Galvanized nut binds halfway down — where would you start?

This topic has 7 replies, 8 voices, and was last updated 28 October 2026 at 17:06 by JasonB.

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28 October 2026 at 08:41 #871721
elowen01
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@elowen01
Hi all,

Quick one about hot-dip galvanized bolts and nuts.

The nut starts fine by hand, then gets tight halfway down the thread. It doesn’t feel cross-threaded, just like it’s binding.

What’s the first thing you’d check? Try a different nut, run a thread gauge over it, check pitch diameter, look at coating buildup?

And should a galvanized nut run all the way by hand, or is a bit of resistance normal?

Just trying to get a sensible order to check things before I start guessing.

Cheers.
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28 October 2026 at 09:34 #871753
Bazyle
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@bazyle
Is that half way down the nut depth or halfway down a yard of all-thread? if the former it is often due to it being a mix of UNC nut on Whitworth bolt, or metric and similar imperial bolt. For the latter it will be a zinc snot on the threaded rod.
28 October 2026 at 10:22 #871756
noel shelley
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@noelshelley55608
As Bazyle has said check that you do infact have the right nut. Whilst zinc coated eg hot dip will stop corrosion it will not improve it’s mechanical attributes. You do not indicate what your doing with it, but heavy loading will cause the zinc to cold weld, fine for fixing timber on a beach but no good if it’s being used as an extractor. I’m picking up some 16mm threaded rod today, I don’t want galv and will be using plain 8.8 grade (bolt) not mild steel. Noel.
28 October 2026 at 10:24 #871757
Neville Chase
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@nevillechase52412
Try a non gal nut on the gal bolt and the gal nut on a non gal bolt and see what happens.
28 October 2026 at 12:49 #871789
JA
Participant
@ja
Try lubricating both threads completely with a heavy oil oil or grease. On final assembly use a spanner or socket by hand, not a power wench.

This may work, it is advice given by the British Stainless Steel Association for preventing galling on stainless nuts and bolts.

JA
28 October 2026 at 13:24 #871796
DC31k
Participant
@dc31k
Take a spare, unplated nut, put a hacksaw cut into it and also cut the threads opposite the cut (to make proto-cutting teeth). Wedge it open just a tad and run it down the male thread. Try the proper nut and see if the problem is solved. If not, reduce the tad to half a tad, repeat the chase and try again.
28 October 2026 at 17:00 #871843
Neil A
Participant
@neila
My experience of hot dip galvanizing is that the coating can be quite thick and also vary in thickness unlike an electroplated part. It was not uncommon to have to run a tap down a hole to enable parts to screw together. Without knowing the application it is difficult to know whether this would be acceptable.

Neil
28 October 2026 at 17:06 #871849
JasonB
Moderator
@jasonb
What the Galvanizers Assoc have to say

https://galvanizing.org.uk/galvanized-nuts-and-bolts/
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