Cage for the Samurai

[George Odell]

Hello to all and Happy Holidays.

Before Christmas, on the Atomos.com web site's open forum, I posted my ideas for creating a "cage" for my Samurai to incorporate standard size BNC connectors, balanced XLR inputs, connections for external power... the whole nine yards. Even posted a picture of a "first thoughts" cage using an old Tektronics waveform monitor case.

My posting was deleted by Atomos and my posting permission revoked with no reason as to why this was done. Hopefully this will not happen here.

I have some ideas and I will gladly share them with others via this forum if there is any interest out there.

Is there?

[George Odell]

Update 1/30/13:

Well, Atomos really did us a major disservice by using not only mini BNC's for the Samurai SDI connections but they went so far as to use non-standard mini BNC's to boot!

Mini BNC connectors, while not that well known do exist from major high-end connector manufactures such as Amphenol. They can be had in straight and right angle male-type plugs quite easily from many US suppliers.

The problem is they do not fit the Samurai. They are still too big, if you can believe that. The Amphenol mini BNC has an outer diameter at the locking ring of 11mm. The Atomos version is 9mm.

That leaves us with having to use the cables supplied to us by Atomos. I have not given up hope of locating these connectors but for the time being will have to purchase them from Atomos. They offer them with a right angle mini BNC ($40 for the pair) which is much "safer" than using the straight ones that came with the kit.

[George Odell]

Have worked out the preliminary drawings for the Samurai cage. These should be quite close to the actual dimensions with only slight variations when I start to lay out the sections for real. To view this drawing left click on the image itself and it will expand.

http://www.webtfg.com/cagecomp.jpg

Basically, it works like this.

There is an additional heat sink plate that is to be affixed to the top of the existing Samurai casing. This will work to reduce the heat now generated by the unit when operating. In my opinion, the unit gets way too hot for its own good and the additional heat sink will work to reduce any possibility of damage under extended periods of use. In addition, the cage itself will be acting as a heat sink and will further work to pass off excess heat to the surrounding air.

At the top of the casing there is a knob with 3/4" long a 1/4 x 20 threaded rod. This will pass through the top 1/4" plate, through the heat sink and into the top of the existing hole on the Samurai. This works to do two things. It locks the unit to the casing when in use and it allows the user to swivel the Samurai's left side back just enough so the hard drive/SSD drive can be removed.

On the left side there are two blocks that each hold female XLR connectors. One for left line in and one for the right line in. Inside the blocks are transformers to take balanced feeds from a mixer and convert them to drive the unbalanced inputs on the Samurai.

Since I will mostly use the Samurai running off external power from my Anton Bauer camera bricks I will be using the "fake" battery case with D tap at the top in position #1. I can still remove the adapter and use a single battery if need be. I have still to locate the DC connector on the cage.

The 1/8" side plates are bolted to the 1/4" top and bottom plates in two places.

There is also a stereo 1/8" phone jack near the bottom for the headphones to connect to.

At the back and facing down are two standard size BNC jacks for SDI in and SDI out.

I plan to provide 1/4 x 20 mounting holes in the top and bottom plates but will wait until I have the unit roughly assembled so I can determine where the center of gravity will be.

[Craig Chartier]

Interesting design. I would put as many 1/4-20 and 3/8-16 treaded holes in the box as you can stand to do. even some non threaded holes would be nice for passive mounting of "X" in the future. it will also help with air circulation. Heat sinks are a great idea, but hot air needs to rise out. Use brass all thread for your swivel point lock as well to prevent insert thread damage. You could even mount a cooling fan that would drive off the AB battery?? for when your not recording.

[George Odell]

I would put as many 1/4-20 and 3/8-16 threaded holes in the box as you can stand to do. even some non threaded holes would be nice for passive mounting of "X" in the future. it will also help with air circulation...

Yes, agree. Good idea. Will also help to reduce the casing's weight.

Also plan to black anodize this on my own. Not that hard to do, really.
Shops around here have huge minimums.

[George Odell]

Been testing out several of these in-line XLR matching/balancing transformers in the hopes of finding one good enough to use with the Samurai cage.

Have tested Radio Shack, Switchcraft, Hosa and Whirwind. The lower end Radio Shack and Hosa rolled way off below around 500 cycles per second. Right where you need the low end most for male human voices. Not that great above around 14,000 cycles per second either.

The Switchcraft 9182, a discontinued product from this fine company, was vastly superior. It offered a high gain pass through together with very decent frequency response. But, since I cannot find them it makes no difference.

That leaves Whirwind. A very respected audio products company here in the US. I'm testing with their ISOXL isolation transformer since I have one in my audio kit. Extremely flat response from around 60 to well over 20,000 cycles per second. Even below 60 the drop off is minor.

These sell for $40 or more so I'm hoping Whirlind will offer to sell me the transformer as a spare part and save me some $$. Either way I will go with a pair of these. They will fit inside the steel barrel of the female XLR with some slight enlarging of the inside diameter on a lathe.

[George Odell]

Update: 1/3/14

Received the Atomos right angle mini BNC cables today.

One is 14" (35.5cm) long and the other is 26" (66.cm) long. Both terminate in standard size female BNC connectors. Both of which will be cut off and soldered direct to chassis mount female BNC jacks on the bottom of the cage.

http://www.webtfg.com/rtbncs.jpg

As you can see from the picture, they protrude much less form the side of the Samurai... little more than 1" vs 1.75" for the factory-supplied straight versions that come in the kit. Add in the cable before it can be safely bent down and it is more like 2.5".

