filling a pipe to make it act like sold shaft?

[npalen]

I'm not sure that adding an unwelded support out in the middle of the pipe would do any good. The smaller shaft thru the support would have only negligible effect to stiffness.

 

[CNC Dan]

I'm not sure that adding an unwelded support out in the middle of the pipe would do any good. The smaller shaft thru the support would have only negligible effect to stiffness.

Yep. The center will see the least stress, and contribute the least to stiffness. Go with the largest diameter you can, then use a wall thickness that will give the required stiffness.

 

[Gary Fowler]

I think my idea of a center axle rod running thru the middle with an inside do-nut tightly fit to the ID of the pipe would work just like a truss. The pipe couldn't bend or even flex without stretching the center rod. Welded on each end tightly with a thick plate that wouldn't bow in from the stress, I think it would even work with lighter wall piping.

 

[ishiboo]

Concrete/mortar is the way to go.

Epoxy would be very expensive, even using sawdust or whatever as filler, and it'd take a long time to fill as 2-part epoxy is exothermic, you'd have to put some in at a time and wait for it to cool. Filling the whole pipe at once would get HOT!

 

[npalen]

The "I" value of a beam determines it stiffness. The "I" (Moment of Inertia) of 4" schedule 160 pipe (4 1/2" OD x 0.531" wall thickness) is 13.25 where the "I" value of 1.5" diameter shaft is only 0.248 or less than 2% of the pipe. The shaft has very little effect even with the donut. I chose the 1.5" diameter shaft just because it would probably take at least 1.5" diameter bearings on the end to carry the load. The shaft does act like a truss but it just doesn't have the needed leverage or strength. The hardness of the steel doesn't have any effect on bending strength either unless it's bent past the yield point of the material.

 

[CNC Dan]

I think my idea of a center axle rod running thru the middle with an inside do-nut tightly fit to the ID of the pipe would work just like a truss. The pipe couldn't bend or even flex without stretching the center rod.

Nope. One side of the pipe will be in compression, the opposite side with in tension, and the center, neither. Look up the term "nutral axis".

 

[slowzuki]

Yup, the pipe is already a truss in a way. The center is mostly useless unless you are supporting the pipe from below with a wheel or similar point load and you need to prevent collapse of the pipe at the point.

 

[jenkinsph]

I recommend you cough up for the solid shaft, make sure you get the right alloy while you are at it. Might save a lot of cash if you can search a few industrial scrap piles.

 

[thorholt]

We used to use "Hard Block" water jacket filler on our drag race engines when we bored them out to the max, It is a concrete type product that you poured into the cooling passages of the block to strengthen the cylinder walls, It should work but I would think it might cost as much as a solid rod.
HardBlok Water Jacket Filler - Increase Horsepower For High Performance Engines.

 

[SPIKER]

While I can see what you are doing & can be done I would think the cost of a used industrial machine would be well under the build costs to make one that works WELL. That means that one that works for occasional rolling of something LIGHT once and a while then the drill pipe and rod would function. That is IF you have access to some old used sprockets to make the drive mech. as the fabrication of those would totally offset the cost of even a NEW import roller.

Using the plates welded to the thru rod that were turned to fit TIGHT to the HW pipe will help support it but others pointed out there is not a LOT of support there...

Mark