filling a pipe to make it act like sold shaft?

[franklin2]

Would adding something in the middle of the pipe like this contribute to it's strength? Welded flat bar?

 

[CNC Dan]

<img src="http://www.tractorbynet.com/forums/attachment.php?attachmentid=364738"/>

Would adding something in the middle of the pipe like this contribute to it's strength? Welded flat bar?

Some....But not as much as increasing the wall thickness of the tube by the same amount.

 

[Egon]

I would just go with 4" pipe in a heavy wall thickness like schedule 80 or even 120. That should not flex on a 50" length. Maybe also put in s support ring in the middle of the shaft also even though you cant weld it, it will keep the "axle" from flexing in the middle and therefore make it much more rigid.

The schedule 80 should not bend in your application. Instead of the shaft through the pipe consider weldalets on each end that transition to your hub sise. Or you could weld series 600 RF flanges on each end and choose a companion flange with the right diameter for your hub. Ring flanges would also work.:thumbsup:

 

[brewdog]

Sch 80 is the right choice, it will not bend in a 50" length for this application. I personally don't think you will need it filled with concrete for a power rake. A weight rack can be added later.

 

[jenkinsph]

View attachment 364738

Would adding something in the middle of the pipe like this contribute to it's strength? Welded flat bar?

The problem with this approach is you can't weld it in place internally to get the maximum benefit.


I agree that a sch 80 weight pipe is the best approach.

 

[Gary Fowler]

The problem with this approach is you can't weld it in place internally to get the maximum benefit.


I agree that a sch 80 weight pipe is the best approach.

This is similar to what I posted about putting a rod thru the middle WITH A DONUT TIGHTLY FIT TO THE PIPE AND PLACE MID LENGTH in the pipe. When a solid rod is placed in the center of the larger pipe with one or more support donuts welded down the length, they only need to be welded securely on the ends. The center donut need not be welded as it is just a fulcrum on which the center rod rests and both ends are welded with thick plate so they wont cup inward from the bending force. Before the outside pipe can bend, it has to stretch the center rod.

Sizing the center rod would need to take into consideration the amount of force that one would be putting on the roller. The rod has to be strong enough that the forces don't exceed the yield strength of the center rod. By doing this, it makes the pipe & center rod act like a truss. The pipe cant bend without stretching the center rod AND stretching the topside of the pipe while compressing the bottom. This makes it extremely strong to resist bending.
If you just put a center rod thru it without the supporting donut, you wont have increased the strength very much at all.

 

[BHD]

The problem with this approach is you can't weld it in place internally to get the maximum benefit.

actually one can weld a web like that in place, if one drills some holes that match up with the web, and plug weld it, I did that on another project, using a thin wall 6 inch pipe,

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a lot to think about and I want to thank you all for your responses,

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under the situation the items I was thinking I was needing to roll here soon I was able to reform with a hammer and wood anvil, they went back nice,

what I was working on was sails on a windmill that had got bent,



here is the guide I was following
Windmill Sail Restoration

A.J. Wodack wrote a number of exelent how to's on windmills a few years back if you have some questions, on windmills restoration, do a search for "A.J. Wodack", most of them have been reposted from the old vintage windmill site that is no longer working,

there is a new windmill discussion site, V i n t a g e W i n d m i l l P a r t s . c o m that has many of the old members of the first "vintage windmills",

I want to thank all for there time and ideas on this project, the project is not dead but delayed for now,

 

[CNC Dan]

......By doing this, it makes the pipe & center rod act like a truss. The pipe cant bend without stretching the center rod AND stretching the topside of the pipe while compressing the bottom. This makes it extremely strong to resist bending.

I think the compression and tention forces on the near and far sides of the outer pipe walls are balanced, and any rod in the center of the pipe will see little forces, and so add little strength. You would be better off if you increased the wall of the pipe by the same amount of metal as you would use in a center rod.

Look up the term "neutral axis".
Here: I looked it up for you:
http://en.wikipedia.org/wiki/Neutral_axis

 

[Egon]

Maybe that center rod could be post tensioned. :thumbsup:

 

[jenkinsph]

I get the parts about tensioning the center rod and plug welding too, but it would seem to me that for rolling the heavy weight pipe or solid shaft would be easier to utilize. Solid shafting isn't so expensive that you need to reinvent the wheel.