Steel size for project

[BukitCase]

For that little distance, I would use a brake cylinder hone instead of a drill - I'd shoot for a clearance of around 20-30 thou (>.030), but for that type use you could just hone a bit, try the fit, repeat.

You want enough "slop" to keep a grease film between them, but not a lot more. Keep in mind, it's not like that fitment is gonna be turning 6,000 rpm or anything... Steve

 

[Pooh_Bear]

How about 1.5 OD and 1.260 ID from Mcmaster-Carr? 7767T431
That's a little over .125 slop which looks like what I have now.
I guess I need to measure what I have.

 

[Baby Grand]

I can't weld that good. And sometime in the near future I need to replace the wheel forks and tires.
I called some more places today. Hard to describe what I need over the phone.
Looking online I found some 1.5 DOM tubing with a center of 1.124
How hard would it be to drill it out to size. And what size am I looking for?

Aha - I see. Then how about changing the DOM size?

Speedy Metals - 1-3/8" OD {A} x 1.135" ID {B} x .120" Wall {C} DOM Steel Tube

this will give you a .010" nominal diametral fit. Just watch the heat when you weld it to the rectangular tube or it'll distort and you'll get something less than .010" nominal - maybe too much less. If that happens, then you'll be wanting a reamer (or brake hone) to open it back up.

 

[Pooh_Bear]

That's what I need right there. I haven't bought the materials yet. I needed the sizes first.
I plan to do all the cutting and drilling and fitting and then just tacking it together.
I'll let somebody with more experience do the actual welding.

I wonder if I could drop the square tube down a size to 1.75 inches.

 

[BukitCase]

Depends on the weight of the mower and the wall thickness of your tubing - if you can find 1-3/4 tubing with a .120" wall thickness, it should be plenty strong to support a few hundred pounds with that span - but you might be better off going with RECTANGULAR tubing, say 1-1/2 x 3", same wall thickness - that works just the same as headers in a house - if the wide dimension is the vertical one, you get more weight support... Steve

 

[Baby Grand]

BukitCase is right about the advantage of using rectangular tubing like a header. Most of the loading will be vertical, so that's where you want the long side of the section. Consider using a 2x3 with .120 wall (if it will fit). Then you could drill a 1 3/8 hole clear thru and slip the DOM tubing thru the hole. This will allow you to weld the DOM to the rectangular tube in a circle around the top and bottom of the rectangular tube, rather than along the sides of the DOM tube. Much easier to get a consistant weld joint gap, keep everything aligned and less distortion this way.

 

[muddstopper]

what I have done in the past to tighten up fit and something easy to try. I take my sawall and saw the lenght of the tube, on just one side. Then heat the tube up with the torch, not redhot, but to hot to hold in your hand Then I take my welder and weld up the slit. This will usually pull the tube tighter, Not an exact science or fit, but it gets me by in a pinch.

 

[Pooh_Bear]

Instead of bigger tubing how about thicker tubing; 2x2 with .25 wall.
Currently it has 2x2 with .125 wall.

 

[BukitCase]

Sure, if the .120 wall 2x2 is what bent then double thick should work - I would still go with Baby Grand's suggestion on drilling the tubing and doing full circumference welds at TOP AND BOTTOM ONLY - if it's done well, I doubt you'd see enough distortion to even NEED cleanup after... Steve

 

[Pooh_Bear]

I got the steel today. 2x2 square tubing with 3/16 wall, 54 inches long,
and 1.75 DOM tube with .25 wall. I ended up with 1/8 of slop in the spindles.
I can live with that. Now to start drilling holes.