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Old April 8, 2016   #16
FourOaks
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Default Update because of issues.

First. Thanks Uncle Doss.

Second. So I have still been toying with the bender. I thought I would update this for anyone who really wants to make this, since some interest has developed. I don't want someone left out in the weeds when their hoops don't work out.

What triggered this is that my second hoop was a disaster. I struggled to compress it enough. I actually ruined a piece of pipe when the swagged end buckled. My 3rd hoop made me realize something was wrong. My 4th hoop gave me redemption that im on to something.

This will be a ongoing update as I have now bent 4 hoops (I guess 4.5 since I had to fix half of #2). Only 9 more to go.

One of the issues to deal with is the "spring back" of the pipe. That is the tendency for the pipe to recoil back. The pipe simply wont stay 100% percent where you bent it. Its just the nature of Alloy Metal.

I have the solution, and the solution creates a second problem. Seems thats how things go for me. I'll cover both starting with the first issue.

The solution is to make your radius tighter then you actually need. I subtracted 1 foot off of my measurements. So, for a 12 foot wide house, the radius is 6. As you recall from above, I said:

"Step 6.

Continue measuring up the length of the long 2x4 until you reach 6 foot. Now add 1 extra inch. 6 foot because this is your radius, plus 1 inch because you measured in 1 inch in the previous step. See photo 4."


Nix that 6 foot. I changed that to 5 foot. So now you are drawing out the arc for a 10 foot circle, instead of 12. This may seem really drastic, but in the real world, you still have to compress the pipe a bit to make it slide over the rebar pounded into the ground. You can thank "spring back" for that.

Right now, I can only comment on a 12 footer. Other sizes of houses would be trial and error. But I would guess that 20 foot wide house would probably need roughly 2 feet taken off the radius. But again that is only a guess.

Now the second problem. Because we have monkeyed around with the radius, there is a tenancy for the ends of the pipe to curve in on itself. I have included a pic below and you can see this for yourself.

The solution is to leave approx 6 inches of pipe sticking out of the bender, when you bend your pipe. 4 inches might work just as well. The original MFR of the Hoop Bender states the same. To mark the pipe and leave 6 inches sticking out. I couldn't figure that out for the life of me as to why. Now I understand.

Now, for a small upgrade to the building process of the bender itself. Switch out the string with a piece of 1x2 pine, or something similar. Drill a hole in the end for a pencil to barely slide thru. When you draw out the arc, it is far more accurate.

Ill keep updating this as I bend more hoops.
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Old April 8, 2016   #17
Worth1
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I have been bending pipe of all kinds for 25 years.
From 4 inch sch 80 steel pipe to you name it.
What you want to do is make a mandrel so the pipe doesn't collapse.
This will work by making the center board just about as wide as the pipe is and have sides that stick up at least as much as 1/2 the diameter of the pipe.
If made it sturdy enough and the sides were all square you can bend square tubing.
The mandrel can also be made on a wood shaper with a hard piece of wood.
Any good cabinet shop with a split collar shaper can do this.
Or you may be able to cut the radius with a router.

Worth
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Old April 8, 2016   #18
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Worth, good info. Thanks.

I might have not been clear. The swagged end buckled after I had assembled the hoop and was putting the hoops over the rebar. Not when bending the section of pipe in the hoop bender.

At some point Im waiting for someone to say "why not just buy the bender?" Its really the point of being resourceful.
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Old April 8, 2016   #19
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Quote:
Originally Posted by FourOaks View Post
Worth, good info. Thanks.

I might have not been clear. The swagged end buckled after I had assembled the hoop and was putting the hoops over the rebar. Not when bending the section of pipe in the hoop bender.

At some point Im waiting for someone to say "why not just buy the bender?" Its really the point of being resourceful.
For the same reasons when someone asked me why I just didn't buy corned beef instead of curing and making my own.
Because I can its cheaper I know what I am getting and I am not reliant on other people.

There is another method of making a hoop or large radius in pipe.
It is a little complected and you have to have your ducks in a row.
This is where you bend angles in the pipe at a certain angle and a certain distance apart.
It can be done with a common conduit bender.
This is a really slick way to do it if you want to install glass panels.
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Old April 8, 2016   #20
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That's why I made my high tunnel have vertical sidewalls:


My hoops have a very shallow curve. It was easy to do, and took virtually zero skill. I didn't crumble any tubing; I don't think I came close, because I didn't bend it very much.

