Odd Threads on Milling Machine

I recently acquired a Tom Senior horizontal milling machine from a garage clearance. A previous owner took it to bits with a view to cleaning and refurbishing it. He then lost all of the bolts but assures me all of the important bits are there. The latest owner bought it in bits as a rainy day project then downsized so it had to go.

There are holes in the casting about 1/2" in size. An M12 bolt will go in about a turn then get stuck. A 1/2" UNC will go in about the same distance before binding up. A 1/2" UNF won't even start as it's clearly far too fine. I've just been and gotten some 1/2" BSW and 1/2" BSF bolts and it's not those either. There are also some holes about 3/8" in size, but again they don't seem to be M8, 3/8" UNC, 3/8" UNF, 3/8" BSW or 3/8" BSF. Oddly though, there's one pair of mounting holes that are definitely 3/8" UNC, which convinced me to try forcing UNC into one of the other holes but I had shards of metal coming out so it's definitely not all UNC. This has got me wondering if a previous owner has hit the same problem and retapped two holes he was working on only.

Are there any other oddball threads out there that might have been in use on an 1950s era British built machine before I get the impact wrench out or the mag drill and start making it all metric?
 

dave mountain

Member
Livestock Farmer
I've got a load of test bolts from the local ag dealer to take back so I'll see if he has anything BSP. He did mention that as a wildcard.

if it is then could just get some M14/M16 bolts, turn them down on a lathe then run a die down them, probably easier than trying to tap an old mill which i assume is cast?
 
You really need a thread pitch gauge to find out what pitch they are then look in thread charts to see what thread it could be.
Can you see an inch of thread or a half inch and count the peaks.
Also take a look on Lathes.co.uk http://www.lathes.co.uk/senior/index.html
And you can always ask Tony he is usually very helpful.
Just ordered a set of gauges but I'll give Tony a try on the off chance.
 

pycoed

Member
your best bet is probably to run a 12.5mm reamer in a mag drill down the holes, then an M14x1.5 machine tap in the mag drill too. 10.5mm and M12 for the smaller ones
Smack yourself on the ar$e will you! Defiling a good old British machine, fabricated with proper Christian threads, with foul foreign (French! FFS!!) rubbish. I bet you're one of those cads that paint your Bentley pink.😭
 

tomlad

Member
Location
nr. preston
Now wen im try to recon what a thread is i go between the od , thread pitch gauge, metric and tuther and google .
Another reason why i spent a bit more on my digital caliper with mm , imp , and fractions
Id personally be very reluctant to start rethreading
My local bolt shop ,AT engineering are very helpful and knowledgeable, presuming u get the right lad :rolleyes: 👌
 
You really need a thread pitch gauge to find out what pitch they are then look in thread charts to see what thread it could be.
Can you see an inch of thread or a half inch and count the peaks.
Also take a look on Lathes.co.uk http://www.lathes.co.uk/senior/index.html
And you can always ask Tony he is usually very helpful.
Tony got back to me very quickly and said he'd never come across one that wasn't BSW or BSF. Going to go back to the ag dealer and ask him if he's absolutely certain those bolts he gave me were BSW. I'm a child of the metric era so I wouldn't know any better :ROFLMAO:
 

MF-ANDY

Member
Location
s.e cambs
Tony got back to me very quickly and said he'd never come across one that wasn't BSW or BSF. Going to go back to the ag dealer and ask him if he's absolutely certain those bolts he gave me were BSW. I'm a child of the metric era so I wouldn't know any better :ROFLMAO:
1/2 bsw and unc are similar but one us 12tpi the other is 13tpi so maybe the bolts you have aren't bsw. Cant see a manufacturer using anything but standard threads
 

Netherfield

Member
Location
West Yorkshire
He was pretty adamant given that one lot had a different shaped head from the other but I'll ask him to double check.
Your UNC should have like ring depression in the head of the bolt and a slight chamfer on the edges as below shows, whereas your BSW should be dead flat across the top.

Mind we moved on to metric since then so maybe they don't bother with such things now.

And at one time some UNC and UNF nuts used to have a band of circles running up the side of one of the flats.

1640082949005.png
 

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Man fined £300 for bonfire-related waste offences

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Written by William Kellett from Agriland

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A man has pleaded guilty at Newtownards Magistrates’ Court to waste offences relating to a bonfire next to the electrical sub-station on the Circular Road in Newtownards, Co. Down.

Gareth Gill (51) of Abbot’s Walk, Newtownards pleaded guilty to two charges under the Waste and Contaminated Land (Northern Ireland) Order 1997, for which he was fined £150 each and ordered to pay a £15 offender’s levy

On June 25, 2018, PSNI officers went to Gill’s yard, where they found a large amount of waste consisting of scrap wood, pallets, carpet and underlay.

Discussion with Northern Ireland Environment Agency (NIEA) officers confirmed the site...
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