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08-04-2018, 08:45
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#1
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Registered User
Join Date: Aug 2010
Location: Arctic Ocean
Boat: Under construction 35' ketch (and +3 smaller)
Posts: 2,739
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Inch sized carriage bolts
A quick question, let's say we have a carriage bolt 5/16-18x8. 5/16 is thickness and 8 (propably?) the length in inches, but what the heck means the 18?
Teddy
https://www.jamestowndistributors.co...+Carriage+Bolt
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08-04-2018, 08:49
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#2
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Registered User
Join Date: Nov 2013
Location: Nice, France
Boat: Hunter Marine 38
Posts: 1,342
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Re: Inch sized carriage bolts
Threads per inch.
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08-04-2018, 08:51
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#3
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Registered User
Join Date: Jan 2015
Location: SoCal
Boat: Formosa 30 ketch
Posts: 1,004
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Re: Inch sized carriage bolts
Of course, to be different, in metric it's mm per thread.
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08-04-2018, 09:39
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#4
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Registered User
Join Date: Aug 2010
Location: Arctic Ocean
Boat: Under construction 35' ketch (and +3 smaller)
Posts: 2,739
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Re: Inch sized carriage bolts
Thanks
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08-04-2018, 16:23
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#5
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Registered User
Join Date: Dec 2009
Posts: 292
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Re: Inch sized carriage bolts
Just to expand a little....
5/16-18 is a course thread
5/16-24 is a fine thread
Also, you are correct, the '8' is the length of the bolt, measured from the underside of the head. This holds true for carriage bolts, cap screws and your everyday hex heads.
Now, If it was a flathead bolt, then it would be the overall lenght, measured from the top of the head.
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08-04-2018, 17:16
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#6
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Senior Cruiser
Join Date: Oct 2007
Location: 29° 49.16’ N 82° 25.82’ W
Boat: Pearson 422
Posts: 16,306
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Re: Inch sized carriage bolts
Quote:
Originally Posted by US1Fountain
Just to expand a little....
5/16-18 is a course thread
5/16-24 is a fine thread
Also, you are correct, the '8' is the length of the bolt, measured from the underside of the head. This holds true for carriage bolts, cap screws and your everyday hex heads.
Now, If it was a flathead bolt, then it would be the overall lenght, measured from the top of the head.
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What about the length of an oval head?
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08-04-2018, 18:57
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#7
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Registered User
Join Date: Mar 2014
Location: Moreton Bay
Boat: US$4,550 of lead under a GRP hull with cutter rig
Posts: 2,135
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Re: Inch sized carriage bolts
ASME has a standard for carriage bolts. But some retailers are carrying bolts (carriage and other) that are not to ASME standards.
One advantage of bricks-and-mortar retailers is I can run my own calipers over the stock. Unless it has to be back-ordered, in which case I'm in the same situation as buying on-line: if it's not specified, it's not known.
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09-04-2018, 08:18
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#8
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Registered User
Join Date: Jun 2017
Posts: 20
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Re: Inch sized carriage bolts
McMaster Carr - any bolt, nut, washer you want. Most flavors too. Brass, Steel, Stainless, plastic , teflon, etc...
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09-04-2018, 09:25
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#9
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Registered User
Join Date: Apr 2012
Posts: 353
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Re: Inch sized carriage bolts
McMaster is an excellent vendor.
If the item is in their catalog they normally have it in stock. They normally ship within a few hours of receiving an order and no minimum order. AND have discounted shipping.
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09-04-2018, 09:49
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#10
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Moderator
Join Date: Jun 2015
Posts: 6,193
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Re: Inch sized carriage bolts
TeddyDiver:
The "18-8" in your specification denotes the KIND of S/S the bolts are made of. The proper, complete specification would be " Capscrew, 5/16"D x18P x (say) 1 1/2", 18-8", which would mean "a hex-headed bolt, hade from 18-8 S/S, being 5/16" in nominal diameter, having 18 threads to the inch (Pitch = 18TPI) and being 1 1/2" long.
"Stainless steel" is not a simple metal, it is an alloy. Each of the many alloys known collectively as "stainless steel" has different characteristics deriving from the proportion of non-ferrous metals that are in the alloy. "18-8" has 18% chromium and 8% nickel incorporated in it, and that is what makes it "stainless", i.e. non-rusting. It is the most common "grade" of S/S used for fasteners intended for marine use.
It is purely coincidental that for 5/16" caps crews intended for marine use, the number "18" appears twice, once in the specification of pitch and once in the specification of the metal.
Cheers
TP
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09-04-2018, 10:34
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#11
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Registered User
Join Date: Apr 2014
Location: Chicago
Boat: Alden auxiliary ketch 48'
Posts: 950
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Re: Inch sized carriage bolts
Quote:
Originally Posted by TrentePieds
TeddyDiver:
The "18-8" in your specification denotes the KIND of S/S the bolts are made of. The proper, complete specification would be " Capscrew, 5/16"D x18P x (say) 1 1/2", 18-8", which would mean "a hex-headed bolt, hade from 18-8 S/S, being 5/16" in nominal diameter, having 18 threads to the inch (Pitch = 18TPI) and being 1 1/2" long.
"Stainless steel" is not a simple metal, it is an alloy. Each of the many alloys known collectively as "stainless steel" has different characteristics deriving from the proportion of non-ferrous metals that are in the alloy. "18-8" has 18% chromium and 8% nickel incorporated in it, and that is what makes it "stainless", i.e. non-rusting. It is the most common "grade" of S/S used for fasteners intended for marine use.
It is purely coincidental that for 5/16" caps crews intended for marine use, the number "18" appears twice, once in the specification of pitch and once in the specification of the metal.
Cheers
TP
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If you click on the link you will find that the OP is referencing a bronze carriage bolt on Jamestown Distributors. So, no, it isn’t SS 18-8 or otherwise.
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09-04-2018, 10:47
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#12
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Moderator
Join Date: Jun 2015
Posts: 6,193
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Re: Inch sized carriage bolts
Ah, Yes - Thank you :-). I didn't look at the link. For bronze the "8" is length, and "18" is pitch.
What I said about S/S may be useful for someone else :-)
Cheers
TP
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