hand benders ideal vs klien?

Status
Not open for further replies.
LawnGuyLandSparky said:
I've never bent 1/2" conduit in my life. Is this really used much in commercial applications?
Click to expand...

Ah - yeah.... I have (not personally but with a crew) put in more than 8000' of 1/2" alone on a single project. But on average go through at least 500' a month myself.
 
We never touch the stuff in NYC. I guess the contractors don't want to carry the parts stock for a size that's rarely needed, and doesn't cost much less than 3/4. Same logic for 1 1/4.
 
some of kliens tools

some of kliens tools

peter said:
Klein bought out Jack Benfield so the Klein is the original, such as it were. They come with a yellow handle and are more expensive. What color is the Appleton bender handle?
Greenlee has the "StraightLine" feature whick is a little peg that you can sight down on to get your angle. One nice feature of the Greenlee is the start arrow is exactly where the end of the bending grove is.
Don't cheap out and get a piece of plumbing pipe for the handle. This will work but the official handle will be painted and the open end will be swaged so that it will fit over the the counduit so you can tweak the bend to get it exact. To get an exact 90?, I compare the bend to a nearby column or wall.
Mention should also be made of the Ericksen bend which will bend 1/2", 3/4" and 1" with one tool. It makes all bends to a super radius of 12" which helps in wire pulling.
~Peter
Click to expand...
Are cheap crap
 
Don,
"According the the wire pull calculations, ..."
Who says these calculations are correct? Do they take into account the pushing effort?
All I know is that when pushing wire, without assistance on the pulling end, I can feel a sharp increase in the amount of effort when I reach a sharp bend. It's there and I can feel it.
Is there any reason why the data/comm guys and the utility people often specify large radius sweeps? Perhaps they know something we don't?
~Peter
 
1/2 inch is not uncommon

1/2 inch is not uncommon

LawnGuyLandSparky said:
We never touch the stuff in NYC. I guess the contractors don't want to carry the parts stock for a size that's rarely needed, and doesn't cost much less than 3/4. Same logic for 1 1/4.
Click to expand...
I remember some time ago there was a lot of talk about not being able to use 1/2 emt. It came from a lot of design/ engineer individuals. Future circuits was the concern. I always responded with "if they did not want you to use it they wouldn't make it"!
 
I have used a few different benders, but mostly Ideal they seem to be common with most contractors in this area. I another note I made sure my new work truck had all iron head shoes. The aluminum heads seem to be weaker and have seen the hook spring on a few of them when bending rigid.

Have never used the klein and I don't think I have ever seen one. I like the Ideal, but it could be that it is what I learned on and used the most.

On another note I don't care what the pulling calculations say, bigger radius bends are much easier to pull. Mabey that is where experience comes in. For example I always try to heat almost all my PVC and make the largest radius bends possible. instead of using factory fittinings.
 
Last edited:
Peter,
Yes, you do input the pushing force and that does make a difference in the total pulling tension. It is my experience runs with very large radius bends are often harder to pull than with standard bends. I am talking about 3/4 rigid with 4 #12s and 5 #14s. When the plant that I work in was original built the plans called for concentric bends for any horizontal conduit rack with 4 or more conduits. In some cases these 90s require more than on 10' length of conduit. I know that the calculation will show that they require the same pulling force as with standard 90s, but it sure feels like it takes more force for the long radius bends.
As far as using the long radius bends, it is most often to prevent damage to the conductors from what is called "side wall pressure". This is the crushing force between the conductors and the inside radius of the conduit when the wire is pulled. The side wall pressure is found by dividing the pulling tension at the bend by the radius of the bend in feet.
As a side note, pulling calculations would not normally be done for pulls where you can push and pull by hand, except maybe for communications wiring that has a very low maximum permitted pulling force...in some cases 25 pounds or less.
Don
 
Don,
Thanks for your lengthy reply.
"but it sure feels like it takes more force for the long radius bends." This is all subjective. I couldn't get a nylon fishtape through a 4" PVC sweep but -- against my bell coupling advice -- my metal fish tape went through just fine.

