-
Scam Alert. Members are reminded to NOT send money to buy anything. Don't buy things remote and have it shipped - go get it yourself, pay in person, and take your equipment with you. Scammers have burned people on this forum. Urgency, secrecy, excuses, selling for friend, newish members, FUD, are RED FLAGS. A video conference call is not adequate assurance. Face to face interactions are required. Please report suspicions to the forum admins. Stay Safe - anyone can get scammed.
How to figure out the 3 wire measurement for a BSW thread
- Thread starter fixerup
- Start date
Tom O
Ultra Member
I found this at…
www.threadcheck.com
The Three Wire Method Of Measuring Pitch Diameter
Measuring thread pitch diameter can present difficulties. Thread Check discusses 3 wire thread measuring, thread measuring diameters and pitch diameters.
Super, thank you so much
Using my .063" wires I should measure .8974" over the 3 wires.
I made a screw earlier and it measured .882 , over the wires, no wonder it was loose. It is hard to properly cut a screw thread without using the 3 wire measuring method. I usually can wing it using a nut has a go no go, or I am getting close take smaller cuts until it fits. But the three wire is the proper spec.
Thank you for the info and the link, there is some good information there.
Cheers!
Using my .063" wires I should measure .8974" over the 3 wires.
I made a screw earlier and it measured .882 , over the wires, no wonder it was loose. It is hard to properly cut a screw thread without using the 3 wire measuring method. I usually can wing it using a nut has a go no go, or I am getting close take smaller cuts until it fits. But the three wire is the proper spec.
Thank you for the info and the link, there is some good information there.
Cheers!
Last edited:
Proxule
Ultra Member
This page sometimes helps me out as well
theoreticalmachinist.com
UN imperial screw thread calculator
Proxule, I will definitely bookmark that page. Thank you.
I was just now looking to see what class would be the screw I made. BSW ( close, medium and free or garbage )
But the calculation are beyond my math skills, ( radical notation went right over my head ) I wish there was a similar site which would do the same calculation for BSW.
My over the wire measurements were .0154 smaller than calculate . so is my screw classification a close, medium or free or total garbage?
I was just now looking to see what class would be the screw I made. BSW ( close, medium and free or garbage )
But the calculation are beyond my math skills, ( radical notation went right over my head ) I wish there was a similar site which would do the same calculation for BSW.
My over the wire measurements were .0154 smaller than calculate . so is my screw classification a close, medium or free or total garbage?
I wasn't able to find an easy peasy plug in numbers calculator on the web. Probably because this whitworth thread was developed in 1841 and it is no longer used in the industry. It always amazes me what they were able to accomplish with so little back in the early 1900.
So instead of trying to find out if the screw I made is good, ok or not, I will just make a new one with the right measurements using the formula Tom O found for me.
Procrastination makes easy things hard and hard things harder,
Cheers!
So instead of trying to find out if the screw I made is good, ok or not, I will just make a new one with the right measurements using the formula Tom O found for me.
Procrastination makes easy things hard and hard things harder,
Cheers!
I don't agree with that! In my world, procrastination either makes things go away, or provides the time needed to think of a better way. Besides, what's the difference between waiting 55 years and 54?
lucsimoneau
Well-Known Member
Using the trusted Machinery's Handbook, this is what you are looking for:
lucsimoneau
Well-Known Member
Using a 0.070" wire, you should get a measurement of 0.9187":
Yay, I found a whitworth calculator which give me a spec for its different thread classes 1 Close, 2 Medium and 3 Free.
I plugged in my numbers into the calculator and got the following.
Pitch dia for close is 20.363mm ( 0.816")
medium is 20.3365mm (0.8006")
free is 20.296mm (0.799")
And the pitch dia of my homemade 7/8 -9 BSW screw is 20.0406mm (.789") Class ? = recycle bin, stop procrastinating and make a new one! LOL
E= M +( 0.9605 X P) - ( 3.16 X W)
E= .882 + ( 0.9605 x .111) - ( 3.16 X .063) = .789"
Here is the link for the calculator
https://www.threadspecification.com/w/
Playing around with these British threads is all new to me. I knew very little about these standards up until I got this old Triumph motorcycle, which also has CEI . Cycle Engineering Institute.
Thanks for all the input, it was motivating.
Cheers!
I plugged in my numbers into the calculator and got the following.
Pitch dia for close is 20.363mm ( 0.816")
medium is 20.3365mm (0.8006")
free is 20.296mm (0.799")
And the pitch dia of my homemade 7/8 -9 BSW screw is 20.0406mm (.789") Class ? = recycle bin, stop procrastinating and make a new one! LOL
E= M +( 0.9605 X P) - ( 3.16 X W)
E= .882 + ( 0.9605 x .111) - ( 3.16 X .063) = .789"
Here is the link for the calculator
https://www.threadspecification.com/w/
Playing around with these British threads is all new to me. I knew very little about these standards up until I got this old Triumph motorcycle, which also has CEI . Cycle Engineering Institute.
Thanks for all the input, it was motivating.
Cheers!