How to Fix a Cross Threaded or Stripped Hole in Aluminum
Introduzione
Vai al passo 1How to re-thread a stripped or mis-threaded aluminum hole.
Cosa ti serve
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Determine which hole has the cross threaded or stripped screws.
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Determine the size of the current thread. Threads are called out by the outer diameter, a dash, and then the thread count. For example, the tap shown is 1/4"-20".
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Select the appropriate tap size.
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Install the tap into the tap handle (See photo).
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After re-tapping your miss threaded check to make sure the threads work by screwing in the bolt or screw the hole is intended for
After re-tapping your miss threaded check to make sure the threads work by screwing in the bolt or screw the hole is intended for
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8Commenti sulla guida
If the hole is truly stripped then the technique in this guide won't work because the hole would then be larger than it was originally and the tap won't bite into the metal and therefore not cut any new threads. So then there are two options:
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1. Choose the next larger size bolt and drill and re-tap the hole to fit that larger size. Or if you really must use the same size bolt then:
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2. Use a helical insert (aka "Helicoil") which is a coil of hardened steel wire that forms both a outer and inner thread.
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I used option #2 to fix a stripped hole in a bicycle shock absorber. I bought the Helicoil kit sized for my bolt from a automotive supply store. The kit came with the drill bit and tap sized for the outside threads of the coil. I drilled the hole, tapped the threads, then threaded the coil into the hole. The inside diameter of the coil was sized to fit the original bolt.
Don is correct that tapping the hole as it exists won't really work and offered some viable solutions. However, if there isn't enough material for a Helicoil to bite into it won't work either on a through hole and sometimes using a larger bolt isn't an option either. In such cases you can add some filler to your existing hole. JB Weld can work as a filler for aluminum. If you apply a thin enough coating, you can tap the hole after it cures without drilling - then use a Helicoil for strength. Option 2 would be to use an aluminum filler rod and a MIG welder to fill, then drill and tap the hole.
Another option, is to drill and tap a larger hole and drive a threaded rod into the hole, grind both sides off flat, then drill a hole into where the threads mesh and lock the two together with a locking pin, then re-drill and tap a hole to match the original. Its more convoluted, but it’ll work if a helicoil won’t work, and the replacement would be very strong.
(Added info) In my case, I had an m7 hole that stripped out, I had some m12 threaded rod, so I drilled and tapped an m12 hole, drove and locked the m12 rod in place and as mentioned above, ground both sides flat. I then drilled and tapped a new m7 hole. It worked perfectly! :)
