Mechanical experts - Help needed.

[Cousin Jack]

I am in need of expert advice from someone with some mechanical knowledge.

On a recent trip to Malta the Mrs spotted some brass door knockers, and I was persuade to part with money for one. They are a through the door fixing, a brass casting with a blind threaded hole and with a length of studding and a nut to fix on the inside. I was hoping to improve the look of the inside by getting a brass stud, and nut, or at least a chromed dome nut.

And now the problem. The thread is NOT the M5 I thought it was. In fact it is not M anything. I don't have any thread gauges and I have no idea what it could be. This is a modern thing, made in Malta recently so I am suspecting it won't be Whitworth or anything ancient.

The diameter of the stud is about 5mm as near as I can measure, but that is only approximate, I don't have any calipers and I am measuring with a plastic ruler.

Back in the day I would go down to my local ironmonger and tell him what I want and he would either produce one from the dusty recesses of he shop, or at least tell me what to search for elsewhere. Unfortunately ironmongers are no more.

Any ideas?

[Rockburner]

I am in need of expert advice from someone with some mechanical knowledge.

On a recent trip to Malta the Mrs spotted some brass door knockers, and I was persuade to part with money for one. They are a through the door fixing, a brass casting with a blind threaded hole and with a length of studding and a nut to fix on the inside. I was hoping to improve the look of the inside by getting a brass stud, and nut, or at least a chromed dome nut.

And now the problem. The thread is NOT the M5 I thought it was. In fact it is not M anything. I don't have any thread gauges and I have no idea what it could be. This is a modern thing, made in Malta recently so I am suspecting it won't be Whitworth or anything ancient.

The diameter of the stud is about 5mm as near as I can measure, but that is only approximate, I don't have any calipers and I am measuring with a plastic ruler.

Back in the day I would go down to my local ironmonger and tell him what I want and he would either produce one from the dusty recesses of he shop, or at least tell me what to search for elsewhere. Unfortunately ironmongers are no more.

Any ideas?

Buy a cheap thread gauge so we can at least get a measurement of the pitch?

Take it to your local independant bike MOT/workshop type place - somewhere that still occasionally works on old bikes, they may be able to help you find a nut that fits, or figure out the thread.

It could one of the "Imperial" threads that are still used - eg some light fittings are still a non-metric thread.

[KungFooBob]

Cut the stud off and no more nails it to the door

[Count Steer]

How big is the nut?

[Horse]

Count the number of threads (yes, I know, it's only one that spirals around) over an inch and 30mm.

As close as possible might identify whether it's metric or imperial. But, even then, it might not really be helpful knowing.

Do you know anyone into model engineering, or is there a nearby group / club? They might like a challenge.

[Cousin Jack]

How big is the nut?

Approx 10 mm across flats.

[Horse]

Cut the stud off and no more nails it to the door

Actually, get someone to saw it òff flush, then drill and tap a new hole. Insert threaded rod, affix to door, decorate with whipped cream and a cherry.

[Cousin Jack]

Count the number of threads (yes, I know, it's only one that spirals around) over an inch and 30mm.

As close as possible might identify whether it's metric or imperial. But, even then, it might not really be helpful knowing.

Do you know anyone into model engineering, or is there a nearby group / club? They might like a challenge.

It's about 20 threads per inch, but that could be out by 1 either way.

Helpfully neither of the two nuts have any useful markings.

One has a mark of some sort that might be a letter, but I cannot make it out, and two curved lines at 120 degrees to the mark.
The other has 3 letters that might be SAE (or might be something else entirely) with another mark that might be numbers 181( or could be something else entirely) at 180 degrees to it.

All the markings are blurred and pretty small too.

[Count Steer]

How big is the nut?

Approx 10 mm across flats.

Probably too big to drill out a domed brass nut to make a cover for it.

