Tiffen Arms to Pro Socket Blocks

[Ryan Toussieng]

Hey everyone! A little piece of info that maybe some other up and comers like myself should know... I'm sure it's floating around deep in the forum somewhere

 

Tiffen arms have some play (about a full 1/2 inch) in the pro socket blocks to the point where you can not use them with your Pro Vest unless you have a Tiffen socket block. O'Shea and I stumbled upon this little discovery yesterday. Could have been a disaster discovering this on a job...

 

Does anybody know why this is? Very interesting. And is there any way to keep the Pro socket block on the Pro vest and use a Tiffen arm?

 

Hope everyone is doing well! Cheers

Edited July 15, 2015 by Ryan Toussieng

[Victor Lazaro]

Jerry Holway mentioned it during the SOA workshop last year and Mike O'Shea told me about it a few days ago. The PRO socket Bloch is a bit too tight (by a micron) so the socket block pin won't fit all the way in. No other option than switching to a Tiffen block.

[Ryan Toussieng]

and Mike O'Shea told me about it a few days ago.

He told me about you two figuring it out! Funny, he was asking if we knew each other. Greetings!

 

It's something I really gave no thought to, glad I'm informed now before I invest in an arm. I thought that might be the case, something we really can't finagle with the block. Oh well!

[Jens Piotrowski SOC]

"about a full half inch" ???

 

that doesn't make any sense, sorry.

 

Different manufacturers have different tolerances, that is normal. Ask the manufacturers before the purchase to avoid headaches later.

[Victor Lazaro]

I think he means the the pin gets stuck about 1/2 in into the socket block.

It's definitely a tolerance thing as some blocks are working and others not.

Changing the socket block is just a matter of turning 8 screws.

[Ryan Toussieng]

A possible over exaggeration on my part, but it's close. Let's call it a quarter inch!

The hole on the Pro socket block where the pin on a Tiffen arm goes through is tighter at the end, not allowing a smooth fit. The threads on the socket block screws don't even get close to the lip of the arms block. I was pretty shocked, seems like an issue for most Pro socket blocks since they squeeze at the end

Edited July 15, 2015 by Ryan Toussieng

[Jess Haas SOC]

Switching the vest socket block is easy, or you can sand down the pin on the tiffen arm.

[Brian Freesh]

Yes, longstanding issue. I sanded down my Master Arm pin 5 years ago, has fit in my Pro vest ever since. I occasionally check the pin to make sure it's not rusting, as that's supposed to be mild steel under the stainless I sanded away, but I've never seen anything of concern.

[Robert Starling SOC]

It is a very minimal amount of sanding on the pin, just take your time.

[Alec Jarnagin SOC]

Yes, long standing issue that stems from the lack of tolerances in the early CP days. What ever male socket block PRO would have measured back in the day that become their blueprint was undersized (we are talking 100th on an inch maybe - not a half inch) and that became their standard. Meanwhile when Tiffen took over form CP and became more serious about standards, they must have measured a male socket block on the larger size and that became their standard. How to fix it? File your male (arm) socket block down a tiny bit or replace your female (vest) socket block with another (standard hole pattern).

[Afton Grant]

For $60, my local machinist took a couple thousandths off of the female side of the socket block. Sanding down the arm pin will work, but then you're only able to use that specific male socket block with your vest. If you find yourself using a different arm for whatever reason someday, you'll be back at square one (assuming it's Tiffen also). Shaving a little bit off of your male pin is a silly religious tradition anyway.

[Ryan Toussieng]

All good things guys, thanks! I thought that might be the only way to make it work. I'll take the easy road... Swapping the socket block!

[Victor Lazaro]

Afton, who is your machinist?

[Alec Jarnagin SOC]

Good points Afton. I'd be carful about shaving any socket block (male or female) if it is Titanium though. Since back mount vests have become popular though, less and less people seem to be making them from this.

[Jerry Holway]

Alec-

 

I did a little research on the socket blocks, and, for the record, it wasn't "sloppy tolerances" that caused the issue. The two parts, male and female, have been essentially the same since 1986. Tolerances were, and are still are, +/- .0005 for both the pins and the holes.

 

In October1986, the nominal diameters of the pins and the holes were increased .001.

 

So perhaps PRO had an old pin from a pre 1986 arm that they measured which was worn. Who knows?

 

Regardless, the solution we use at the workshops is to temporarily swap the PRO female socket blocks out for Tiffen ones, and then everything fits.