Top rail is ridiculously thin. The only thing thinner are the sleeve clamps that connect two unswagged ends. Those things are like aluminum foil. I learned that after 10" of ice smashed the tunnel in the picture, and I had to put it back together.

Last edited by Cole_Robbie; April 8, 2016 at 05:25 PM.
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Old April 8, 2016   #21
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Quote:
Originally Posted by Worth1 View Post
For the same reasons when someone asked me why I just didn't buy corned beef instead of curing and making my own.
Because I can its cheaper I know what I am getting and I am not reliant on other people.

There is another method of making a hoop or large radius in pipe.
It is a little complected and you have to have your ducks in a row.
This is where you bend angles in the pipe at a certain angle and a certain distance apart.
It can be done with a common conduit bender.
This is a really slick way to do it if you want to install glass panels.
Worth
I ran across an article a while back on that. I believe for a 10 foot piece of conduit, you would bend 5 degrees every 6.28 inches.

Radius (in inches) x 1.57 =a
then divide by 18

I think thats it..

Quote:
Originally Posted by Cole_Robbie View Post
That's why I made my high tunnel have vertical sidewalls:


My hoops have a very shallow curve. It was easy to do, and took virtually zero skill. I didn't crumble any tubing; I don't think I came close, because I didn't bend it very much.

Top rail is ridiculously thin. The only thing thinner are the sleeve clamps that connect two unswagged ends. Those things are like aluminum foil. I learned that after 10" of ice smashed the tunnel in the picture, and I had to put it back together.
I have seen your pictures. Really sorry that you had the disaster that you did. 10 inches of ice is nothing to laugh about.
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Old April 8, 2016   #22
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It was a learning experience. It cost me three days work and about $35 of new pipe. I re-used all the old stuff. I've never using those sleeve clamps again. EMT conduit is much better as a sleeve clamp.
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Old April 8, 2016   #23
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Quote:
Originally Posted by Cole_Robbie View Post
It was a learning experience. It cost me three days work and about $35 of new pipe. I re-used all the old stuff. I've never using those sleeve clamps again. EMT conduit is much better as a sleeve clamp.
So.. Im guessing your hoops are fence rail, and the conduit slides over the outer diameter?

Also, what size of house? Looks like 16 foot?
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Old April 8, 2016   #24
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Yes. It's 1 3/8" chain link top rail. It will slide into 1 1/2" metal conduit fittings. Top rail is tubing, which quotes the outside diameter as the size. EMT is pipe, which quotes the inside diameter for sizes. For the building pictured, I cut 90 degree conduit elbows in half to make 45s. Those sink into chain link posts, and the conduit goes into that. Here's a pic: http://i.imgur.com/CoWb0Um.jpg

The high tunnel pictured is 18x48. The peak is 8' and the sides are 4'. I built it low to the ground for the sake of being strong against the wind. The compromise is that it doesn't handle snow very well. I really should take the plastic off every fall, but I end up just going out there and knocking the snow off when we have it. I only had to do that once this past winter.
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Old April 15, 2016   #25
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Well i am hooked on this idea and i already have some top rail just laying in a pile. Not enough to do a 20x40 but every little bit helps.

Here is an Instructable http://www.instructables.com/id/Hoop-Bender/ I am sure all of you have seen this one.

I like how he uses his router to hold the top rail in place on the plywood.
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Old April 15, 2016   #26
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Quote:
Originally Posted by MrSalvage View Post
Well i am hooked on this idea and i already have some top rail just laying in a pile. Not enough to do a 20x40 but every little bit helps.

Here is an Instructable http://www.instructables.com/id/Hoop-Bender/ I am sure all of you have seen this one.

I like how he uses his router to hold the top rail in place on the plywood.
The groove is what I was talking about in an earlier post.

Worth
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Old April 15, 2016   #27
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Yea I know Worth... You posted a few ways for the top rail not to collapse. I just remember reading that over there the other day and thought to myself I am not paying 85.00 bucks to do this. I will build my own from salvaged crap around here.

Now if you could figure out my math problem in the grow bag thread. lol my math does suck...
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Old April 15, 2016   #28
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For anyone interested. I have been working on and finished all the rail for this greenhouse. All 13 sections. Ill post pictures tomorrow. Kinda dark out now.
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Old April 15, 2016   #29
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I am always interested in this sort of thing.
Tomato crossing no but this yes.

Worth
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Old April 15, 2016   #30
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Quote:
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I am always interested in this sort of thing.
Tomato crossing no but this yes.

Worth
Talk about something confusing.. I have off and on studied up on crossing. Honestly, if you have the patience be my guest.
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