Help figuring out socket size for large bolt

[Srseaman]

I have an old massive Chas Parker vise that I am now stripping and repainting. I need to separate the base from the vise and don’t know how to determine what size socket would fit the large bolt head. Flat to flat it measures 1.38”, point to point is 1.575. I’d be grateful for an explanation of how to convert these to the proper socket size. I’ve soaked the threads with Kano “Sili Kroil” penetrating solvent and tapped the bolt with a hammer but can’t get any conventional wrench onto the head.

 

[Junkdrawer Dog]

Just a shot in the dark here but if it measures 1.38 across flats, I'd guess it requires a 1 3/8" (1.375) wrench or socket. The small extra increment (.005") is probably just rust.

 

[cmandp]

Hexagon headed fasteners are measured in the across flats dimension, never points. So you measured 1.38" that would be 1-3/8" nominal. So a 1-3/8" socket or wrench size is what you need.

 

[gleman]

Good luck with your refurb! Post pics as you go along, this place has given me a lust for old vise's.

 

[Srseaman]

Hexagon headed fasteners are measured in the across flats dimension, never points. So you measured 1.38" that would be 1-3/8" nominal. So a 1-3/8" socket or wrench size is what you need.

Thank you. I over-thought this….1 1/4 was too small and 1 1/2 sounded too big. The Goldilocks solution was too obvious.

 

[Srseaman]

Just a shot in the dark here but if it measures 1.38 across flats, I'd guess it requires a 1 3/8" (1.375) wrench or socket. The small extra increment (.005") is probably just rust.

Thank you, I was trying to be too precise and it distracted me from the obvious.

 

[cmandp]

Thank you. I over-thought this….1 1/4 was too small and 1 1/2 sounded too big. The Goldilocks solution was too obvious.

I was confused as to why you were confused. You clearly know tools and fastener sizes if you have and can read a vernier caliper!

 

[WillyBoy]

Come on back with pictures when it's all cleaned up.

 

[JoshGuitar]

Your decimal measurements won't usually match the nominal size exactly, so what I usually do is multiply the decimal portion by 16 (or sometimes 32, 64, etc.). 0.38 x 16 = 6.08. That tells you how many 16ths it is - so about 6/16 or 3/8. Then add back the 1 to get 1 3/8".

Edit: that's also juuuust a gnat's whisker over 35 mm, so if you have the right size axle nut socket laying around that may be another option.

 

[gleman]

I was confused as to why you were confused. You clearly know tools and fastener sizes if you have and can read a vernier caliper!

It's a crown top Craftsman tool! Very nice.

 

[SweetD]

I had the same issue a while back, measured and bought the impact socket for like $14, I think Sunex brand. I had tried everything else to get that bolt out. Hit it with the socket and it came right out. Haven't used that socket since, but it was worth it!

Nice vise, keep us updated.

 

[Srseaman]

Here’s the update: the right sized impact socket 1 3/8 with an impact wrench made easy work of the bolt. Here’s before, during, and after pics. Thanks for this forum’s inspirations. I decided to leave bronze brazing exposed and set it off with a red accent.