3:20 am
May 13, 2010
Grant and I were talking on the chat the other night and I mentioned the problem I sometimes had with breaking pipe while bending it on the Hossfeld using the Hossfeld dies. He mentioned that he often used a follower like a swage and then a roller rather than the drag type die Hossfeld sells. Last week I forged a long half round follower for the 3/4" pipe I have to bend.
Today I finished making a roller and tried the roller and follower. I tried it on an offcut of pipe I had from the last time I did this job. It worked beautifully, nice smooth bend and and the bending force needed was much less it was a real struggle before now it is quite doable by myself. I then bent the first parts and then noticed it was crushing the first 3" of the bend and the bend is not as smooth as it should be. In the morning I am going to have to try making the groove in the follower a little deeper it is only 1/3 the dia depth right now. I will try and make it almost 1/2. This pipe acted a lot differently when I bottled the end in a progressive swage. Previously I crimped it down step by step like making candle cups and then used a cutoff to cut the end off. These pipes almost all broke off when I got to the smallest swage, so I did not have to cut them off.
i will snap some pictures of the bender setup tomorrow after i deepen the swage. to post later.
4:08 pm
March 22, 2010
Sounds interesting John...
I have done some bending tooling and my experience is if you want to make a really nice bend you need to totally contain the material at the bending moment. So the deepening the follow bar should help but the shoe should also be 1/2 of the diameter of the material... they should make a oval when you put them together that is the exact dimension of the tube from bottom to bottom but maybe .050- .100 taller from split to split...
Whatever you are, be a good one.
Abraham Lincoln
11:05 pm
May 13, 2010
Here is the follower and die on the Hossfeld.
11:18 pm
May 13, 2010
The die was already 1/2 the depth of the pipe I made the follower half the depth as well. The follower and the die almost touched while bending. Is that the .050-.100 you are talking about Larry? Making the follower deeper also allowed me to move the roller one hole closer the the pivot point. I think the further out roller may have moved the bending point slightly as well.
12:20 am
March 18, 2010
So, what's the verdict now? Working better, bout the same or worse? I often use a follower, usually just a flat bar if I'm bending round bar, prevents marking and sometimes I slip a thicker one behind it at the end to get a tight tuck.
“There are painters who transform the sun into a yellow spot,
but then there are others who, with the help of their art and their intelligence,
transform a yellow spot into the sun.” ~ Pablo Picasso ~
5:01 am
March 22, 2010
Yeah John, Forget what I said, (I dont know what I was thinking but it didn't pertain to what your doinging) What you got looks to me like what you should be doing... Its going to be tough to get a super clean bend with that tight of radius any way you do it, My 10 thousand dollar bender does a lousy job of anything under a 2" radius
Whatever you are, be a good one.
Abraham Lincoln
10:53 pm
May 13, 2010
I made an anchor point for my Hossfeld in front of the shop. Its a piece of square tubing set into the concrete. When I am not using it I have a piece of plate over the hole in the ground. To use it I have a smaller piece of tubing that fits into it the hossfeld mounts to the top of this piece of tubing. Having the extra room around the bender allowed me to use a longer handle which made bending the pipe much easier.
I did have 3 out of 30 pipes break as I bent them even using the follower. Two peeled open like a banana. Looking at them later all the pipes that broke had the weld on the outside of the bend. In the future I will have to make sure that the weld is on the inside of the bend.
11:59 pm
March 26, 2010
JNewman;2236 wrote: . Two peeled open like a banana. Looking at them later all the pipes that broke had the weld on the outside of the bend. In the future I will have to make sure that the weld is on the inside of the bend.
I guess its's cos the outside is under tension and the inside compression and the weld can take a lot more stress in compression
12:26 pm
August 14, 2010
david hyde;2241 wrote: I guess its's cos the outside is under tension and the inside compression and the weld can take a lot more stress in compression
What about putting the weld on top or bottom so that the weld is only being bent, not stretched or compressed? Seems like the lowest stress position to me.
6:18 pm
NWBA Member
June 17, 2010
Lewis;2261 wrote: What about putting the weld on top or bottom so that the weld is only being bent, not stretched or compressed? Seems like the lowest stress position to me.
The areas of the highest stress when bending pipe are about 30 degrees from the center of the inside of the bend. If 9 o'clock were the inside of the bend, the areas of the highest stress are around 10:30 and 7:30.
Placing the weld at the 12:00 (top) or 6:00 (bottom) position is an excellent idea.
8:07 pm
March 18, 2010
Swartzcoff (plain and ornamental forging) recommended putting the weld on the neutral axis too. That is, at the side on the bend where it neither stretching or compressing. Seems like good plan to me.
“There are painters who transform the sun into a yellow spot,
but then there are others who, with the help of their art and their intelligence,
transform a yellow spot into the sun.” ~ Pablo Picasso ~
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