Stanchion Hardware Search - Please Help!

I have a 1982 Bristol trawler, 42'. We have removed all of our stanchions and toprail, and have now refinished the cap rails. Some of the flat head machine screws we removed in the process are not reusable. I cannot find anything like them anywhere! They appear to be 5/16" diameter, but not quite; or #8 metric, but not quite. Neither of those sizes (new) will sit flush in the stanchion base plate b/c the heads are far too large, nor will they fit the threads on the tapped plate under the cap rail. The original screws are 1-1/2" long, brass or bronze. They are definitely NOT standard (at least, anymore), and custom made replacements are $7.75 each (OK) and require a 4-week lead time (not OK). Alternatively, I could have all the stanchions re-bored, the cap rail holes re-drilled, and the inside plates re-tapped. I would much rather find the darned machine screws! Where did these odd fasteners come from? More importantly, how can I get some?

Fastenal or similar? https://www.fastenal.com/

I have tried them, McMaster-Carr, etc. and everyone has the standard sizes--all with heads too large and threads that are a little too large in diameter as well. Is there anywhere to get original fasteners used by Bristol?

Try Jamestown Distributers but I'm with RT on this. Go into the store not the website and talk with the countermen face to face at Fastenal. FYI, I've been a satisfied customer of theirs for over a decade and have never waited more than 4 days for anything, regardless how rare.

OK, I will do both of those. Thank you.

Have you tried talking to your local Hamilton Marine?

What is the exact diameter? How many threads per inch?
This is really strange. I have an antique brass bed that is put together with 1/4- 24 tpi machine screws. This is no longer a standard size but it used to be.

I'll be interested to know what you figure out.

Yes, Hamilton Marine was one of my many stops. They weren't much help, offering the same standard 5/16" x 1-1/2" with the large head and suggesting that I re-bore and re-tap everything.

No fun , but I would bite the bullet and re drill and re tap to a common US size.

These will need to be re bedded every so often so make the future EZ on your self.

The diameter is 0.311" and the diameter of the head is 0.437". There are 18 threads per inch. But a 5/16-18 is too large to fit into the hole through the cap rail or the nut in the fiberglass below.

FF, thanks for the suggestion. I am thinking it may be the way to go, but I have never done it. Is it easy enough for a newbie to do it?

Once you determine the correct thread diameter and pitch (this should be easy with a thread gauge and bolt sizer), Chuck the bolts in a drill and hold up against a grinder to reduce the head size to something that will work.

5/16ths has a major diameter of .3125 so that must be it. Standard Pitch's range from 18 to 24 to 32.
As mentioned, you might need to run a tap though there..

seasidemom said:

FF, thanks for the suggestion. I am thinking it may be the way to go, but I have never done it. Is it easy enough for a newbie to do it?

Click to expand...

Why don't you ask the people at Hamilton who suggested it in the first place? Lot of expertise in that organization.

The only hard part of drilling a SS part is holding it as its drilled.

A drill press is nice , but a 3/8 slow speed hand drill with the part held in a vice works just fine.

Pressure and a sharp (new?) drill bit is a help, even a drill bit held in a hand brace will work if you can be above the work and lean hard on the brace.

Tapping holes requires a drill bit that fits the MINOR diameter of the threads .

Look up what is required for a 75% fit and simply purchase that drill when you purchase the tap you will use.

It may be a 32 size or a number or letter drill bit.

Oil helps the tap process as does removing the tap every so often.

After the first couple you will be an expert.

Dont forget to clean the oil before using some sealing goop.

I prefer Dolphinite as its the easiest to take down and clean for the next rebedding exercise..

Thank you so much for all the information. I appreciate the generosity on this forum!

Sure it's not an M8 x 1.25 or M8 x 1 thread ?

Greetings,
Ms. ssm. I cannot see any vessel manufacturer using a fitting that was not a standard size (SAE or metric). Before you go to the trouble and frustration of re-tapping everything, you must confirm the existing bolt size regardless of what any "counter person" thinks it may be. Forget about the head size for the time being. It's the thread configuration and the potential of re-tapping that will cause headaches. There HAS to be something that readily fits.

If, as you say, the nut portion in the hull is just that, a nut and not a solid plate, attempts at re-tapping could be a quick journey to hell IF the nut starts spinning halfway through a re-tap to a different thread.

Take several bolts into a good fastener center as suggested and have at it.

What about going to a pan head screw that would cover the hole in the stantion base. If you can find one with the correct thread size, I would not be concerned about having the screw flush. As far as bedding, I love using butyl tape. It stretches if the stantion has any give to it and is removable if you need to rebed (probably will not ever be needed with butyl). You do have to tighten it several times as the butyl squeezes out, but it is worth it.

No one would use screw threads that do not exist, why would a builder raise their costs? This sounds very strange that the thread size is unique to this boat.
Tapping new threads, if the original thread is a close match will be easy. Oil the tap, you go like 1/2 to 1/4 turns, and you back off to clear the chips..