[Yambo]

10mm across the flats of the nut would make it around a 6mm thread, not 5mm. I use 5mm and 6mm bolts, machine screws all the time so familiar with the nut size - I have a bag of 30+ 6mm boss head machine screws, nuts and washers sitting on my table for a tart up job on my boat. The thread pitch is a different matter and personally I'd just dig around in my box of bits and see if I have one to fit. It may be 6 x 0.75 or 6 x 1. Needs to be measured.

How is the stud secured in the body of the ol' knocker (as the actress said to the bishop)? Maybe that can be replaced.

[kendo57]

10 - 24 UNC is about 5mm, little under.

[Sadlonelygit]

1/4" unf probably!
Worst case scenario is a fill/drill/tap to something metric
Or some airfix paint!

[Mr. Dazzle]

Yeah if it's modern my guess would have been 1/4" or 5/16" UNF if it's not M6ish. Those imperial sizes are still made by the bucket load for aerospace, which is very much still imperial dominated.

Or maybe it was made in Malta by a little guy in his little shop with his little box of ancient Whitworth taps and dies.

Cheapo callipers on Amazon or find someone who's got some, get the actual dims and then you're away. Even a 5 quid chinese set would be sufficient.

[Horse]

Cheapo callipers on Amazon or find someone who's got some, get the actual dims and then you're away. Even a 5 quid chinese set would be sufficient.

Just find someone to:
Saw
Drill
Tap
Rod
Saw
Nut
Beer to celebrate

[petrolpete]

I would get one of these and then wind it onto the rod and you can use an M5 bolt or rod on the other side
https://www.ebay.co.uk/itm/383719537128 ... edia=EMAIL

[Horse]

Dear Repair Shop,
My auntie was evacuated from Malta just before the Nazi invasion. She was only able to bring one treasured item. It's a traditional brass door knocker, that had been with the family for generations.
In England, she was so grateful for being safe that she dedicated her life to charity work. When she died, we cleared out the box she lived in - and there was the brass door knocker. I've cleaned it so it looks like new. But could you help with fittings? I'd like it on my front door. Then, when anyone knocks, I'll be reminded of her. I'll shout "Fuck off!" Because she was a miserable cow.
Love, John


Dear Who Do You Think You Are,
I am a minor celebrity on the Internet.  You won't have heard of me, but that's ok because you have run out of stars anyway. There is a rumour that I have Maltese roots, so please may I go for a holiday? I promise to cry.
Love, John


Dear One Show,
My Maltese heritage is a wonderful story and would make a fascinating item for your viewers.
Love, John


Dear Rogue Traders,
I ride a motorbike and have recently committed scams. Can I be on your show?
Love, John


Dear Points of View,
Who the Hell is this John bloke and why oh why oh why is he on every BBC programme?

[DefTrap]

I also have a Maltese brass door knocker! (Bought on eBay some years ago but I doubt it's likely to break any granny's knicker elastic if featured on Antiques Roadshow). It similarly has some non-metric threading - no doubt post-war Malta was full of ancient British tooling.

I did what any normal gent our age does - I rummaged in my massive bucket of random nuts until I found something that worked.

[DefTrap]

Look at my knocker(s)!

[porter_jamie]

Use a known metric M5 bolt as a thread gauge to see if it's the same pitch, coarser or finer.
M5 is 0.8mm fine is 0.5
M6 is 1.0.fine is 0.75
it almost certainly won't be fine
Take a picture of up against a known bolt

It could be 1BA which is 5mm and has a pitch of 28.2 tpi or 0.9mm the af of the nut is 9.29mm.
Ffs.
Good luck with that.
Id drill it out to M6 tapping size drill is 5mm so it will clean up and then you can get your stuff for it anywhere

[Yorick]

I thought metric was metric. But no.

Had to buy a front brake lever guard for the Suzuki . So took the 12mm bolt out of the bar end and wandered into town to buy a longer one.
Bugger, it's a finer thread than standard 8mm
No shops had them.

So had to buy another guard with adapter kit.
50 of your feelthy Engleesh Quids