Bending thin-walled tube can be difficult because materials want to do
what they naturally want to do, that's why the right tool can make the job
easier, so let's make a tube a bender.
This is Cosador, Johnathan here.
So, I want to make a tube bender, to bend various types of metal tube, I want
something that's easy and doesn't require too much time to make, I don't
mind if the bend is imperfect on the basis that the internal volume isn't
detrimentally reduced and producing something that makes the tube square is
only a reduction of the cross-sectional area of about one-sixth, which is not
that bad, and of course I want to make something that produces a better bend
than bending by hand. For that, I'm going to need to make a plan, I need to make
the part that the tube bends around. Let's call it the head. I'm going to bend
4mm tube on a 6.25mm radius, so I need to make
a 12.5mm spacer and the flat side of an M8 nut is close
to that size, so I'll have to modify one of them and surround it by washers the
washers are 20.5mm which is a good size for the
guides on the side, with a bolt through the middle as a pivot point for a
bearing to roll around the top, it leaves a 4mmx4mm gap,
which will ensure that the tube fits and that it doesn't push out excessively
while bending and I'll need to make some type of handle or main body to fit these
things onto and also a gripping point to hold the tube. I'll start with the main
body, I'm going to use a piece of 25x15x3mm thick galvanized
steel angle, I put the angle on the bench and I measure out 225mm and
then I mark it using a square, I bring it close to the edge of the bench and I
clamp it down, and with a hacksaw I cut through the mark and rotate and clamp it
and I cut the other side. Now on another piece, I mark out 250mm
I make some straight lines with the square and I cut it the same as I did the other piece.
On the 225mm piece of angle I
measure out 25mm and once again I mark it using the square, I clamp
it and I cut the line, now I clamp it vertically and I cut off a little square
and I'll save that little piece for later, then I file off any excess to meet
the other flat side of the angle and I file off any rough or sharp edges. Now I
have the two main parts of the body of the tube bender, I lay them on a flat
surface and I line up the ends and I clamp them tightly together and they
should be lined up perfectly on the other side. I clamp it all down to the
bench and using a bit of oil, I drill a pilot hole then I drill out an 8mm
hole. I want the edge of this hole to be about 4mm away
from the other inner side of the angle and I need it to be about 4mm
because that's the thickness of the tube that I want to bend, and now I'll put the main
body aside for later because I need to make the head of the tube bender that's
the part that the tube bends around. So, I put a nut a washer and a nut onto a bit
of threaded rod and I tighten it up, I clamp a flat file to the bench and I put
the threaded rod into the chuck of my drill, I use the rotation of the drill to
file the edges of the nut off, riding the edge of the file with the washer.
This probably isn't the nicest thing to do with a file but it works well in
place of a lathe. Now the nut is well rounded but it's a little thick and I
need to bring it down to about 4-4.5mm, I can do
this manually or I can do it again with the drill in the file. Now the nut is to
size, I need to do a partial assembly. I put two washers onto the bolt then I put
the spacer and I tighten it down, I put another two washers then I put the bolt
through the hole that I made in the main body of the bender, I put a washer and a
couple of nuts to lock it down. I oil in between the two handles and I
tighten the bolts and I check that the handles are well lubricated against one
another. Now I need to make space for the bearing, I mark around the top of the
head with a pencil and I disassemble, I clamp the handle down to the bench and
with a hacksaw, I cut off any excess that I've marked then I file it down to the
line checking my work as I go, I reassemble
and find a good placement for the bearing and I mark through the hole of
the bearing with a pencil, I clamp down the assembly and I drill a pilot hole
then an 8mm hole now I need to install the bearing, it's important that
I have a smaller washer that doesn't interfere with how the bearing turns, I
put the bearing onto the bolt then the small washer and some other washers so
that the bearing lines up with the head. I insert the bolt, I put a washer and nut
and I tighten it together and I check that the tube fits well in between the
head and the bearing. Now it's time to make the grip, I get the small metal off-cut
from earlier and I clean off any rough edges with a file, I clamp it down
the best that I can for a small part, I drill a hole and I tap an M8 thread, I
check the alignment on the main body and I mark where I want to put a hole, then I
clamp the main body and I drill it out I put another M8 bolt through the hole and
I tighten it on to the grip and it's done. The evaluation, I'm going to bend
two different types of tube, aluminum and brass. Let's start with the aluminium.
With the tube bender in a 90-degree position, I insert the tube in between
the head and the bearing all the way to the grip and I tighten the grip, I have
to be careful not to compress the tube as aluminium is soft, I bend to the
required angle
and then I remove the bent tube from the bender. The tube does compress a bit
however the flow through the tube doesn't seem to be significantly
affected. Now for the brass, with the tube bender in a 90-degree position, I insert
the tube between the head and the bearing down to the grip, I tighten the
grip. The brass is harder than the aluminium, so more force is required to
bend it therefore the grip needs to be tighter than the aluminium, but the brass
is harder and it can handle the pressure. I bend it to the required angle and I
remove it from the bender. The result of the brass is much the same as the
aluminium. On Reddit, there was a suggestion that filling the tubes with
water then freezing them makes for a better bend. So, I did that and I capped the
ends with plasticine substitute, then I put them in the freezer and once they
were frozen, I bent things too. The aluminium seems to perform better with
the ice but there's less improvement with the brass. The aluminium is much
softer than the brass which is likely the reason behind this result. The tube
bender did bend both of the materials, however it did flatten them but it did
as well as what could be expected.
I really could have gone to the effort of
making a head and roller to fit the tube and I'm sure that my bends would have
come out perfectly, this is a really good example that the result of my input was
proportional to the output and if more effort was put into the construction, it
would have ended with a better quality product and if it was useful to you
please like, subscribe and turn on notifications and if you would like me
to make something else just drop a comment below, and remember guys
Break it til you make it!
and I'll see you next time.