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Saturday, February 6, 2010

••◊ Custom movie making equipment, first attempts

I like to make stuff - always have. I recently saw a number of videos recorded on the 5Dm2 that used the Kessler Crane PocketDolly or Glidetrack Pro. For a lot of shots the one meter distance limitation seemed like just enough, but at $400 a pop it was out of the question to just buy as a toy to experiment with. However...I do have access to a machine shop and with a little engineering I figured I could make something suitably similar and good enough for my personal usage. As I'm writing this blog post I just found the Indifocus IndiSLIDER, which seems very similar in concept to my design.

Below is a picture of the resulting assembly; framed in CinemaScope (2.35:1) by the way. I have to say that the sled movement is very smooth; more so than I originally envisioned it would be. The design was a collaboration between my co-worker Josh (a mechanical engineer) and I. The best part...still have all of my fingers and can cross them for further good luck. Click on the picture to see the assembly in detail.

First off in the structure is the extruded Aluminum beam which was purchased from a hardware store. I machined end caps out of Delrin and bought rubber bumpers made for furniture to screw into the side caps as feet. The adjustable bumpers allow the track to sit flat on most semi-flat surfaces. I just found out that the coffee table pictured above isn't flat!

You may have noticed that at the center bottom of the beam there is a flat piece of metal. This piece has 3/8"-16 threading and allows me to attach the assembly to my tripod. I just tried it today and have to say that unfortunately my tripod is a little too weenie weight to hold the dolly steady. Time to buy a real video tripod I guess (no, I'm not going to attempt to make one).

The sled is made out of Delrin and aluminum. Josh recommended that we try Delrin over the conventional linear bearing design for cost reasons. Surprisingly, Delrin is silky smooth on an anodized surface and seems to slide nice and quiet on beam. What I didn't want is the typical linear bearing noise, although I think the Glidetrack/PocketDolly sleds are similarly quiet. I also designed in a quick release sled lock for obvious reasons. The lock handle was purchased at the same hardware store as the beam, thus the matching colors.

The time spent on this was a good investment in general. I now need to build some rails for my camera so I can mount a D-focus follow focus assembly. I also need to build a few more things, but only have so much time to give as it's still a hobby. This dolly is going into use later in the month with a dance production I'm going to DP.

Below is a very quick and dirty video showing the sled in operation with the lock down and a dolly move with my 5Dm2. I obviously need to practice, but this is my first time actually using the dolly. Not impressive, but it shows the concept.

So what was the damage for this bad boy. $39+tax. Yep, about 1/10th the price. This, of course, doesn't take into account my labor or cuts and bruises (no joke about those). Also, a lot of the sled and attachment materials were scraps just laying around the shop, so these items didn't figure into the cost.

Lots more to work on. Happy sledding.


Roberto said...

Could you tell me what sort of store do you usually find delrin? I'm having a hard time trying to find this in brazil.

Goes.2.Eleven said...

I have a machine shop with a "play pen" at work and so I was just grabbing delrin out of the scrap bin. I have no clue where to buy it, but I imagine there are plenty of places on the net to buy a slab of it.

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