What are some good methods of tightening bolts on dumbbells?

This is not directly related to fitness or nutrition, but most people here have likely encountered loose weights at the gym.

Our dumbbells take Allen cap screws.

When tightening the screws on one side of the dumbell, the screw on the other side will typically turn.

I have used Allen wrenches on both sides; however, the ratio of distance between the two screws makes it difficult to get much leverage when tightening the screws. The problem is compounded by the fact that Allen wrenches are typically shorter than the radius of the plates used on the dumbbells.

I am just interested to know what other techniques people that work at gyms use to keep their dumbells tight.

3 Answers 3


I do not operate a gym, but I've been involved in mechanical engineering.

What I would do is to get hold of some threadlocking substance (I've personally only ever used Loctite's products. There might be others available).

Depending on if you would ever want to loosen them again (repair?), there are different strenghts (medium is possible to take apart, the strong stuff is not meant to be removed, ever)

Then, partner up with someone. It'll make the tightening procedure much easier. It's fairly quick, and if you use threadlocking, you won't have to do it very often.

  • Ah! I have already been putting red Loctite on the threads, but having someone hold the other side is a good idea.
    – jp2code
    Feb 20, 2012 at 14:58

I have spin lock bars that I made permanent. I put a pipe wrench on a star on one side with the floor to hold it and wrench down the other side with another pipe wrench. So far they have stayed tight. No lock lite, this way if you want to take them apart you still can.

  • That about sums up what I'm doing, too, Ian. I tried Blue Loctite, but it would not hold.
    – jp2code
    Jan 8, 2016 at 19:26

Until I find someone to hold the other side for me (as Markus suggested), I have been using a small 14-inch pipe wrench on the grip area of the dumbells.

The only negative aspect to this is that the teeth on the pipe wrench tends to cut into the dumbell grip, leaving minor sharp edges.

If I could find a way to soften the bite on the pipe wrench without sacrificing its effective grip, I would be done!

Aluminum 14-inch pipe wrench by Ridgid

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