Clearly the right angles are the way to go and should, IMHO, be part of the package.

Was pondering how I would be attaching the heat sink to the top of the Samurai. As it turns out 3M makes a special heat transfer double sided tape for just such a purpose. Not cheap but the nice folks at 3M will be sending me a generous free sample to test out. This heat transfer tape will insure the thermal bond between the Samurai's aluminum casing and the aluminum heat sink will be perfect without having to use that messy goop from days of old.

Thank you 3M!

[George Odell]

The construction begins...

Roughed out the cage yesterday. All four plates cut to size. Top has the Samurai mounting hole in place and the notch for the Anton Bauer D connector. This stock is from my junk pile of aluminum scraps. The top and bottom had black anodize and the sides... an old 19" rack cabinet plate... were painted black. All will be stripped off and re-anodized black when the machining is complete.

http://www.webtfg.com/roughcage.jpg

The heat sink for the Samurai is almost done save for adding the 1/4" hole to line up with the tapped version in the top of the unit. A knob with 1/4 x 20 thread will pass down and into that tapped mount to allow the Samurai to be swiveled out for removal/installation of the SSD or hard drive.

http://www.webtfg.com/heatsink.jpg

Special heat transfer double-sided tape, courtesy of 3M, will be used to secure the heat sink to the top of the unit.

Right now the cage and heat sink weight in at 20 ounces. That's before I "Swiss cheese" the cage with both tapped and clear through holes. Some for mounting whatever and all for air flow and to reduce the weight.

[George Odell]

Update: 1/13/13

More progress this weekend. This view shows the cage assembled temporarily with screws (will use black hex screws in the final version).

The heat sink is affixed to the top of the Samurai with tiny strips of carpet tape. After all the metal is anodized black the special heat transfer tape from 3M will be used. The 1/4 x 20 knob is in place and now mates up with the matching threads in the top of the Samurai. The right angle sub mini BNC's plugs can be seen on the left side.

http://www.webtfg.com/front.jpg

These side-by-side pictures show how the Samurai will swing towards the back on the left side allowing the hard drive or SSD to be reached for installation and removal.

http://www.webtfg.com/swing.jpg

Finally, the XLR blocks are mounted to the right side of the cage. Tilted down, they will contain standard size XLR female connectors for the line inputs as well as the balancing transformers. At the very bottom is the counter sunk mounting hole for the 1/8" head phone jack.

http://www.webtfg.com/xlr.jpg

Still more work to do. Need to locate the two BNC jacks on the rear of the bottom plate. Will also locate a mini 4-pin XLR jack in the same location for the DC input from an external battery source.

When all jacks have their spots I will "cheeze up" the remainder of the metal with clear through holes and a few threaded versions for additional mounting use in the future.

Thinking about running a second 1/4 x 20 bolt up from the base plate to meet with the hole on the bottom of the Samurai. Will give more stability when accessing the removable drive. Probably use a socket head screw recessed partially into the plate. A jam nut to secure it to the Samurai's socket so it does not unthread with the swinging.

BTW: Found an anodizing company in Texas, Dell's Plating, that will do the work of black anodizing the cage pieces for $65... their minimum rate. At that low charge it make no sense for me to try and do it myself and have to mess with sulfuric acid and all that. Besides, deep black is the hardest color to anodize.

[George Odell]

Update: 3/17/14

My apologies for letting this go so long without an update. Things have progressed a bit slowly so I could be sure I had added what was going to be needed before sending the plates out to be anodized. Basically, the final step before it got assembled.

I am providing two additions to the Cage. The first, I call it the called the Koby Plate, is detailed here. A friend of mine suggested adding support for a 15mm and/or 19mm rod system so the Samurai could be attached to the back of a fluid head dove plate. I have provided four 8-32 tapped holes in the bottom of the Cage. They are off center so as not to interfere with the BNC jacks and the DC power jack on the other side of the bottom panel.

http://www.dvinfo.net/forum/attachme...1&d=1395073151

A new block was machined out of .25" aluminum and holes provided to mate up with the tapped holes on the bottom panel. As you can see, this block fits the spacing between, in this case, a 19mm rod bracket. This will only be attached when there is a need to mount the Samurai on rods. It will be an option at the ready.

http://www.dvinfo.net/forum/attachme...1&d=1395073151

When I do have the need I will purchase one of these (from B&H Photo probably) and add two countersunk holes to this block to accommodate the tapped holes in the rod bracket.

http://www.dvinfo.net/forum/attachme...1&d=1395073333

I'm also thinking of adding an Anton Bauer battery bracket to the back of the Cage. Also on a plate that can be attached when needed. If the Samurai is being used off camera on a table for recording/playback or for client logging the A-B battery will provide power for as long as needed.

[George Odell]

Update: 3/31/14

All the machining is completed. I abandoned the idea of attaching an Anton Bauer battery to the back of the Cage after I realized there would not be enough room to swing back the Samurai to remove the drive. Anyway, it's easy enough to attach a cable either from a small AC adapter or AB battery.

http://www.dvinfo.net/forum/attachme...4&d=1396273516

All the paint and old anodizing has been removed and, now, it's off to the anodizing shop in Texas for a new deep black finish and a clear sealer coat.

The next update will show the finished Cage project fully wired and ready to go. It's been a trip making this but in the end I feel it will be well worth the effort.

Stay Tuned!