Model Engineers’ Workshop – July 2019

(Chris Devlin) #1

July 2019 35



Hydraulic Press


When doing any bending with the
press it was important not to over-bend.
Experience showed that less is always
better than too much. Restraightening
was always an unwanted chore and in the
early stages it often meant scrap metal.
I had a salutary lesson on the
importance of proper weld penetration.
During an initial trial. I was bending 30mm
x 5mm. It proved to be well within the
capabilities of the jack, so I kept pumping
for maximum shape, pushing the tool
down between the die sides. With a shot
like a gun one side of the die flew off in a
very dangerous manner. Photograph 31
shows the result and the very poor weld
I had on it. My welds definitely had more
attention after that!
I found that initially I still ended up with
a small flat at the start of each curve, so
this end was hacksawed off each time.
Later on, I found that placing a section
of 20 x 5mm flat against one of the Die
rounds, I was able to form a full curve
from the outset.
Photograph 32 shows some of the
curled flats and photo 33 a gate they
formed part of.
I’ve made a number of garden arches
out of half inch rebar by pulling the metal
around in the vice. After shoulder damage
I can no longer do it this way. The press
now takes all the hard work out of it.
Incidentally, the ridged pattern on Rebar
provides a brilliant surface for climbing
plants. Photograph 34 shows typical
results. The large radii were achieved by
continually checking the result against a
template. I found after a bit of practise
that a bite every 50mm or so produced
satisfying results. I made sure that all
welds were continuous, which, coupled
with heavy coats of Hammerite keeps the
rust out for a good while.

Broaching Keyways
Again, in the past, I’ve had to cut keyways
the hard way usually by sawing and fi ling.
I thought the press would provide an ideal
opportunity to produce machine quality
keyways.
My method however was not a success.
Nevertheless, it’s worth a brief explanation

I made sure that all the


welds were continuous,


which, coupled


with heavy coats of


Hammerite keeps the


rust out for a good while


26


27

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