Button head / coach bolts ?

[polaris]

Can anyone please advise me where I can source these from? I’m not having a lot of luck in locating them.
Bolts from Bryan square cup. I think possibly M4 in today's money?

[tallstory]

Unlikely to be M4. Much more likely to be Whitworth. Have a look at https://www.ebay.co.uk/sch/i.html?_from ... s&_sacat=0

[pennymachines]

There are several traditional fastener suppliers listed in the Archive/Services.
EC Pitcher's my local go-to, but his website doesn't list his stock.
I have the below chromed roundheads, but looks like you don't want the square lock head.

[slotalot]

you could always try this, not sure if they come in the domed type. Might be worth a Google.

https://www.powertoolsdirect.com/timco- ... m-timpac-4

[polaris]

Thank you all kindly for info. Given the imperial aspect, I think I’m now looking for 3/16, so will give that a try. I’m happy to use square locking type PM. I can always file them if necessary. Will most likely need to go down that road as I doubt I will find anything close to original.

[treefrog]

Coach boots are useless. Apart from the square lock under the head, the heads themselves are way too wide.

I have bought small dome head machine screws from these guys for award cards etc. Not chromed, but worked OK.
https://www.ekpsupplies.com/index.php

[bryans fan]

I have used this company several times for various vintage fixings. They also trade on ebay

https://www.thevintagescrewcompany.com/

[polaris]

Brilliant. That’s why this site is second to none. Spent many hours trying to find these. Should have asked here first.
Thank you

[pennymachines]

I have used this company several times for various vintage fixings. They also trade on ebay

https://www.thevintagescrewcompany.com/

Have added that one to Archive/Services.

[treefrog]

This company does a range as well, but only brass in slot less

https://www.gwr-fasteners.co.uk/8ba-x-1 ... 8202-p.asp

Another company with a large range of screws, based in US, but ships and does nickel plated versions

https://blacksmithbolt.com/en-gb/collec ... ine-screws

And another, steam hobbyist supplier

https://www.steamtractionworld.com/prod ... ornplates/