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I need to affix a fastener deep inside a tube
- Thread starter jmarkwolf
- Start date
You apparently didn't see the picture in the first post.
I'm trying to put my mill up on leveling feet spaced far enough apart so I can get a pallet jack under it, from the front.
I'm a novice welder and would worry about getting adequate penetration.
You are WAY over-thinking this. You wrote that your welder has 3/8" capability. Regarding the 'threaded bushing' approach. Just grind a .1" chamfer around the ends (OD) of the bushings and the holes and set the welder for 1/8-3/16 material thickness and make sparks. Four big tack welds, equally spaced, in each groove would be plenty but you'd better go all the way around.
Make a practice piece. Cut the tube away so only one wall is left. Drill a hole through that wall and weld one end of a rod in there. Now try to pound, bend, beat that rod loose.
Yeah, practice piece is good since you can cut it apart and check penetration.
I'm inclined towards the full-length flat bar, tacked on the ends, and plug welded in the center. Drill and tap it UNF 1/2-20 and you're golden.
Normal load is pure compression on the tube. The only time you'll put stress on the bolts is if the mill starts to tip over. Other than that they're just convenience and could be replaced with a roll of duct tape or bailing wire.
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I'm inclined towards the full-length flat bar, tacked on the ends, and plug welded in the center. Drill and tap it UNF 1/2-20 and you're golden.
Normal load is pure compression on the tube. The only time you'll put stress on the bolts is if the mill starts to tip over. Other than that they're just convenience and could be replaced with a roll of duct tape or bailing wire.
Sent from my Pixel XL using Tapatalk
OK, I believe I've got my solution (pic below).
Making nut plates such as those below is well within the capacity of my welder and welding skills. I'll make up several (practicing) and keep the best four. I may or may not elect to plug weld them inside the tube or "pre-bolt" them in with smaller bolts (1/4-20 shear load only).
I was erroneously thinking in terms of drilling and tapping 1/2in thick plate, and then trying to plug weld the 1/2in thick plate to the 1/4in thick tube wall (problematic for me), but this option is very do-able.
The failure mode of this option is pulling the nuts through the 1/4in thick wall tube (not gonna happen), or stripping the threads (also not likely), instead of a failure of my weld joints.
The weld nuts and flat stock is readily available locally.
Thanks for all the excellent ideas everybody.
Making nut plates such as those below is well within the capacity of my welder and welding skills. I'll make up several (practicing) and keep the best four. I may or may not elect to plug weld them inside the tube or "pre-bolt" them in with smaller bolts (1/4-20 shear load only).
I was erroneously thinking in terms of drilling and tapping 1/2in thick plate, and then trying to plug weld the 1/2in thick plate to the 1/4in thick tube wall (problematic for me), but this option is very do-able.
The failure mode of this option is pulling the nuts through the 1/4in thick wall tube (not gonna happen), or stripping the threads (also not likely), instead of a failure of my weld joints.
The weld nuts and flat stock is readily available locally.
Thanks for all the excellent ideas everybody.
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Did not read all but we been there as we made a similar type thing for a fuel tank and needed nets in middle of a thin tube.
Drill hole where bolt goes and also drill some smaller holes where the OD of a nut would fit.
Get a chunk of tubing that a bolt fits through to be a spacer.
Now get a stick and tape a nut to the end and use it to hold nut and with the spacer on bolt secure the nut inside the tube with bolt.
The spacer allows the drilled holes to be visible.
Set mig welder a but on high side and place wire through hole against nut inside tube.
Pulse the trigger to spot wire weld it and repeat in other holes.
Remove bolt while hot then after cool chase with tap
Sent from my SAMSUNG-SGH-I337Z using Tapatalk
Drill hole where bolt goes and also drill some smaller holes where the OD of a nut would fit.
Get a chunk of tubing that a bolt fits through to be a spacer.
Now get a stick and tape a nut to the end and use it to hold nut and with the spacer on bolt secure the nut inside the tube with bolt.
The spacer allows the drilled holes to be visible.
Set mig welder a but on high side and place wire through hole against nut inside tube.
Pulse the trigger to spot wire weld it and repeat in other holes.
Remove bolt while hot then after cool chase with tap
Sent from my SAMSUNG-SGH-I337Z using Tapatalk