Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

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Default bending 5 foot dia circles of 1/2 or 3/4 EMT pipe

I would like to make some 360 degree hoops of either 1/2 EMT, or preferably
3/4 EMT for a model RR project ( helix construction). Would like to get approx
60" dia circle. Can you tell me how I might best go about this?

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for full context, visit http://www.polytechforum.com/metalwo...pe-639050-.htm


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Default bending 5 foot dia circles of 1/2 or 3/4 EMT pipe

Tubing roller.

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Default bending 5 foot dia circles of 1/2 or 3/4 EMT pipe

On Tue, 11 Jul 2017 00:18:03 GMT, brian
wrote:

I would like to make some 360 degree hoops of either 1/2 EMT, or preferably
3/4 EMT for a model RR project ( helix construction). Would like to get approx
60" dia circle. Can you tell me how I might best go about this?


A tubing roller works most smoothly, but a hickey is a lot cheaper.
How smooth do you want the bends, and how many of these are you
making? I'd suggest buying the tubing bender, making 3x the number
you need, and selling the rest to pay for the bender. Make sure the
tubing stays straight through the bender or you'll end up with a
spiral. And, whatever you do, don't tell us what you're making. We
love staying in suspense.

Show them to the local gardening club to get sales. Women love that
crap for their gardens. g

https://www.harborfreight.com/tubing-roller-99736.html

http://tinyurl.com/y8vzswmk

--
The door of opportunity is marked "PUSH".
--anon
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Default bending 5 foot dia circles of 1/2 or 3/4 EMT pipe

"brian" wrote in
message ...
I would like to make some 360 degree hoops of either 1/2 EMT, or
preferably
3/4 EMT for a model RR project ( helix construction). Would like to
get approx
60" dia circle. Can you tell me how I might best go about this?

--
for full context, visit
http://www.polytechforum.com/metalwo...pe-639050-.htm


If you can't justify the cost of a tubing roller
https://www.harborfreight.com/tubing-roller-99736.html
you could bend it around a plywood form. I'd start at full size to
measure the springback, then reduce the diameter accordingly. You only
need a half circle which is all you'll get from a 10' length. 1" pipe
will slide over 3/4" EMT to give you better leverage at the ends.

If you have a good eye for shapes it can be bent between closely
spaced tree trunks, using a circle on cardboard as the pattern. I
straighten bent antenna mast tubing that way and once made a spiral
handrail from EMT for a staircase for a theatre set.
-jsw


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Default bending 5 foot dia circles of 1/2 or 3/4 EMT pipe

On Monday, July 10, 2017 at 8:18:06 PM UTC-4, brian wrote:
I would like to make some 360 degree hoops of either 1/2 EMT, or preferably
3/4 EMT for a model RR project ( helix construction). Would like to get approx
60" dia circle. Can you tell me how I might best go about this?

--
for full context, visit http://www.polytechforum.com/metalwo...pe-639050-.htm


Certainly, mate; fill the tubing with (possibly wet) sand and bend it as though it were a solid rod; the peculiar "Poisson's Ratio" of the sand will make your tubing behave like a solid. Loverly, eh, wot?
Cheers,
Doug
Admin AT Replikon DOT Net also keeps the spam way down


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Default bending 5 foot dia circles of 1/2 or 3/4 EMT pipe

On Tue, 11 Jul 2017 08:13:17 -0700 (PDT), DGoncz
wrote:

On Monday, July 10, 2017 at 8:18:06 PM UTC-4, brian wrote:
I would like to make some 360 degree hoops of either 1/2 EMT, or preferably
3/4 EMT for a model RR project ( helix construction). Would like to get approx
60" dia circle. Can you tell me how I might best go about this??

--
for full context, visit http://www.polytechforum.com/metalwo...pe-639050-.htm


Certainly, mate; fill the tubing with (possibly wet) sand and bend it as though it were a solid rod; the peculiar "Poisson's Ratio" of the sand will make your tubing behave like a solid. Loverly, eh, wot?
Cheers,
Doug
Admin AT Replikon DOT Net also keeps the spam way down


If you use that method, use *dry* sand and pack it as tightly as you
can. It requires stoppers on each end -- typically wooden plugs that
are held in place with bolts or pieces of rod through holes
cross-drilled into the tube. Expect some distortion here after you're
done. It's best to assume that the ends will be waste.

