Monday, July 23, 2012

Squeezers!


One of the most ubiquitous items I've encountered on sets are dimmers - or hand squeezers as they are also known. Used to knock down the intensity of tungsten fixtures, it's one of the strange tools in the electric department that have to be built - it's not something that is manufactured as a product by a single company and sold off the shelf at the average home improvement store.  The basic component is a rotary (or slider) dimmer mechanism like one would find on a living room wall. These are made to handle varying wattages - 600, 800, 1000, 1500, and 2000. The higher the wattages, the higher the price, and the more robust the mechanism.

Now, these dimmers are often sold by individuals or companies pre-assembled - the one pictured above for instance is sold by Filmtools - but at a high price, usually between $90 and $120, before shipping costs. This leads a lot of people - professionals and amateurs alike - to build their own. But the homemade ones I've come across, while practical, are hardly as sleek or robust - often using $1 galvanized steel components, blaze orange household extension cord for the "tails," etc -

Above: a 1k homemade dimmer - one of a pair I purchased on ebay for a pretty fair price, considering.

While these will do the job, and I've seen many a janky squeezer on gigs, it got me thinking - just how much would it cost to build your very own to the exact specifications of the sexy "$100 dimmer" in the first image?

Surprisingly, all my scouring the internet for answers turned up nothing about making your own professional dimmer in a clear, concise step by step fashion. You have a guy who makes a 600w dimmer for under $10 using a cheap plastic box and a non-grounded cable he happened to already have. You have this janky as all Hell and potentially dangerous instructional from your friends at IndyMogul. You have directions for wiring it directly to dual outlets within the same electrical box, and though admittedly there's some useful information there in regards to wiring, it doesn't offer the blow by blow nor the parts list I was looking for.

So I guess it's up to me.

Yes folks, for the first time on the internet (as far as I know) I'm gonna give a step by step on how to make a DIY 1K hand squeezer that will hold a candle to the prefabricated ones from Filmtools, Barndoor Lighting Outfitters, or your local G/E house.

Firstly, most of these prefabricated dimmers utilize as the main dimmer component either the Leviton "Van Gogh" style, or the Lutron "Centurion" line. These are heavier duty dimmers with huge heat sinks beneath the faceplate. They are differentiated from "residential" dimmers - which typically max out at 600w - by being branded as "commercial" or "architectural" dimmers.

Let's focus only on making a 1000w dimmer for the purposes of this post. So grab yourself a Leviton 61000-W or a Lutron C-1000. (Note: There are such things as "3-way" dimmers - which I made my first prototype dimmer with - it just results in a mess of extra wires, since the 3-way [simply put, this is so you can have more than one switch controlling the same light - your house may have this] functionality is completely moot for the purposes of this device.)

These dimmers run about $40-$45 new.

Step 2: The box. If you go to your local hardware store's electronics aisle, you will see bins full of ugly galvanized boxes with knockout holes, and cheap blue or grey molded plastic ones. What you want are the more robust, outdoor, weather resistant ones. They should be there too - Solid die-cast aluminum and painted grey (as a result, it might appear plastic at first). You want the Deep Single-Gang Box from Hubbell Electrical Products (Will be under the product family name of Bell Outdoor or Bell Weatherproof). Key word is DEEP. I've seen people use shallow ones, but in my experience you want to have plenty of room for the dimmer mechanism and all the wires. The standard boxes are 2" deep, while the deep one is 2 5/8."

You'll want the one with 3 holes, one in the bottom, and one at each of the narrow ends. Electrical boxes have several different standardized diameters for these holes, 1", 3/4", 1/2". 1/2" seems to be the standard for industry squeezers. As such, Part #5385-0 is you friend. This should cost $7-$8. It should come with plugs to seal the unused hole or holes. Seal the one at the bottom.

Step 3: Cable.
12/3 cable is the film industry standard. So it's what I used for the "tails." This stuff costs just over $1 per foot, and is usually purchasable by the foot at your local hardware store. I use 2 separate 1' lengths. Total cost: $2-$3.

Step 4: Male and Female Edison connectors.
Like these.  At my local hardware store, they price about $8-$9 for male connectors and $12-$13 for female connectors.

