i have some screw terminal capacitors but i cannot tighten them up fully as the threads are probably partly stripped.
any tips for this problem?
any tips for this problem?
Get yourself a thread repair kit. This consists of an oversized drill but, an oversized tap, and a set of helicoils that you thread into the new thread to bring it back to size. Probably M4.
Normally, they should be 10/32 UNF, which is very close to M5, but slightly smaller. You can try to (carefully) insert a M5 screw and tighten it (don't overtighten!). If it works, you are saved, otherwise you'll to look at more complicated solutions
Does the screw stop or keep turning?
If several capacitors do this, they may not be stripped.
If it stops, make sure the screws are not too long.
If it keeps turning, make sure you are using the right thread of screw, esp metric vs imperial.
If several capacitors do this, they may not be stripped.
If it stops, make sure the screws are not too long.
If it keeps turning, make sure you are using the right thread of screw, esp metric vs imperial.
If you can get a stud to thread in deeper than the screws, you can use a jam nut to retain that. Then use another nut to capture the terminal. And be careful of the torque, aluminum is pretty feeble once compromised.
That looks like they are re-tapping the threads. If they are slightly damaged, that will work, but likely not if it is actually stripped out.
If there’s enough material in the lugs, you can drill up a size and cut new threads for a larger screw. To do that you will probably need to have both a regular tap, and a bottoming tap in order to get the threads all the way down in the bores.
If there’s enough material in the lugs, you can drill up a size and cut new threads for a larger screw. To do that you will probably need to have both a regular tap, and a bottoming tap in order to get the threads all the way down in the bores.
You can still buy capacitors with screw terminals. Mouser currently lists 1014 part numbers in stock of various values. So if you can't fix the ones you have, you do have some options for new ones.
Tom
Tom
This seems a feasible way for metric screws.
https://www.amazon.co.uk/Rustark-Stainless-Inserts-Helicoil-Assortment/dp/B07Y32V7KK
Edited to change link to UK site.
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It's in the video description. He is just chasing the threads. As they were badly damaged, this is not sufficient, even with Loctite, which he shouldn't have used at all. He should have used a thread repair kit, as everyone is telling you.
He should also not have filed across both terminals at once.
Yes, not to mention the fact that what we saw in that video is actually a barbarity that has nothing to do with Audio.
That guy glued a stripped wire inside a stripped bolt of that monstrous capacitor (of an industrial washing machine?) to make it make an electrical contact.
In fact he uses a normal drill bit to enlarge the hole so that the sheath of the electrical wire could enter inside.
In total disregard for any rule of reliability, safety and common sense.
He says it's a tap but it looks like a drill bit.
He is also relying on the conductivity of Loctite in a high current application, and he has not considered future repairs.
The whole thing is stupid beyond words.
He is also relying on the conductivity of Loctite in a high current application, and he has not considered future repairs.
The whole thing is stupid beyond words.
Surely the end of the spring is then clipped off and a terminal can then be bolted, electrical contact is through the flat end of the terminal so the threading doesn't have to conduct well - note the flat ends were filed to make a fresh metal surface. How else could it be repaired? A little petroleum jelly on the end would delay contact corrosion as Al and Cu contact is at risk of electrolytic action. Think of it as similar to the terminals on a big battery, the important thing is the main contact areas being clean, protected from moisture.
My point is: would I do that with an audio capacitor in a my piece of equipment?
I don't think so.
Then if we want to try to find the best practice to repair that monstrous industrial capacitor as a last resort instead of throwing it away, then we can always try, but it is a different thread. IMO
However, just to put down two possibilities, I could think about redoing the thread, just as already said more than one time here.
That bolt is so big that it has a lot of material to work with and choosing the right size it would solve the issue well.
Or, given the size of the object and the relative bolts, even a suitable self-tapping screw, why not?
The contact will be made by the upper surface, just asyou already said, that he has filed.
Or the system (new for me) I proposed, which seems very interesting to me (not because I proposed it!).
With a thread repair kit, as stated by almost everybody here. Drill oversize, tap oversize, insert helicoil to restore original thread size, job done. In fact helicoils are stronger than the original threads. Not with Loctite, file, etc., all of which are foreign to this application.