If the sand isn't really tight, it will get pushed away at the point
of highest stress -- your bend point -- and do no good at all.

Be aware that this approach tends to leave the outer part of the bend
somewhat thinned. Unlike a commercial pipe bender, it doesn't
distribute the displacement of metal equally on the comperssion side
(the inside of the bend) and the tension side (the outside of the
bend). At least, that was my experience, when I used it to make
aluminum tent frames.

But it does work well. I've had to drive the sand in with a hammer to
get it packed tightly enough.

--
Ed Huntress
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Default bending 5 foot dia circles of 1/2 or 3/4 EMT pipe

On 7/11/2017 9:31 AM, Ed Huntress wrote:
I've had to drive the sand in with a hammer


To get it all up yer arse?
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Default bending 5 foot dia circles of 1/2 or 3/4 EMT pipe

On Mon, 10 Jul 2017 21:48:50 -0700, Larry Jaques
wrote:

On Tue, 11 Jul 2017 00:18:03 GMT, brian
m wrote:

I would like to make some 360 degree hoops of either 1/2 EMT, or preferably
3/4 EMT for a model RR project ( helix construction). Would like to get approx
60" dia circle. Can you tell me how I might best go about this?


A tubing roller works most smoothly, but a hickey is a lot cheaper.
How smooth do you want the bends, and how many of these are you
making? I'd suggest buying the tubing bender, making 3x the number
you need, and selling the rest to pay for the bender. Make sure the
tubing stays straight through the bender or you'll end up with a
spiral.


And you wouldn't want that if you seek a helix. (Sorry, I can't read.)


And, whatever you do, don't tell us what you're making. We
love staying in suspense.

Show them to the local gardening club to get sales. Women love that
crap for their gardens. g

https://www.harborfreight.com/tubing-roller-99736.html

http://tinyurl.com/y8vzswmk


--
The door of opportunity is marked "PUSH".
--anon
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Default bending 5 foot dia circles of 1/2 or 3/4 EMT pipe

replying to Larry Jaques, brian wrote:
Hi Larry,
Tubing bender is just two expensive for fabrication just a few (as little as
2) hoops. Just yesterday I found a contractor friend who says he has a hand
conduit bender i can borrow. I figure I can just make small incremental bends
and get my circular hoops. Now I just have to figure out how to calculate
those incremental bends to get my 5 foot hoop.

If you google "model railroad helix" you will see imagines of what I am
looking to build,...but an alternative method/materials.
Here is a forum subject thread I started on the project...
_http://model-railroad-hobbyist.com/node/30323?page=4_
In these photos you will see a 4 foot dia metal ring I found at a junk yard
(likely a rim of of outdoor table). This would work for a 4 foot dia helix,
but I was looking for 5 foot dia,...hence my search for bending conduit into 5
foot dia circles. One hoop at the bottom, and one hoop at the top,...then 8
vertical pieces joining the 2 hoops. Inside this 'open style barrel' I would
coil up a spiral hoop(s) of PVC pipe onto which to lay the rr track.

https://www.polytechforum.com/img/5r

--
for full context, visit http://www.polytechforum.com/metalwo...pe-639050-.htm


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Default bending 5 foot dia circles of 1/2 or 3/4 EMT pipe

replying to Ed Huntress, brian wrote:
How about this relatively simple bender, ....with no sand involved?
Lady bends 3./4 EMT conduit
_https://www.youtube.com/watch?time_continue=2&v=4ftPHtz9tzg_

--
for full context, visit http://www.polytechforum.com/metalwo...pe-639050-.htm




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Default bending 5 foot dia circles of 1/2 or 3/4 EMT pipe

On Wed, 12 Jul 2017 02:18:06 GMT, brian
wrote:

replying to Ed Huntress, brian wrote:
How about this relatively simple bender, ....with no sand involved?
Lady bends 3./4 EMT conduit
_https://www.youtube.com/watch?time_continue=2&v=4ftPHtz9tzg_


Oh, yeah. That will do it. I didn't even pay attention to the early
posts, so I didn't note the radius you're working with. A single-side
rig like that, with no follower, is the way they have made big-radius
bends like that for many years.