Step 5: Cable clamps/cable connectors/cord grips.
These are the nubs sticking out of the side of the box in the first photo, holding the tails in place and sealing the holes. You buy these based on the diameter of the threaded hole in the box you purchased in step one (1/2" in this case) These were a bit trickier to find, and it took some trial and error before I found the ideal part. The ones they sell at my local hardware store are these fool things.

No, no, no, my friend. You want the dimmer box to be as airtight as possible to prevent dirt and moisture from getting in.

What you want, and what those $100 squeezers use are Heyco liquid tight cordgrips. You'll want one specifically for the 1/2" threaded holes in your gang box. That gives you about 4 options (click the specifications tab in the previous link to see the different choices). Within those 4 are different ranges of cable diameters the connectors can handle. Fortunately, I had a pair of calipers handy that told me my 12/3 cable was about 0.4" wide. With that, I can deduce that part #M3231 seems optimal, opening at it's widest to just over my cable diameter, with the ability to tighten down far enough to ensure a secure fit. These cost about $1 each and come in packs of ten on Amazon. Total cost for a single dimmer box: $2.

This means to build your own, with all new parts, you'll spend only $71-$80!!!

HOORAY! YOU'LL SAVE A WHOPPING TWenty dollars....

Wait a second. What I didn't tell you is you don't have to buy retail!

EBAY IS YOUR FRIEND. Those $40 dimmers can go for as low as $20 shipped, and a few weeks ago I bought 20 feet of 12/3 for about $15. Those Edison connectors, when purchased in bulk lots of 5 to 10 or more can come down to about $4 or $5 per connector.  Congrats, you just built a sleek industry standard 1000w dimmer for $45! Less than half the cost of buying a prefabricated one.

By shopping on ebay and buying bulk when I could, I now have the materials to build 6 of these dimmers at a lower cost per dimmer.


***

Now that you have all the components, you might want a quick run through on the assembly and wiring! PLEASE NOTE, I am hardly an experienced electrician, but this is what worked for me...

First, take the box, screw the cordgrips into the pre-threaded end holes.

Second, take each of your 1' lengths of 12/3 cable and pass one through each of the box's holes. Strip 2" of the outermost insulation off the ends that will be inside the box. This should reveal the three colors of wires inside - green, white, and black. Strip each of these individual colored wires about .5".

Within the box, connect the white ends of one cable to the white ends of the other with a wirenut. Do the same with the green ends.

Get the dimmer unit. If it's a single-pole unit it should just have 2 black wires, already stripped. I know for sure that's how the Leviton units are. Lutron units have the addition of a green ground wire. The ground will be connected to the grounding screw built into the gang box. Connect the black wires of each cable to one of the black wires of the dimmer unit. It doesn't matter which goes to which.

Close up the box: push all the wires down and fasten the dimmer unit over the top of the box with the provided screws. Pull the "tails" so there is not excessive slack inside the box. Tighten down those cordgrips with a crescent wrench.

Attach the Edison plugs to the other cable ends like so.

Yay. You're done!

Test and use only with tungsten or halogen lights.

Above: Done!

Note #1 - since I was on a mission for the best deals, I used a gang box with 3/4" openings and the appropriate cordgrips. This was also a 3-way dimmer unit which was a little more complex to wire.

Note #2 - A lot of people are selling these little units online claiming them to be 1000w dimmers. They are not. They are what's known as router speed controls. A router being a woodworking tool. While it does indeed dim lights, and you will find its fans (I saw one of these being used on a professional set to dim practicals), in my experience they do not have butter smooth action, do not dim completely off, can result in flickering, overheat after an extended period of time, and create a hum that will drive your sound guy crazy. Also the people selling them as dimmers are asking upwards of $35 for them. If you really want to go this route, then at least save your money, and pop on over to Harbor Freight Tools and pick it up for $20.

2 comments:

  1. Thanks for the guide. Might make one after I get a good gig.

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  2. Hey, Thanks for this guide. I just made one of these last week but I wish I would have seen this page first. I went with the double gang box with 1/2' openings and just have a dimmer and an outlet on the front. I did use a pretty hefty grounded tail. X-MAS tree was way too bright. Wish I was building this for a show... that would rock.

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