Headstock Thread
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J-G
Established Member
The only way anyone can provide a suggestion from just a photo - albeit with a scale included - is by measuring the image on screen, interpolating and looking at thread tables for a 'close' match.
A rough estimate makes it 18mm Ø x 2.5mm pitch and that does align with the ISO Standard but 2.5mm calculated this way could also be 10 tpi.
Without knowing the make/model of the Lathe - which might indicate whether it might be Metric or imperial - it's impossible to be more positive.
With that size image it's also impossible to determine whether it is Whit (55°) or 60° form.
A rough estimate makes it 18mm Ø x 2.5mm pitch and that does align with the ISO Standard but 2.5mm calculated this way could also be 10 tpi.
Without knowing the make/model of the Lathe - which might indicate whether it might be Metric or imperial - it's impossible to be more positive.
With that size image it's also impossible to determine whether it is Whit (55°) or 60° form.
Thanks for the info J-G, makes sense.
Some additional info;
The lathe is Sealey SL-100. I understand it’s long been discontinued and way back when, it was probably a bit a bit naff then!
Sealey themselves tell me it’s a 3/4 x 16 thread but as I say, no joy with the adapter I have.
thanks
Paul
Some additional info;
The lathe is Sealey SL-100. I understand it’s long been discontinued and way back when, it was probably a bit a bit naff then!
Sealey themselves tell me it’s a 3/4 x 16 thread but as I say, no joy with the adapter I have.
thanks
Paul
J-G
Established Member
I don't know the Sealey products but a quick 'Google' pulls up a thread from 2013 about a Sealey - SL-1000 - which I suspect is more likely to be the designation if the 1000 is intended to indicate the distance between centres -- 100 would be somewhat short 
18mm is well under-size if it is in fact a 3/4" x 10 UNC which is another 'Standard' so possible. 3/4" is 19.05mm and I wouldn't expect even a new thread to be full size but the 'worst case' to still conform to the standard is 18.51mm (0.7288").
My next test would be to accurately measure the OD and if it is above 18.5mm then I'd look to finding ( or getting made ) a 3/4" x 10 UNC adapter.
18mm is well under-size if it is in fact a 3/4" x 10 UNC which is another 'Standard' so possible. 3/4" is 19.05mm and I wouldn't expect even a new thread to be full size but the 'worst case' to still conform to the standard is 18.51mm (0.7288").
My next test would be to accurately measure the OD and if it is above 18.5mm then I'd look to finding ( or getting made ) a 3/4" x 10 UNC adapter.
Paul Hannaby
Established Member
It's probably 3/4" x 10tpi. That looks like one of the old generic chinese lathes. I had one like that (but a different colour and manufacturer) which was also 3/4" x 10tpi.
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