That should work just fine. What I was thinking of was much tighter
bends.

BTW, just as I retired (last September) the publishing company I
worked for was starting up a new magazine just for tube and pipe
fabricating, including bending, of course. I think they got through
one issue before they realized it wasn't going to fly. g

http://www.fsmdirect.com/tube-and-pi...ber-2016-issue

Anyway, in preparation for it, I was accumulating everything I could
find on tube bending. The basic fact is that nothing much has changed,
mechanically, for the past 50 years or so. But computer control now
allows them to make some wild and crazy bends.

--
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Default bending 5 foot dia circles of 1/2 or 3/4 EMT pipe

"brian" wrote in
message ...
replying to Larry Jaques, brian wrote:
Hi Larry,
Tubing bender is just two expensive for fabrication just a few (as
little as
2) hoops. Just yesterday I found a contractor friend who says he has
a hand
conduit bender i can borrow. I figure I can just make small
incremental bends
and get my circular hoops. Now I just have to figure out how to
calculate
those incremental bends to get my 5 foot hoop.

If you google "model railroad helix" you will see imagines of what I
am
looking to build,...but an alternative method/materials.
Here is a forum subject thread I started on the project...
_http://model-railroad-hobbyist.com/node/30323?page=4_
In these photos you will see a 4 foot dia metal ring I found at a
junk yard
(likely a rim of of outdoor table). This would work for a 4 foot dia
helix,
but I was looking for 5 foot dia,...hence my search for bending
conduit into 5
foot dia circles. One hoop at the bottom, and one hoop at the
top,...then 8
vertical pieces joining the 2 hoops. Inside this 'open style barrel'
I would
coil up a spiral hoop(s) of PVC pipe onto which to lay the rr track.

https://www.polytechforum.com/img/5r

--
for full context, visit
http://www.polytechforum.com/metalwo...pe-639050-.htm


In that case you could bent the conduit into the two halves of an
octagon.

See "Offset Bends:"
https://www.gridalternatives.org/sit...enderGuide.pdf

The nominal OD of 3/4" conduit is 0.922", the ID is 0.824". If an EMT
compression coupling isn't rigid enough I don't know of another common
material to join the two halves unless you can turn down 1/2" pipe
from 0.840" to a snug press fit on a metal lathe (the R.C.M.
solution).
https://www.garvinindustries.com/fit...Fc6XfgodwMIG_A

-jsw


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Default bending 5 foot dia circles of 1/2 or 3/4 EMT pipe

On Wed, 12 Jul 2017 02:18:02 GMT, brian
wrote:

replying to Larry Jaques, brian wrote:
Hi Larry,
Tubing bender is just two expensive for fabrication just a few (as little as
2) hoops.


True, but if you did buy one, you'd have another =tool=. scritch,
scritch, scritch

Don't discount the possibility of selling extras, though.


Just yesterday I found a contractor friend who says he has a hand
conduit bender i can borrow. I figure I can just make small incremental bends
and get my circular hoops. Now I just have to figure out how to calculate
those incremental bends to get my 5 foot hoop.


Conduit is cheap, so trial and error isn't too prohibitive. Make a
pattern so you can physically lay the bent tube on it to compare? Did
you ask the electrician? Perhaps ask on an electrical newsgroup. One
of the many math wizards here should be able to give you a tip.

Good luck getting the spacing right. That would seem harder than the
diameter to me.

How will you fasten the track to it, on plywood screwed to the tubing?


If you google "model railroad helix" you will see imagines of what I am
looking to build,...but an alternative method/materials.


OK, cool. I favor the more open models, and the inverted cone or
stadium style with the smaller lower diameters and larger uppers.

--
The door of opportunity is marked "PUSH".
--anon
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