Saturday, 22 November 2008

DIY PocketWizard Holder

After being inspired by Rui M Leal's PW holder I was always looking to replicate this for my own Manfrotto 026 umbrella adaptor.

However, getting the items for the mod wasn't as easy as I thought (not in the UK anyway) - the usual places (such as B&Q, Wickes etc) will simply not have the correct screws and nuts. And this is where its important.

All the screw threads on the PocketWizard (as most photo gear) conform to 1/4-20 UNC. Say what now? For our purposes, all we need to know is that the screws we need will have to be 1/4" in diameter AND have to be confirm to UNC; for the 1/4" diameter, UNC requires that there be 20 threads per inch (TPI).. you may see ppl quoting 1/4" UNC or 1/4-20 or 1/4-20 UNC but as far as I understand they are the same thing.

See wikipedia for better explaination of this rambling. In the UK, the 1/4" diamater screws/wing nuts will most likely be M6 which won't be compatible with 1/4" UNC screw threads which have a thread angle of 60 degrees.

FWIW, I got my UNC screws/wing nuts/bolts from these guys based in the UK. If there find alternative suppliers, let me know.

Note, in the UK, there are 1/4" Whitworth (BSW) which also screw into a UNC threaded socket. However, 1/4" Whitworth have a 55 degree thread angle. This may not appear significant but the difference in the thread angle means that the load and stress is transferred different resulting in a considerable loss of holding force, fatigue resistance and strength will result - i.e. possibly unscrewing and seperation.

Now, back to the science. For the PW holder I used the following:

  • 1 x 1/4 UNC x 1" Socket Setscrew Cup Point
  • 1 x 1/4 UNC Wing Nut
  • 1 x 1/4" metal washer (not UNC)
  • 2 x 5/16" metal washers (not UNC)
  • 1 x 1/4 UNC Thin nut
  • 1 x 4" plastic strip (2x 1/4" bottom holes are for PW, 1x 5/16" top hole for umbrella adaptor)
All metal objects were from the UK supplier mentioned above. Click through the image for identification of each peice.

This differs from Rui's mod as he suggests replacing the screw (see Rui's picture below) that controls tilt on the umbrella adaptor - I didn't bother.

I did actually order a 5/16 UNC screw but found that it didn't screw into the handle correctly so I went with the original screw. To make sure that grip was still going to be ok, I used the 2x 5/16" washers (see later).

The next thing that is required is the actual holder - the thing that will connect the umbrella adaptor to the PW. This was also a little painful.

Rui had used some (exotic?) plastic corner furniture connector, but I tried looking in the usual places again but found nothing suitable - everything was either heavy or/and expensive (sorry, you want how much [2.95GBP] for 4" flat piece of metal?!?). I did source some aluminium strips but I would not recommend them either as they are difficult to shape and I found that they had a nasty habit of cutting my hands.

In the end, I found some cheap (very cheap!) plastic curtain tracks. These were perfect as they were reasonable strong, flexible, easy to shape and lightweight (and also didn't cut huge chunks out of my hands). I was able to cut a 4" strip using sciscors and then cut off the tracks on the back using a craft knife, resulting in a flat plastic strip. I also rounded off the ends so when attached to the umbrella adaptor the position of the PW holder could be rotated without catching.

Next up was some drilling. Make sure you measure the drill bits against the intended holes - you need a 1/4" (drill bit size #7) for attaching the PW and a 5/16" (drill bit size #8) to attach to the Manfrotto umbrella adaptor (other brands may have different requirement)

And that was that.. all done! All thats left is to put everything together.

The 2x 5/16" washers go on either side of the plastic strip (any length between 3-4.5" is good) as we attach it to the umbrella adaptor.

The 1/4" UNC wing nut and 1/4" washer sit on one side of the plastic strip, held via the 1" 1/4 UNC socket setscrew cup, as the PW will sit on the other side.

The remaining 1/4" UNC thin nut is used in place of PW to ensure we don't lose anything whilst in transit and can be attached next to the wing nut when the PW is mounted.

Click through the image for notes on the flickr page or here for larger image.

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