geometries and clearances.
-jsw