Best 1/4" to 3/8" adapter?

[Greg]

The best is the LInhof brass one.

Found two Arca-Swiss 8mm 3/8"-16 to 1/4"-20 adapters that I had bought years ago, never used (still in original packaging), but stored and forgot about. They look to be a lot, I mean a lot better than my 4mm generic brass bushings that I just didn't trust to do the job. Also looks to me that there are different hardnesses of brass out there? Arca-Swiss quality and machining has to be akin to Linhof's from what I can tell. Ended up throwing away a couple of them that were between 4-5mm in "height".
Thanks to everyone who posted...

[Drew Wiley]

There's brass, and then there's brass. It's not all the same. Some types machine well and are relatively durable, some are not. Linhof is very familiar with the reason for using die-cast alloys, as would be most Euro manufacturers. Generic substitutes made in China, well, you take your chances; they might even be zinc "pot metal".

[reddesert]

Brass is a good material for this kind of application because it is resistant to galling. Brass typically has good machinability and ductility, which is why it is resistant to galling, and why it is often used for bushings, etc. Obviously there are many different types of brass alloys, but these are applicable to most. Compared to other materials, brass is for example weaker than steel and heavier than aluminum, but this is an application where maximum material strength isn't as critical, *if* you screw enough threads into the adapter. Sometimes, even the tripod screw itself appears to be made of a brass or bronze. I'm sure the number of threads and the quality of the machining matter.

[Tin Can]

Bob, I often buy from reputation

I will buy a $30 Linhoff just to test it

I have been using Wimberley BS-100 3/8"-16 to 1/4"-20 Brass Reducer Bushing $4

Arca-Swiss Adapter Screw 8mm 3/8"-16 to 1/4"-20 Reducer Bushing $10

The best is the LInhof brass one.

I really like the Latest, perhaps old Deardorff method that adapts from inside the camera

I have chipped broken diecast crap out after it broke

I vastly prefer to switch the tripod male screw

The best design and adjust for length are the Majestic screws, also spring loaded popup and long enough even for a KMV

I bought the last 2 inventoried Majestic at the last warehouse from the last owner by telephone, not that long ago

in box

[Greg]

Found two Arca-Swiss 8mm 3/8"-16 to 1/4"-20 adapters that I had bought years ago, never used (still in original packaging), but stored and forgot about. They look to be a lot, I mean a lot better than my 4mm generic brass bushings that I just didn't trust to do the job. Also looks to me that there are different hardnesses of brass out there? Arca-Swiss quality and machining has to be akin to Linhof's from what I can tell. Ended up throwing away a couple of them that were between 4-5mm in "height".
Thanks to everyone who posted...

Available from B&H: Arca-Swiss Adapter Screw 8mm 3/8"-16 to 1/4"-20 Reducer Bushing BH #ARB.2538 • MFR #809011
Just ordered 2 spares.

[Drew Wiley]

I think that if Linhof sold you their bushing in a paper bag they'd charge you an extra $30 for the bag itself if their own name and logo was on it. I have no idea what the distribution markup is, other than ridiculous, but it's hard to imagine that something like the bushing in question originally cost more than fifty cents to make, no matter how allegedly good.

Tin Can - you are obviously using the terms "diecast" in a very different manner from me. I've sold literally tons of the real deal. It's an entirely different kind of brass alloy especially high in copper content, and the billets are put under extreme pressure to force out all the voids and impurities. It's very strong stuff and machines well, but is not equal to most bronze alloys. Much the the brass gearing and hardware I've personally seen on field cameras is actually a very inferior kind of brass. And most of the hardware store style reducing inserts are more in the "basement of junk" classification rather than marginally respectable ground floor junk itself.

[RivetGun]

For what it is worth silicone bronze is stronger than brass and the threads will last longer. It is sometimes used in threaded machine tool carriages.

The main thing with threads (or bushings supporting rotating shafts) is to use different types of metal or different hardness. In other words aluminum on aluminum or stainless on stainless or very hard steel on very hard steel will quickly destroy each other. Aluminum on stainless will last a long time.

[Bernice Loui]

There are various grades of bronze from silicon to zinc to marine specific bronze to bearing bronze. Majority of them are higher strength than brass.

Aluminum alloys can be higher strength than brass (7xxx series and others)
Aluminum on Stainless steel is a recipe for galvanic corrosion that can wreck havoc on the parts involved.

Fact is, these thread adapters are not that highly stressed making common yellow brass more than good enough for the stress they are will be subjected to in service. That said, Aluminum is a gosh awful material for threads. It has a fabulous tendency to gall, has an ill-defined yield point or where it begins to bend-stretch-give is variable and not well defined. High strength Aluminum alloys tend to be brittle with a similar fondness for galling.

Stainless steel is available in a variety of types, some are not as high strength or corrosion resistant than is believed, other grades of stainless steel are magnetic (4xx series), some are not. Some are extremely corrosion resistant (316, 321 and related), some are far less so.

There plenty of exotic alloys that far exceed the application demands for any 3/8-16" to 1/4"-20 tpi adapter, reality is, these exotic materials cannot make a technically proper justification for their usage in this application.


Bernice

For what it is worth silicone bronze is stronger than brass and the threads will last longer. It is sometimes used in threaded machine tool carriages.

The main thing with threads (or bushings supporting rotating shafts) is to use different types of metal or different hardness. In other words aluminum on aluminum or stainless on stainless or very hard steel on very hard steel will quickly destroy each other. Aluminum on stainless will last a long time.

[Drew Wiley]

One simply does not want something especially hard or strong. The whole point is that if something gives over time, it should be the insert device itself rather than the primary thread. Same goes for cable release materials, filter ring material etc. But the alloy does need to be consistent and reliable. Cost has damn little to do with it. Machinability does. Visit any marine supplier and see how much people are willing to spend on even a tiny silicon-bronze tie cleat. I have one on each leg of my Ries tripod for hanging the light meter, loupe, etc. I once managed the biggest selection of forged bronze and brass hardware on the West Coast, plus a lot of stainless too. Single sales tabs in the twenty to forty thousand dollar range were routine. A past era - now most items are melt-cast junk alloy instead.

[BrianShaw]

Wiser words have rarely been written:

“ Fact is, these thread adapters are not that highly stressed making common yellow brass more than good enough for the stress they are will be subjected to in service. ”

I think all that I use are stainless but that’s only because they were cheap and easy to source.

Why over-think this????