If it is just a tapped support plate AND NO LOOSE NUTS.

Ms. ssm. I cannot see any vessel manufacturer using a fitting that was not a standard size (SAE or metric). B

Many Bristol 42 were sold for "owner completion".

A factory finished boat will be mostly OTS material from the local distributor , a home brew may have anything!

Perhaps brush standard

seasidemom said:

I have a 1982 Bristol trawler, 42'. We have removed all of our stanchions and toprail, and have now refinished the cap rails. Some of the flat head machine screws we removed in the process are not reusable. I cannot find anything like them anywhere! They appear to be 5/16" diameter, but not quite; or #8 metric, but not quite. Neither of those sizes (new) will sit flush in the stanchion base plate b/c the heads are far too large, nor will they fit the threads on the tapped plate under the cap rail. The original screws are 1-1/2" long, brass or bronze. They are definitely NOT standard (at least, anymore), and custom made replacements are $7.75 each (OK) and require a 4-week lead time (not OK). Alternatively, I could have all the stanchions re-bored, the cap rail holes re-drilled, and the inside plates re-tapped. I would much rather find the darned machine screws! Where did these odd fasteners come from? More importantly, how can I get some?

Click to expand...

While working on my boat, i decided to change hull zincs. One of the mounting bolts appeared bent and the nut mis threaded. I took the bolt to a place specializing in bolts and learned that the old one was something called brush standard, which the company could not match.

Gordon

Greetings,
Mr. FF. Thanks. I was unaware of the "manufacturing/finishing" process. That being said, one would think that a home finisher would source commonly available fasteners. Even today, metrics, for example, are not all that common. More readily available to be sure but you have to look for them.

Perish the thought that some bozo actually used Whitworth nuts and bolts although it's not out of the realm of possibility... https://en.wikipedia.org/wiki/British_Standard_Whitworth

Mr. GJ. Could brush standard be British Standard?

My heading should have read British standard... Not brush.

Gordon

Back when the Bristols were built owners frequently "worked up" in size to a larger vessel.

So many folks had a "20 year box" of goodies from past adventures to use.

Unlike today where a credit line will put a newby in a 60 ft bucket.

Happily world trade is reducing the number of fasteners, Metric will probably win over the coming decades.

Many bolts on my Albin are a British standard something or other.....

No known sore for all sizes...someone might have the source (British car enthusiast in NY state)....don't have it in this computer.

My suggestion is to figure out how to convert to standard.....you have and will probably have spent more time searching than just bite the bullet and convert.

Used to deal with BST stuff once in a while back in the days when I worked in a friends body shop. He had lots of older Britsh cars.

http://www.metricmcc.com/catalog/ch10/10-1008.pdf

RT Firefly said:

. . . . There HAS to be something that readily fits.

. . . . attempts at re-tapping could be a quick journey to hell IF the nut starts spinning

Click to expand...

I'm with RT on both counts.

And: If the countersunk head is too large, don't file down the edge, it won't help; the face will still stand proud of the stanchion base-plate. Use a countersink bit in an electric drill to deepen the recess.

I strongly recommend using a pillar-drill, and always clamp the workpiece. Never hold it by hand - it doesn't work and the blood gets everywhere!

Regarding BSW screw sizes

Comment is these locomotive 19th century bolt sizes you may be able to use UNC bolts as they will fit.

https://www.britishfasteners.com/threads/bsw.html

British Standard Whitworth (BSW)

These are the original, 19th Century, coarse-threaded industrial bolts designed to hold locomotives together. Because of their coarse pitch, they are more prone to vibrating loose, so are little used on motorcars. Except for threading into aluminum (e.g. crankcase studs), where a coarse thread is less prone to stripping than a fine one. It turns out that, except for 1/2" (where the British use 12 threads per inch (tpi) and Americans use 13 tpi) the thread pitches for the rest are the same as for American Unified Coarse (UNC). However, the thread form is different; Whitworth = 55 degrees; UNC = 60 degrees. In spite of this, mismatched nuts and bolts mate nicely, so you're likely to find UNC bolts or studs where BSW should have been.

Then there exists BSF thread, which is just more TPI.

If this is BSF, then just retap if you can do so. I would retap every one of those suckers.

Since they should fit regardless British thread to UNC thread, and they do not as you have said, then likely you do not have British Standard Whitworth bolts.

The origin of this boat was India, but I don't know which parts were completed there. If it was one of the owner completed boats, it seems to me that it would be just as likely to include OTS parts. I guess I have been assuming that they used to make these machine screws and something changed such that they aren't made anymore. I hope I am wrong about that.

OK, I am chasing the BSW lead....the literature even mentions that they used smaller heads. And India = England in terms of manufacturing, right? Give me some hope!