I need to affix a fastener deep inside a tube

jmarkwolf

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I am fabricating some leveling feet tubes that will reside under my Bridgeport clone (similar to the pic below, but 2in x 3in and thicker wall).

The leveling feet will be spaced a little wider apart than those in the pic to accommodate the forks on my pallet jack, consequently the rectangular tube will be longer.

I need to "attach" a fastener inside the tube in order to screw in the long 1/2-13 bolts circled in white. The 1/4 inch thick tube wall would not provide adequate thread engagement if I were to simply tap the hole.

I originally thought I would simply turn a shoulder on some standard nuts, carefully located them inside the tube, and weld them in place at the outside surface, but then I thought that this might anneal the nut ruining it's strength.

I can't simply run the bolt through both sides of the the tube and apply a nut on the far side because it needs to clear the forks on the pallet jack.

I'm not finding any nutsert type system for 1/2-13.

Now I'm thinking I may drill and tap some appropriately thick flat stock for 1/2-13 and "pin it" in place inside the tube for a no-weld solution.

I know I'm probably over thinking this but...

Can anyone offer some pears of wisdom, or an alternative approach?

Bridgeport_leveling_feet1_annotated.jpg
 
I am fabricating some leveling feet tubes that will reside under my Bridgeport clone (similar to the pic below, but 2in x 3in and thicker wall).

The leveling feet will be spaced a little wider apart than those in the pic to accommodate the forks on my pallet jack, consequently the rectangular tube will be longer.

I need to "attach" a fastener inside the tube in order to screw in the long 1/2-13 bolts circled in white. The 1/4 inch thick tube wall would not provide adequate thread engagement if I were to simply tap the hole.

I originally thought I would simply turn a shoulder on some standard nuts, carefully located them inside the tube, and weld them in place at the outside surface, but then I thought that this might anneal the nut ruining it's strength.

I can't simply run the bolt through both sides of the the tube and apply a nut on the far side because it needs to clear the forks on the pallet jack.

I'm not finding any nutsert type system for 1/2-13.

Can anyone offer some pears of wisdom, or an alternative approach?

View attachment 265971

Why wouldn't you just thread the tube. Or drill through the tube and put the nut on the underside.
I would just thread the tube.
 
Why wouldn't you just thread the tube. Or drill through the tube and put the nut on the underside.
I would just thread the tube.

Not enough thread engagement (just 3 threads and well under the recommended) and it needs to clear the forks on my pallet jack on the underside.
 
I like your idea about a thicker piece of flat stock placed inside the tube, but instead of 'pinning' it, I would drill holes in the tube, locate the flat stock, and then 'plug weld' the stock to the tube... then locate the 1/2-13 holes and drill/tap with the flat stock in place.

FWIW, I have welded flange nuts in steel tube also...

-Bear
 
Correct me if I'm wrong, but...

Won't the only tension load on the tube be if it's hanging from the mill? If the concern is with the tube trying to roll, plate welded at 90 to the tube should take care of it, the bolts wouldn't be under a great deal of stress and the machined-to-flange-nuts welded in would likely be several times as strong as you'd need...?

Personally, I'd run a piece of thick-walled tube right through the box section and weld both ends, drill and tap the upper end perhaps 1/2" deep minimum for the 1/2" bolt thread, but add the stabilising tabs anyway!

Dave H. (the other one)
 
Why not just a single piece of flat stock that runs the full length of the square tube. Drill and tap the flat stock on the same centres as the clearance holes in the tube under the mill. Then you should be able to hold everything in place from the ends and line it up and not have to worry about fiddly pieces way inside the tube.

David
 
In a length of scrap wood, counterbore a hole just large enough to hold a 1/2-13 hex nut under the clearance hole. Make the clearance hole in the tube large enough so you can weld the nut to the tube. Chase with a tap after welding.
 
I don't think there is any danger of annealing the nut. The nut is probably not hardened. Normal nuts are mild steel. Is this a graded nut?
Weld it to the top side, an you are done. If you are sure you need it graded, you can use cool air from a compressor to cool it quickly. It won't be full grade, but it won't be soft, and it won't warp the tube by cooling it way to fast in water or oil.
 
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