A strong, simple workshop crane
Here's my implementation of a 'Corner Crane', the
design of which may interest others who need some heavy lifting performed in
a workshop (build at your own risk though - these things can be dangerous if not done right).
Its corner fixing works on the same principle as the keystone in an arch, but it uses the idea horizontally rather than vertically. It took about a week to prototype and make from 'free' scrap that I had around the place. I tried aluminium scaffold poles first but they were too
flexible and appeared to take a 'set' after a few heavy lifts, whereas steel
ones just spring a little and then hold firm. The crane was installed originally
to help move the body casting and innards of my rebuilt Astra mill from the
bench onto its stand (est. 150 kgs), but has since come in useful for all kinds
of weighty objects. I guess it would be ideal for lifting heavy models too, but
I don't have any to try it on as I'm still 'making stuff to make stuff', like
the half-finished Worden tool grinder you can see on the bench.
Here the winch is swung out ready, for instance, to un-ship the Astra's vertical head. The wide
angle lens makes the ceiling look rather tall but it's only 7' high in reality.
Even doubled for extra lifting capacity, the winch cable will drop to well below
An example of the sort of thing I used to break
my back lifting onto the bench. Now it's all over with the press of a button -
the remote hand control has quite a long cable (coiled around the winch in this
pic), so I can stand well clear when necessary. The crane is also useful for
just swinging things round on the bench, or flipping them over to work on
Here's where it's normally 'parked' -
completely out of the way in otherwise 'dead' space. As you can see, it's
constructed from a couple of lengths of steel scaffold pole, locked together
with chopped up and modified scaffold clamps. The vertical pole rests on the
bench top just out of sight in the corner (see later pic). The ceiling junction
box shows where I moved the lamp onto the wall so I could get maximum height for
the jib pole.
This top clamp is the sawn-off half of a
pole-extending clamp. There are a number of 'patterns' of these clamps - I chose
the type with flats on one side so I could use them to clamp the brace as well
as the scaffold pole. The brace is from an old garage up-and-over door (I knew
it would come in handy one day!).
This in-line right-angle clamp was made by
halving and reversing a full clamp and then welding the pieces together on one
side only, so that both halves could still spring when tightened up. I'm
surprised there isn't an 'official' form of this type of clamp - the only
right-angle ones I could find were all offset which would have meant moving the
upright about 6" further out from the corner to allow a full 90 degree swing.
This in turn would have needed a much more complex wall bracket (see below).
Obviously, all the clamps have to be wound up real tight for safety.
is the all-important wall bracket, made from a couple of pieces of 3/8" x 2"
plate welded to the tips of a reversed half clamp (here I used a pattern of
clamp with symmetrical curved sides - see below). The little messy brace pieces
were an afterthought to prevent flex when the arm is swinging a heavy weight -
they may be unnecessary but better safe than sorry. They are just two lengths of
scrap angle jammed into the space and welded. The opposed, expanding wall-bolts
effectively jam the bracket in place in the corner. The only way it can pull off
is by hauling three or four bricks through the corner, which is as difficult as
pulling a keystone out of an arch. The original plate holes were changed to a
staggered pattern to avoid any danger of the bolts expanding in the same line of
mortar. They also align roughly with the line of force that the crane applies.
The bearing area was pre-greased, so the nipple is probably superfluous. A
certain amount of clearance is needed in this bearing (about 1mm) as the bar
flexes naturally (and safely) under load and the bearing needs to be able to
accommodate it. I found the clamp showed just the right amount of clearance when
in its relaxed state so I just welded it 'as is'. The brace clamp underneath is
the other half of the one on the top pole.
This is the
plain base bearing which is really just any piece of plate with a small slice of
clamp welded in place to hold the pole away from the wall. I slipped the bottom
half of an old BSA steering head cone bearing under the end of the pole, but I
think I could just have left the squared end to swivel on the greased plate. The
crane swivels smoothly under finger pressure, even when fully loaded. There's an
upright of 2" x 4" timber in the corner under the bench which transmits the load
straight down to the concrete floor.
bolts I used were 10x100mm from the local diy multiple. The right-hand one shows
the correct size but it's a stud that I bought before I realised I couldn't get
the bracket on with studs in place (duh!). On the left is an example of the
style of bolt (but too short). I assembled two bolts on one side of the bracket,
inserted them in the wall, expanded the sleeves and then withdrew the bolts
before performing the same operation on the other side. This left the jammed,
expanded sleeves in place so that I could repeatedly offer up and 'adjust' the
bracket to suit the out-of-square corner. Note that the plate holes need to be
the size of the inner bolt, not the outer sleeve. The plate's thickness replaces
the plastic sleeve you can see under the bolt head.
This is the
single-phase winch that I bought new from a trader on eBay.uk for 99 pounds. He
often has them on at this price, but with occasional breaks in supply. Machine
Mart do an identical one for rather more. I use the pulley doubled up to get the
half-speed 250 kg capacity. The straight 125 speed is a bit too fierce for
delicate lifting and placing of heavy loads. The original hook on the 250 kg
pulley doesn't swivel (unlike the 125 kg hook which can twist on its cable). I
needed the hook to swivel so I swapped it for a similarly rated swivelling
version from a cheap lever winch that I happened to have (came from a car
accessory shop).The square mounting brackets on top of the winch wouldn't quite
fit round a scaffold pole but I was able to dish them slightly to achieve a good
loose fit. The winch can slide in or out a foot either side of the stop screw
you can see threaded into the jib bar.
Even without an electric winch, the jib
could be used with a plain pulley system, a simple chain winch or the lever
winch that donated its swivel hook. Overall measurements of the crane are: top
bar 52", vertical bar 53", wall bracket fitted 12" down from top corner (to
ensure it has a sound course of bricks to bite into), bottom bearing 31" above
floor level, brace is 3/8" x 1 1/2" x 32" and shows no sign of flexing,
underside of jib bar to raised portion of bench is 44".
decides to knock up something similar, remember every setup is different so
you'll need to do due diligence in judging your own safety parameters and
calculations and welding abilities etc. I definitely can't take responsibility
for anyone else's setup or workmanship. Having said that, this crane has
performed faultlessly from day one and I now use it regularly without giving it
a second thought. The key features are the 'jammed' corner bracket set in a
sound brick wall, load transmitted to concrete floor, strong triangulating brace
for upper arm, steel scaffold poles of limited length and use of a proven
© neil f, 2003-2018.
web dot master at riscy dot uk
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