I've been thinking about our little disagreement. You are saying it takes the same force to pull through a 4" radius, standard bend and I am saying it is easier with a 12" bend. A 90? short bend would have, oddly enough, 3.14" of tube. A 12" radius bend would have 9.42" of tube or 1/3rd as much. At a certain point in the pull -- due to length, bends and other variables -- it may take 20 pounds of force to pull the wire 3" in straight conduit. The bend exacts a penalty, say your calculation total of say 30 lbs. With your short bend, then it would take 30 + 20 lbs of force to move the wires 3". With a super bend, it would take only 10 + 20 lbs of force to move the wire 3". Of course, the total would be the same [10 + 10 + 10 +20] but each 3" tug would be easier.

I hope this clarifies the issue.
~Peter
 
Peter,
The extra force to pull around a bend is caused by the extra friction from the pressure against the inside radius of the bend. While the pressure against the inside radius is less for a longer radius bend, it is applied over a longer distance. Once you are around the bend, your theory does not apply as you are pulling the wire against the total length of the radius. Also as I said in my last post, the super long radius bends seem much harder to pull than a standard radius bend.
Don
 
Don,
You've used the word "seem". "...the super long radius bends seem much harder to pull than a standard radius bend." This is subjective. I apologize for your difficulty in making that pull.
What is needed is an objective, laboratory test to settle this issue once and for all.
Dirt27 states that "bigger radius bends are much easier to pull. " I agree with him.
The problem is to explain why the calculations must be wrong. I will withdraw my theory since you have nullified that with your wise logic. Instead I will point out that it is impossible to pull through a plumbers' 90? elbow and a straight pull is easiest of all. A large radius bend more closely approximates a straight pull than a short radius bend. This may be intuitive. Think of how freeway curves are laid out: Large radius.
~Peter
 
The problem is to explain why the calculations must be wrong.
Click to expand...
I don't think that the formulas are wrong. I expect that they do not include things like plumber's fittings as that radius is not permitted for raceways.
Dirt27 states that "bigger radius bends are much easier to pull. " I agree with him.
Click to expand...
And that is not subjective???
Think of how freeway curves are laid out: Large radius.
Click to expand...
I don't see how driving where the forces are pushing you to the outside of the curve have anything to do with pulling where the forces are pulling you to the inside of the curve.
Don
 
don_resqcapt19 said:
As far as using the long radius bends, it is most often to prevent damage to the conductors from what is called "side wall pressure". This is the crushing force between the conductors and the inside radius of the conduit when the wire is pulled. The side wall pressure is found by dividing the pulling tension at the bend by the radius of the bend in feet.
Click to expand...

Side wall pressure equals friction, friction equals more pulling force. I know say there is the same amount or more friction on a large radius bend just spread out over a larger area. I don't agree with that but could think of any better examples than peter. Another think to cosider because you are talking about 12's in a 3/4 is the head. Almost ever time wire gets hung up in a pipe or gets very hard it is the head reaching a bend so the longer raduis would help with the side wal pressure the head was getting at that time. I have had many pulls when the head gets through the bend, other pulls get to a point where they are just hard untill the end.

I hope some one can get on here and really explain this matter. My logic tells me it is easier to pull through a long raduis. Dons logic is that it is harder for a longer raduis. Like Peter I can not prove Don wrong. Even if an engineer could explain Dons logic I would still stick to my large radius bends. Field experience tells me other wise and just because it looks good on paper doesn't mean it will work in reality. I always say the guy that runs the pipe should also be the guy that pulls the wire.

Perter also says A large radius bend more closely approximates a straight pull than a short radius bend. This is what imediatlly comes to my mind explaining this issue and is my total reasoning behind it.
 
larger sweeps are easier i think(totally opinion) because the wire does not have to bend as sharply, when that wire bends it takes alot of force to pull it into a sharp bend, think about it take some big wire, 3/0, bend it in a large radius ..easy. now make a tight bend ooohh much harder. so not only friction but the copper inside the insulation has to bend and the insulation and copper dont want to.

what do you think???
 
JohnJ0906 said:
Not true of the GB benders I have. (?" and ?") Both are 30? handle straight up.
Click to expand...

Check this out, there is a flat edge that you line up with the arrow that also gives you 15 degrees on GB benders.

Anybody seen the ads for the new bender that Rack A Tiers is pitching? They claim it is way easy to figure bends using it, but the description of the method to employ has me scratching my head. Hoppy Bender
 
Status
Not open for further replies.
Top