A Welded-In Tube Adapter Is Cracked, Loose or Has a Stripped Thread: Re-Tap, Insert, Cut Out and Replace, or Scrap the Link?
First find out what is damaged. If only the thread is damaged and the weld and tube are sound, repair the thread, with an insert if the wall can take it. If the weld is cracked or the adapter is loose in the tube, the problem is structural: take the link out of service and […]
Where Does a Tube-Adapter Joint Fail First: Rod-End Thread, Adapter Thread, Weld or Tube, and How Do I Check Each Under Tension, Compression and Cyclic Load?
The joint is a chain with four links in series: the rod end’s male thread, the adapter’s internal thread, the weld (or pin) into the tube, and the tube wall. Whichever has the lowest capacity fails first, and the best design makes the ductile male thread that link. Check each link on its own, check […]
How Should a Rod End or Clevis Be Attached to a Tube in a Machine Linkage: Weld-In Adapter, Pinned or Bolted Insert, or Threaded-In Insert?
Use a weld-in adapter when the joint is permanent and you can weld to a procedure. Use a pinned or bolted insert when you cannot weld or must take the link apart, and accept that the holes in the tube wall set the strength. Use a threaded insert in a thick-walled or internally threaded tube […]
How Do I Choose Tube Diameter and Wall Thickness for a Push-Pull Link or Frame Member: Buckling, Bending and Torsion, and How Much Do the Adapter Ends Change the Answer?
For a link that pushes, buckling decides the tube, not strength. Treat the link as a column with a pin at each end, work out its slenderness L ÷ r, and use the Euler formula if it is slender and the Johnson formula if it is not. A tube beats a solid rod of the […]
How Do I Size a Tube Adapter to a Real Tube: Inside-Diameter Tolerance, Weld Seam, Seating Shoulder, Thread Size Limits and Which Tube Standard Controls the Fit?
The adapter fits the real inside of the tube, not the nominal one. The inside diameter moves with the outside-diameter tolerance, the wall tolerance and the out-of-roundness, and a welded tube may have a seam inside. Size the adapter to the smallest inside diameter it must enter, check the gap at the largest, choose a […]