Start of tube die. Just because you can does not mean you should!AdrianH - 27/12/12 at 10:49 PM
I was getting bored so needed some time in the workshop/garage, project would be a home made tube bender, on the cheap!
Looked around my metal pile and found some 10mm plate and some old rusting metal around 18mm thick, formed a sandwich with 3 x 10mm pieces approx
200mm square and then 2 x 18mm pieces across diagonally. Drilled for 6 10mm bolts and one big hole at 1" diameter for the pivot point.
Lots of work on the band saw to rough cut and then down to the job of rounding the piece to a 100 degree quadrant. I completely trashed a dividing
table, just was not big enough for the job as I ended up breaking the gears, so had to improvise.
I will just be doing the 1 3/4" die as that is 45mm for roll cages.
That is why I say just because you can, sometimes locost can be more expensive. Still a challenge though!
Adrian
[Edited on 28-12-12 by AdrianH]
splitrivet - 27/12/12 at 11:28 PM
Just made my roll bar with a dry bollock bender from machinemart filled with sand, also made the crash bars for my bike by the same method. Nice to
build it yourself though.
Cheers,
Bob
AdrianH - 27/12/12 at 11:35 PM
I have a 12 tonne unit sat in the garage with all the dies, how did you find the fit on tube and what size did you use?
Would also like to know just how much deformation you had, or oval-ling if you know what I mean.
Adrian
p.s.
I still find the bounce very hypnotic!
[Edited on 27-12-12 by AdrianH]
spiderman - 28/12/12 at 12:10 AM
quote:Originally posted by AdrianH
I still find the bounce very hypnotic!
I have wasted so much time through being hypnotized! Never seem to get tired of it though.
I find using the die one size down on the 12 tonne hydraulic bender helps stop ovaling and tube collapsing as the dies are sized for internal diameter
pipe and not outside diameter tube. I also cut a piece of the tube I am bending lengthways and place that between the tube and the rollers on the
bender with plenty of grease, this stops the rollers denting the tube being bent.
Spider
splitrivet - 28/12/12 at 08:20 AM
quote:Originally posted by AdrianH
I have a 12 tonne unit sat in the garage with all the dies, how did you find the fit on tube and what size did you use?
Would also like to know just how much deformation you had, or oval-ling if you know what I mean.
Adrian
p.s.
I still find the bounce very hypnotic!
[Edited on 27-12-12 by AdrianH]
I just ignored pipe size on the die and used the tightest die, there was no deformation. There are lots of videos on tweb regarding the sand method,
it was how they did it back in the old days and it worked for them.
Cheers,
Bob
[Edited on 28/12/12 by splitrivet]
Peteff - 28/12/12 at 09:11 AM
If you cut the inner pieces down before you bolted them together would it give your mill a bit of a start with less to remove ?
The jogger is from the movie Click
trikerneil - 28/12/12 at 09:38 AM
I used a similar method only using my lathe.
The large die was steel and cut with three different radii. I then cut it into 120 degree segments.
It took a while but worked OK.
Neil
AdrianH - 28/12/12 at 11:30 AM
trikerneil
I have done some work on dies in my lathe previously, using 6" dia steel bar and made dies for 3/4" and 1" tube
I could not get hold of 12" diameter piece at a reasonable price to start with so gave up on that idea. I do like what you did with then going
to three 120 degree segments, that is very good lateral thinking.
Even did one for 1" Square tube, but not very successful on a 3" radii. Needed to fit the internal 'hump' to ridge the inner face
along the tube.
[U]Peteff[/U]
I thought it best to keep it all in register. I had a little dos program written for me years ago that calculated individual cuts to rough out the
shape first before finishing, I have a few slitting disks or thin cutters with round cutting profiles, one is 4mm thick and the other is 3/16"
thick. So cutting will be done in slices to start with. Need to weld up the fixture to hold it as it is presently just welded in place and I am
getting some movement.
Adrian
AdrianH - 4/1/13 at 12:34 PM
I have sort of finished machining the die, may need a bit of emery work, but will do for a starter.
I ended up over the 90 degrees with spring back so need to work that out.
Adrian
AdrianH - 12/1/13 at 09:54 PM
There is a slight kink starting on the inner edge of the bend, not sure if you can see this in the pictures.
I think this could be down to the tube guide is not under the die centre line. It needs to have shoulders on the front face to allow it to sit below
the die, so at present is 1&1/2 " behind the line, when I have done that I should be able to check for clearances and make sure the guide is
as close to the die as possible.
quote:Originally posted by trikerneil
I used a similar method only using my lathe.
I like that, more cunning than a very cunning thing. Top marks
quote:Originally posted by AdrianH
Oval-ation is less then 90% so happy with that.
I'd certainly be happy with that, all the effort has certainly paid off.
[Edited on 13/1/13 by MikeRJ]
clanger - 13/1/13 at 09:15 AM
decent bit of engineering, well done
AdrianH - 13/1/13 at 09:44 PM
The unit is now all but finished, changes to the guide height by lifting it up by 4mm kept the tube tight against the die on the inside bend. Decided
to do a proper test bend on a new piece of tube so I marked out rings at 20mm spacing. Final test bend 1
Stuck it in the rig with the first mark at the end of the half clamp Final test bend 2
Took it out and stuck against a plate to take picture. No kinks at all nice and smooth so very pleased with the result. Final test bend 3
Again checked the squash and got 41.25 mm so still happy with that. Final test bend 4
Basic measurements are 70mm from first mark to start of bend and bend radius is 6.2 inches so I have 0.2 inch (5 mm) of spring when I take the tension
off, the die is 6 inch radius.
I think I will clean and paint the unit before it goes rusty with the cold weather.
Now I need a tube notch-er!
Adrian
Theshed - 22/1/13 at 09:58 AM
You already have a tube notcher...... Use your milling machine in horizontal mode with a hole saw mounted on an arbour.
Never seem to get tired of it though. 
